Hyperparasitoids of Xenostigmus bifasciatus (Hymenoptera: Braconidae), parasitoid of Cinara spp. (Hemiptera: Aphididae), in Pinus plantations in Brazil.

Abstract

Hyperparasitoidism can reduce the biological control of Cinara spp. (Hemiptera: Aphididae) in Pinus (Gymnospermae: Pinaceae) plantations in Brazil. Cinara atlantica (Wilson, 1919) and Cinara pinivora (Wilson, 1919), introduced into Brazil in the 1990s, damage young Pinus plants. The primary parasitoid Xenostigmus bifasciatus (Ashmead, 1891) (Hymenoptera: Braconidae) was introduced and released between 2002 and 2004 in the states of Paraná, Santa Catarina, and São Paulo, Brazil. The dispersion of this biological control agent was extensive, with parasitoidism near 100%, stabilizing Cinara spp. populations for years, however, the population increase of these aphids in Pinus taeda (Linnaeus, 1753) plantations up to 2.5 years old between 2022 and 2025 suggests a reduction in the efficiency of biological control. Eight hundred and eighty-four mummies of Cinara spp. were collected from commercial plantations in Santa Catarina and reared in laboratory, from which 203 Hymenoptera specimens emerged, including 24 (11.82% of the total mummies collected) of X. bifasciatus and 179 (88.18%) of the hyperparasitoids Asaphes californicus Girault, 1917 (Hymenoptera: Chalcidoidea: incertae sedis) (55.17%); Dendrocerus carpenteri (Curtis, 1829) (Hymenoptera: Megaspilidae) (10.80%); D. ramicornis (Boheman, 1832) (Hymenoptera: Megaspilidae) (9.90%); and Euneura sopolis (Walker, 1844) (Hymenoptera: Pteromalidae) (12.31%). This is the first record of D. ramicornis and the four species associated with Cinara spp. in P. taeda in Brazil. The high incidence of hyperparasitoidism may be the main cause of the reduced efficiency of Cinara spp. biological control in Pinus plantations in southern Brazil by X. bifasciatus.