Submitted to: Entomological Experimental Applied
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/1998
Publication Date: N/A
Interpretive Summary: The Colorado potato beetle (CPB) is an exceptionally destructive pest of potato, eggplant and tomato crops both in the United States and abroad. Populations of CPB in New Jersey eggplant fields were greatly suppressed by mass release of the parasitic wasp, Edovum puttleri. Since the wasp cannot overwinter in temperate North America, yearly agumentative releases are required to control the beetle. E. puttleri has been mass reared on CPB eggs, a method which is too costly for routine use without subsidization. However, if a rearing system using artificial diet and artificial eggs was developed, production of the wasp could become cost-effective. Our results provide important information (i.e., optimum age of host eggs for parasitization and lack of a requirement for the sticky, kairomone-containing coating of the CPB egg) for the development of such a system. These findings have made possible the development of an artificial egg in which adult female wasps will lay eggs, and have permitted us to select those CPB eggs which would be most useful for the identification of nutritional and growth factors to be included in an artificial diet. Our results concerning the effects of UV radiation and freezing of CPB eggs on parasitization by the wasp will facilitate and optimize the rearing and maintenance of Edovum colonies until an artificial rearing system is developed.
Technical Abstract: Effects of various physical and chemical treatments of Colorado potato beetle [Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)] eggs on parasitization and development of the egg parasitoid Edovum puttleri (Hymenoptera: Eulophidae) were investigated. UV irradiation did not affect host acceptance but reduced host suitability for parasitoid survival. Susceptibility of host eggs to UV irradiation varied with host age; eggs were most vulnerable to damage from irradiation at 12, 18, and 24 h post-oviposition. The rate of parasitization also was influenced by host age. Percent parasitization was greatest in 24- and 30-h old eggs. Seventy four percent of host eggs frozen at -20 degree C were parasitized by E. puttleri, but extended exposure of eggs to -20 degree C reduced both acceptance and suitability. Host eggs that had been washed with hexane (removal of kairomone) also were parasitized, although re-application of kairomone did increase the rate of parasitism. The sticky material(s) coating the egg did not appear to be essential for parasitization to occur. Our results provide effective methods and times for treating Colorado potato beetle eggs to maximize parasitization and development of E. puttleri. Selected eggs now can be analyzed to identify components and their concentrations (e.g. amino acids, sugars, hormones, growth factors, etc.) which are required by the wasp and thus, should be incorporated into an artificial diet.