Sexual identity and sexual attractiveness of a gynandromorph of the lawn ground cricket, Polionemobius mikado (Orthoptera: Trigonidiidae)

Abstract

A gynandromorph adult of the lawn ground cricket Polionemobius mikado (Shiraki, 1913) (Orthoptera: Trigonidiidae) was collected from a natural population. It had complete male forewings and a female ovipositor at the end of abdomen. A normal male that encountered the gynandromorph performed a courtship song and tried to transmit a spermatophore, whereas a normal female was indifferent to the gynandromorph. The gynandromorph showed aggressive behavior toward the normal male but not against the normal female. The gynandromorph raised its forewings immediately after the antenna touched the body of the normal male and female, but no sound was produced. Overall, the gynandromorph behaved as a male, but was courted by conspecific males. Thus, the sexual identity of the gynandromorph was masculine, but sexual attractiveness was feminine.

Photoperiodic control of protogyny in the lawn ground cricket, Polionemobius mikado (Orthoptera: Trigonidiidae)

“…During studies on the biology of crickets (Taniyama et al . 2018; Matsuda et al . 2018), I found that P. mikado has protogynous tendencies and protogyny is regulated by photoperiod.…”

“…In this paper, I would like to suggest that the lawn ground cricket, Polionemobius mikado (Shiraki, 1913), a univoltine species with egg-overwintering and adults usually appear in late summer and autumn, would be a suitable animal model to study the adaptive significance of protogyny. During studies on the biology of crickets (Taniyama et al 2018;Matsuda et al 2018), I found that P. mikado has protogynous tendencies and protogyny is regulated by photoperiod. Hence, protogyny in this species is expected to occur seasonally, and therefore, the adaptive significance of protogyny should be considered from the perspective of environmental seasonality of the adult crickets encounter.…”