Search

For effective pest control, nano-insecticides have recently been proposed as a promising alternative to traditional ones. Thus, this study aimed to compare the efficacy of the traditional and nano-forms of thiocyclam (a natural toxin-based insecticide) and chlorantraniliprole (a diamide insecticide) against two major insect pests, the cotton leafworm, Spodoptera littoralis (Boisd.), and the black cutworm, Agrotis ipsilon (Hufnagel). The residue levels of the two insecticides in tomato fruits were also assessed. The results showed that chlorantraniliprole was more effective against both insects than thiocyclam, and the nano-forms were more effective than the traditional ones. This higher insecticidal activity of chlorantraniliprole could be attributed to its novel action by binding tightly to ryanodine receptors in insects. The study also optimized and validated an analytical method for residue determination of thiocyclam and chlorantraniliprole in tomato fruits using QuEChERS method and LC-MS/MS. Percentage recovery ranged from 70 to 104%, with good precision and expanded uncertainty of up to ± 23%. The half-life times of thiocyclam and its nano-form in tomatoes were 0.38 and 0.57 days, respectively, compared to 0.7 and 0.38 days for chlorantraniliprole and its nano-form. On the other hand, the calculated pre-harvest intervals for thiocyclam and its nano-form, using the EU maximum residue limit, were 7 and 3 days, respectively, compared to 1 day for both forms of chlorantraniliprole. [ABSTRACT FROM AUTHOR]

Background: The cabbage moth, Mamestra brassicae, is a polyphagous pest that attacks several crops. Here, the sublethal and lethal effects of chlorantraniliprole and indoxacarb were investigated on the developmental stages, detoxification enzymes, reproductive activity, calling behavior, peripheral physiology, and pheromone titer of M. brasssicae. Methods: To assess pesticide effects, the second instar larvae were maintained for 24 h on a semi-artificial diet containing insecticides at their LC10, LC30, and LC50 concentrations. Results: M. brassicae was more susceptible to chlorantraniliprole (LC50 = 0.35 mg/L) than indoxacarb (LC50 = 1.71 mg/L). A significantly increased developmental time was observed with both insecticides at all tested concentrations but decreases in pupation rate, pupal weight, and emergence were limited to the LC50 concentration. Reductions in both the total number of eggs laid per female and the egg viability were observed with both insecticides at their LC30 and LC50 concentrations. Both female calling activity and the sex pheromone (Z11-hexadecenyl acetate and hexadecenyl acetate) titer were significantly reduced by chlorantraniliprole in LC50 concentration. Antennal responses of female antennae to benzaldehyde and 3-octanone were significantly weaker than controls after exposure to the indoxocarb LC50 concentration. Significant reductions in the enzymatic activity of glutathione S-transferases, mixed-function oxidases, and carboxylesterases were observed in response to both insecticides. [ABSTRACT FROM AUTHOR]

Cotton leafworm, Spodoptera littoralis (Boisd.) is a key pest affecting many field crops and vegetables in Egypt. Therefore, in the current study, the susceptibility of the 2nd instar larvae of S. littoralis laboratory strain to eight insecticides was investigated and the insecticide resistance levels of two field populations were monitored. The two populations were collected from two governorates in Egypt, namely El-Monufia (MS) and El-Fayoum (FS). Resistance monitoring showed that the field population from El-Fayoum was highly resistant to chlorantraniliprole, emamectin benzoate (EMB), spinotram, and spinosad. However, the El-Monufia field population only exhibited high resistance to chlorantraniliprole and spinosad. The relative toxicity showed that the laboratory strain is highly sensitive to EMB (LC50= 0.001 ppm) followed by spinotram (LC50= 0.006 ppm), chlorantraniliprole (LC50= 0.008 ppm), spinosad (LC50= 0.008 ppm), and indoxacarb (LC50= 0.021 ppm), while chlorfenapyr, fipronil, and alpha-cypermethrin exhibited low toxicity to the laboratory strain of S. littoralis. Moreover, the biochemical determinations of detoxification enzymes revealed that carboxylesterase (a, and ß -esterase), and AChE activity were significantly increased in the FS population. Thus, Glutathione S-Transferase (GST) showed significant increase in the two populations. [ABSTRACT FROM AUTHOR]

Frequent applications of synthetic insecticides might cause environmental pollution due to the high residue. In addition, increasing insecticide resistance in many insect pests requires novel pest control methods. Nanotechnology could be a promising field of modern agriculture, and is receiving considerable attention in the development of novel nano-agrochemicals, such as nanoinsectticides and nanofertilizers. This study assessed the effects of the lethal and sublethal concentrations of chlorantraniliprole, thiocyclam, and their nano-forms on the development, reproductive activity, oxidative stress enzyme activity, and DNA changes in the black cutworm, Agrotis ipsilon, at the molecular level. The results revealed that A. ipsilon larvae were more susceptible to the nano-forms than the regular forms of both nano chlorine and sulfur within the chlorantraniliprole and thiocyclam insecticides, respectively, with higher toxicities than the regular forms (ca. 3.86, and ca.2.06-fold, respectively). Significant differences in biological parameters, including developmental time and reproductive activity (fecundity and hatchability percent) were also observed. Correspondingly, increases in oxidative stress enzyme activities were observed, as were mutagenic effects on the genomic DNA of A. ipsilon after application of the LC50 of the nano-forms of both insecticides compared to the control. These promising results could represent a crucial step toward developing efficient nanoinsecticides for sustainable control of A. ipsilon. [ABSTRACT FROM AUTHOR]