Conditional embryonic lethality to improve the sterile insect technique in Ceratitis capitata(Diptera: Tephritidae)

Marc F Schetelig,Carlos Caceres,Ernst A Wimmer,Gerald Franz,Antigone Zacharopoulou

doi:10.1186/1741-7007-7-4

Abstract

BackgroundThe sterile insect technique (SIT) is an environment-friendly method used in area-wide pest management of the Mediterranean fruit fly Ceratitis capitata (Wiedemann; Diptera: Tephritidae). Ionizing radiation used to generate reproductive sterility in the mass-reared populations before release leads to reduction of competitiveness.ResultsHere, we present a first alternative reproductive sterility system for medfly based on transgenic embryonic lethality. This system is dependent on newly isolated medfly promoter/enhancer elements of cellularization-specifically-expressed genes. These elements act differently in expression strength and their ability to drive lethal effector gene activation. Moreover, position effects strongly influence the efficiency of the system. Out of 60 combinations of driver and effector construct integrations, several lines resulted in larval and pupal lethality with one line showing complete embryonic lethality. This line was highly competitive to wildtype medfly in laboratory and field cage tests.ConclusionThe high competitiveness of the transgenic lines and the achieved 100% embryonic lethality causing reproductive sterility without the need of irradiation can improve the efficacy of operational medfly SIT programs.

Highlights

The sterile insect technique (SIT) is an environment-friendly method used in areawide pest management of the Mediterranean fruit fly Ceratitis capitata (Wiedemann; Diptera: Tephritidae)
None of the genes shows maternal expression or expression at later stages, except C.c.-sub2_63, which is expressed during germ band elongation (Figure 1E3)
Gene expression is shown by WMISH on embryos from a 0–48 h egg collection of wildtype (WT) medflies with gene-specific RNA probes for different stages during embryogenesis: early blastoderm (×1), cellularization (×2), germ band elongation (×3) and germ band retraction (×4)

Summary

Introduction

The sterile insect technique (SIT) is an environment-friendly method used in areawide pest management of the Mediterranean fruit fly Ceratitis capitata (Wiedemann; Diptera: Tephritidae). The Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann; Diptera: Tephritidae), is one of the most devastating and economically important insect pests [1]. The SIT reduces a pest population by mass release of reproductively sterile male insects into a wildtype (WT) population of the same species. This leads to the decrease of progeny by competition of sterilized males with WT males for WT females [3]. The sterilization of the pest species in SIT programs is of major importance and is commonly induced by radiation.

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