The Study Of Parasitism Charactertistics Of Aenasius Bambawalei, A Predominant Parasitoid Of Phenacoccus Solenopsis

Phenacoccus solenopsis appeared in recent years is an alien invasive pest, which has a seriousthreat to field crops, ornamental plants, fruit trees and vegetable crops. It is predicted that outbreakingsof this pest in China will result in nearly100million losses. The parasitoid, Aenasius bambawalei Hayat,has been recently reported as the predominant natural enemy of P. solenopsis. This paper studies1) thebiological characteristics of A. bambawaleiis;2) the parasitic efficiency of A. bambawaleiis underco-existence of Acerophagus coccois;3) based on DC-EPG, feeding behaviors of P. solenopsisparasitized by A. bambawaleiis; and4) the sensitivity of A. bambawaleiis to chlorpyrifos andimidacloprid and detoxification enzymes activity by the spray and dipping methods. These results areexpected to provide a scientific basis for the biological control of P. solenopsis.The results were asfollows:(1) A. bambawaleiis could target on the nymphs and adults of P. solenopsis; and the parasitizationefficiency to the adults was higher than that to the nymphs, and the individual developmental durationof the parasitoid parasitized in the adults was shorter than those parasitized in the nymphs. For A.coccois compared to A. bambawaleiis, the parasitization rate was much lower, the parasitoiddevelopmental duration was shorter, and the adult parasitoid emergence was fewer.(2) Under co-existence of A. coccois, parasitization effeciency of A. bambawaleiis wassignificantly affected. Parasitization rate of A. bambawaleiis seperately on P. solenopsis was higher thanthat of A. coccois and co-existence of the two parasitoids. Among the treatments of the co-existence oftwo parasitoids, the order of the different parasitism was significantly different with parasitization rateof the2instar nymphs.(3) EPG analysis showed that the feeding behaviors of P. solenopsis parasitized by A.bambawaleiis were affected. At3and6days post-parasitization, time of non-probing intervals ofmealybug is significantly longer than non-parasitized mealybug; time to first feeding probe, the numberof C, the number of E1, and the frequency and duration of pd were significant difference compared withnon-parasitized mealybug. But the number of probing intervals and non-probing intervals and total timeof C were not significant different from the control. At6days post-parasitization, the frequency andduration of pd of the mealybugs parasitized by A. bambawaleiis was significantly different from those parastized by A. coccois. At3days post-parasitization, the duration of mealybug stylet into the phloem(E1) was significant difference between the two parasitoids, and A. bambawaleiis was longer than the A.coccois.(4) Toxicity to A. bambawalei were estimated by spray and leaf-dipping methods, The resultsshowed that1) By spray, LC50to chlorpyrifos was2.595μg L-1, and imidacloprid was0.115mg L-1,2)by leaf dipping method, chlorpyrifos was0.112μg L-1, and imidacloprid was0.234mg L-1, and3) thelethality of chlorpyrifos was higher than imidacloprid. These two pesticides had significant effects onthe parasitization efficiency of the parasitoid, but no effect on the hind tibia length of the adults emergedfrom the mummies. Activity of AchE after chlorpyrifos treatment was inhibited by76.4%, whileactivities of CarE and MFO in the imidacloprid treatments were inhibited by32.2%and85.3%,respectively.