Frass-mediated, Host-finding Behavior of Cotesia flavipes, a Braconid Parasite of Diatraea saccharalis (Lepidoptera: Pyralidae)

Host-finding behavior of the parasitic wasp, Cotesia flavipes (Cameron), is mediated by a water-soluble substance present in the fresh frass of larval Diatraea saccharalis (F.). Larval frass elicited a characteristic host-seeking response by the parasite. Upon contacting fresh larval frass, female C. flavipes exhibited a decreased rate of locomotion, coupled with intense palpitation of the frass with their antennae. Ovipositional probing was initiated only when physical contact was made with a D. saccharalis larva. Dry frass did not elicit a host-seeking response. However, fresh, moist frass dried for 6 h and remoistened retained original attractiveness. The presence of frass did not significantly enhance parasite oviposition. D. saccharalis frass from sugarcane, Saccharum officinarum L., was more attractive to C. flavipes females than frass from Johnson grass, Sorghum halepense (L.) Pers, when the parasite was given a choice. However, frass from both sources were equally attractive in a no-choice situation.