Phylogenetic analysis of New World screwworm fly, Cochliomyia hominivorax, suggests genetic isolation of some Caribbean island populations following colonization from South America

Abstract

. Larval infestations of the New World screwworm (NWS) fly, Cochliomyia hominivorax , cause considerable economic losses through the direct mortality and reduced production of livestock. Since the 1950s, NWS populations in North and Central America have been the target of virtually continuous eradication attempts by sterile insect technique (SIT). Nevertheless, in some areas, such as Jamaica, SIT-based control programmes have failed. Reasons for the failure of SIT-based programmes in some locations are unknown, but it is hypothesized that failure may be related to the mating incompatibility between sterile and wild flies or to the existence of sexually incompatible cryptic species. Accordingly, the current research investigates intraspecific phylogenetic relationships and associated biogeographic patterns between NWS populations from the Caribbean and South America, which represent those populations involved in, or earmarked for, forthcoming SIT programmes. Uniquely, this study also includes analyses of two North American samples, collected in Texas in 1933 and 1953 prior to initiation of the SIT-based eradication programme. The study utilizes three nucleotide datasets: elongation factor-1 ␣ (nuclear); cytochrome oxidase subunit 1 (mitochondrial), and 12S rRNA (mitochondrial). Phylogenetic analysis of these data, representing populations from across the Caribbean, South America and Texas, indicates sub-structuring of fly populations on several of the larger Caribbean islands, suggesting a period of isolation and/or founder effects following colonization from South America; significantly, our findings do not support a North American origin for Cuban flies. The importance of these findings in the light of proposed SIT programmes in the region is discussed.

The utility of microsatellite DNA markers for the evaluation of area-wide integrated pest management using SIT for the fruit fly, Bactrocera dorsalis (Hendel), control programs in Thailand

“…The SIT program in Jamaica in 1999-2005 failed because the sterile flies originated from Mexico. This failure might be a result of mating incompatibility between the sterile and the wild flies or the existence of sexually incompatible cryptic species (McDonagh et al 2009). Comparisons of the genetic variation within and between populations of target species should be investigated in order to infer the genetic similarity.…”

“…In italics, the proportions of individuals derived from the source population. Values of m above 0.1000 are in bold Table 6 Tests of the demographic contraction in each population based on mode-shift distortion in allele frequency distributions and heterozygosity excess with three underlying mutation models (IAM, SMM, and TPM) performed using BOTTLENECK (Cornuet and Luikart 1996) Population Probability values were determined using one-tailed Wilcoxon tests NS refers to no significant value a A shift in the distribution at allelic frequency classes is expected in bottleneck populations b Parameters for the TPM model included 90% signal step mutation and 10% multi-step mutation that caused failure of the control program (Macleod and Donnelly 1961;McDonagh et al 2009). If the level of sterility is insufficient, the trapping survey and the fruit sampling would reveal the expansion of the fruit fly population size and a higher fruit damage level, respectively.…”

Feasibility of Using a Caribbean Screwworm for SIT Campaigns in Brazil

“…Genetic diversity patterns of C. hominivorax populations have been extensively investigated through nuclear and mitochondrial markers, restriction fragment length polymorphism (RFLP) analyses and sequence data (Roehrdanz 1989;Taylor et al 1996a,b,c;Lyra et al 2005Lyra et al , 2009Torres et al 2007;McDonagh et al 2009;Torres and AzeredoÐEspin 2009;Fresia et al 2011). The majority of genetic studies have suggested low differentiation among C. hominivorax populations.…”

“…These results and some recent molecular studies suggesting signiÞcant genetic differentiation in C. hominivorax populations, speciÞcally in the Caribbean and south of the Amazon basin (McDonagh et al 2009, Fresia et al 2011, prompted us to conduct crossing studies to evaluate mating competitiveness, mating preference, and reproductive compatibility between two screwworm strains.…”

A new DNA extraction protocol for screwworm fly Cochliomyia species (Diptera: Calliphoridae)

“…The aim of this study was to prove a fast and user-friendly protocol of DNA isolation, that will allow to study the genetic variability and molecular taxonomy of the species in Ecuador. In order to contribute to an efficient biological control method with more genetic information based on a large number of samples in a short period of time (Klassen and Curtis, 2005;McDonagh et al, 2009).…”