Male-biased Adult Production of the Striped Fruit Fly, Zeugodacus scutellata, by Feeding dsRNA Specific to Transformer-2.

Md Abdullah Al Baki,Yonggyun Kim,Mohammad Vatanparast

doi:10.3390/insects11040211

Abstract

Sterile insect release technique (SIT) is effective for eradicating quarantine insects including various tephritid fruit flies. When SIT is used for fruit flies, it is challenging to remove females from sterile males due to oviposition-associated piercing damage. This study developed a sex transition technique by feeding double-stranded RNA (dsRNA) specific to a sex-determining gene, Transformer-2 (Zs-Tra2) of the striped fruit fly, Zeugodacus scutellata. Zs-Tra2 is homologous to other fruit fly orthologs. It is highly expressed in female adults. RNA interference (RNAi) of Zs-Tra2 by injecting or feeding its specific dsRNA to larvae significantly increased male ratio. Recombinant Escherichia coli cells expressing dsRNA specific to Zs-Tra2 were prepared and used to feed larvae to suppress Zs-Tra2 gene expression levels. When these recombinant bacteria were fed to larvae during the entire feeding stage, the test population was significantly male-biased. Some females treated with such recombinant E. coli exhibited mosaic morphological characters such as the presence of male-specific abdominal setae in females. This study proposes a novel technique by feeding dsRNA specific to Transformer-2 to reduce female production during mass-rearing of tephritid males for SIT.

Highlights

A number of tephritid fruit flies are designated as quarantine pests in many countries [1]
Z. scutellata larvae were collected from a pumpkin field in Andong, Korea and reared on a larval artificial diet consisting of 1 g agar, 5 g pumpkin powder, 5 g yeast, 4 g wheat bran, 5 g sugar, 4 g casein, 1 g citric acid, 0.5 g sodium benzoate, 0.1 g methyl-p-hydroxybenzoate, and 0.02 g streptomycin in 73.38 mL water
This study aimed to develop a technique for the sex transformation of Z. scutellata using sex determination system

Summary

Introduction

A number of tephritid fruit flies are designated as quarantine pests in many countries [1]. These fruit flies are classified into the Tephritoidea superfamily of about 7300 species [2] with two possible origins based on molecular phylogenetic analysis [3]. In Korea, 90 tephritid species have been identified, of which two species (Zeugodacus depressa and Z. scutellata) are regarded as insect pests [6]. The striped fruit fly, Z. scutellata, occurs in Asian countries such as Korea, Japan, Taiwan, China, Bhutan, Thailand, India, and Malaysia [7]. Chinese cucumber (Trichosanthes kirilowii) is the main wild host of Z. scutellata. Chemical and biological control tactics have been developed to control fruit fly populations, sterile insect release technique (SIT) is known to be effective in eradicating the fruit flies [12]

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