HOST BODY-SIZE AS A FACTOR DETERMINING THE EGG COMPLEMENT OF STREPSIPTERA, AN INSECT PARASITE

The egg complement (total number of eggs produced by a single female) differs greatly among the species of Strepsiptera. The maximum is foun d in Stichotrema dallatorreanum (750,000 eggs), and the minimum in Tri ozocera minor (984 eggs). Based on the egg complement of 31 species in 11 genera, the following conclusions were drawn: (1) The egg compleme nt is generally smaller in those species whose hosts gregariously coha bit in a very limited area, or are distinct flower-visitors, compared with those whose hosts display the above two traits weakly; (2) The eg g complement is determined by the size of the maternal body. The size of female strepsipterans is reduced when they parasitize smaller host such as males and workers, as compared with those that parasitize larg er host such as females and queens; Likewise, the size of the strepsip terans becomes larger on increase in size of hosts, showing that their egg complements are principally determined by the size of host specie s; (3) The increase in the egg complement is compensated for by the re duction in egg size. The relative egg size (length of the first-instar larva/length of maternal body) is conspicuously reduced according to an increase in the size of the female strepsipterans. (C) 1998 Elsevie r Science Ltd. All rights reserved.