REGARDING TO HOST CONDITIONING IN CITRUS MEALYBUG Planococcus citri (RISSO) (HEMIPTERA: PSEUDOCOCCIDAE)

Mealybug probing behavior studied by Electrical Penetration Graphs (EPG) method showed that either they do not reach the phloem or this is delayed to 9 hours. However, the phloem phase was reached earlier and more frequently when the mealybugs were reared on the same host used for monitoring. This result indicates the presence of host conditioning so far not reported for mealybugs. This study aimed to detect the effect of the previous experience of the citrus mealybug, Planococcus citri (Risso) (Hemiptera: Pseudococcidae) on host choice, probing behavior and development. The citrus mealybug was reared on coffee (Coffea arabica L.), citrus (Citrus sinensis L.) and squash (Cucurbita maxima L.) whose were named as source hosts, and transferred to coffee or citrus as receptor host plants. The study included choice tests, electrical penetration graphs (EPG) and development studies. The choice test between coffee and citrus in the first 72 hours showed that mealybugs reared on coffee showed a preference to settle on coffee. When the source plant was citrus the insects showed a trend, even not significant, to select citrus over coffee. On the other side, those mealybugs taken from a squash culture did not show any preference neither for coffee nor citrus. The probing behavior monitoring showed that the phloem phase, considered important in plant acceptance, was more frequent in coffee plants, regardless using coffee or citrus as source plants. Those insects transferred from squash to coffee or citrus showed none or a very short phloem phase. Transferring the mealybugs, from any host to coffee or citrus did not modify the development time, fecundity or mortality. However, those reared and transferred to squash presented a higher fecundity. Thus, even showing some preference for the source plants in the choice test, the transferring from coffee or citrus does not modify significantly the mealybug development or probing behavior.