More is not always merrier: Does increased parasitoid community complexity disrupt biological control of giant whitefly Aleurodicus dugesii (Hemiptera: Aleyrodidae) in California?

When multiple conspecific or heterospecific parasitoid females parasitize the same host, intense larval (intrinsic) competition can occur. Because parasitoids are widely used as control agents for many economically important pest species, a significant effort has gone into elucidating the form, function, and outcome of competitive interactions between multiple parasitoid species, so that these interactions can be manipulated in a predictive manner. Recently classical intraguild predation (IGP) theory has been applied to examine how coexistence between multiple parasitoid species is mediated in systems with high levels of intrinsic competition. It is still unclear however, whether applying IGP theory is a valid approach due its successful application in only a few parasitoid communities under laboratory conditions. In order to further test the applicability of IGP theory for explaining parasitoid coexistence we examined the role of intrinsic interactions in mediating coexistence between three parasitoid species Encarsia noyesi, Idioporus affinis, and Entedononecremnus krauteri under laboratory and field conditions. These parasitoids were introduced to California to control the invasive giant whitefly (Aleurodicus dugesii). In this talk, we will present preliminary data from our efforts and discuss our plans to further address this question.