Nano-insecticides against the black cutworm Agrotis ipsilon (Lepidoptera: Noctuidae): Toxicity, development, enzyme activity, and DNA mutagenicity.

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.

Genome-wide In Silico Analysis, Characterization and Identification of Microsatellites in Spodoptera littoralis Multiple nucleopolyhedrovirus (SpliMNPV).

In this study, we undertook a survey to analyze the distribution and frequency of microsatellites or Simple Sequence Repeats (SSRs) in Spodoptera littoralis multiple nucleopolyhedrovirus (SpliMNPV) genome (isolate AN-1956). Out of the 55 microsatellite motifs, identified in the SpliMNPV-AN1956 genome using in silico analysis (inclusive of mono-, di-, tri- and hexa-nucleotide repeats), 39 were found to be distributed within coding regions (cSSRs), whereas 16 were observed to lie within intergenic or noncoding regions. Among the 39 motifs located in coding regions, 21 were located in annotated functional genes whilst 18 were identified in unknown functional genes (hypothetical proteins). Among the identified motifs, trinucleotide (80%) repeats were found to be the most abundant followed by dinucleotide (13%), mononucleotide (5%) and hexanucleotide (2%) repeats. The 39 motifs located within coding regions were further validated in vitro by using PCR analysis, while the 21 motifs located within known functional genes (15 genes) were characterized using nucleotide sequencing. A comparison of the sequence analysis data of the 21 sequenced cSSRs with the published sequences is presented. Finally, the developed SSR markers of the 39 motifs were further mapped/localized onto the SpliMNPV-AN1956 genome. In conclusion, the SSR markers specific to SpliMNPV, developed in this study, could be a useful tool for the identification of isolates and analysis of genetic diversity and viral evolutionary status.

Possible functional co-operation of palindromes hr3 and hr4 in the genome of Cydia pomonella granulovirus affects viral replication capacity.

After previous studies had shown that natural transposon insertion between the two homologous regions hr3 and hr4 of the genome of the Mexican (M) strain of Cydia pomonella granulovirus (CpGV-M) resulted in a loss of viral competitiveness, the function of these homologous regions was investigated. A CpGV-based bacmid (CpBAC) was constructed and mutants with deleted hr3 and hr4 palindromes (CpBAChr3/hr4KO) and a construct (CpBAChr3-kan-hr4) with physically separated hr3 and hr4 repeats were generated to investigate their involvement in in vivo replication. Based on median lethal concentration (LC50) and median survival time (ST50) of the mutant viruses vCpBAChr3/hr4KO and vCpBAChr3-kan-hr4 it was found that the infectivity of both mutants for codling moth Cydia pomonella L. (Lep.: Tortricidae) larvae was not influenced compared with the parental virus vCpBAC. Co-infection experiments with vCpBAChr3-kan-hr4 and vCpBAC using different virus ratios revealed that vCpBAChr3-kan-hr4 was efficiently out-competed by vCpBAC during in vivo replication. These findings suggested that the separation of hr3 and hr4 resulted in a replication disadvantage of the mutant similar to the observation made in previous co-infection experiments using the transposon-carrying mutant CpGV-MCp5 and WT CpGV-M. It was concluded that the palindromes hr3 and hr4 may play a non-essential but co-functional role in the replication of CpGV-M.