Does thermal history affect field dispersal ability of the oriental fruit fly, Bactrocera dorsalis (Hendel), under diverse environmental conditions?

Abstract

As ectotherms, insects are particularly dependent on the thermal environment. Temperature directly affects life-history traits such as development rate, lifespan, reproduction and dispersal ability. Understanding the factors that influence the dispersal ability of insect pests is key to implement successful biological control methods, the sterile insect technique and to predict invasion potential. The oriental fruit fly, Bactrocera dorsalis (Hendel), is an invasive horticultural pest that rapidly spread throughout Africa after colonising the continent in the early 2000s. However, despite the severe yield loss that the agricultural sector may suffer due to this species, little is known about how B. dorsalis may spread under various climatic conditions and if thermal history might influence such dispersal patterns. In this study, to determine the effect of thermal history on dispersal ability of B. dorsalis we used coloured pigments to mark 6 day-old adults pre-treated to either 20, 25 or 30°C for a period of 4 days. These sterile flies were then released in an agricultural environment where 28 baited-traps (Methyl Eugenol, Biolure or a combination of both) were located on a trapping grid and ambient microclimate temperature and humidity recorded. Traps were inspected daily and the flies caught assigned to a treatment group based on visual identification of the pigments. Using a release-recapture method, we will determine how thermal history modulates dispersal performance of the oriental fruit fly under cold, mild and hot environmental conditions in the field. This data will help to understand the rapid spread of the species and inform pest management procedures.