Superparasitismo de Palmistichus elaeisis (Hymenoptera: Eulophidae) y comportamiento de defensa de dos hospederos Translated title: Superparasitism by Palmistichus elaeisis (Hymenoptera: Eulophidae) and defense behaviors of two hosts

Abstract

Varias familias de parasitoides son capaces de discriminar entre los hospederos parasitados y no-parasitados. Sin embargo, algunos casos de superparasitismo pueden ocurrir en especies de Eulophidae. El objetivo del presente estudio fue investigar si hembras de Palmistichus elaeisis (Eulophidae) superparasitan pupas de Thyrinteina arnobia (Lepidoptera: Geometridae) y de Hylesia sp. (Lepidoptera: Saturniidae) en laboratorio, describiendo mecanismos de defensa de dichos hospederos. El experimento se realizó en el insectario de la Universidade Federal de Viçosa, Brazil. Se utilizaron cajas de Petri como cámaras de oviposición, conteniendo dos pupas de T. arnobia, una de ellas parasitada por P. elaeisis y otra sin parasitar. De igual forma se mantuvieron cajas de Petri con dos pupas de Hylesia sp. Para los dos tratamientos, se liberaron diez hembras de P. elaeisis en la parte central de cada caja de Petri, el cuál constó una repetición. Se usó un total de ocho repeticiones por cada tratamientio. Se observó la preferencia de oviposición de P. elaeisis sobre las pupas hospederas durante seis horas y se analizaron mediante la prueba de chi-cuadrado (X²) (P 0,01). Observando el comportamiento de defensa de los hospederos, las pupas de T. arnobia presentaron movimientos giratorios, lo que indujo el superparasitismo en las pupas de menor movilidad. Los individuos de Hylesia sp. no presentaron comportamiento de defensa, y en este caso la discriminación llegó a una preferencia clara para las pupas no parasitadas.

Translated abstract

Several families of parasitoids are capable of discriminating among parasitized and unparasitized hosts. However, some cases of superparasitism have been recorded in species of Eulophidae. The objective of this study was to investigate whether females of Palmistichus elaeisis (Eulophidae) superparasitize pupae of Thyrinteinaarnobia (Lepidoptera: Geometridae) and Hylesia sp. (Lepidoptera: Saturniidae) in the laboratory and to describe the defense mechanisms of those hosts. The experiment was done in the insectary of the Universidade Federal de Viçosa, Brazil. Petri dishes were used as oviposition chambers and contained two T. arnobia pupae, one of them parasitized by P. elaeisis and the other not. The pupae were placed on each side of the dish. Petri dishes were likewise set up with two pupae of Hylesia sp. For both treatments, ten females of P. elaeisis were released in the center of the dish, which represented a replicate. A total of eight replicates were used for each treatment. The oviposition preference of P. elaeisis on host pupae was observed for six hours and analyzed using the chi-square test (X²) (P 0.01). In observing the defense behavior of the hosts, T. arnobia pupae showed spinning movements which in turn induced superparasitism in less mobile pupae. Individuals of Hylesia sp. did not show any defense behavior and in this case the discrimination led to a clear choice for the unparasitized pupae.