Effect of Telenomus podisi, Trissolcus urichi, and Trissolcus basalis (Hymenoptera: Platygastridae) Age on Attack of Piezodorus guildinii (Hemiptera: Pentatomidae) Eggs

Abstract

Parasitoid's performance is subject to parasitism decisions inßuenced by host quality and parasitoidÕs age. We evaluated parasitism, emergence, and the progeny sex ratio proportions of Telenomus podisi (Ashmead), Trissolcus urichi (Crawford), and Trissolcus basalis (Wollaston) (Hymenoptera: Platygastridae) females of different age attacking Piezodorus guildinii (Westwood) (Hemiptera: Pentatomidae), an important soybean pest. Eggs were offered to females of T. podisi 1Ð10 d old, T. urichi 1, 3, 4, or 6 d old, or T. basalis 1Ð 6 or 8 d old. Average egg parasitism proportions were 0.71 and 0.79 to T. podisi and T. urichi, respectively; and preimaginal survivorship was 97% for both species. Trissolcus basalisfemales 1, 2, and 3 d old did not parasitize P. guildinii eggs, and high parasitism proportions were recorded from older females, but only 0.5 of females attacked host eggs. A greater proportion of males were produced in the progeny of T. podisi and T. urichi as maternal age increased, but no differences were found in the progeny of T. basalis wasps of different ages. The results from this study indicate that performance of T. podisi and T. urichi would not be affected by the age of the females. However, aging would induce T. basalis females to attack P. guildinii, although it is known that their main host is Nezara viridula (L.) (Hemiptera: Pentatomidae). Under certain circumstances, such as shortage of preferred host availability, high egg load, and short life expectancy, this wasp may include P. guildinii as a host.

El desempeño delos parasitoides depende delas decisiones de parasitismo,influenciadas por la calidad del hospedador y la edad del parasitoide. Evaluamos las proporciones de parasitismo, emergencia de la progenie, y sexos en la progenie de hembras de Telenomus podisi (Ashmead), Trissolcus urichi (Crawford) y Trissolcus basalis (Wollaston) (Hymenoptera: Platygastridae) de diferentes edades, parasitando huevos de Piezodorus guildinii (Westwood) (Hemiptera: Pentatomidae), principal plaga de soja. El hospedador fue ofrecido a hembras de T. podisi de 1Ð10 días de edad, T. urichi 1, 3, 4 o´ 6 días, o´ T. basalis 1, 2, 3, 4, 5, 6 o´ 8 días. Las proporciones promedio de parasitismo fueron 0,71 y 0,79 (T. podisi y T. urichi respectivamente), y la supervivencia preimaginal superior al 97% para ambas. Hembras de T. basalis de 1, 2 y 3 dõ´as no parasitaron. La proporción de parasitismo fue alto para las avispas mayores, si bien solo 0,5 de las hembras ataco´ los huevos ofrecidos. A mayor edad de las avispas, mayor proporción de machos en la progenie de T. podisi y T. urichi, pero en la progenie de T. basalis de distintas edades no hubo diferencias. El desempeño de T. podisi y T. urichi no será afectado por la edad de las hembras. Sin embargo, a mayor edad, las hembras de T. basalis serían inducidas a atacar a P. guildinii, un hospedador de baja calidad. Con escasez del hospedador preferido, alta carga de huevos y baja expectativa de vida, esta avispa utilizaría a P. guildinii como hospedador.