Prey range of Nephaspis bicolor Gordon (Coleoptera: Coccinellidae), a potential biological control agent of Aleurodicus dispersus and other Aleurodicus spp. (Homoptera: Aleyrodidae)

Nephaspis bicolor Gordon is a potential candidate for the biological control of Aleurodicus dispersus Russell. Its prey range was assessed based on the published literature, and field and laboratory studies. Tests were carried out to assess the suitability of 20 potential prey species selected based on a modified centrifugal system and/or perceived importance by importing authorities. In general, Nephaspis spp. were only associated with non-aleyrodid prey when these occurred together with aleyrodid prey. On all prey except Aleyrodidae, survival of N. bicolor adults and larvae was similar or lower than controls (no food) suggesting that these were unsuitable as a food resource. Generation survival and reproduction occurred only on Aleyrodidae and the presence of wax appeared to be an important cue for oviposition. As expected, no feeding occurred on honeybees, silkworms or predatory mites. N. bicolor adults attacked parasitized whitefly prey but they appeared to recognize and avoid prey with mature parasitoid larvae or pupae. Based on the information adduced, it was concluded that N. bicolor was an aleyrodid predator. Within the Aleyrodidae, the prey range could not be delimited without doing specific tests on individual species, but there was ample field and laboratory evidence that N. bicolor was specialized to attacking wax-producing species, in particular Aleurodicus spp. and Aleurothrixus flocossus Maskell.