Next Article in Journal
Evaluation of the Physiological Host Range for the Parasitoid Ooencyrtus mirus, a Potential Biocontrol Agent of Bagrada hilaris
Next Article in Special Issue
Current Distribution and Diagnostic Features of Two Potentially Invasive Asian Buprestid Species: Agrilus mali Matsumura and A. fleischeri Obenberger (Coleoptera: Buprestidae)
Previous Article in Journal
Parasitism of Locally Recruited Egg Parasitoids of the Fall Armyworm in Africa
Previous Article in Special Issue
Minimum Winter Temperature as a Limiting Factor of the Potential Spread of Agrilus planipennis, an Alien Pest of Ash Trees, in Europe
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Insects
Volume 11
Issue 7
10.3390/insects11070431
insects-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Comparative Toxicity of Helicoverpa armigera and Helicoverpa zea (Lepidoptera: Noctuidae) to Selected Insecticides

by
Fernando R. da Silva
1,2,
Dario Trujillo
2,
Oderlei Bernardi
3,
Jose Carlos Verle Rodrigues
2,
Woodward D. Bailey
4,
Todd M. Gilligan
5 and
Daniel Carrillo
1,*
1
Tropical Research and Education Center, University of Florida, 18905 SW 280th, St. Homestead, FL 33031, USA
2
Center for Excellence in Quarantine & Invasive Species, University of Puerto Rico (UPR), San Juan, PR 00926-1118, USA
3
Department of Plant Protection, Federal University of Santa Maria, CCR-Building 42-Room 3233, Campus-Camobi, Santa Maria 9710590, RS, Brazil
4
United States Department of Agriculture, Animal and Plant Health Inspection Service, Plant Protection and Quarantine, Science and Technology, Miami, FL 33158, USA
5
United States Department of Agriculture, Animal and Plant Health Inspection Service, Plant Protection and Quarantine, Science and Technology, Fort Collins, CO 80526, USA
*
Author to whom correspondence should be addressed.
Insects 2020, 11(7), 431; https://doi.org/10.3390/insects11070431
Submission received: 10 June 2020 / Revised: 24 June 2020 / Accepted: 7 July 2020 / Published: 10 July 2020
(This article belongs to the Special Issue Invasive Arthropod Pests)
Versions Notes

Abstract

:
Until recently, the Old World bollworm (OWB) Helicoverpa armigera (Hübner) and the corn earworm Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) were geographically isolated. Both species are major pests of agricultural commodities that are known to develop insecticide resistance, and they now coexist in areas where H. armigera invaded the Americas. This is the first study to compare the susceptibility of the two species to conventional insecticides. The susceptibility of third instar H. armigera and H. zea larvae to indoxacarb, methomyl, spinetoram, and spinosad was determined using a diet-overlay bioassay in a quarantine laboratory in Puerto Rico. Mortality was assessed at 48 h after exposure for up to eight concentrations per insecticide. Spinetoram exhibited the highest acute toxicity against H. armigera, with a median lethal concentration (LC50) of 0.11 µg a.i./cm2, followed by indoxacarb and spinosad (0.17 µg a.i./cm2 for both) and methomyl (0.32 µg a.i./cm2). Spinetoram was also the most toxic to H. zea (LC50 of 0.08 µg a.i./cm2), followed by spinosad (0.17 µg a.i./cm2) and methomyl (0.18 µg a.i./cm2). Indoxacarb was the least toxic to H. zea, with an LC50 of 0.21 µg a.i./cm2. These findings could serve as a comparative reference for monitoring the susceptibility of H. armigera and H. zea to indoxacarb, methomyl, spinetoram, and spinosad in Puerto Rico, and may facilitate the detection of field-selected resistance for these two species and their potential hybrids in areas recently invaded by H. armigera.

1. Introduction

The noctuid moths Old World bollworm (OWB), Helicoverpa armigera (Hübner, 1809) and corn earworm, Helicoverpa zea (Boddie, 1850), are major lepidopteran pests attacking crops worldwide. The latter is restricted to the New World and attacks more than 120 host species in 29 plant families [1,2,3,4]. Helicoverpa armigera feeds on more than 180 hosts in 70 plant families, and it is widely distributed in Europe, Africa, Asia, and Oceania [5,6,7,8,9]. It was first reported in the New World in 2013, infesting soybean and cotton fields in Brazil [10]; a year later, it was detected in Argentina and Puerto Rico [11,12]. The two species have similar external morphologies, and their identification requires the labor-intensive dissection of male genitalia and/or molecular analysis [13,14,15]. Surveys in Puerto Rico revealed low H. armigera population densities in areas where H. zea is found, suggesting that it is still in an early stage of invasion. A phylogenetic analysis using the cytochrome b (Cytb) region determined that H. armigera from Puerto Rico has two haplotypes. One of these is the second most frequently found worldwide, the other is only present in the north western region of Brazil, suggesting that the population in Puerto Rico may have originated in South America [16].
The larvae of both Helicoverpa species commonly feed on the reproductive tissue of their host plants [17]. The last instar of H. armigera can account for more than 85% of the total damage caused by the larval stage on cotton [18,19]. In the U.S.A., H. zea attacks more than 30 crops, and it is considered one of the most injurious pests of tomato, corn, and cotton, contributing to recurring losses of around one billion USD per year [20,21,22,23,24]. Even higher annual losses are attributed to H. armigera, estimated at 5 billion USD worldwide [19,25,26]. Approximately 50% of the total insecticides applied in India and China are used to control H. armigera [27]; in Brazil, its damage was estimated at 2 billion USD during the 2012/2013 season [28].
H. armigera and H. zea utilize similar resources and ecological niches [29,30]. Recent studies have suggested that H. zea derived from H. armigera and lost genes related to detoxification [31,32], as well as certain genes that confer resistance to insecticides [33,34,35,36,37]. However, the two species can mate with each other and produce fertile progeny that may have resistance levels that are unlike those of the parental species [36,38,39]. Wild hybrids of H. armigera and H. zea have been reported in Brazil [39], and a few individuals were detected in Puerto Rico in 2014/2015 that are presumed to be hybrids based on molecular analysis (Gilligan, T.M.; unpublished).
These species have exhibited reduced susceptibility to groups of insecticides, including carbamates, organophosphates, pyrethroids, and Bacillus thuringiensis proteins. The unsatisfactory control of H. armigera with the pyrethroids deltamethrin, cypermethrin and fenvalerate was reported in Brazil [37,40]. Previous studies have also reported a high resistance frequency to pyrethroids in Australian populations [41]. Reports of pyrethroid resistance in H. zea started in the early 1990’s [42,43]. Consequently, insect resistance management (IRM) programs have been adopted around the world to delay or prevent resistance development in these two species.
Potential changes in the susceptibility of H. armigera and H. zea to conventional insecticides represent a major threat to agriculture in areas with established populations of these species and their potential hybrids. Hence, it is important to develop susceptibility tests and monitor changes in resistant ratios on target populations for these two species. This study compared the susceptibility of a population of H. armigera from Brazil, the presumed epicenter of the infestation in South America, and a population of H. zea from Puerto Rico to four commercial insecticides. Our study aimed to support proactive integrated pest management programs in Puerto Rico and other areas recently invaded by H. armigera.

2. Materials and Methods

2.1. Insect Populations

The H. armigera colony was established with five larvae and 30 pupae from a laboratory population maintained at the University of São Paulo, Piracicaba, SP, Brazil. This population was originally collected from soybean in Mato Grosso, Brazil, and maintained in the laboratory for five generations before being shipped to the quarantine facility at the Center for Excellence in Quarantine and Invasive Species (CEQIS) in Puerto Rico on the 4 February 2017 (Puerto Rico Department of Agriculture permit number OV-1617–03 and United States Department of Agriculture, Animal and Plant Health Inspection Service permit number P526P-15-04600). No information is available on the previous exposure of this population to insecticides.
The H. zea colony was started with larvae collected in Isabela, Puerto Rico, on unsprayed pigeon pea on the 11 November 2015 (18°0′34′′ S; 66°53′33′′ W), and it was replenished multiple times with additional specimens collected from corn in the same area to maintain colony vigor. There are no large row crop operations in this area of Puerto Rico, and the H. zea individuals were collected from unsprayed experimental plots at the University of Puerto Rico—Isabela Agricultural Experimental Station.

2.2. Species Confirmation

Morphological and molecular tools (real-time PCR analysis) were used to determine species. Male genitalia were extracted and analyzed following the methods described by Brambila [44]. Males and females of both Helicoverpa species were identified by real-time PCR with specific primers for the internal transcribed spacer 1 (ITS1) region, as well as the sequencing of cytochrome c oxidase subunit I (COI) and Cytb regions [14]. Both populations were maintained at the CEQIS and were shared with other laboratories to be used as a reference for future studies and screening of other populations.

2.3. Rearing Procedure

Larvae were reared individually in 30 mL transparent plastic cups containing an artificial moth diet (Frontier Agricultural Sciences, Product # F9630B, Newark, DE, USA) until pupation. Pupae were transferred to Petri dishes with autoclaved vermiculite (Vigoro®, Lake Forest, IL, USA). One day before adult emergence, pupae were placed in white 5-gallon (19 L) plastic buckets (15.6” × 11.8”) with lids lined with cheesecloth (DeRoyal, BIDF2012380-BX, Powell, TN, USA) that served as an oviposition substrate. Adult moths were provided with a 10% sucrose solution. The oviposition substrate was replaced daily and stored in 3.8 L Ziploc® (Racine, WI, USA) bags with thin strips of diet. Third instar larvae were transferred to cups with an artificial diet (described above). Colonies were maintained at 25 ± 2 °C, 65 ± 9% relative humidity (RH), and a 14:10 light:dark (L:D) photoperiod, with the exception of female pupae. They were placed in incubators (Sanyo®, MLR-351H, New York, NY, USA) set at a lower temperature (22 ± 1.5 °C, 75 ± 4% RH, and a 14:10 L:D photoperiod) to synchronize their emergence with that of the adult males [45,46]. Prior to this study, H. armigera and H. zea were reared for 11 and 24 generations, respectively.

2.4. Insecticides

The variability of response of H. armigera and H. zea to spinetoram and spinosad (allosteric modulators of nicotinic acetylcholine receptors, IRAC MoA (Insecticide Resistance Action Committee Mode of Action) group 5), indoxacarb (voltage-dependent sodium channel blockers, IRAC MoA group 22A), and methomyl (acetylcholinesterase inhibitor, IRAC MoA group 1A) were evaluated (Table 1).

2.5. Bioassays

The same artificial diet used to maintain the colonies was used in the bioassays. Bioassay cups placed on 30-well trays were filled with 1 mL of diet per well (4.3 cm top diameter, 3.3 cm bottom diameter, and 3 cm height). A 100 ppm A.I. stock solution of each insecticide was serially diluted to obtain the test concentrations. Triton X-100 (0.1%, Sigma Aldrich, MO, USA) was used as a surfactant to obtain a uniform distribution over the diet surface. The control treatment was composed of distilled water and a surfactant. Up to eight concentrations of each insecticide were tested for each species. The insecticides were applied to the diet surface with a replicating pipette, ultimately delivering 140 µL per cup (equivalent to 20 µL per cm2). The diet surface area in each cup was 7.0 cm2. After a 30 min drying period, one H. armigera or H. zea third instar larva was transferred to each cup using a fine paintbrush (AIT Art®, 10/0, Danbury, CT, USA). The cups were closed with a perforated lid that allowed for gas exchange and stored in a climate chamber (25 ± 2 °C, 65 ± 9% RH, and a 14:10 L:D photoperiod). The bioassays were repeated four times for each species, and each replication consisted of 30 larvae per concentration. Larvae were inspected after 48 h and recorded as dead if there was no movement when gently touched with a fine paintbrush.

2.6. Statistical Analysis

Mortality data were subjected to Probit analysis (PROC PROBIT, SAS Institute 2000) [47] to estimate the lethal concentrations (LC50 and LC90—insecticide concentrations (µg a.i./cm2) required to kill 50% and 90% of larvae, respectively, in 48 h) and their confidence intervals (CIs). A likelihood test was conducted to determine whether the response of the two species differed significantly in either slope or intercept [48]. Pairwise comparisons were performed, and significance was declared when CIs did not overlap [48,49]. Significant differences among slopes were determined through a likelihood ratio test for parallelism and equality [48]. For each insecticide, the tolerance ratio (TR) was determined by dividing the LC50 and LC90 of the more susceptible species by the corresponding parameter of the other species.

3. Results

The Indoxacarb-induced mortality of third instar larvae for both H. armigera and H. zea was concentration-dependent (Table 2). Concentrations ranging from 0.0051 to 1.60 µg a.i./cm2 caused 4–100% mortality. The LC50 of indoxacarb on H. armigera was 0.17 µg a.i./cm2, and the LC90 was 1.70 µg a.i./cm2; they were slightly higher for H. zea at 0.21 and 2.64 µg a.i./cm2, respectively. The tolerance ratios for the LC50 and LC90 values were similar at 1.24 and 1.55-fold, with H. zea exhibiting a slightly lower susceptibility. The response for both species were also statistically similar, as indicated by the 95% fiducial limits overlap.
Methomyl produced the greatest variation in response between the species (Table 2). Concentrations from 0.0051−3 to 2.88 µg a.i./cm2 caused mortality ranging from 5% to 100% in both species; however, the LC50 and LC90 for H. armigera were 0.32 and 3.20 µg a.i./cm2, respectively, which were much higher than those for H. zea (0.18 and 1.88 µg a.i./cm2, respectively). The tolerance ratios were lower than 1.8-fold, indicating a similar response of these species to methomyl.
Spinosad and spinetoram also induced high mortality for both species (Table 2). Concentrations ranging from 0.0051 to 1.60 µg a.i./cm2 caused 3–100% mortality. The spinosad LC50 value for both species was 0.17 for µg a.i./cm2. The spinetoram LC50 values were 0.11 and 0.08 µg a.i./cm2 for H. armigera and H. zea, respectively. In contrast, a lower LC90 of spinosad was detected for H. armigera (1.48 µg a.i./cm2) than on H. zea (3.30 µg a.i./cm2). The LC90 of spinetoram was similar for both species (0.67 and 0.68 µg a.i./cm2 for H. armigera and H. zea, respectively). The tolerance ratios, based on LC50, were 1.0- and 1.4-fold to spinosad and spinetoram, respectively.

4. Discussion

This is the first study to compare the response of H. armigera and H. zea to broad spectrum and selective insecticides. Earlier studies with biological and chemical insecticides have evaluated the two species separately due to their former geographic isolation [1,2,3,4,5,6,7,8,9,10]. Among the insecticides tested in this study, high levels of resistance of H. armigera to methomyl were reported in Pakistan [50,51,52], India [53,54], and Greece [55]; in contrast, low levels of resistance were reported in populations from Spain and Turkey [56,57], and no resistance was reported in invasive populations of H. armigera in Brazil [58]. In the U.S.A., a low frequency of resistance alleles to methomyl in H. zea populations from Virginia was reported [59]. However, Vemula et al. [60] found variations in the tolerance of H. zea to methomyl between bean crop seasons in Texas and New Mexico.
Populations of H. armigera from Australia were highly susceptible to indoxacarb, with toxicity ratios between 1.2 and 3.5 among several populations. The most tolerant strain had an LC50 value of 0.518 mg/mL [61]. However, follow-up studies identified field populations with up to a 198-fold resistance [62]. In addition, a population of H. armigera from China subjected to 11 generations of selection to indoxacarb resistance decreased its susceptibility by 4.43-fold (LC50 increased from 5.93 to 26.25 mg L−1) [63]. Helicoverpa assulta Guenée, another related species, also demonstrated resistance to this pesticide in China [64]. In south-eastern U.S.A., first instar larvae of H. zea under high indoxacarb pressure were very susceptible, with LC50 values ranging from 1.05 to 1.54 ppm using diet overlay bioassays [65], and no evidence of resistance was found in cotton fields in the U.S.A. [66].
The use of spinosyns, which include spinosad and spinetoram, to control Helicoverpa spp. has increased in recent years. Spinetoram has been reported to have high efficacy against Helicoverpa species under field conditions [67,68]. Interestingly, spinosad resistance is associated with a reduced fitness, as reflected in prolonged egg, larval, and pupal periods and decreased pupal survival and overall fecundity [66]. However, a remarkable variation in H. armigera population susceptibility, especially to spinosad, was reported in Pakistan [69], and populations in China developed more than 20-fold resistance after 15 generations [70]. In contrast, low levels of resistance to spinosad were reported in Pakistan [71] and populations of H. armigera from two intensive cotton growing areas in India [72]. The results in our study are similar to Pereira’s [73], who found two-fold variations in the susceptibility to spinosad among different populations of H. armigera in Brazil, thus suggesting low levels of resistance; unfortunately, after a few years of exposure, resistance increased, resulting in a 22% survival (LC99). Helicoverpa zea susceptibility to spinosad is also variable by population. In the U.S.A., high LC50 values were obtained for H. zea third instar larvae [65]; the authors suggested that this was due to the reduced rates used in cotton systems. In contrast, López Jr. et al. [74] indicated that this pesticide is highly effective against H. zea adults in insecticide-baited traps in the southern U.S.A.
Our results indicated that spinetoram is highly toxic to both Helicoverpa species. This insecticide is considered an important alternative for controlling Helicoverpa pests, especially for Cry1Ac-resistant populations [68]. Xie et al. [67] found spinetoram to be effective against H. armigera, inducing high mortality rates and sublethal effects similar to spinosad in H. armigera populations from China [66]. Visnupriya and Muthukrishnan [75] also reported low LC50 values for spinetoram on H. armigera, ranging from 1.94 to 5.20 ppm. There have been few reports of Helicoverpa species resistance to spinetoram; nevertheless, if usage patterns and exposure to sublethal concentrations of spinetoram increase, selection for resistance to it is also likely to rise [68].
The diet overlay bioassay is a valuable tool for monitoring changes in susceptibility to insecticides in Helicoverpa species [66,76]. This bioassay has been used to evaluate a range of insecticides (permethrin, thiodicarb, chlorfenapyr, cypermethrin, di-ßubenzuron, cyanamid, emamectin, benzoate, and spinosad) on larvae of Diatraea saccharalis (Fabricius, 1794), H. armigera, H. zea, and Spodoptera frugiperda (Smith, 1797), among other lepidopteran pests [77,78,79,80]. The overlay diet bioassay may better simulate the field application of insecticides than commonly used techniques such as a diet-incorporation bioassay. It allows for the even distribution of insecticides over the diet surface, thus simulating field deposition of insecticides over the surface of the larval feeding substrate. There is a caveat, as Roush et al. [81] pointed out that laboratory colonies are formed from a small number of individuals that lack the high frequency of alleles that confer field populations with resistance to insecticides, so results for laboratory populations could differ from field-selected resistance.

5. Conclusions

The recent establishment of H. armigera populations in the H. zea native range, as well as the potential for hybridization of these two species, may form a Helicoverpa complex in the Western Hemisphere. Monitoring the susceptibility of this complex to insecticides is essential for implementing IRM programs to prevent control failures. We present data on an invasive population of H. armigera from Brazil and a population of H. zea from Puerto Rico that showed similar responses to indoxacarb, methomyl, spinetoram, and spinosad. These populations can be used as a reference for future studies to develop baselines for monitoring field-selected resistance in Helicoverpa species.

Author Contributions

Conceptualization, D.C., T.M.G., W.D.B., and J.C.V.R.; methodology, F.R.d.S.; formal analysis, F.R.d.S. and O.B.; resources J.C.V.R., D.C., W.D.B., and T.M.G.; data curation, F.R.d.S. and D.T.; writing—original draft preparation F.R.d.S.; writing—review and editing, all authors; project administration and funding acquisition, D.C. and J.C.V.R. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by USDA APHIS-UF Cooperative Agreement No. 16-8130-0744-CA and APHIS-UPR AP17PPQS&T00C189. The findings and conclusions in this preliminary publication have not been formally disseminated by the U.S. Department of Agriculture and should not be construed to represent any Agency determination or policy. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA; USDA is an equal opportunity provider and employer.

Acknowledgments

We thank Rita Duncan, Alejandro Calixtho and Melissa Willrich Siebert for reviewing earlier versions of this manuscript. We are grateful to Thiago Mastrangelo (Centro de Energia Nuclear na Agricultura, USP, Brazil) for providing H. armigera specimens and fruitful discussion on rearing methods.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Fitt, G.P. Host selection in Heliothinae. In Reproductive Behaviour of Insects: Individuals and Populations; Bailey, W.J., Ridsdill-Smith, J., Eds.; Chapman & Hall: London, UK, 1991; pp. 172–201. [Google Scholar]
  2. Matthews, M. Classification of the Heliothinae; NRI Bulletin No. 44; Natural Resources Institute: Chatham, UK, 1991. [Google Scholar]
  3. Cunningham, J.P.; Zalucki, M.P. Understanding Heliothine (Lepidoptera: Heliothinae) pests: What is a host plant? J. Econ. Entomol. 2014, 107, 881–896. [Google Scholar] [CrossRef] [PubMed]
  4. Center for Agriculture and Bioscience International (CABI). Helicoverpa armigera; CABI: Wallingford, UK, 2018. [Google Scholar]
  5. Sharma, H.C.; Stevenson, P.C.; Gowda, C.L.L. Helicoverpa armigera management: Emerging trends and prospects for future research. In Helicoverpa armigera Management: Emerging Trends and Strategies for Future Research; Sharma, H.C., Ed.; Oxford and IBH Publishers: New Delhi, India, 2005; pp. 453–454. [Google Scholar]
  6. Ramaswamy, S.B. Host finding by moths: Sensory modalities and behaviours. J. Insect Physiol. 1988, 34, 235–249. [Google Scholar] [CrossRef]
  7. Manjunath, T.M.; Bhatnagar, V.S.; Pawar, C.S.; Sithanantham, S. Economic importance of Heliothis spp. in India and an assessment of their natural enemies and host plants. In Proceedings of the Workshop on Biological Control of Heliothis: Increasing the Effectiveness of Natural Enemies, New Delhi, India, 11–15 November 1985; pp. 197–228. [Google Scholar]
  8. King, A.B.S. Heliothis/Helicoverpa (Lepidoptera: Noctuidae). In Insect Pests of Cotton; Matthews, G.A., Tunstall, J.P., Eds.; University Press: Cambridge, UK, 1994; pp. 39–106. [Google Scholar]
  9. Ravi, K.C.; Mohan, K.S.; Manjunath, T.M.; Head, G.; Patil, B.V.; Greba, D.P.A.; Premalatha, K.; Peter, J.; Rao, N.G.V. Relative abundance of Helicoverpa armigera (Lepidoptera: Noctuidae) on different host crops in India and the role of these crops as natural refuge for Bacillus thuringiensis cotton. Environ. Entomol. 2005, 34, 59–69. [Google Scholar] [CrossRef] [Green Version]
  10. Czepak, C.; Albernaz, K.C.; Vivan, L.M.; Guimarães, H.O.; Carvalhais, T. First reported occurrence of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) in Brazil. Pesqui. Agropec. Trop. 2013, 43, 110–113. [Google Scholar] [CrossRef] [Green Version]
  11. Murúa, M.G.; Scalora, F.S.; Navarro, F.R.; Cazado, L.E.; Casmuz, A.; Villagrán, M.E.; Lobos, E.; Gastaminza, G. First Record of Helicoverpa armigera (Lepidoptera: Noctuidae) in Argentina. Fla. Entomol. 2014, 97, 854–856. [Google Scholar] [CrossRef]
  12. Hayden, J.E.; Brambila, J. Pest Alert: Helicoverpa armigera (Lepidoptera: Noctuidae), the Old World Bollworm. Available online: https://www.fdacs.gov/ezs3download/download/61696/1411969/Media/Files/Plant-Industry-Files/Pest-Alerts/PEST%20ALERT%20Helicoverpa%20armigera-1.pdf (accessed on 9 July 2020).
  13. Pogue, M.G. A new synonym of Helicoverpa zea (Boddie) and differentiation of adult males of H. zea and H. armigera (Hübner) (Lepidoptera: Noctuidae: Heliothinae). Ann. Entomol. Soc. Am. 2004, 97, 1222–1226. [Google Scholar] [CrossRef] [Green Version]
  14. Perera, O.P.; Allen, K.C.; Jain, D.; Purcell, M.; Little, N.S.; Luttrell, R.G. Rapid identification of Helicoverpa armigera and Helicoverpa zea (Lepidoptera: Noctuidae) using ribosomal RNA internal transcribed spacer 1. J. Insect Sci. 2015, 15, 155. [Google Scholar] [CrossRef] [Green Version]
  15. Gilligan, T.M.; Tembrock, L.R.; Farris, R.E.; Barr, N.B.; van der Straten, M.J.; van de Vossenberg, B.T.L.H.; Metz-Verschure, E. A multiplex real-time PCR assay to diagnose and separate Helicoverpa armigera and H. zea (Lepidoptera: Noctuidae) in the New World. PLoS ONE 2015, 10, e0142912. [Google Scholar] [CrossRef]
  16. Gonçalves, R.M.; Mastrangelo, T.; Rodrigues, J.C.V.; Paulo, D.F.; Omoto, C.; Corrêa, A.S.; Azeredo-Espin, A.A.L. Invasion origin, rapid population expansion, and the lack of genetic structure of cotton bollworm (Helicoverpa armigera) in the Americas. Ecol. Evol. 2019, 9, 1–24. [Google Scholar] [CrossRef] [Green Version]
  17. Hardwick, D.F. The corn earworm complex. Mem. Entomol. Soc. Can. 1965, 97, 5–247. [Google Scholar] [CrossRef]
  18. Twine, P.H. Effect of temperature on the development of larvae and pupae of the corn earworm, Heliothis armigera (Hübner) (Lepidoptera: Noctuidae). Qld. J. Agric. Anim. Sci. 1978, 35, 23–28. [Google Scholar]
  19. Nibouche, S.; Goze, E.; Babin, R.; Beyo, J.; Brévault, T. Modelling Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) damages on cotton. Environ. Entomol. 2007, 36, 151–156. [Google Scholar] [CrossRef] [Green Version]
  20. Wilcox, J.; Howland, A.F.; Campbell, R.E. Investigations of the Tomato Fruitworm: Its Seasonal History and Methods of Control; US Department of Agriculture Techical Bulletin No. 1147; U. S. Government Printing Office: Washington, DC, USA, 1956; Volume 1147, pp. 1–47. [Google Scholar]
  21. Capinera, J.L. Corn Earworm, Helicoverpa zea (Boddie); Department of Entomology and Nematology, Florida Cooperative Extension Service Publication No. EENY-145 (IN30200); University of Florida: Gainesville, FL, USA, 2001. [Google Scholar]
  22. Blanco, C.A.; Terán-Vargas, A.P.; López, J.D., Jr.; Kauffman, J.V.; Wei, X. Densities of Heliothis virescens and Helicoverpa zea (Lepidoptera: Noctuidae) in three plant hosts. Fla. Entomol. 2007, 90, 742–750. [Google Scholar] [CrossRef]
  23. Blanco, C.A.; Gould, F.; Vega-Aquino, P.; Jurat-Fuentes, J.L.; Perera, O.P.; Abel, C.A. Response of Heliothis virescens (Lepidoptera: Noctuidae) strains to Bacillus thuringiensis Cry1Ac incorporated into different insect artificial diets. J. Econ. Entomol. 2009, 102, 1599–1606. [Google Scholar] [CrossRef] [PubMed]
  24. Rhino, B.; Verchère, A.; Thibaut, C.; Ratnadass, A. Field evaluation of sweet corn varieties for their potential as a trap crop for Helicoverpa zea under tropical conditions. Int. J. Pest Manag. 2016, 62, 3–10. [Google Scholar] [CrossRef]
  25. Adamson, D.; Thomas, G.; Davis, E. An Economic Estimate of Helicoverpa’s Effect on Australian Agricultural Production; CRC for Tropical Pest Management: Brisbane, Australia, 1997. [Google Scholar]
  26. Australian Genome Alliance. Cotton Bollworm Genome Project. 2009. Available online: http://www.genomealliance.org.au/projects/Bollworm/Bollworm.htm (accessed on 18 August 2015).
  27. Lammers, J.W.; MacLeod, A. Report of a Pest Risk Analysis: Helicoverpa armigera (Hübner, 1808). Available online: https://secure.fera.defra.gov.uk/phiw/riskRegister/downloadExternalPra.cfm?id=3879 (accessed on 9 July 2020).
  28. Tay, W.T.; Walsh, T.K.; Downes, S.; Anderson, C.; Jermiin, L.S.; Wong, T.K.F.; Piper, M.C.; Chang, E.S.; Macedo, I.B.; Czepak, C.; et al. Mitochondrial DNA and trade data support multiple origins of Helicoverpa armigera (Lepidoptera, Noctuidae) in Brazil. Nat. Sci. Rep. 2017, 7, 45302. [Google Scholar] [CrossRef] [Green Version]
  29. Kriticos, D.J.; Ota, N.; Hutchison, W.D.; Beddow, J.; Walsh, T.; Tay, W.T.; Borchert, D.M.; Paula-Moreas, S.V.; Czepak, C.; Zalucki, M.P. Correction: The potential distribution of invading Helicoverpa armigera in North America: Is it just a matter of time? PLoS ONE 2015, 10, e0133224. [Google Scholar] [CrossRef]
  30. Bentivenha, J.P.F.; Paula-Moraes, S.V.; Baldin, E.L.L.; Specht, A.; da Silva, I.F.; Hunt, T.E. Battle in the new world: Helicoverpa armigera versus Helicoverpa zea (Lepidoptera: Noctuidae). PLoS ONE 2016, 11, e0167182. [Google Scholar] [CrossRef] [Green Version]
  31. Behere, G.T.; Tay, W.T.; Russell, D.A.; Heckel, D.G.; Appleton, B.R.; Kranthi, K.R.; Batterham, P. Mitochondrial DNA analysis of field populations of Helicoverpa armigera (Lepidoptera: Noctuidae) and of its relationship to H. zea. BMC Evol. Biol. 2007, 7, 117. [Google Scholar] [CrossRef] [Green Version]
  32. Pearce, S.L.; Clarke, D.F.; East, P.D.; Elfekih, S.; Gordon, K.H.J.; Jermiin, L.S.; McGaughran, A.; Oakeshott, G.; Papanikolaou, A.; Perera, O.P.; et al. Genomic innovations, transcriptional plasticity and gene loss underlying the evolution and divergence of two highly polyphagous and invasive Helicoverpa pest species. BMC Biol. 2017, 15, 1–30. [Google Scholar] [CrossRef] [Green Version]
  33. Mallet, J. Hybridization as an invasion of the genome. Trends Ecol. Evol. 2005, 20, 229–237. [Google Scholar] [CrossRef] [PubMed]
  34. Joußen, N.; Agnolet, S.; Lorenz, S.; Schöne, S.E.; Ellinger, R.; Schneider, B.; Heckel, D.G. Resistance of Australian Helicoverpa armigera to fenvalerate is due to the chimeric P450 enzyme CYP337B3. Proc. Natl. Acad. Sci. USA 2012, 109, 15206–15211. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  35. Leite, N.A.; Alves-Pereira, A.; Corrêa, A.S.; Zucchi, M.I.; Omoto, C. Demographics and genetic variability of the New World Bollworm (Helicoverpa zea) and the Old World Bollworm (Helicoverpa armigera) in Brazil. PLoS ONE 2014, 9, e113286. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  36. Leite, N.A.; Correa, A.S.; Michel, A.P.; Alves-Pereira, A.; Pavinato, V.A.C.; Zucchi, M.I.; Omoto, C. Pan-American similarities in genetic structures of Helicoverpa armigera and Helicoverpa zea (Lepidoptera: Noctuidae) with implications for Hybridization. Environ. Entomol. 2017, 46, 1024–1034. [Google Scholar] [CrossRef] [PubMed]
  37. Durigan, M.R.; Corrêa, A.S.; Pereira, R.M.; Leite, N.A.; Amado, D.; de Sousa, D.R.; Omoto, C. High frequency of CYP337B3 gene associated with control failures of Helicoverpa armigera with pyrethroid insecticides in Brazil. Pestic. Biochem. Physiol. 2017, 143, 73–80. [Google Scholar] [CrossRef] [PubMed]
  38. Anderson, C.J.; Tay, W.T.; McGaughran, A.; Gordon, K.; Walsh, T.K. Population structure and gene flow in the global pest, Helicoverpa armigera. Mol. Ecol. 2016, 25, 5296–5311. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  39. Anderson, C.J.; Oakeshotta, J.G.; Taya, W.T.; Gordona, K.H.J.; Zwicka, A.; Walsha, T.K. Hybridization and gene flow in the mega-pest lineage of moth, Helicoverpa. Proc. Natl. Acad. Sci. USA 2018, 115, 5034–5039. [Google Scholar] [CrossRef] [Green Version]
  40. Rasool, A.; Joußen, N.; Lorenz, S.; Ellinger, R.; Schneider, B.; Khan, S.A.; Ashfaq, M.; Heckel, D.G. An independent occurrence of the chimeric P450 enzyme CYP337B3 of Helicoverpa armigera confers cypermethrin resistance in Pakistan. Insect Biochem. Mol. Biol. 2014, 53, 54–65. [Google Scholar] [CrossRef]
  41. Mahon, R.J.; Downes, S.J.; James, B. Vip3A resistance alleles exist at high levels in Australian targets before release of cotton expressing this toxin. PLoS ONE 2012, 7, e39192. [Google Scholar] [CrossRef] [Green Version]
  42. Stadelbacher, E.A.; Snodgrass, G.L.; Elzen, G.W. Resistance to cypermethrin in first generation adult bollworm and tobacco budworm (Lepidoptera: Noctuidae) populations collected as larvae on wild feranium, and in the second and third larval generations. J. Econ. Entomol. 1990, 83, 1207–1210. [Google Scholar] [CrossRef]
  43. Abd-Elghafar, S.F.A.; Knowles, C.O.; Wall, M.L. Pyrethroid resistance in two field strains of Helicoverpa zea (Lepidoptera: Noctuidae). J. Econ. Entomol. 1993, 86, 1651–1655. [Google Scholar] [CrossRef]
  44. Brambila, J. Instructions for Dissecting Male Genitalia of Helicoverpa (Lepidoptera: Noctuidae) to Separate H. zea from H. armigera. Available online: https://www.aphis.usda.gov/plant_health/plant_pest_info/owb/downloads/owb-screeningaids2.pdf (accessed on 9 July 2020).
  45. Armes, N.J.; Bond, G.S.; Cooter, R.J. The Laboratory Culture and Development of Helicoverpa armigera; Natural Resources Institute, Technology & Engineering: Chatham Maritime, Kent, UK, 1992. [Google Scholar]
  46. Colvin, J.; Cooter, R.J. Laboratory mating behaviour and compatibility of Helicoverpa armigera (Lepidoptera: Noctuidae) originating from different geographical regions. J. Econ. Entomol. 1994, 87, 1502–1506. [Google Scholar] [CrossRef]
  47. (SAS) Statistical Analysis System Institute. Statistical Analysis System: Getting Started with the SAS Learning; SAS Institute: Cary, NC, USA, 2000. [Google Scholar]
  48. Savin, N.E.; Robertson, J.L.; Russell, R.M. A critical evaluation of bioassay in insecticide research: Likelihood ratio tests of dose-mortality regression. Bull. Entomol. Soc. Am. 1977, 23, 257–266. [Google Scholar] [CrossRef]
  49. Robertson, J.L.; Russell, R.M.; Preisler, H.K.; Savin, N.E. Bioassays with Arthropods; CRC: Boca Raton, FL, USA, 2007. [Google Scholar]
  50. Ahmad, M.; Arif, M.I.; Attique, M.R. Pyrethroid resistance of, Helicoverpa armigera Hub. in Pakistan. Bull. Entomol. Res. 1997, 87, 343–347. [Google Scholar] [CrossRef]
  51. Ahmad, M.; Arif, M.I.; Ahmad, Z. Pattern of resistance to O/P insecticides in field population of H. armigera Hub. in Pakistan. Pestic. Sci. 1999, 55, 626–632. [Google Scholar] [CrossRef]
  52. Ahmed, S.; Rassol, M.R.; Ullah, I.; Rauf, I. Comparative efficacy of some insecticides against Helicoverpa armigera Hub. and Spodoptera spp. on tobacco. Int. J. Agric. Biol. 2004, 6, 93–95. [Google Scholar]
  53. Upendhar, S.; Sree, K.V.; Satyanarayana, J.; Singh, T.V.K. Cypermethrin and Methomyl Resistance in Helicoverpa armigera (Hübner). Int. J. Econ. Plants 2017, 4, 70–75. [Google Scholar]
  54. Chaturvedi, I. Status of insecticide resistance in the cotton bollworm, Helicoverpa armigera (Hübner). J. Cent. Eur. Agric. 2007, 8, 171–182. [Google Scholar]
  55. Mironidis, G.K.; Kapantaidaki, D.; Bentila, M.; Morou, E.; Savopoulou-Soultani, M.; Vontas, J. Resurgence of the cotton bollworm Helicoverpa armigera in northern Greece associated with insecticide resistance. Insect Sci. 2013, 20, 505–512. [Google Scholar] [CrossRef]
  56. Avilla, C.; González-Zamora, J.E. Monitoring resistance of Helicoverpa armigera to different insecticides used in cotton in Spain. Crop Prot. 2010, 29, 100–103. [Google Scholar] [CrossRef] [Green Version]
  57. Ugurlu, S.; Gurkan, M.O. Insecticide resistance in Helicoverpa armigera from cotton-growing areas in Turkey. Phytoparasitica 2007, 35, 376–379. [Google Scholar] [CrossRef]
  58. Carneiro, E.; Silva, L.B.; Maggioni, K.; dos Santos, V.B.; Rodrigues, T.F.; Reis, S.S.; Pavan, B.E. Evaluation of insecticides targeting control of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae). Am. J. Plant Sci. 2014, 5, 2823–2828. [Google Scholar] [CrossRef] [Green Version]
  59. Herbert, D.A., Jr.; Malone, S.; Kuhar, T.P.; Portillo, H.E.; Saienni, J.P.; Williams, R.W. Adult corn earworm (Helicoverpa zea) susceptibility to methomyl. Plant Health Prog. 2008, 9, 23. [Google Scholar] [CrossRef] [Green Version]
  60. Vemula, S.R.; Porter, P.; Schuster, G.L.; Lewis, B.E. Susceptibility of Helicoverpa zea to commercial insecticides used in green bean production on Texas High Plains. Tex. J. Agric. Nat. Resour. 2012, 25, 1–12. [Google Scholar]
  61. Bird, L.J. Baseline susceptibility of Helicoverpa armigera (Lepidoptera: Noctuidae) to indoxacarb, emamectin, benzoate, and chlorantraniliprole in Australia. J. Econ. Entomol. 2015, 108, 294–300. [Google Scholar] [CrossRef]
  62. Bird, L.J. Genetics, cross-resistance and synergism of indoxacarb resistance in Helicoverpa armigera (Lepidoptera: Noctuidae). Pest Manag. Sci. 2017, 73, 575–581. [Google Scholar] [CrossRef]
  63. Cui, L.; Wang, Q.; Qi, H.; Wang, Q.; Yuan, H.; Rui, C. Resistance selection of indoxacarb in Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae): Cross-resistance, biochemical mechanisms and associated fitness costs. Pest Manag. Sci. 2018, 74, 2636–2644. [Google Scholar] [CrossRef]
  64. Wang, K.Y.; Zhang, Y.; Wang, H.Y.; Xia, X.M.; Liu, T.X. Influence of three diets on susceptibility of selected insecticides and activities of detoxification esterases of Helicoverpa assulta (Lepidoptera: Noctuidae). Pestic. Biochem. Physiol. 2010, 96, 51–55. [Google Scholar] [CrossRef]
  65. Cook, D.R.; Leonard, B.R.; Gore, J.; Temple, J.H. Baseline responses of bollworm, Helicoverpa zea (Boddie), and tobacco budworm, Heliothis virescens (F.), to indoxacarb and pyridalyl. J. Agric. Urban Entomol. 2005, 22, 99–109. [Google Scholar]
  66. Brickle, D.S.; Turnipseed, S.G.; Sullivan, M.J. Efficacy of insecticides of different chemistries against Helicoverpa zea (Lepidoptera: Noctuidae) in transgenic Bacillus thuringiensis and conventional cotton. J. Econ. Entomol. 2001, 94, 86–92. [Google Scholar] [CrossRef] [PubMed]
  67. Xie, B.; Zhang, L.; Wang, B.; Liang, G. Effects of spinetoram on detoxifying enzyme and acetylcholin esteraseactivity in Helicoverpa armigera (Hübner). Chin. J. Appl. Entomol. 2015, 52, 600–608. [Google Scholar]
  68. Wei, J.; Zhang, L.; Yang, S.; Xie, B.; An, S.; Liang, G. Assessment of the lethal and sublethal effects by spinetoram on cotton bollworm. PLoS ONE 2018, 13, e0204154. [Google Scholar] [CrossRef] [PubMed]
  69. Ahmad, M.; Arif, M.I.; Ahmad, Z. Susceptibility of Helicoverpa armigera (Lepidoptera: Noctuidae) to new chemistries in Pakistan. Crop Prot. 2003, 22, 539–544. [Google Scholar] [CrossRef]
  70. Wang, D.; Qiu, X.; Ren, X.; Zhang, W.; Wang, K. Effects of spinosad on Helicoverpa armigera (Lepidoptera: Noctuidae) from China: Tolerance status, synergism and enzymatic responses. Pest Manag. Sci. 2009, 65, 1040–1046. [Google Scholar] [CrossRef] [PubMed]
  71. Alvi, A.H.K.; Sayyed, A.H.; Naeem, M.; Ali, M. Field Evolved Resistance in Helicoverpa armigera (Lepidoptera: Noctuidae) to Bacillus thuringiensis toxin Cry1Ac in Pakistan. PLoS ONE 2012, 7, e47309. [Google Scholar] [CrossRef] [Green Version]
  72. Stanley, J.; Chandrasekaran, S.; Regupathy, A. Baseline toxicity of emamectin and spinosad to Helicoverpa armigera (Lepidoptera: Noctuidae) for resistance monitoring. Entomol. Res. 2009, 39, 321–325. [Google Scholar] [CrossRef]
  73. Pereira, R.M. Characterization of the Susceptibility to Diamide and Spinosyn Insecticides in Helicoverpa armigera (Lepidoptera: Noctuidae) Populations from Brazil. Ph.D. Dissertation, University of São Paulo, Piracicaba, Brazil, 2017. [Google Scholar]
  74. López, J.D., Jr.; Latheef, M.A.; Hoffmann, W.C. Toxicity and feeding response of adult corn earworm (Lepidoptera: Noctuidae) to an organic spinosad formulation in sucrose solution. Adv. Entomol. 2014, 2, 33–41. [Google Scholar] [CrossRef] [Green Version]
  75. Visnupriya, M.; Muthukrishnan, N. Acute toxicity and field evaluation of spinetoram 12 SC against Helicoverpa armigera Hübner on tomato. J. Entomol. Zool. Stud. 2017, 5, 1608–1613. [Google Scholar]
  76. Joyce, J.A.; Ottens, R.J.; Herzog, G.A.; Bass, M.H. A laboratory bioassay for thiodicarb against the tobacco budworm, bollworm, beet armyworm, and fall armyworm. J. Agric. Entomol. 1986, 3, 207–212. [Google Scholar]
  77. Mascarenhas, R.N.; Boethel, D.J. Responses of field-collected strains of soybean looper (Lepidoptera: Noctuidae) to selected insecticides using an artificial diet overlay bioassay. J. Econ. Entomol. 1997, 90, 1117–1124. [Google Scholar] [CrossRef]
  78. Mascarenhas, V.J.; Graves, J.B.; Leonard, B.R.; Burris, E. Susceptibility of field populations of beet armyworm (Lepidoptera: Noctuidae) to commercial and experimental insecticides. J. Econ. Entomol. 1998, 91, 827–833. [Google Scholar] [CrossRef]
  79. Oppert, B. Rapid bioassay to screen potential biopesticides in Tenebrio molitor larvae. Biopestic. Int. 2010, 6, 67–73. [Google Scholar]
  80. Bernardi, O.; Amado, D.; Sousa, R.S.; Segatti, F.; Fatoretto, J.; Burd, A.D.; Omoto, C. Baseline susceptibility and monitoring of Brazilian populations of Spodoptera frugiperda (Lepidoptera: Noctuidae) and Diatraea saccharalis (Lepidoptera: Crambidae) to Vip3Aa20 insecticidal protein. J. Econ. Entomol. 2014, 107, 781–790. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  81. Roush, R.T.; McKenzie, J.A. Ecological genetics of insecticide and acaricide resistance. Annu. Rev. Entomol. 1987, 32, 361–380. [Google Scholar] [CrossRef] [PubMed]
Table
Table 1. Commercial insecticides used to compare the susceptibility of Helicoverpa armigera and Helicoverpa zea in Puerto Rico.
Table 1. Commercial insecticides used to compare the susceptibility of Helicoverpa armigera and Helicoverpa zea in Puerto Rico.
Active IngredientTrade NameInsecticide GroupManufacturerConcentration Range (µg a.i./cm2)
IndoxacarbAvaunt® 30WGOxadiazinesFMC, Philadelphia, PA, USA.0.0051–1.60 µg a.i./cm2
MethomylLannate® LVCarbamateCorteva Agriscience, Wilmington, DE, USA.0.0051–2.88 µg a.i./cm2
SpinetoramRadiant® SCSpinosynCorteva Agriscience, Wilmington, DE, USA.0.0051–1.60 µg a.i./cm2
SpinosadEntrust® SCSpinosynCorteva Agriscience, Wilmington, DE, USA.0.0051–0.90 µg a.i./cm2
Table
Table 2. Concentration–mortality response (lethal concentration (LC); µg a.i./cm2) of the third instar Helicoverpa larvae exposed to the insecticides overlaid on artificial diet.
Table 2. Concentration–mortality response (lethal concentration (LC); µg a.i./cm2) of the third instar Helicoverpa larvae exposed to the insecticides overlaid on artificial diet.
InsecticideSpeciesnSlope ± SELC50 (95% FL) a, bLC90 (95% FL) a, bχ2 cDf dTR50 eTR90 e
IndoxacarbH. armigera9601.27 ± 0.21 a0.17 (0.09–0.31) a1.70 (0.73–3.06) a13.265--
H. zea9601.17 ± 0.09 a0.21 (0.17–0.27) a2.64 (1.74–4.56) a2.2551.241.55
MethomylH. armigera9601.28 ± 0.32 a0.32 (0.05–0.55) a3.20 (1.49–4.82) a10.0141.781.70
H. zea8401.26 ± 0.33 a0.18 (0.02–0.56) a1.88 (0.60–4.99) a11.034--
SpinosadH. armigera8401.37 ± 0.24 a0.17 (0.07–0.34) a1.48 (0.66–3.00) a8.9641.00-
H. zea9600.99 ± 0.16 a0.17 (0.09–0.26) a3.30 (1.97–7.94) a8.015-2.23
SpinetoramH. armigera9601.64 ± 0.30 a0.11 (0.06–0.17) a0.67 (0.37–2.81) a13.4651.38-
H. zea10801.35 ± 0.18 a0.08 (0.04–0.12) a0.68 (0.40–1.62) a9.736-1.01
a LC50 and LC90 are the insecticide concentrations (µg a.i./cm2) required to kill 50% and 90% of larvae in 48 h. b LC50 and LC90 values designated by different letters within a column are significantly different from each other through a nonoverlap of 95% fiducial limits. The significance of differences among slopes was determined by a likelihood ratio test of equality followed by pairwise comparisons using nonoverlapping fiducial limits. c Chi-square significant (p < 0.05). d Degrees of freedom. e Tolerance ratio (TR) = (LC50 or LC90 of the lower susceptible species)/(LC50 or LC90 of the other species).

Share and Cite

MDPI and ACS Style

da Silva, F.R.; Trujillo, D.; Bernardi, O.; Verle Rodrigues, J.C.; Bailey, W.D.; Gilligan, T.M.; Carrillo, D. Comparative Toxicity of Helicoverpa armigera and Helicoverpa zea (Lepidoptera: Noctuidae) to Selected Insecticides. Insects 2020, 11, 431. https://doi.org/10.3390/insects11070431

AMA Style

da Silva FR, Trujillo D, Bernardi O, Verle Rodrigues JC, Bailey WD, Gilligan TM, Carrillo D. Comparative Toxicity of Helicoverpa armigera and Helicoverpa zea (Lepidoptera: Noctuidae) to Selected Insecticides. Insects. 2020; 11(7):431. https://doi.org/10.3390/insects11070431

Chicago/Turabian Style

da Silva, Fernando R., Dario Trujillo, Oderlei Bernardi, Jose Carlos Verle Rodrigues, Woodward D. Bailey, Todd M. Gilligan, and Daniel Carrillo. 2020. "Comparative Toxicity of Helicoverpa armigera and Helicoverpa zea (Lepidoptera: Noctuidae) to Selected Insecticides" Insects 11, no. 7: 431. https://doi.org/10.3390/insects11070431

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop