Studies on the Bionomics of the Sheep Ked, Melophagus ovinus, L., in West Wales

Abstract

A method is described for studying the life-cycle of Melophagus ovinus. The female ked matures in 6 to 7 days and the male in 10 to 11 days. Copulation takes place 16 hours after emergence and the first pupa is deposited by the female about 13 days after its emergence. The second and successive pupae are deposited at intervals of seven to eight days. The pupal stage covers 20 to 26 days (an average of 22·5 days for 28 observations). The life-cycle is completed in 33–36 days. Experimental conditions did not affect the duration of the various stages observed in the life-cycle.An investigation of the periodic fluctuations in the infestation of a flock of Welsh sheep showed that the degree of infestation is influenced by the transference of keds between the sheep. Before lambing, keds are transferred from hoggs to two- to three-year old ewes and, after lambing, from ewes to lambs. The peak infestation of ewes and hoggs occurs before lambing. The maximum infestation of lambs occurs before shearing. At shearing the majority of adult keds and pupae are removed with the fleece. Adults surviving after shearing are killed at dipping. Depending on the nature of the dip, re-infestation results from pupae hatching in fleece or by the transference of keds from infested sheep coming into contact with the dipped flock. Keds disappear from the fleece through being devoured by the sheep, by the activity of insectivorous birds and through natural death. The transference of keds between sheep is achieved through contact and occurs readily when the ked is on the surface of the fleece. The vertical migration of the insect in the fleece is controlled by temperature and is not influenced by light.The distribution of pupal and adult stages of M. ovinus in the fleece of lambs, hoggs and ewes is given. The position of attachment to the pupae is controlled by the depth of the fleece, deposition occurring on the wool fibres at a point where the temperature is suitable for their development. The age of the sheep influences the distribution of the ked, young sheep being more susceptible than older animals. In a flock, the higher infestation of hoggs compared to older ewes may be due to the higher initial infestation of the hoggs after dipping. Open fleeced sheep are more susceptible to ked infestation than tight fleeced sheep.

Parasitism of the deer ked,Lipoptena cervi, on the moose,Alces alces, in eastern Finland

“…Over 45% of all fleas were located on the head and neck; the next preferred region was the dorsum, which accounted for over 27% of fleas. Sheep keds appeared to prefer the rib and shoulder regions (Legg et al , 1991) and sheep with an open, long and fairly greasy fleece were considered ideal hosts for sheep keds (Evans, 1950). The deer ked displays negative geotaxis and phototaxis (Ivanov, 1981), which may explain why most of the keds were attached to the withers of the moose.…”

The population of the louse‐fly, Crataerina pallida (Diptera, Hippoboscidae) on the European swift, Apus apus (Aves, Apodidae)

“…hirundinis, but C. pallida has a rather different life-cycle and it seems more likely that the males are dying, leaving the females to live on and produce offspring. Working on Melophugus ovinus, Graham & Taylor (1941) and Evans (1950) have demonstrated that males mature more slowly than females and that females can store sperm from one mating to last for the whole of their reproductive life. Decline of the female population would be expected to follow the decline of the males, but at a much slower rate.…”

An excess of males: skewed sex ratios in bat flies (Diptera: Streblidae)

“…The total life-span of Basilia hispida Theodor (Nycteribiidae) averaged 136 and 195 days for males and females, respectively; this time included 97 days (males) or 156 days (females) in the adult stage (Marshall 1970). Maximum longevities have also been reported for some species of hippoboscid flies: 60 days for male and 135 days for female Hippobosca variegata Megerle (as H. maculata Macquart; Schuurmans Stekhoven 1926); 25 days for male and 165 days for female Melophagus ovinus Linnaeus (Evans 1950); 20 days for male and 120 days for female Ornithomya fringillina Curtis (Corbet 1956). Where known, longevity differences between the sexes in nycteribiids and hippoboscids would produce female-biased sex ratios.…”