Life History Studies of Pergamasus crassipes and Amblygamasus septentrionalis (Acarina: Parasitidae)

Abstract

Specimens of these two mites, both of which occur throughout Europe, were obtained from soils from Tully Forest, Tully, N. Y. Their separation from one another and from other related mites, as well as specific pairing of males and females, is practicable on the basis of size differences, shape of the tectum, characters of the modified setae on the pedipalpal genu, and morphological characters of the female genitalia and the male leg II. Both species have essentially similar life histories, and both prey largely on certain Collembola, Oribatei, and Aphidae, and to a lesser extent upon certain Mesostigmata and other Arachnida. Copulation is not necessary for subsequent egg production. Eggs are produced and laid singly. At laboratory temperatures of 20° C. and near 90% r.h., larvae hatch 24 to 36 hours after oviposition, transform after 2 days to protonymphs, which are succeeded by deutonymphs after another week. Adults appear 3 weeks after the eggs are deposited. All developmental stages of both species are described and figured. Probably there are four or five generations a year in the field. The A. septentrionalis (Oudem.) studied were of the “variety” norvegicus Berlese, 1905. Both P. crassipes (L.) and its varietal form longicornis Berlese, 1905, were included in this study.