Distribution of invasive versus native whitefly species and their pyrethroid knock-down resistance allele in a context of interspecific hybridization

The invasion success of a species in an agrosystem is greatly influenced by environmental factors such as the use of insecticides, by the intrinsic evolutionary capabilities of the species, and also by interactions with resident species. On the island of La Reunion, the successive invasions of MEAM1 and MED whitefly species over the last 20 years have not only led an increased use of insecticides, but have also challenged the resident 10 species. To trace the evolution of the 3 species, and the distribution of the kdr mutation (resistance to pyrethroid) in the para-type voltage-gated sodium channel, we genotyped 41 populations (using neutral nuclear markers) and look at the prevalence of the kdr allele. MEAM1 was predominantly present in agrosystems showing quasi fixation of the resistant kdr allele whereas 10 was mainly in natural environments and did not have any resistant allele. Hybridization between the two former species was detected in low frequency but has not led to introgression of resistant alleles in the resident species so far. MED showed a limited distribution in agrosystems but all individuals displayed a resistant allele. These highly contrasting patterns of distribution and resistant mutations between invasive and resident whitefly species are further discussed.

Automated summary

The success of species invasion in agrosystems is affected by factors such as insecticide use, species evolutionary capabilities, and interactions with resident species. The invasions of MEAM1 and MED whitefly species have led to increased insecticide use and challenges for resident species on La Reunion Island. The study genotyped 41 populations and found that MEAM1 predominantly existed in agrosystems with a resistant kdr allele, while 10 mainly existed in natural environments without any resistant allele. Hybridization between the two species was detected in low frequency, but resistant alleles did not introgress into the resident species. MED showed limited distribution in agrosystems, but all individuals displayed a resistant allele.