Search Results (10)

Tenebrio molitor is a common stored grains pest. The conventional way for its management involves the use of synthetic fumigants. Despite their effectiveness, these can cause environmental damage. The use of essential oils has emerged as an alternative for its management. Therefore, the aim of this study was to assess Lantana camara essential oil (EO) and endo-borneol biological activities against T. molitor. Insecticidal activity and weight gain were evaluated through the impregnated paper method against larvae and adults, while repellency was conducted with a Y-tube olfactometer; L. camara EO showed higher mortality for T. molitor adults (LC₅₀ = 7.2 μL EO L⁻¹ air) than for larvae (LC₅₀ = 13.7 μL EO L⁻¹ air) after 30 d. Furthermore, L. camara EO was found to be repellent for T. molitor adults (RC₅₀ = 0.08 μL EO cm⁻²). Regarding the EO composition, endo-borneol was identified by GC-MS as a major compound with 14.24% abundance. Larvae exhibited higher susceptibility (LC₅₀ = 7.8 μL L⁻¹ air) to endo-borneol than adults (LC₅₀ = 46 μL L⁻¹ air) after 72 h. Notably, endo-borneol demonstrated significantly higher repellent activity (RC₅₀ = 0.03 μL cm⁻²) than L. camara EO (RC₅₀ = 0.08 μL EO cm⁻²). These findings suggest that endo-borneol has potential as a natural source alternative for T. molitor management. Full article

In this study, we tested the insectistatic and insecticidal effects of the ethanolic extract of stems and bark of Ficus petiolaris Kunth (Moraceae) in laboratory bioassays with an artificial diet against newly hatched larvae of the fall armyworm, Spodoptera frugiperda Smith (Lepidoptera: Noctuidae). The extract was evaluated at five different concentrations (500, 1000, 1500, 2000, and 2500 ppm). The 2500 ppm extract had the strongest inhibitory effects on larval (89%) and pupal (20%) weight as well as the highest mortality (80%). The positive control, methyl parathion (Methyl Parathion^®) at 1%, eliminated 100% of the fall armyworm, and the negative control (artificial diet) had a mortality of only 5%. Chemical fractionation of F. petiolaris stem and bark extract produced five fractions of FpR1-5, each of which was evaluated at 250, 500, 750, 1000, and 1250 ppm. FpR4 presented the strongest inhibitory effect, reducing the weight of the larva and pupa by 35% and 18%, while FpR2 had the strongest insecticidal effect, with 90% mortality at 1250 ppm. The pure 8-Methoxypsoralen compound extracted from this fraction was even more effective, with 100% S. frugiperda mortality at 100 ppm. The 50% lethal concentration (LC₅₀) of 8-Methoxypsoralen was 67.68 ppm. Our results indicate that the F. petiolaris extract showed toxic activity against the fall armyworm, and its compound 8-Methoxypsoralen showed strong insecticidal activity at low concentrations. Full article

Spodoptera frugiperda is the main pest of maize. One of the alternatives proposed for its control is the implementation of products of botanical origin, such as those derived from Ricinus communis. In this work, the insecticidal and insectistatic activities of methanolic and hydrolyzed methanolic extracts of the aerial parts of R. communis and kaempferol against S. frugiperda are evaluated. The methanolic extract presented a larval mortality rate of 55% and an accumulated mortality rate of 65% starting at 4000 ppm, with LC₅₀ values of 3503 (larvae) and 2851 (accumulated); meanwhile, from a concentration of 1000 ppm, a decrease in pupa weight at 24 h of 20.5 mg was observed when compared to the control. The hydrolyzed methanolic extract presented a larval mortality and accumulated mortality rate of 60% from a concentration of 1000 ppm, and a decrease in pupa weight at 24 h of 35.31 mg was observed, when compared to the control. For the compound kaempferol 3-β-D-glucopyranoside, a larval mortality rate of 65% and an accumulated mortality rate of 80% were observed from 800 ppm, with LC₅₀ values of 525.2 (larvae) and 335.6 ppm (accumulated); meanwhile, at 300 ppm, a decrease in pupa weight of 25.59 mg after 24 h was observed when compared to the control. Full article

The use of botanical extracts of the plant Jatropha curcas (Euphorbiaceae) represents a valuable alternative to control insect pests and avoid the detrimental effects on the environment and health that arise due to synthetic chemical insecticides. Thus, we conducted a systematic review to summarize the published evidence on the bioactivity of J. curcas against insect pests. Electronic databases were searched to identify studies that assessed J. curcas extracts against insect pests in various types of crops. We included 39 articles that reported the insecticidal and insectistatic activity of several botanical extracts from J. curcas against insects of eight different taxonomic orders. The evidence demonstrates that aqueous and methanolic extracts from seeds and leaves, seed oil, and petroleum ether seed extracts were effective against insect pests of stored grains, aphids of cabbage and sorghum, fruit flies, and desert locusts. The extracts caused high mortality, controlled the populations, reduced oviposition, diminished hatchability, and increased the antifeedant effect. However, the type of solvent used to obtain the botanical extract and the method of application (contact or food) are fundamental to increase its bioactivity. Therefore, botanical extracts from seeds and leaves of J. curcas should be considered as an alternative against insect pests and may be incorporated into integrative and sustainable management for insect control. Full article

Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) is one of the most damaging pests in maize crops. In order to manage it, synthetic insecticides such as diamides, neonicotinoids, and pyrethroids are used, but they present a risk for humans and the environment. Investigations of safer alternatives include the use of natural extracts. Thus, this research evaluated the effects of chloroform extract (CHCl₃Sc) (5000, 4000, 2000, 1000, and 500 ppm) on aerial parts of Salvia connivens and of nonanal and pyrocatechol (1000, 600, 400, and 80 ppm) on S. frugiperda mortality, duration of the larva and pupae phases, and pupae weight after 24 h. The second instars of S. frugiperda larvae were fed an artificial diet incorporating the extract and compounds. The CHCl₃Sc had insecticidal activity against S. frugiperda, showing an LC50 of 1504 ppm. Insectistatic activity began at 1000 ppm, increasing pupal and larval duration in 7.6 and 1.4 days, respectively. Pyrocatechol and nonanal were found in this extract. The first did not have any significant difference in larval or pupal mortalities. On the other hand, insectistatic activity was shown at 500 ppm, increasing the larval duration by 1.7 days compared with the control. In the case of nonanal, the insecticide activity was LC50 of 200 ppm, and insectistatic activity started at 80 ppm, increasing larval duration by 3.2 days compared with the control and reducing pupal weight by 3.4%. The results show that chloroformic extract had insecticidal and insectistatic activities against S. frugiperda; nonanal was an aldehyde compound present in this extract, which confers insecticidal and insectistatic activities against this pest. Full article

Haematobia irritans is a cosmopolitan obligate blood-feeding ectoparasite of cattle and is the major global pest of livestock production. Currently, H. irritans management is largely dependent on broad-spectrum pesticides, which has led to the development of insecticide resistance. Thus, alternative control methods are needed. Essential oils have been studied as an alternative due to their wide spectrum of biological activities against insects. Thus, the main aim of this study was to evaluate the insecticidal, repellent and antifeedant activity of the essential oils from Blepharocalyx cruckshanksii leaves and Pilgerodendron uviferum heartwood against horn flies in laboratory conditions. The composition of the essential oils was analyzed using gas chromatography coupled to mass spectrometry. Accordingly, α-pinene (36.50%) and limonene (20.50%) were the principal components of the B. cruckchanksii essential oil, and δ-cadinol (24.16%), cubenol (22.64%), 15-copaenol (15.46%) and δ-cadinene (10.81%) were the most abundant compounds in the P. uviferum essential oil. Mortality of flies and feeding behavior were evaluated by non-choice tests, and olfactory response was evaluated using a Y-tube olfactometer. Both essential oils were toxic to horn flies, with LC₅₀ values for B. cruckchanksii essential oil of 3.58 µL L⁻¹ air at 4 h, and for P. uviferum essential oil of 9.41 µL L⁻¹ air and 1.02 µL L⁻¹ air at 1 and 4 h, respectively. Moreover, the essential oils exhibited spatial repellency in the olfactometer using only 10 µg of each oil, and these significantly reduced the horn fly feeding at all doses evaluated. Although further laboratory and field studies related to the insectistatic and insecticide properties of these essential oils against H. irritans are necessary, B. cruckshanksii leaves and P. uviferum heartwood essential oils are promising candidates for horn fly management. Full article

Castor bean (Ricinus communis) seeds contain ricinine, an alkaloid with insecticidal and insectistatic activities. Elicitation with salicylic acid (SA) has proven to stress R. communis and might modify the ricinine concentration. The aim of this study was to evaluate the concentration of ricinine in the bagasse of seeds from R. communis elicited with exogenous SA under greenhouse conditions. Plants were grown and divided into five groups, which were sprayed with SA and drench with 50 mL 60 days after sowing with concentrations of SA (0, 100, 300, 600 and 900 µM). Clusters were mixed and separated according to the treatment, and dried. The seeds were ground, the oil was extracted by Soxhlet with hexane, and then the bagasse was extracted with methanol. Ricinine was determined by HPLC. Elicitation did not change the plant height or diameter; the control group had 9.17 µg mL⁻¹ of ricinine; and the concentrations followed a hormesis curve with the peak at 300 µM of SA that had a ricinine concentration of 18.25 µg mL⁻¹. Elicitation with SA might be a cost-effective technique to increase ricinine from R. communis bagasse. Full article

Fall Armyworm (FAW) (Spodoptera frugiperda) is a polyphagous and highly destructive pest of many crops. It was recently introduced into Africa and now represents a serious threat to food security, particularly because of yield losses in maize, which is the staple food for the majority of small-scale farmers in Africa. The pest has also led to increased production costs, and threatens trade because of quarantines imposed on produce from the affected countries. There is limited specific knowledge on its management among smallholders since it is such a new pest in Africa. Some synthetic insecticides have been shown to be effective in controlling FAW, but in addition to the economic, health and environmental challenges of pesticide use insecticide resistance is highly prevalent owing to years of FAW management in the Americas. Therefore, there is a need for the development and use of alternatives for the management of FAW. These include plant-derived pesticides. Here we review the efficacy and potential of 69 plant species, which have been evaluated against FAW, and identify opportunities for use among small-scale maize farmers with a focus on how pesticidal plants might be adopted in Africa for management of FAW. The biological activities were diverse and included insecticidal, insectistatic (causing increased larval duration), larvicidal, reduced growth and acute toxicity (resulting in adverse effects within a short time after exposure). While most of these studies have been conducted on American plant taxa many South American plants are now cosmopolitan weeds so these studies are relevant to the African context. Full article

Essential oils can be used as an alternative to using synthetic insecticides for pest management. Therefore, the insectistatic and insecticidal activities of the essential oil of aerial parts of Salvia ballotiflora (Lamiaceae) were tested against the fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae). The results demonstrated insecticidal and insectistatical activities against this insect pest with concentrations at 80 µg·mL⁻¹ resulting in 20% larval viability and 10% pupal viability. The larval viability fifty (LV₅₀) corresponded to a concentration of 128.8 µg·mL⁻¹. This oil also increased the duration of the larval phase by 5.5 days and reduced the pupal weight by 29.2% withrespect to the control. The GC-MS analysis of the essential oil of S. ballotiflora showed its main components to be caryophyllene oxide (15.97%), and β-caryophyllene (12.74%), which showed insecticidal and insectistatical activities against S. frugiperda. The insecticidal activity of β-caryophyllene began at 80 µg·mL⁻¹, giving a larval viability of 25% and viability pupal of 20%. The insectistatic activity also started at 80 µg·mL⁻¹ reducing the pupal weight by 22.1% with respect to control. Caryophyllene oxide showed insecticidal activity at 80 µg·mL⁻¹ giving a larval viability of 35% and viability pupal of 20%.The insectistatic activity started at 400 µg·mL⁻¹ and increased the larval phase by 8.8% days with respect to control. The LV₅₀ values for these compounds were 153.1 and 146.5 µg·mL⁻¹, respectively. Full article

The composition of a chloroform seed extract of C. papaya was determined by GC-MS. Nineteen compounds were identified, with oleic (45.97%), palmitic (24.1%) and stearic (8.52%) acids being the main components. The insecticidal and insectistatic activities of the extract and the three main constituents were tested. Larval duration increased by 3.4 d and 2.5 d when the extract was used at 16,000 and 9,600 ppm, respectively, whereas the pupal period increased by 2.2 d and 1.1 d at the same concentrations. Larval viability values were 0%, 29.2%, and 50% when the extract was applied at 24,000, 16,000, and 9,600 ppm, respectively; pupal viability was 42.9% and 66.7% at 16,000 and 9,600 ppm; and pupal weight decreased by 25.4% and 11.5% at 16,000 and 9,600 ppm. The larval viability of the main compounds was 33.3%, 48.5%, and 62.5% when exposed to 1,600 ppm of palmitic acid, oleic acid, or stearic acid, respectively. Full article