Search Results (39)

Habrobracon hebetor is a globally acknowledged larval ectoparasitoid that is widely used to control lepidopteran pests. Wolbachia is a natural endosymbiont that regulates various aspects of the insect host biology. The ability of H. hebetor to paralyze and develop on lepidopteran larvae from five families was tested under laboratory conditions. Two lines of the wasp were used, “W+” containing a naturally occurring Wolbachia from the supergroup B, and “W−”, with the endosymbiont eradicated by antibiotic treatment, followed by propagation of 20 subsequent generations. The proportions of larvae in which host paralysis, as well as parasitoid oviposition, larval, pupal, and adult development were observed, were usually higher in W+ compared to W−. In Loxostege sticticalis, differences in these indices were not statistically significant. In Galleria mellonella, Mamestra brassicae, and Ostrinia nubilalis, some of the parasitism indices were significantly higher in W+ than in W−. In Bombyx mori and Plutella xylostella, H. hebetor could not complete its life cycle, but parasitism levels at the initial steps (from paralysis symptoms to the presence of larvae/pupae of the parasitoid) were 2–5 times lower in W− compared to W+ (p < 0.01). It can be suggested that the presence of Wolbachia is advantageous for H. hebetor, as it increases the success of parasitism in a broad range of lepidopteran hosts. Full article

Maize (Zea mays L.) is one of the most important agricultural crops in the world; however, its production is often threatened by several harmful insects, one of which is the European corn borer, Ostrinia nubilalis (Hübner). This study aimed to examine the efficacy of several biological control methods against this pest. A randomized block design was used in the study, which included three treatments: parasitic wasps (Trichogramma brassicae), common green lacewings (Chrysoperla carnea), a combination of both agents and a control. The results showed that the treatment with T. brassicae wasps, as well as their combination with C. carnea predators, significantly improved the maize grain yield over the control treatment. The same combined treatment significantly improved the yield over treatments with only Trichogramma and only C. carnea predators, suggesting a higher efficacy of the combination of both agents in improving grain yield. Fewer tunnels and larvae in stalks, compared to other treatments, including the control, were also observed in this treatment. The reduced number of tunnels and larvae in stalks directly enabled plants to allocate more resources into grain development, which contributed to improved grain yield. In light of the growing focus on minimizing insecticide applications to mitigate environmental impacts, a combination of parasitic wasp and lacewings predator could be a suitable biological alternative to the use of chemical insecticides. Full article

The insecticidal Cry proteins from Bacillus thuringiensis are used in biopesticides or transgenic crops for pest control. The Cry1I protein family has unique characteristics of being produced during the vegetative rather than sporulation phase, its protoxins forming dimers in solution, and exhibiting dual toxicity against lepidopteran and coleopteran pests. The Cry1Ia protoxin undergoes sequential proteolysis from the N- and C-terminal ends, producing intermediate forms with insecticidal activity, while in some cases, the fully processed toxin is inactive. We investigated the oligomerization and toxicity of Cry1Ia intermediate forms generated through trypsinization (T-Int) and larval gut fluid (GF-Int) treatments, as well as the fully trypsinized protein (toxin). Heterologously expressed intermediate forms assembled into oligomers and showed similar toxicity to Cry1Ia protoxin against Ostrinia nubilalis (European corn borer) larvae, while the toxin form was ~30 times less toxic. In contrast, bioassays with Leptinotarsa decemlineata (Colorado potato beetle) larvae did not show significant differences in toxicity among Cry1Ia protoxin, T-Int, GF-Int, and fully processed toxin. These results suggest that the Cry1I mode of action differs by insect order, with N-terminal cleavage affecting toxicity against lepidopteran but not coleopteran larvae. This knowledge is essential for designing pest control strategies using Cry1I insecticidal proteins. Full article

A series of novel triazone derivatives containing aldehyde hydrazone or ketone hydrazone moieties were designed, synthesized and their biological activities were investigated against Aphis craccivora, Culex pipiens pallens, Helicoverpa armigera, Ostrinia nubilalis, Mythimna separata and 14 Kinds of fungi. Most of the aldehyde hydrazone exhibited excellent insecticidal activities against A. craccivora. In particular, the aphicidal activities of compounds 3t (35%) and 3w (30%) were equivalent to pymetrozine (30%) at 5 mg/kg. The aphicidal activities of derivatives 3p, 3u, 3y, 5g, 5i, 5l, 5q and 5u against C. pipiens pallens were higher than that of pymetrozine. Compound 3u (100%) exhibited good larvicidal activities against C. pipiens pallens at 0.25 mg/kg. Most derivatives exhibited broad-spectrum fungicidal activities against 14 kinds of plant fungi at 50 mg/kg. Thirty-nine compounds exhibited a more than 50% inhibition rate against Physalospora piricola. Compounds 3h, 3t and 3w were expected to be the leading structure for the development of new triazone insecticides agents. Full article

This article describes the results of the studies related to the occurrence of the European corn borer (Ostrinia nubilalis Hbn) pest carried out at the Technical University of Bydgoszcz. The studies concerned the real occurrence of the pest in corn stubble (cultivated variety SY Collosseum). The research issue undertaken is in line with an IPM (integrated pest management) system and is important since the feeding of the European corn borer can lead to large, direct yield losses estimated nationally at an average of up to about 20%, which does not differ significantly from that of world crops. Corn, for the purposes of this study, was harvested for green fodder in September, and for grain in November 2022, using a John Deere X9 1110 harvester. The average stubble height when cut for green fodder was 280 mm, while for grain it was 265 mm. The experimental studies conducted clearly showed that European corn borer larvae colonized as much as 12% of corn samples harvested for grain at an average stubble height of 155 mm, and 19% of corn samples harvested for grain at an average height of 75 mm. The conducted studies also showed that the average diameter of the stems at the height of the residence of the corn borer larvae when harvested for green fodder is 19.80 mm, and 21.80 mm for grain. The studies conducted by the authors showed the randomness of the locations of the pest larvae, which clearly indicates that the generally known and used mechanical methods of its control are not fully effective. Therefore, the authors presented their own design of a machine construction (filed with the patent office of the Republic of Poland) for destroying the European corn borer in a mechanical way without the use of crop protection chemicals. The presented research problem in this paper is of national and global importance considering the fact that corn is grown on an area of nearly 162 million hectares, where we have to deal with the European corn borer pest. In the case of implementing the design of the construction of a machine for destroying the pest, there will be no need to use chemical pesticides, which will significantly contribute to environmental protection. Full article

The aim of this work was to determine the influence of chosen biostimulants and microbiological preparations on the yield of sweet corn and the occurrence of Ostrinia nubilalis Hbn, and diseases. In both years of the study, the preparations used in this experiment did not have a statistically significant effect on marketable yield; however, in 2017, the highest weight was observed in the cobs of plants treated with Rizocore and Polyversum WP while the lowest in the cobs treated with RhizoVital 42. The biostimulant Asahi SL and the biological fungicide Serenade ASO proved to be the most effective in protecting sweet corn against cob and shoot infections by fungi of the genus Fusarium. All the preparations reduced the development of the common smut in corn, especially on the cobs. There were no statistically significant differences in cob infection by the O. nubilalis in the combinations treated with different preparations, although the lowest number of cobs damaged by pest in both years were observed on plots treated with Serenade ASO and RhizoVital 42, while the highest on plots treated with Goëmar BM. Full article

Plant resistance mechanisms to pathogens can lead to a lowered efficacy of insect microbial biocontrol agents, but the influence of plant variety has been little-studied. Leaves and stalks from twelve maize (Zea mays L.) inbreds with different plant pathogen resistance were evaluated for their influence on the efficacy of Beauveria bassiana (Bals.-Criv.) Vuill. against European corn borers (Ostrinia nubilalis (Hübner)). For leaf assays with first instar caterpillars, mortality on day 2 ranged from an inbred-dependent high of 76.1% to a low of 10.0% for European corn borers in leaf assays. For stalk assays with third instar caterpillars, mortality on day 4 ranged from an inbred dependent high of 83.0% and 75.0% to a low of 0.0% and 8.3% for fall armyworms and European corn borers, respectively. Lesion size ratings due to Fusarium graminearum (Schwabe) applied to tissues were often significantly correlated with the mortality levels of B. bassiana-treated caterpillars that fed on leaves and stalks. This study suggests that the influence of plant varieties on the efficacy of insect microbial pathogens can vary depending on the insect species involved and the plant tissue, and this is worth considering when new plant varieties and biocontrol strains are being developed whenever practical. Full article

The European corn borer (ECB) (Ostrinia nubilalis Hübner) and to a lesser extent the western corn rootworm (Diabrotica virgifera virgifera LeConte) are a threat to maize in the Po Valley (Northern Italy), and their control can require insecticide applications. The results of a study to evaluate the effects of insecticide sprays on the beneficial insect Trichogramma brassicae (Hymenoptera: Trichogrammatidae) and aphid predators are reported. A three-year research project was carried out in two Study Areas, in Lombardy. In area 1, crop rotation was a common practice, while in area 2 repeated maize crop was practiced. The natural trend of ECB egg masses attacked by T. brassicae was affected and parasitism rates were reduced as a result of insecticide exposure (chlorpyriphos methyl, cypermethrin, alphacypermethrine). Repeated maize crop and insecticides spraying increased the abundance of the aphid population and negatively affected the aphid predator community, which mainly included ladybirds, hoverflies, true bugs and lacewings. The predator community was dominated by hoverflies in sprayed fields managed according to repeated maize crop protocols, whereas ladybirds and Orius spp. dominated in maize fields managed according to crop rotation protocols. Crop rotation protocols help to prevent ECB outbreaks; when the risk of exceeding the economic threshold limit is high, and this may be the case when maize is cultivated for seeds or for horticultural crops such as sweet corn, inundative release of T. brassicae and/or microbial control (i.e., use of Bacillus thuringiensis preparations) can integrate natural biocontrol, and provide a valuable alternative to chemical insecticides. Full article

During diapause, a state of temporarily arrested development, insects require low winter temperatures to suppress their metabolism, conserve energy stores and acquire cold hardiness. A warmer winter could, thus, reduce diapause incidence and duration in many species, prematurely deplete their energy reserves and compromise post-diapause fitness. In this study, we investigated the combined effects of thermal stress and the diapause program on the expression of selected genes involved in antioxidant defense and heat shock response in the European corn borer Ostrinia nubilalis. By using qRT-PCR, it has been shown that response to chronic heat stress is characterized by raised mRNA levels of grx and trx, two important genes of the antioxidant defense system, as well as of hsp70 and, somewhat, of hsp90, two major heat shock response proteins. On the other hand, the expression of hsc70, hsp20.4 and hsp20.1 was discontinuous in the latter part of diapause, or was strongly controlled by the diapause program and refractory to heat stress, as was the case for mtn and fer, genes encoding two metal storage proteins crucial for metal ion homeostasis. This is the first time that the effects of high winter temperatures have been assessed on cold-hardy diapausing larvae and pupae of this important corn pest. Full article

The European corn borer (Ostrinia nubilalis, Hübner) has been managed successfully in North America since 1996 with transgenic Bt-corn. However, field-evolved resistance to all four available insecticidal Bt proteins has been detected in four provinces of Canada since 2018. Evidence suggests resistance may be spreading and evolving independently in scattered hotspots. Evolution and spread of resistance are functions of gene flow, and therefore dispersal, so design of effective resistance management and mitigation plans must take insect movement into account. Recent advances in characterizing European corn borer movement ecology have revealed a number of surprises, chief among them that a large percentage of adults disperse from the natal field via true migratory behavior, most before mating. This undermines a number of common key assumptions about adult behavior, patterns of movement, and gene flow, and stresses the need to reassess how ecological data are interpreted and how movement in models should be parameterized. While many questions remain concerning adult European corn borer movement ecology, the information currently available is coherent enough to construct a generalized framework useful for estimating the spatial scale required to implement possible Bt-resistance prevention, remediation, and mitigation strategies, and to assess their realistic chances of success. Full article

Between 2020 and 2021, we conducted research in eastern Romania to monitor the bioecology of the European corn borer (Ostrinia nubilalis Hbn.), an important pest of corn. The bioecology research established the pest stage duration (egg, larva, pupa, and moth), the flight curve, and the flight peak. The bioecological study occurred in the experimental corn field and a field cage. According to our findings, the insect has one generation per year. The European corn borer hibernates as a mature larva in corn residues and continues developing in the spring, when the weather warms. It pupates from May to July over 37 days. Analyzing the data recorded during the winters of 2020 and 2021, we observed that the warming trend favored the high survival of hibernating larvae (60.7%). Due to the large number of mature larvae that had favorable conditions during the winter, there is an intense flight, starting in June and ending in September. When the first moth was caught in the light trap, the ∑(tn-10) °C (sum of degree days) was 245.6 °C. In 2020, the flight was recorded for 94 days. In 2021, the European corn borer flight lasted 104 days. The initial egg masses were detected when the total of ∑(tn-10) °C reached 351.5 °C. Moths laid the eggs for 25 days, mostly during peak flight in late June and early July. The first larvae hatched when ∑(tn-10) °C totaled 438.4 °C, and stages III–V were recorded in the harvested crop. Understanding the bioecology of the European corn borer can offer valuable insights into managing population levels and identifying optimal timing for addressing infestations in corn crops. Full article

Maize is one of the most important food and feed sources at the worldwide level. Due to this importance, all the pathogens that can infect this crop can harm both food safety and security. Fungi are the most important pathogens in cultivated maize, and Fusarium spp. are one of the most important families. Reduction in yield and production of dangerous mycotoxins are the main effects of Fusarium spp. infection. Fusarium graminearum (part of the Fusarium graminearum species complex) is one the most important fungi that infect maize, and it is the causative agent of Gibberella ear rot (GER). The main characteristics of this species include its ability to infect various species and its varying infection pressures across different years. This fungus produces various harmful mycotoxins, such as deoxynivalenol, zearalenone, butanolide, and culmorin. Infection can start from silk channels or from ear wounds. In the first case, the environmental conditions are the most important factors, but in the second, a key role is played by the feeding action of lepidopteran larvae (in Europe, Ostrinia nubilalis). All these factors need to be taken into account to develop a successful management strategy, starting from cropping methods that can reduce the source of inoculum to the direct control of the fungus with fungicide, as well as insect control to reduce ear wounds. But, the most important factor that can reduce the effects of this fungus is the use of resistant hybrids. Different studies have highlighted different defensive methods developed by the plant to reduce fungal infections, like fast drying of silk and kernels, chemical compounds produced by the plant after infection, and mechanical protection from insects’ wounds. The aim of this paper is to review the scientific evidence of the most important management strategies against GER in maize and to highlight the genetic basis which is behind hybrid resistance to this disease, with a focus on genes and QTLs found in studies conducted across the world and with different types of maize from tropical cultivars to European flint. Full article

Although corn production is affected by several harmful insects, its most important pest in the southeastern region of Europe is the European corn borer (ECB), Ostrinia nubilalis Hübner, 1796 (Lepidoptera: Pyralidae). Chemical control of O. nubilalis remains the main strategy in conventional corn production. The key to successfully achieving a high efficiency of insecticides is determining the appropriate moment of application, including the exact time in the insect’s life cycle when it is most vulnerable. In this study, monitoring data on the flight dynamics of ECB adults from a seven-year period (2014–2020) were exploited for the development of a predictive model of adult numbers within the growing season. ECB monitoring was performed by using light traps at 15 different locations in the Vojvodina region (Serbia) during the specified time period. First, the calendar for Vojvodina was created based on the analytics of the collected monitoring data. Additionally, the calendar was converted to the probability of ECB occurrence during the growing season, specifying the time interval between the appearance of each generation of the pest. Second, using machine learning techniques, a phenological model was designed that included daily values of relevant meteorological features, such as cumulative degree-days, relative humidity, and precipitation. The calendar had a lower prediction error when compared to the phenological model, and it was tested as a supporting management tool for the ECB in 2021, with a root-mean-square error of the number of adults of 46.67. Such an approach could significantly reduce both the consumption of insecticides and the number of chemical treatments, respectively. Above all, this approach has broad potential in IPM and organic farming, and it is fully compatible with biological control methods. Full article

The pink stem borer (PSB), Sesamia cretica (Lepidoptera: Noctuidae) purple-lined borer (PLB), Chilo agamemnon (Lepidoptera: Crambidae) and European corn borer Ostrinia nubilalis, (Lepidoptera: Crambidae) are considered the most devastating insect pests of maize production in the Mediterranean region. The frequent use of chemical insecticides has resulted in the evolution of resistance to various insect pests as well as the pernicious impact on natural enemies and environmental hazardousness. Therefore, developing resistant and high-yielding hybrids is the best economic and environmental approach to cope with these destructive insects. Accordingly, the objective of the study was to estimate the combining ability of maize inbred lines (ILs), identify promising hybrids, determine gene action controlling agronomic traits and resistance to PSB and PLB, and investigate inter-relationships among evaluated traits. A half-diallel mating design was employed to cross seven diverse maize inbreds to generate 21 F₁ hybrids. The developed F₁ hybrids, alongside high-yielding commercial check hybrid (SC-132), were assessed in field trials for two years under natural infestation. Substantial variations were obtained among the evaluated hybrids for all recorded characteristics. The non-additive gene action was major for grain yield and its contributing traits, while the additive gene action was more important in controlling the inheritance of PSB and PLB resistance. The inbred line IL1 was identified to be a good combiner for earliness and developing short-stature genotypes. Additionally, IL6 and IL7 were recognized as excellent combiners to enhance resistance to PSB, PLB and grain yield. The hybrid combinations IL1×IL6, IL3×IL6, and IL3×IL7 were determined to be excellent specific combiners for resistance to PSB, PLB and grain yield. Strong positive associations were identified among grain yield, its related traits, and resistance to PSB and PLB. This implies their importance as useful traits for indirect selection for improving grain yield. Otherwise, the resistance against PSB and PLB was negatively associated with the silking date, indicating that earliness would be favorable for escaping from the borer’s attack. It could be concluded that the inheritance of PSB and PLB resistance can be governed by the additive gene effects, and the IL1×IL6, IL3×IL6, and IL3×IL7 hybrid combinations can be recommended as excellent combiners for resistance to PSB and PLB and good yield. Full article

We aimed to monitor the species diversity and the dynamics of the number of soybean pests using light traps with an original design to develop protection systems against the main phytophages. Traps lured 44 species of insects from eight orders and 27 families. The capture of 15 species of economically important phytophages was recorded—representatives of various orders and families: order Lepidoptera—Noctuidae, Crambidae, Erebidae, and Geometridae; order Hemiptera—Flatidae; order Coleoptera—Elateridae, etc. Insect identification was carried out via morphological methods. Over the study period (93 days), 4955.41 insect specimens were caught on average per one trap. Most of the attracted insects belong to harmful entomofauna: namely the cotton bollworm (Helicoverpa armigera, Hübner)—58.9%, the beet webworm (Loxostege sticticalis, L.)—12.74%, the nutmeg moth (Anarta trifolii, Hufnagel)—6.5%, the European corn borer (Ostrinia nubilalis, Hübner)—2.68%, and some other species—19.2%. In addition to economically significant phytophages, we registered some indifferent and beneficial species. The summer dynamics of the cotton bollworm and the nutmeg moth were obtained for the entire research period. Then, we calculated the values of the indices of biodiversity and the dominance of insect species. An analysis of the index values allows us to conclude a balanced entomocomplex at the research site. Full article