Seasonal Parasitism of the Leaf-Cutting Ant Atta sexdens Linnaeus (Hymenoptera: Formicidae) by Phorid Flies (Diptera: Phoridae) in a Brazilian Cerrado-Atlantic Forest Ecotone

Abstract

Phorid flies (Diptera: Phoridae) parasitize insects of many orders including leaf-cutting ants, which are pests of several crops. These parasitoids may have a significant impact on ant behavior by altering their foraging rhythm. Seasonal variations in climatic variables, such as temperature and humidity, influence the abundance, activity period, distribution, and reproduction of insects. Therefore, knowledge of parasitoid seasonal patterns is important for biological control success. In this study we evaluate the parasitism of the leaf-cutting ant Atta sexdens L. (Hymenoptera: Formicidae) by Apocephalus attophilus Borgmeier and Eibesfeldtphora tonhascai Brown (both Diptera: Phoridae) across seasons throughout a yr in a Brazilian Cerrado-Atlantic Forest ecotone, and compare their parasitism in a semi-deciduous seasonal forest fragment and urban area. The number of ants parasitized by A. attophilus and E. tonhascai was higher in the winter and spring, respectively, but similar in summer and fall. Apocephalus attophilus parasitism was negatively correlated with temperature but not with relative humidity, whereas ant parasitism by E. tonhascai presented no correlation with either parameter. The number of ants parasitized by A. attophilus and E. tonhascai in the semi-deciduous seasonal forest fragment was higher than in urban areas. Knowledge of biotic and abiotic factors influencing the population dynamics of phorid flies is important for rearing and releasing protocols for these parasitoids.