Quantitative genetics of ultrasonic advertisement signalling in the lesserwaxmoth Achroia grisella (Lepidoptera : Pyralidae)

Males of the lesser waxmoth Achroia grisella (Lepidoptera: Pyralidae) produ ce ultrasonic advertisement signals attractive to females within several me tres. Previous studies showed that females prefer male signals that are lou der, delivered at a faster rate, and have a greater asynchrony between puls es produced by the right and left wings. These three signal characters vary considerably within populations but are repeatable within individuals. Bre eding experiments employing half-sib designs were conducted on both collect ively and individually reared moths to determine genetic variance within an d covariance among these signal characters. Heritabilities of all signal ch aracters were significant among collectively reared moths. Heritabilities f or signal rate and right-left wing asynchrony interval were not significant , however, among individually reared moths, suggesting the presence of sign ificant nonadditive genetic variance or common environmental variation. Dev elopment time was also significantly heritable, but only under individual r earing. The only significant genetic correlation was between signal rate an d length of the right-left wing asynchrony and this was negative. Our findi ngs on heritability of signal characters are consistent with a coevolutiona ry sexual selection mechanism, but the absence of signal x development gene tic correlation fails to support specifically a good-genes mechanism. The v ariation in heritability among conditions suggests that environmental varia nce may be high, and may render selection on signal characters by female ch oice ineffective. Thus, additive genetic variance for these characters may be maintained in the presence of directional female choice.