FORAGING BEHAVIOR OF THE WHITEFLY PARASITOID ENCARSIA-FORMOSA ON TOMATO LEAFLETS

Individual Encarsia formosa parasitoids were observed continuously until the parasitoids flew away, either on clean tomato leaflets, on leaflets with honeydew, or on leaflets with unparasitized and parasitized whitefly larvae. Encounters with unparasitized and parasitized whitefly larvae, and contact with honeydew arrested the parasitoids on the leaflet. The walking speed increased linearly from 0.179 to 0.529 mm/s between 15 and 25-30 degrees C. The walking activity showed another relationship with temperature: it was below 10% at 15 and 18 degrees C, and increased to about 75% at 20, 25 and 30 degrees C. It was not affected by host encounters or by 1 to 4 ovipositions. The total handling time of hosts was between 1.8-21.8% of the total time on the leaflet. Self-superparasitism was not observed. Conspecific-superparasitism did occur in 14% of the encounters with hosts containing a parasitoid egg,but was not observed anymore when the parasitoid egg had hatched. Experienced parasitoids superparasitized as often as naive females. The foraging behaviour of E. formosa from landing on a leaf until departure has now been quantified and is discussed.