Demographic dynamics of Platygaster demades in response to host density
2014; Elsevier BV; Volume: 72; Linguagem: Inglês
10.1016/j.biocontrol.2014.02.008
ISSN1090-2112
Autores Tópico(s)Insect behavior and control techniques
ResumoAbstract Platygaster demades Walker (Hymenoptera: Platygastridae) is the only hymenopteran parasitoid of apple leaf-curling midge, Dasineura mali Kieffer (Diptera: Cecidomyiidae), in New Zealand. Prior to the present study the mechanisms behind the parasitoid–host density interactions were poorly understood. In this study we carried out both laboratory and field experiments to determine the response of P. demades to D. mali density. In the laboratory, when only a single parasitoid was allowed to forage D. mali eggs of a given density, P. demades displayed a Type II functional response leading to an inverse density-dependent parasitism. However, P. demades showed a Type III functional response in the field where females were able to freely search and disperse between apple shoots infested with D. mali eggs of different densities. As a result, the Type III response reflects a more realistic nature of P. demades in response to D. mali density. Our results also indicate that the numeric response and mutual interference in P. demades significantly contributed to the stability of the parasitoid–host system. The density-dependent parasitism in a host range of 50–300 D. mali eggs per apple shoot suggests that P. demades is highly efficient in controlling D. mali populations of the first, third and fourth generations and when necessary, argumentation measures may be taken before the onset of the second generation.
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