Size, hatching rate, and hatching period of sexually and asexually produced eggs in the facultatively parthenogenetic termite Reticulitermes speratus (Isoptera: Rhinotermitidae)

Abstract

Facultative parthenogenesis, or condition-dependent alternation of sexual and asexual reproduction, is widespread in animals. Parthenogenesis enables unmated females to reproduce and thus has a great adaptive significance, especially under low pairing efficiency. In the termite Reticulitermes speratus Kolbe, females that fail to pair with males found colonies cooperatively with partner females and reproduce parthenogenetically. We compared the quality of parthenogenetic and sexual eggs in terms of size, hatching rate, and hatching period. We developed a method to culture isolated eggs until hatching under sterile conditions and in appropriate humidity. We successfully isolated, sterilized, and maintained the eggs on agar plates containing 200 ppm tetracycline. Females of female-female (FF) pairs began to lay eggs at the same time as those of female-male (FM) pairs. Nevertheless, the parthenogenetic eggs were significantly larger than sexual eggs. While the two types of eggs had similar hatching rates, parthenogenetic eggs had longer hatching periods (36.36±0.16 [SE] days) than sexual eggs (34.95±0.12 SE). We conclude that primary queens invest more resources into each parthenogenetic egg than each sexual egg, and that parthenogenetic eggs are as viable as sexual eggs.