Mass production of Anagyrus ananatis Gahan (Hymenoptera: Encyrtidae) for the augmentative biological control of pink pineapple mealybug Dysmicoccus brevipes (Cockerell) (Homoptera: Pseudococcidae).

摘要

Pink pineapple mealybug (PPM), Dysmicoccus brevipes (Cockerell) (Homoptera: Pseudococcidae), transmits Pineapple Mealybug Wilt Associated Virus (PMWaV) (Closteroviridae: Closterovirus) in Hawaii. In the presence of PMWaV, feeding by PPM induces Mealybug Wilt of Pineapple, which can completely devastate a pineapple planting if PPM is not managed. Studies were conducted to develop an augmentative biological control program for PPM management using the encrytid endoparasitoid Anagyrus ananatis Gahan.Use of vermiculite in PPM rearing protocols effectively removed PPM generated honeydew that commonly entrapped mealybugs and interfered with collection of PPM individuals from squash. Infestation of Kobocha squash with mature adult PPM produced more than 2200 mature adult PPM (&ge0.6 mg) per kg squash in about 8 weeks. The size of parasitized PPM significantly affected A. ananatis body size, which partially determined the parasitoid's reproductive ability. PPM weighing &ge0.6 mg produced normal sized A. ananatis.The lower developmental threshold (To) for A. ananatis was 12.65°C. Total heat accumulation required for development from egg to adult was 265 and 275 Degree Days (DD) for males and females, respectively. Eggs began hatching after accumulating 22 DD and larval development was completed after 88--110 DD. Anagyrus ananatis pupae can be stored at 10.1°C (below the To) for one week, if preconditioned at 14.8°C (above the To) for one week, without significant effects on their survival and reproductive abilities.Big headed ant (BHA), Pheidole megacephala F. (Hymenoptera: Formicidae), effectively reduced A. ananatis parasitization of PPM to almost half of that recorded in its absence. Increased A. ananatis densities increased PPM parasitization in the presence of BHA, which suggested that augmentative field releases might help suppress PPM even when ants are present. The disruptive effects of BHA on A. ananatis parasitism could potentially be neutralized by doubling (via augmentative release) the densities of A. ananatis that provide effective PPM suppression in the absence of BHA.The most common weed hosts of PPM included rhodes grass, Chloris gayana, and wire grass, Eleusine indica, which were found in both mowed and unmowed weed bands within disturbed areas around pineapple plantings. No mealybugs collected from these weeds produced parasitoids.