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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., Competing Interests: The authors have declared that no competing interests exist.

The use of biological control products enhances the reduction of harmful pressures on the environment caused by the use of conventional pesticides. Therefore, this study aims to evaluate the toxicity of eight bioinsecticides on the black cutworm Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) to understand the relationships between insecticide exposure and insect response at the individual and population levels. The bioassay results showed that emamectin benzoate had high toxicity against A. ipsilon second instar larvae with an LC50 of 0.007 (mg/L). Sublethal concentration (LC30) of emamectin benzoate, spinosyn group and Bacillus thuringiensis formulation (Dipel 2X) had significantly prolonged pupal period. In addition, emamectin benzoate significantly decreased the number of eggs laid per female (135.3 ± 6.919) compared with the control treatment. Thus, the formulation of chlorfenapyr showed a 1.26-fold reduction in hatching rate. Meanwhile, the activities of oxidative stress enzymes (catalase, superoxide dismutase, lipid peroxidase, and glutathione reductase) were significantly affected due to exposure to sublethal concentration. Changes in adipokinetic hormone (AKH) transcriptional regulation were detected via SQ-PCR via using cDNA synthesized from mRNA isolated from treated A. ipsilon larvae. The results showed a higher transcription rate of AKH in spinotram- -treated larvae with a 1.42-fold increase over untreated larvae. Our results provide useful information for integrated pest management programs for A. ipsilon by using bioinsecticides. [ABSTRACT FROM AUTHOR]

Background: The genetic diversity is naturally occurring in baculovirus population, which may affect the potency of the bio-agent. The Spodoptera littoralis nucleopolyhedrovirus is a promising bio-control agent that can be used to control the cotton leafworm, S. littoralis in Egypt. This study described the virulence and genetic variability of 3 S. littoralis nucleopolyhedrovirus isolates named Cab2, P2 and P3 previously recovered from diseased S. littoralis larvae of cabbage, pepper and eggplant cultivation fields. Results: The viral genomic DNA restriction analysis using PstI and ScaI endonucleases showed identical Pst1 restriction pattern of 10 fragments in both Cab2 and P3 isolates, while there are 7 extra fragments present in P2 isolate of about 25, 19.8, 15, 14, 11, 9 and 6.7 (kbp). On the other hand, the restriction pattern using ScaI revealed 10 common fragments in all three isolates, in addition to an extra marker fragment of about 25 kb in P3 isolate absent in both P2 and Cab3 isolates. The phylogenetic analysis of the partial nucleotide sequence of the polyhedrin gene confirmed an extensive degree of co-linearity among the genomes of the 3 tested isolates, with pairwise sequence identities of 97.04% with S. littoralis nucleopolyhedrovirus isolate A26-5 (Acc. No. AY706717). The median lethal concentration (LC50) value revealed that Cab2 had the best virulence toward the first instar of S. littoralis larvae with LC50 value of 1.59 × 104 Obs/ml compared to the virulence recorded by P3 and P2 which were 1.23 × 106 and 2.7 × 104 OBs/ml, respectively. The median survival time (LT50) value of Cab2 isolate was the highest speed of treated larval mortality with 120 hpi compared to P2 and P3, which recorded 132 hpi for both isolates. Conclusions: Although all three S. littoralis nucleopolyhedrovirus isolates showed considered genotypic variation and insecticidal activity against S. littoralis larvae, the variant Cab2 showed the highest virulence and speed mortality against the first instar larvae of S. littoralis. The new variant proved to possess promising insecticidal properties for the development of virus-based biopesticide for the control of S. littoralis population in Egypt. [ABSTRACT FROM AUTHOR]