Female accessory reproductive gland activity in the yellow dung fly Scathophaga stercoraria (L.)

The role of the female accessory reproductive glands has been investigated in relatively few insects. Gland secretion has a number of potential functi ons, including lubrication during copula, involvement in fertilization and protection of eggs. Female yellow dung flies (Scathophaga stercoraria) have large paired accessory glands whose function(s) prior to this study were u nknown. Our study indicated glands were involved in copulation and egg layi ng. The volume of secretion remaining in glands was negatively associated w ith copulation duration, and this effect was most pronounced in non-oviposi ting females. Gland volume and secretion volume remaining in the glands wer e significantly smaller in females which were allowed to oviposit. In addit ion, there was a significant interaction between male size, female size and whether or not females were allowed to oviposit which affected the volume of the secretion remaining in the glands, with changes in secretion volume being greatest when males were large. Sperm were found in the accessory gla nds of some females and this was apparently not related to age, mating hist ory of either sex, to female nutrition or male size. Our results indicate t hat either large males stimulate greater secretory responses from females o r that females alter their responses based on male size. (C) 1999 Elsevier Science Ltd. All rights reserved.