OVIPOSITION IN CRYPTOLAEMUS-MONTROUZIERI STIMULATED BY WAX FILAMENTS OF ITS PREY

The oviposition responses of Cryptolaemus montrouzieri Mulsant (Coleop tera: Coccinellidae) to the soft scale Eupulvinaria hydrangeae (Steinw eden) (Homoptera: Coccidae) and to the mealybug Planococcus citri (Ris so) (Homoptera: Pseudococcidae) have been compared in the laboratory. The females delay oviposition and withhold mature eggs in their latera l oviducts in the absence of wax filaments produced by the prey (only present in the ovisac of E. hydrangeae, present in all stages of P. ci tri). Contact chemical cues perceived by females when probing the wax filaments with their mouthparts are the signals inducing the search fo r oviposition sites. The second step is under the control of the ovipo sitor by which females locate confined sites to lay eggs. This oviposi tion behaviour could have a considerable impact on the prey exploitati on strategy of this important biocontrol agent and might help to under stand its apparent ineffectiveness in situations of low prey density.