First occurrence of Euneura sopolis (Hymenoptera, Pteromalidae) hyperparasiting Xenostigmus bifasciatus (Hymenoptera, Braconidae) in Brazil: implications for biological control of pine aphids.

Abstract

It is estimated that the planting of pinus in Brazil exceeds 2 million hectares comprising mainly two species Pinus taeda and P. elliottii. Due to the expansion of this culture and the often inappropriate cultural methods, this crop became increasingly susceptible to pest insects (Zaleski et al., 2005 ). Among these the aphids are outstanding due to their characteristics such as high fertility, presence of both wingless and winged forms, thus facilitating dispersal, parthenogenetic reproduction that coupled to the favorable Brazilian climatic conditions make them one of the most important pests of Pinus spp. plantations (Penteado et al., 2004).Because aphids are easily dispersed, several species some of the genus Cinara occur in the regions with conifers plantations, usually of the families Pinaceae and Cupressaceae as hosts. They are observed feeding on pine branches, sprouts and even the roots ( Penteado et al., 2004 ). In this genus there are ca. 200 species ( Costa et al., 1993 ). According to Sousa-Silva and Ilharco (1995) , the species Cinara atlantica, C. cupressi, C. fresai, C. maritimae, C. piniformosana, C. pinivora and C. tujafilina occur in Brazil.Infestations of aphids on pine can cause considerable decrease on growth and morphological changes that significantly reduces the economic value of wood (Zaleski et al., 2005 ). The control of aphids is based mainly on biological methods using predators, parasitoids and entomopathogenic fungi.Predators as the coleopterans (Coccinellidae), neuropterans (Chrysopidae) and the larvae of the dipterans (Syrphidae), are found near the colonies of aphids, which occur in abundance in the winter, when the number of predators decreases and the control of large pest populations decreases as well. Therefore, the use of parasitoids, besides being specific is also more efficient (Penteado et al., 2004 ). The state to control the species parasitoids species belonging to the genera Pauesia and Xenostigmus (Hymenoptera: Braconidae) are the most frequently used to control aphids attacking pine plantations.To control populations of C. atlantica C. pinivorain pinus plantations in Parana state, Brazil, a program was started to introduce the parasitoid Xenostigmus bifasciatus from the USA east coast. The mummified aphids were collected in North America and a quarantined was carried out in Brazil before these parasitoids were cultured and released in the field (Penteado et al., 2004). The release occurred between 2002 and 2004 in different municipalities of Parana and Santa Catarina states. Shortly thereafter, this parasitoid was recorded in several areas attacked by the pine aphid and its dispersion was estimated at approximately 80 km per year, and so its establishment in Brazil was confirmed (Penteado et al., 2004).This study aimed to determine the occurrence of aphid species in a P. elliottii plantation in a Cerrado area at the Sao Carlos region and the possible occurrence of their natural enemies. Ten samplings were carried out from October 2013 to August 2014 in P. elliottii plantation area of approximately 4,000 square meters at the 21 ° 58’24.02 “S, 47 ° 53’7.39” W. The collected aphids were placed in bottles containing 100% alcohol and later mounted on microscope slides, according to the methodology described by Ilharco and Lemos (1981). They were subsequently identified under an optical microscope using the key of Costa et al. (1993). The mummies were placed in Eppendorf tubes and after the emergence the parasitoids were preserved in 70% ethanol and then mounted and identified.Cinara maritimae was the aphid with the highest frequency of occurrence during the collection period. From the 63 mummies of C. maritimae collected, the parasitoid Xenostigmus bifasciatus (Ashmead) emerged from only two, whereas the hyperparasitoid Euneura sopolis (Walker) emerged from 23 mummies.Xenostigmus bifasciatus was introduced in 2002 in Parana C. atlantica and C.pinivora,