Ovarian development in females of the Australian sheep blowfly Lucilia cuprina (Diptera: Calliphoridae) fed on sheep faeces and the effect of ivermectin residues

Abstract

AbstractThis study demonstrates that only a proportion of Lucilia cuprina (Wiedemann) females, which have fed exclusively on sheep dung collected from spring improved pastures, are able to mature a complement of oocytes at the cost of high resorption. Fifty percent of females developed mature oocytes after 11 d of continuous feeding on sheep dung. After 14 d feeding, 80% of females had matured an average of 143 eggs. Females given ad lib access to sheep's liver developed mature oocytes within 2–3 d feeding, producing an average of 223 eggs. Results show that sheep dung is a resource used by L. cuprina adults, but by itself appears to be a poor source of protein for field females to mature oocytes. Females given continuous access to dung collected from sheep 18 h after being drenched with ivermectin, were virtually unable to develop oocytes beyond the resting stage after 10 d feeding. Female adults in particular, became distended with fluid over successive days feeding and both sexes suffered significantly higher mortality compared with adults fed on untreated sheep dung. Knowledge on the feeding frequency and amounts of sheep dung ingested by L. cuprina adults may enable an assessment of the potential for manipulation of ivermectin treatment in a control strategy.