Interspecific extrinsic competition between egg parasitoids

CINGOLANI, M.F.; BARAKAT, M.C.; LILJESTHRÖM, G.G.

Ribeirão Preto

Congreso; XV SICONBIOL; 2017

Sociedade Entomológica do Brasil

In host-parasitoid interaction, parasitoids explore diverse stimuli during hosts? search. This behavior can lead to competition between adults exploiting the same host (extrinsic competition) or between larvae developing inside a host (intrinsic competition). Relative magnitude of parasitoid?s abilities in extrinsic and intrinsic competition promotes the coexistence of several parasitoids ("Counterbalanced competition"). Generally, extrinsically superior parasitoids show better abilities to locate and attack hosts. Piezodorus guildinii West. (Hemiptera: Pentatomidae) is an important soybean pest, and its main natural enemies are the oophagous parasitoids Telenomus podisi Ashmead and Trissolcus urichi Woll. (Hymenoptera: Platygastridae). Trissolcus urichi is intrinsically superior to T. podisi, but the latter is the predominant species in field parasitized hosts. Understanding competitive interactions between parasitoids is very important to improve pests? biological control as they can affect host mortality. Our objective was to evaluate the comparative abilities of T. podisi and T. urichi to exploit footprints left by P. guildinii. Parasitoids? response to walking traces was investigated in an open arena with a central circular area exposed to the stimuli. The stimuli were P. guildinii male or P. guildinii mated females in preoviposition state. Telenomus podisi and T. urichi females were tested singly by gentle release in the middle of the circular area. Trissolcus urichi spent more time exploiting the area with ♀ host traces, and showed a more active searching behavior than T. podisi. These results may indicate that T. urichi is less efficient when exploiting P. guildinii as host, as this wasp wasted more time than T. podisi exploring cues that were not directly associated with the presence of host eggs in the vicinity. These results contribute to understand the coexistence of these parasitoids in the field.