Background: The indiscriminating and intensive use of insecticides to control the cotton leafworm (CLW), Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae), usually induces high levels of resistance. The insecticides are the principal method for controlling this pest because of its critical role in reducing insects when the economic threshold (ETL); therefore, the effectiveness of these insecticides should be maintained. So, the target of the present work was directed to focus on studying the change in the activities of some important enzymes as a result of sublethal treatment concentrations (viz. LC 25 values) of tested new insecticides (profenofos, cyfluthrin, emamectin benzoate, lufenuron, and spinetoram). The expected results could offer better understanding and more specific information about the resistance development in field populations of CLW because resistance is a significant challenge to pest control workers and these results may contribute to making the right decision at the right time. Materials and methods: Bioassays were performed on fourth instar larvae of S. littoralis field populations compared with the laboratory strain to assess the activity of the emamectin benzoate, lufenuron, and spinetoram by LC 25 and study the biochemical activities of some detoxification enzymes, like acetylcholinesterase (AChE), glutathione S-transferases (GST), alkaline phosphatase (ALP), and acid phosphatase (ACP) in fourth larval instar which was treated with LC 25 ; protein content is also determined.

Background Spodoptera littoralis is mostly controlled by the use of synthetic insecticides. Nonetheless, the use of these insecticides causes a slew of issues. On this pest, the antifeedant activity of Melaleuca alternifolia essential oil (EO) and its two principal components was investigated. Results The gas chromatography–mass spectrometry (GC/MS) analysis revealed that the M. alternifolia EO was composed of eleven compounds. Terpinen-4-ol (40.1%) and γ-terpinene (21.9%) were chosen as the major constituents. In terms of antifeedant efficacy, treatment with M. alternifolia EO and these components reduced leaf consumption and the efficiency of food conversion in larvae in a concentration-dependent manner. When compared to untreated larvae, weight, growth, and pupation percentage were all significantly lower. Conclusions The findings show that M. alternifolia EO and its components, terpinen-4-ol and γ-terpinene can be effectively combined for cotton leafworm management.

Background Chemical control is used as a rapid and reliable method for insect control. Still, there is an ongoing need to replace older conventional insecticides with new insecticides to maintain efficacy and environmental protection. Emamectin benzoate, indoxacarb and chlorantraniliprole are broad-spectrum insecticides with a novel mode of actions. The effects of these compounds on some biological aspects of the black cutworm, Agrotis ipsilon, and their field persistence residues were estimated. Results The results showed that egg hatch was affected by high concentrations (50 and 100 ppm) of the tested compounds. Larvae that hatched from treated eggs were significantly affected at concentrations of 25 ppm and higher. 1st-instar larvae were the most susceptible developmental stage. There was strong suppression of adult formation; 65 and 91% at 25 and 50 mg L−1, respectively. Profoundly affected larvae died before pupation; slightly affected ones reached pupation 2–4 days later, were smaller than larvae in the untreated control, and were sometimes unable to develop into normal adults. Comparatively high concentrations (50 and 100 mg L−1) of the test compounds were necessary to affect adults by ingestion. According to the results, the tested insecticides could be arranged according to their potency descendingly as follows: emamectin benzoate, indoxacarb, and chlorantraniliprole, respectively. Based on the field application, emamectin benzoate proved to be the most effective in initial and residual activity, causing 100% mortality while indoxacarb was least effective. Data also indicated that emamectin benzoate had the longest half-life (Lt50) while indoxacarb recorded the shortest one. Conclusions The results obtained in this study indicate that emamectin benzoate, indoxacarb and chlorantraniliprole are potent compounds for controlling A. ipsilon. Therefore, these compounds are promising materials that can be used as alternative components in integrated pest management programs to reduce as possible the harmful of using conventional insecticides under field conditions.

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Background: Cotton growers in Egypt have experienced severe economic loss from cotton bollworms, especially the pink bollworm, Pectinophora gossypiella (Saund.), and spiny bollworm, Earias insulana (Boisd.), so a field experiment was carried out to determine efficiency of eight insecticides in their seven sequence programs to evaluate the best solution for cotton bollworms problems, during two successive seasons. Results: The highest reduction percentages are effective sequences 7 and 5 (gave about 90% infestation reduction) were started and mediated with new insecticides, and when started and mediated with spinosad, or with cypermethrin, sequences 2 and 3 (gave about 86%) respectively, also, the repetition of the same insecticide twice in a regimen might increase, might decrease, or has no effect on the insecticide efficiency against cotton bollworms. The tested sequence programs showed high protection for green bolls with protection percentages ranged from 66.1 and 67.2% (sequence 1) to 92.6 and 94.1% (sequence 7) during two seasons respectively. On the other hand, the superiority in yield loss reduction can arrange in the following descending order: sequences 7, 5, 2, 3, 6, 4, and 1 respectively. Conclusions: From this study, it can be concluded that the importance of sequence insecticide programs included new groups of insecticides to directing tactics to fight against resistance development and used this sequence programs to restore susceptibility for conventional insecticides. This study devoted to obtaining the optimum regimen of insecticides that give low reduction of cotton bollworms' infestation and high cotton yield.