| Abstrakt: |
Microctonw hyperodae Loan is an effective parasitoid against Listronotus bonariensis (Kuschel) in New Zealand. To determine the potentialfor M. hyperodae as a biological control agent for L. macubcollis Dietz, live specimens were imported to a quarantine facility in New Zealand. A series of experiments examined the suitability of 3 South American geographic populations (ecotypes) of M. hyperodae in terms of parasitism rates, prepupal emergence, and development times compared with the natural host, L. bonariensis. Limited development occurred inL. mamhcollis by all 3 ecotypes, but parasitism rate was significantly lower than in L. bonariensis. Comparison with a related parasitoidshowed higher rates of prepupal emergence from L. mamlicollis for M.aethiopoides Loan than for M. hyperodae. The presence of annual bluegrass, Poa annua, in the test arena and prior experience on L. maculicollis increased parasitism rate significantly when a combination of L. maculicollis and L. bonariensis were exposed to M. hyperodae. The low rate of successful prepupal emergence by M. hyperodae in L. maculicollis was attributed in part to a physiological response by L. maculicollis which led to encapsulation of the developing parasitoid egg and larva. Based on these results, M. hyperodae probably would not bea suitable biological control agent of L. maculicollis in the UnitedStates because of the low rates of parasitism observed under laboratory conditions and delayed development times compared with those in the natural host, L. bonariensis. M. aethiopoides is more successful in parasitizing and developing in L. maculicollis, but this parasitoidalso exhibited significantly lower levels of parasitism compared with L. bonariensis, although development times were comparable. Furthermore, M. aethiopoides used in these trials probably originated in North Africa and may not be suited to a northeastern United States climate. [ABSTRACT FROM AUTHOR] |
