Changes in Diachasmimorpha longicaudata (Hymenoptera: Braconidae) Functional Response as a Consequence of Host Density Choice

NÚÑEZ CAMPERO, REGUNDO RICARDO; BENITEZ-VIEYRA, SANTIAGO; GORLA, DAVID E.; OVRUSKI, SERGIO MARCELO

ANNALS OF THE ENTOMOLOGYCAL SOCIETY OF AMERICA

ENTOMOLOGICAL SOC AMER

Lugar: Lanham; Año: 2016 vol. 109 p. 730 - 736

0013-8746

Most predator and parasitoid functional response studies have been carried out by using experimental designswhere insects are confined to an arena and subsequently exposed to different host densities, which are evaluatedindividually. In the case of a parasitoid that looks for profitable patches, this design forces it to use the singlehost density patch available, and therefore the possibility of selection by the parasitoid is not considered atall. A selective functional response, in which the host is distributed in discrete patches at different densities,could be a solution to avoid such a limitation. However, the disadvantage of this design is that it does not meetthe independence assumption required to perform a parametric statistical analysis. Nevertheless, the use ofnonparametric analyses such as GAM and GAMM models allows the performance of this kind of design, makingthe relationship between the response and the explanatory variable more flexible, looking for general behavioralpatterns. The behavior of the fruit fly parasitoid Diachasmimorpha longicaudata (Ashmead) in apatched condition was assessed in order to demonstrate that nonparametric analyses are useful tools whenstudying the selective functional response. Results showed that the functional response changed from a ?sigmoidcurve? to a ?bell-shape curve? when the parasitoid had the chance to choose freely among different hostdensities. The female parasitoid distributed their ovarian load among the eight host densities. The present studysuggests that the bell-shape curve displays a general behavior pattern of the parasitoid population.