Implications of mitonuclear interactions for the Trojan Female Technique in pest biocontrol: A case study on the seed beetle Acanthoscelides obtectus

Abstract

The seed beetle (Acanthoscelides obtectus) is a pest of common beans and other legumes that causes considerable losses of stored products. Its populations are universally regulated with insecticides, but novel, safer and more efficient methods of control are needed. One such method is the Trojan Female Technique (TFT) which is based on the existence of male harming/female benign mitochondrial haplotypes. The introduction of females carrying haplotypes with male-specific negative effect into the target population can lead to its self-perpetuating suppression over generations. Due to the coevolution of mitochondrial and nuclear genomes, it is possible for nuclear variants that compensate for the negative effects of male harming mitochondrial haplotypes to evolve. Therefore, one of the requirements for the applicability of TFT is that candidate mitochondrial haplotypes confer their negative effects on males in diverse nuclear backgrounds. In this study, we used the previously described mitochondrial haplotype, MG3b, which reduces male-only fertility, and placed it in a range of nuclear backgrounds from three different natural populations. The goal was to test whether its effects on male and female fertility are dependent on interactions with different nuclei. Our results showed that MG3b consistently decreases male fertility independently of the nuclear environments, while having no negative effect on females. Additionally, we found no statistically significant effect of mitonuclear interactions, suggesting that there is no standing variation of compensatory mutations in nuclear backgrounds. These results indicate that the MG3b haplotype could be used in the TFT in different natural seed beetle populations.