RNAi-Mediated Knockdown of Chitin Synthase 1 (CHS1) Gene Causes Mortality and Decreased Longevity and Fecundity in Aphis gossypii

Abstract

Chitin is a vital part of the insect exoskeleton and peritrophic membrane, synthesized by chitin synthase (CHS) enzymes. Chitin synthase 1 (CHS1) is a crucial enzyme in the final step of chitin biosynthetic pathway and consequently plays essential role towards insect growth and molting. RNA interference (RNAi) is an agent that could be used as an extremely target-specific and ecologically innocuous tactic to control different insect pests associated with economically important crops. The sole purpose of the current study is to use CHS1 as the key target gene against the cotton-melon aphid, Aphis gossypii, via oral feeding on artificial diets mixed with dsRNA-CHS1. Results revealed that the expression level of CHS1 gene significantly decreased after the oral delivery of dsRNA-CHS1. The knockdown of CHS1 gene caused up to 43%, 47%, and 59% mortality in third-instar nymph after feeding of dsCHS1 for 24, 48, and 72 h, respectively, as compared to the control. Consistent with this, significantly lower longevity (approximately 38%) and fecundity (approximately 48%) were also found in adult stage of cotton-melon aphids that were fed with dsCHS1 for 72 h at nymphal stage. The qRT-PCR analysis of gene expression demonstrated that the increased mortality rates and lowered longevity and fecundity of A. gossypii were attributed to the downregulation of CHS1 gene via oral-delivery-mediated RNAi. The results of current study confirm that CHS1 could be an appropriate candidate target gene for the RNAi-based control of cotton-melon aphids.

Molecular Characterization of Chitin Synthase Gene in Tetranychus cinnabarinus (Boisduval) and Its Response to Sublethal Concentrations of an Insecticide

“…In grain aphid Sitobion avanae, mRNA expression level was the highest during the first-instar stage and was more than twice that what was obtained during the second-, third-or fourth-instar and adult stages [18]. The recent study performed by Ullah et al revealed that mRNA transcription of CHS1 of Aphid gossypii was highest in the first-instar nymph [38]. In the present study, the peak expression level of TcCHS1 was detected in the eggs.…”

“…The molting during metamorphosis of arthropods is a complex process containing a new cuticle forming and an old one degrading, simultaneously [38]. Several studies have demonstrated that chitin synthases (CHSs) catalyze the polymerization of Nacetylglucosamine into chitin in the final step of the chitin biosynthetic pathway, so they play crucial roles in the process of the arthropod's growth and development [27].…”

RNAi-Mediated Knockdown of Imaginal Disc Growth Factors (IDGFs) Genes Causes Developmental Malformation and Mortality in Melon Fly, Zeugodacus cucurbitae

“…RNA interference (RNAi) was simultaneously discovered as a tool for functional genomics ( Fire et al, 1998 ) and antiviral resistance strategy ( Waterhouse et al, 1998 ). Since then, it has been explored and applied as an effective tool for the control of aphids ( Zhao et al, 2018 ; Tariq et al, 2019 ; Ullah et al, 2020b ), whiteflies ( Grover et al, 2019 ), beetles ( Mehlhorn et al, 2020 ), and lepidopterans pests ( Rana et al, 2020 ), etc. Because of RNAi’s robustness and target precision, it has lowered pesticide pressure on humans and the atmosphere while minimizing negative effects on non-target and beneficial insects.…”

In Silico Studies of Lamiaceae Diterpenes with Bioinsecticide Potential against Aphis gossypii and Drosophila melanogaster

“…Aphis gossypii (Hemiptera: Aphididae) is found in many countries: India, China, the United States, Brazil, Pakistan, Australia, and Turkey, and is a global agricultural pest that affects cotton crops worldwide [ 27 , 28 , 29 ]. The pest damages many plant species worldwide causing significant economic losses, including in the families of Cucurbitaceae (melon, marrow, zucchini, watermelon) [ 27 , 30 , 31 ], and Solanaceae (chili and tomato), and in various ornamental flower species [ 31 , 32 ].…”