The Role of the Spermatophore in the Reproductive Biology of Protogynes of Aculus cornutus (Acarina: Eriophyidae)1

Abstract

Newly emerged protogynes of Aculus cornutus (Banks) inseminated from one fresh spermatophore containing about 50 sperm cells produced predominantly females (an average 23) for several days but later produced only males. Such protogynes failed to recognize and/or visit fresh spermatophores 4, 8, 12, or 16 days later, even though they began producing only males before the 9th day, but 5- or 10-day-old noninseminated protogynes that had previously produced only males, readily visited the spermatophores and became inseminated. When protogynes were exposed continuously to spermatophores in laboratory colonies or were newly inseminated from a single spermatophore, the sperm were found in only the left or right spermatheca. This one spermatheca in the continuously exposed protogynes contained few to many sperm cells, and its shape varied correspondingly; in newly inseminated protogynes, the one spermatheca always contained many sperm and was globose. Protogynes readily visited newly deposited or 2-dayold spermatophores (and subsequently produced females), but they neither recognized nor visited 4-, 6-, or 8-dayold spermatophores though sperm from 1- to 6-day-old spermatophores did not differ morphologically from younger sperm. Males and protogynes commenced depositing spermatophores and eggs, respectively, within a few hours after they became adults, and protogynes visited spermatophores less than a minute after eclosion. At 26°C, males deposited an average 35 spermatophores/day, and protogynes laid an average 4 eggs/day. The largest number of spermatophores deposited by one male was 614.