BIOLOGICAL CONTROL OF CITRUS WOOLLY WHITE FLY ALEUROTHRIXUS FLOCCOSUS MASK (HOMOPTERA: ALEYRODIDAE) BY CALES NOACKI HOW (HYMENOPTERA: APHELINIDAE) IN SOME TANZANIAN SMALL-SCALE CITRUS ORCHARDS

Cales noacki How (Hymenoptera: Aphelinidae) wwas released in citrus groves in Muheza (05°10' 0S, 38°46' 0E) and Morogoro (06° 49' 0" S, 37° 40' 0 E) Townships to control Aleurothrixus floccosus Mask (Homoptera: Alleyrodidae). Sleeve cage and “free release” methods were used to introduce the parasitoid onto selected citrus trees. C. noacki adults and mummies were released at selected sites between 08:00 and 09:30 am on 14th September 1999. Adults were first observed 90 days after introduction. They were also recovered from 2nd and 3rd CWWF instars. At Morogoro, CWWF infestations by adults, eggs and nymphs were reduced by between 6 and 12 fold 90 days after release and between 30 and 300 fold 60 months after. At Muheza decreases were between 140 and 700 and 12 and 17 fold, respectively compared. Parasitoid recovery indicated its establishment. Recoveries were also on trees up to two kilometres away from release sites. Parasitoid release was also accompanied by vigour improvement of previously heavily infested citrus trees. This is the first report of successful use of C. noacki for control of A. floccosus in Tanzania, which was prevented from spreading from the original small infestation foci.