The Impact of Climate on the Biological Control of Citrus Mealybug [Planococcus citri (Risso)] by the Parasitoid Coccidoxenoides perminutus Girault as Predicted by the Climate-Matching Program CLIMEX

摘要

We used the climate-matching program CLIMEX to assess the influence of climatic conditions in Southeastern Queensland, Australia on the effectiveness of the parasitoid, Coccidoxenoides perminutus Girault, against the citrus mealybug, Planococcus citri(Risso). Climate was compared across areas where the parasitoid has shown successes and failures in controlling mealybug populations. If climatic conditions impact significantly on C. perminutus biocontrol performance, the CLIMEX output of Ecoclimatic Index (El) would indicate that the localities worldwide where the species is relatively successful have suitable climatic conditions (El > 40). Southeastern Queensland data indicated C. perminutus population is relatively low in citrus mealybug samples from two citrus-producing localities, Mundubbera and Nambour. If climatic conditions impact significantly on C. perminutus survival, the model should also predict that the climates, as expressed by the climate Match Index (Ml), of southeastern Queensland are not particularly suitable for C. perminutus (Ml < 40). CLIMEX predicted Mundubbera and Nambour to be favorable for the population growth and persistence of C. perminutus. Also, the climates of these two Australian localities matched closely with thoseof localities worldwide where C. perminutus does impose some degree of biocontrol. Although the model requires adjustment, it does establish that the citrus-producing areas of southeastern Queensland are suitable for the persistence of C. perminutus. Presumably, other factors in combination with climate reduce the efficacy of the species as a control agent against citrus mealybug.