Sperm Storage Patterns in Singly Mated Females of the Caribbean Fruit Fly, <I>Anastrepha suspensa</I> (Diptera: Tephritidae)

Abstract

Insemination and fertilization are temporally dissociated in most insects thus creating conditions for female-mediated processes to influence paternity. One possible response to copulatory and postcopulatory sexual selection may be to increase the number of sperm-storage organs allowing for differential storage and use of sperm from multiple males. Differential sperm storage was tested in singly mated females of the tephritid fruit fly species, Anastrepha suspensa, which has four sperm-storage organs with separate entries to the bursa. Females mate multiply, and males display copulatory courtship. Copulation duration was examined in relation to female size, male size, and the quantity and distribution of spermatozoa in the four storage organs. Sperm quantity stored in females ranged from 141 to 2,617 spermatozoa, and the time spent in copulation ranged from 6 to 45 min. Spermatozoa were present in the ventral receptacle after all copulations, although this was not the case for the spermathecae. There was no significant correlation between body size and the duration of copulation or the quantity of sperm stored, but copulation duration was positively correlated to the quantity of sperm stored (r = 0.38, P = 0.02).