Effects of Nucleopolyhedrovirus Infection on the Development ofHelicoverpa armigera(Lepidoptera: Noctuidae) and Expression of Its 20-Hydroxyecdysone—and Juvenile Hormone—Related Genes

Abstract

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Effect of Four Multiple Nucleopolyhedrovirus Isolates on the Larval Mortality and Development ofSpodoptera exigua(Lepidoptera: Noctuidae): Determination of Virus Production and Mean Time to Death

“…However, these data were not analyzed statistically because the numbers of survivors were few. Reductions in weight of pupae derived from larvae treated with their homologous nucleopolyhedrovirus compared with control pupae also were observed in S. exigua (Cabodevilla et al 2011b) and H. armigera (Zhang et al 2015).…”

“…Similarly, Cabodevilla et al (2011b) found that when second-instar S. exigua larvae were inoculated with 3.8 × 10 2 occlusion bodies per mL, the larval development time was about 2 d longer than that of healthy insects. When fourth-and fifth-instar H. armigera larvae were treated with different concentrations (1 × 10 6 to 1 × 10 10 occlusion bodies per mL) of its homologous nucleopolyhedrovirus (HaSNPV), the development time was longer significantly in most of the treated larvae (range: 16 to 32% and 17 to 27% for fourth and fifth instars, respectively) than in healthy insects (Zhang et al 2015). Additionally, in the occlusion body-production experiment of the present study, the weight of pupae derived from treated larvae (about 70 mg) was reduced by 30% relative to that of the control pupae (about 100 mg; data not shown).…”

“…These debilitating effects of viruses might arise due to the re-allocation of host energy reserves to combat the disease (Bong & Sikorowski 1991) and hormonal changes induced in the host (O'Reilly & Miller 1989). Recently, Zhang et al (2015) determined that virus infection might suppress the growth of host insects by disturbing the hormonal balance via influence on the viral Egt gene, which encodes an enzyme that modifies a hydroxyl group on 20E, thereby inactivating the molting hormone and resulting in a delay in or absence of molting in infected larvae (O'Reilly et al 1992;Chen et al 1997;Slavicek et al 1999).…”

Host miRNAs are involved in hormonal regulation of HaSNPV‐triggered climbing behaviour in Helicoverpa armigera

“…To obtain virus suspension, 0.02 g of HaSNPV raw powder (5 × 10 11 OBs/g) was diluted in sterile water to two different concentrations (10 8 and 10 6 OBs/ml; Zhang, Wu et al., ). Newly moulted fourth instars were inoculated with HaSNPV by feeding on a piece of artificial diet (0.8 cm L × 0.8 cm W × 0.5 cm H) contaminated with 10 μl of HaSNPV suspension at one of the two virus concentrations (i.e., a single larva ingested either 10 6 or 10 4 OBs).…”

“…In these studies, baculovirus infection altered the expression of host genes responsible for antivirus peptide production, detoxification, hormone activity and energy generation, among others using transcriptome analysis in baculovirus‐infected larvae (Breitenbach, Shelby, & Popham, ; Choi et al., ; Li et al., ). HaSNPV infection in H. armigera larvae led to down regulation of several 20E‐related genes and up regulation of JH‐related genes, indicating probable hormone mediation of climbing behaviour (Zhang, Wu et al., ). 20E and JH are the principal hormones that coordinately control growth and metamorphosis of holometabolous insects (Riddiford, Hiruma, Zhou, & Nelson, ).…”