Field effectiveness of native isolates of Spodoptera frugiperda nucleopolyhedrovirus (SpfrNPV) from Jammu and Kashmir
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Date
2024-05-24
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Sher-e-Kashmir University of Agricultural Sciences & Technology of Jammu
Abstract
Invasive pests cause severe damage if accidently introduced in any agro-ecosystem in absence of their natural enemies. The fall armyworm (Spodopterafrugiperda) (J.E. Smith) (Lepidoptera: Noctuidae), is one of the recent examples that had introduced into the Indian state of Karnataka in India in July 2018. This pest is causing serious damage to economically important crops across the country including the union territory of Jammu and Kashmir. The outbreaks of this pest over the past few years spurred interest towards sustainable bio-intensive approaches for quality crop production for agricultural export in Jammu & Kashmir (J&K). The exploratory surveys were conducted for the isolation of native strains of Spodopterafrugiperdanucleopolyhedrovirus (SpfrMNPV) and field evaluation was conducted to determine the most promising strain as a potential biological control agent of this pest. The virus was recovered from different locations of J&K with its natural incidence varying from 0.78% to 6.07%. This is the first report from Jammu region of Northern India about the occurrence of NPVs in Spodopterafrugiperdalarval population. Among all these isolates, Jammu isolate of SpfrNPV was found to be most effective because of its higher viral activity and speed of kill against all the instars tested when inoculated via leaf disc method and intrahaemocoelic injections. Significant differences were observed in larval development period, percent pupation, adult emergence, adult longevity, percent oviposition, fecundity, percent egg hatching and per cent larval survival. However no significant difference was observed in the sex ratio of the adults emerged from the treated larvae as compared to control.
The in vivo mass production was optimised by inoculating per os 2nd instar S. frugiperda larvae with an inoculum dose of 1×106POBs/larva and followed by a 7 day incubation period. However, optimum yield was obtained when late fourth larval instar were inoculated viaintrahaemocoelic injection with the inoculum dose of 1×104 POBs/larva and subjected to 3 days incubation period. To prevent the disintegration of larval cuticle and microbial contamination, moribund larvae were harvested despite the loss of POBs.
In laboratory and field experiments, emamectin benzoate and SpfrNPV +Bt were found to be most effective treatments in reducing the larval population of Spodopterafrugiperda followed by SpfrNPV + sericin+ tinopal, SpfrNPV + maize flour+ jaggery and SpfrNPV suspension alone. All the treatments were found superior over control. This suggests that the Jammu isolate of SpfrNPV is likely better suited for the development as a biological insecticide for the management of S. frugiperda larval populations in J&K as a promising viable alternative to chemical insecticides
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Rashid, S. 2024. Field effectiveness of native isolates of Spodoptera frugiperdanucleopolyhedrovirus (SpfrNPV) from Jammu and Kashmir. Ph.D. Thesis, Sher-e-Kashmir University of Agricultural Sciences and Technology, Jammu