Life-history and oviposition behaviour of Amitus bennetti, a parasitoid ofBemisia argentifolii

Amitus bennetti Viggiani & Evans (Hymenoptera: Platygasteridae) is a recent ly described parasitoid of the silverleaf whitefly, Bemisia argentifolii Be llows & Perring (Homoptera: Aleyrodidae). Behaviour and life history of the parasitoid are described. The first nymphal instar of B. argentifolii is p referred by the parasitoid, but the 1st through 4th instar may be parasitis ed. Females first investigate hosts with their antennae, then walk over the host, and eventually step with their front legs on the leaf and insert the ir ovipositor inside the host facing away from the host, while the hind leg s are still on the host. The time from encounter to oviposition (=latency t o oviposition) is shortest on the 1st instar. Oviposition duration (mean=39 s) comprises 50% of the handling time. Development time from egg to adult decreases from 72 days at 15 degrees C to 42 days at 20 degrees C to 28 day s at 25 degrees C. We estimate that 400 degree days is required for develop ment, with a development threshold of 10 degrees C. Adult longevity in the absence of hosts was 29, 26 and 19 days and with hosts present 8, 8 and 5 d ays at 15, 20 and 25 degrees C, respectively. Amitus bennetti is proovigeni c and oviposits most eggs shortly after adult emergence. During the first d ay of their adult lives females laid 1, 31 and 49 eggs at 15, 20 and 25 deg rees C, respectively. Compared with other parasitoid species, the developme nt time of A. bennetti is very long, and the implications of this for manag ement of B. argentifolii are discussed.