Seasonal phenology and natural enemies of the oleander mealybug, Paracoccus burnerae (Brain) (Hemiptera: Pseudococcidae), in South Africa

摘要

The importance of Paracoccus burnerae has risen over the years to an extent where it is now not only a serious pest of citrus, but is also a quarantine pest for citrus fruit imported from South Africa. The field biology of P. burnerae on citrus in theWestern Cape Province of South Africa was studied through periodic sampling of leaves from twigs enclosed in sleeve cages. The species composition and abundance of natural enemies was investigated. Both adult and immature stages attained maximum population peaks in March and P. burnerae had four generations. The highest level of mortality was experienced in the immature stages. Climate and an unidentified fungus were the key mortality factors. The level of abundance of the two observed predators, the harlequin beetle, Harmonia axyridis, and the green lacewing, Chrysoperla sp., was relatively low. Although parasitism occurred in some cages, the level was low, ranging between 1.62 and 9.43 %. If biocontrol is the preferred method of controlling P. burnerae, suitable candidate parasitoids for inoculative biocontrol are Acerophagus sp., Leptomastix sp. and Microterys nietneri. The oleander mealybug does not share the same parasitoids with Planococcus citri, Pseudococcus calceolariae and Pseudococcus longispinus except for the parasitoid Coccophagus sp. The most popular species of parasitoids used in the biolological control of mealybugs, Anagyrus sp. and Coccidoxenoides sp., were insignificant in the case of P. burnerae.