The effect of sperm storage and timing of mating on offspring sex ratios in the yellow dung fly Scatophaga stercoraria

Abstract

Summary 1. Offspring sex ratios in the yellow dung fly Scatophaga stercoraria were examined in the laboratory. 2. Previous work indicated that females using previously stored sperm to fertilise their eggs produced male‐biased sex ratios. This result may have been due to female influences or the effects of sperm storage per se. 3. This pattern was not reproduced in the study presented here. Females that were allowed to mate just prior to oviposition produced similarly male‐biased sex ratios to those females that used previously stored sperm to fertilise their clutch. 4. Captive‐reared females may have perceived a lack of males in the population and thus produced a male‐biased offspring sex ratio. Alternatively, gamete ageing or extra‐chromosomal sex ratio distorters may have produced the male bias.

Sperm numbers, sperm storage duration and fertility limitation in the Odonata

“…---------------R e i n h a r d t Another possible costs of sperm storage could arise if sperm quality declines during the storage process. Fitness consequences of female insects using aged sperm do not show consistent results (Stockley & Simmons 1998;Reinhardt et al 1999;Seal 2000;Simmons 2001;Snook & Hosken 2004). Odonates with a direct sperm removal mechanism could be very useful in assessing the effect of sperm quality, especially in the calopterygids in which hand-pairing can be used (Oppenheimer & Waage 1987).…”

Measuring the sperm competition successes of field males of the yellow dung fly

“…The yellow dung fly has been used extensively to examine sperm competition and cryptic female choice, the female influence on the outcome of sperm competition (e.g. Parker, 1978; Simmons & Parker, 1992; Parker et al ., 1999; Seal, 2000; Ward, 2000; Hosken et al ., 2001). Males wait for females arriving to lay eggs in fresh dung.…”