Trojan Female Technique for the biocontrol of the seed beetle Acanthoscelides obtectus: mitochondrial haplotype has negative male-specific effect on fertility across different nuclear backgrounds

Abstract

The seed beetle Acanthoscelides obtectus is one of the most economically important pests of stored legume seeds worldwide and is traditionally controlled with synthetic pesticides. However, the frequent use of these toxic compounds leads to environmental and health damage and the evolution of resistant insect populations. The Trojan Female Technique (TFT) is a novel species-specific, transgenerational biocontrol method for pest management. Sustained population control is achieved by releasing of Trojan females (TF) that carry naturally occurring mitochondrial DNA mutations (TFT mutation) that impair male fertility, but have no effects on females. TF and their female offspring could continuously, over multiple generations, produce males that sire fewer offspring than their wild-type counterparts. A candidate TFT mutation that causes male-only subfertility was recently described in A. obtectus. However, the applicability of TFT depends on mitochondrial TFT mutations whose male-sterilizing effects are general across different nuclear genomic contexts. We tested this assumption by expressing the candidate TFT mitochondrial haplotype alongside a range of three nuclear backgrounds and comparing its fertility in males with that of control haplotypes. We found that the fertility of males harbouring the candidate TFT mutation is consistently lower in all three nuclear backgrounds.