Browsing by Author "Vijayan, Vishakh"

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    Identification of novel target genes for RNAi mediated management of the pest, Fall Armyworm (Spodoptera frugiperda, J. E. Smith)
    (Elsevier B.V., 2025) Bera, Paramita; Suby, S.B.; Dixit, Sameer; Vijayan, Vishakh; Kumar, Naveen; Sekhar, J.C.; Vadassery, Jyothilakshmi
    RNA interference (RNAi) of vital insect genes is a potential tool for targeted pest management. However, the selection of the right target genes and its dsRNA delivery method is also a challenge because the RNAi efficacy is known to vary among insect species. Fall Armyworm (FAW; Spodoptera frugiperda) is a polyphagous generalist insect pest that can feed on more than 100 plant species, with a strong preference for maize. In the present study, we evaluated the RNAi efficiency of three vital genes coding for Coatomer Subunit alpha (COPIα), Coatomer Subunit beta (COPIβ) and Glutathione-S-transferase U1 (GSTU1) as potential targets for managing FAW. Real-time PCR analysis showed that the target genes' expression level reduced to 75–80% in FAW larvae, after their continuous oral delivery through diet for 8 days. It also caused significant mortality in larvae (40–50%) and pupae (40–62%), and resulted in deformed intermediates (28–38%) and adults (25–40%). It also affected reproduction as evidenced by an approximately 50% reduction in oviposition. Moreover, exogenous application of dsRNA in maize leaves resulted in significant feeding deterrence by FAW larvae, which enhanced the frequency of cannibalism. The impact of target genes’ dsRNA on the biology and behaviour of FAW suggests their insecticidal potential. Thus, the current study reveals the novel target genes and their utility in RNA based pesticides for sustainable management of FAW.
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    Secret weapon of insects: The oral secretion cocktail and its modulation of host immunity
    (Oxford University Press, 2024) Prajapati, Vinod Kumar; Vijayan, Vishakh; Vadassery, Jyothilakshmi
    Plants and insects have co-existed for almost 400 million years and their interactions can be beneficial or harmful, thus reflecting their intricate co-evolutionary dynamics. Many herbivorous arthropods cause tremendous crop loss, impacting the agro-economy worldwide. Plants possess an arsenal of chemical defenses that comprise diverse secondary metabolites that help protect against harmful herbivorous arthropods. In response, the strategies that herbivores use to cope with plant defenses can be behavioral, or molecular and/or biochemical of which salivary secretions are a key determinant. Insect salivary secretions/oral secretions (OSs) play a crucial role in plant immunity as they contain several biologically active elicitors and effector proteins that modulate plants’ defense responses. Using this oral secretion cocktail, insects overcome plant natural defenses to allow successful feeding. However, a lack of knowledge of the nature of the signals present in oral secretion cocktails has resulted in reduced mechanistic knowledge of their cellular perception. In this review, we discuss the latest knowledge on herbivore oral secretion derived elicitors and effectors and various mechanisms involved in plant defense modulation. Identification of novel herbivore-released molecules and their plant targets should pave the way for understanding the intricate strategies employed by both herbivorous arthropods and plants in their interactions.