Life of Acrobasis rubrifasciella (Lepidoptera: Phycitidae), Its Main Parasite, Agathis calcarata (Hymenoptera: Braconidae), and Three Hyperparasites (Chalcidoidea)

Abstract

In northeastern Minnesota, the young caterpillar of Acrobasis rubrifasciella (Packard) resumes life in May in the wintered leaf-buds of Alnus . As it grows, mostly in June, it constructs a silken growth tube with an external layer of its fecal pellets, from which shelter it feeds until full-grown. As pupation approaches, it enlarges the end portion of the tube to form a pupal chamber that eventually is bulbous and sealed, separated from the tube by a plug, but with an escape hatch left near the base of the chamber for emergence of the moth. From 1 to 9 caterpillars, each in its own tube, may occur in a single nest, obscured in plant parts bound with gray silk. The pupal and adult stages appeared from June 22 to August 9; apparently the small larvae overwinter. Four instars of Agathis calcarata (Cresson) are described. The first instar was found in host larvae from mid-May to July. Diapause usually ends when the host seals its pupal chamber preparatory to transformation, and the second to fourth instars of Agathis develop in a few days, destroying the host before it can pupate. A cellophane-like cocoon is spun in the host chamber, and the red-and-black adult emerges about 15 days later, through the hatch prepared by the caterpillar. Although actual parasitization and the egg were not observed, the first-instar Agathis apparently winters in first- or, possibly, second-instar caterpillars. Both Acrobasis and Agathis are univoltine. The cocoon phase of this Agathis is subject to attack by 3 chalcid hyperparasites, Perilampus tristis Mayr, Habrocytus sp., and Eupelmella vesicularis (Retzius).