A metabolomics approach for improved mass-rearing

Abstract

The Sterile Insect Technique (SIT) plays a pivotal role in pest control programs, relying on the competitiveness of mass-reared sterile males when mating with wild females. Mating compatibility, a crucial element of competitiveness, involves intricate behaviors and the transfer of the ejaculate, comprising spermatozoa and seminal fluid. Established quality control guidelines for tephritid fruit flies delineate a series of routine and periodic tests to be conducted at mass-rearing facilities and fly emergence and release sites. Additional tests include assessing the rate of sperm transfer and storage invthe reproductive organs of mated female, providing relevant data on sperm quality and use. However, these tests are labor-intensive and time-consuming, rendering them impractical for routine implementation. The identification of new biomarkers capable of rapidly offering direct insights into mating abilities is highly advantageous, potentially enabling the evaluation of the impact of production enhancements on sterile males’ performance, and serving as a proxy for assessing male quality in newly developed strains. Metabolomics, the comprehensive analysis of the metabolites within a given system, instrumental in identifying such markers, could pinpoint key molecules involved in critical metabolic pathways, including those relevant to insect biology and reproduction. This study aims to generate metabolomic fingerprints for the male gut, testes and accessory glands in the Mediterranean fruit fly, Ceratitis capitata, our model species, and in the two invasive pests of EU priority, Bactrocera dorsalis and B. zonata. We are currently assessing the impact of factors such as irradiation, larval nutrition, and laboratory colonization, which can potentially alter the behavior of mass-reared males, on the metabolism of these species. A metabolomics pipeline was developed to analyze the 6,000 samples collected for the three target species using Liquid Chromatography-Mass Spectrometry (LC-MS) approaches. This biochemical information will be cross-referenced with behavioral parameters we are currently deriving to identify metabolites with the potential to become quality markers for male performance. The future development of biochemical assays to quantify these markers may facilitate the monitoring of quality parameters in mass-reared fruit fly colonies, potentially improving quality control routines in mass-rearing facilities worldwide and benefiting other tephritid pests. Funding for this study was provided by REACT (Horizon Europe, 101059523).