Although artificial feeding models for the poultry red mite (Dermanyssus gallinae) most frequently use biological membranes consisting of day-old chick skin, there are ethical considerations associated with the use of skin. The few studies reported in the literature that have investigated the use of synthetic membranes to feed D. gallinae in vitro have reported limited success. The current study describes an investigation into the use of synthetic membranes made from either Nescofilm® or rayon and silicone, used either alone or in combination with different feather or skin extracts, as well as the use of capillary tubes. In all, 12 different treatments were used, and the feeding rate of D. gallinae was compared to that of day-old chick skin. Allowing mites to feed on a membrane consisting of Nescofilm with a skin extract resulted in the highest proportion of mites feeding (32.3%), which was not significantly different to the feeding rate of mites on day-old chick skin (38.8%). This study confirms that synthetic membranes can be used to feed D. gallinae artificially. Further optimization of the membrane and mite storage conditions is still necessary, but the study demonstrates a proof of concept.

The feeding behaviour of parasitic 3rd-stage larvae (L3) of the hookworms Ancylostoma caninum, A. ceylanicum and Necator americanus was examined. Less than 11% of A. caninum L3 recovered from the small intestines of dogs infected orally were feeding at 4–48 h post-infection (p.i.). and none of the A. ceylanicum L3 recovered from the intestines of orally infected hamsters had resumed feeding. All L4 of both species recovered at 36 and 48 h p.i. had resumed feeding. On the other hand, approximately 16% of the A. ceylanicum L3 recovered from the skin of percutaneously infected hamsters at 18 h were feeding, and the percentage feeding increased to nearly 58% at 44 h p.i. Necator americanus L3 recovered from the skin of percutaneously infected neonatal hamsters resumed feeding at 6–12 h p.i. and reached 90–94% by 18 h. Feeding began to decline at 66 h, and reached 29% at 120 h p.i. This decrease was associated with the migration of larvae from the skin to the lungs. By 192 h p.i. over 95% of the larvae had reached the small intestine, and all had moulted to the L4. The results indicate that parasitic L3 resume feeding in the skin during percutaneous infections, and suggest that feeding by hookworm L3 correlates with the resumption of development.

A technique is described for the efficient feeding of Rhipicephalus appendiculatus nymphae on cattle blood through an artificial membrane bearing tactile and olfactory stimuli. The effect of four anticoagulation methods on the feeding of nymphae was compared and heparinized blood was found to be the most efficacious, followed by defibrinated blood. Blood treated with acid citrate dextrose (ACD) or ethylenediamine tetraacetate (EDTA) inhibited nymphal feeding. Nymphae fed on heparinized and defibrinated blood obtained engorgement weights within the range of ticks fed on mammalian hosts and they subsequently moulted and fed normally as adults and produced viable eggs. Nymphae fed on membranes using either defibrinated or heparinized blood infected with Theileria parva piroplasms developed salivary gland infections as adult ticks and transmitted East Coast fever (ECF) to susceptible cattle. There were indications that T. parva-infected defibrinated blood was not as infective to the feeding nymphae as the infected heparinized blood. When T. parva-infected heparinized blood was used to feed nymphae through membranes in two experiments, it was found that the infections in the resultant adult ticks could be comparable to those of nymphae fed on donor cattle, but were usually lower. The membrane feeding technique will enable the study of factors affecting the tick and T. parva transmission without the complication of host/T. parva interactions and could be useful for both tick maintenance and Theileria parasite isolation and maintenance.

The phytosterols inokosterone, makisterone A, ecdysterone and ecdysone were effective growth regulators and abortifacients (70%) at estimated doses of 1.4 × 10−4 M, 6.8 × 10−4 M, 5.2 × 10−5 M, and 7.8 × 10−5 M respectively when fed to female tsetse Glossina morsitans morsitans. The sterols, added to defibrinated cow or pig blood, were fed to the flies in an in vitro system through a silicone rubber membrane. Cyasterone and ponasterone A were only slightly effective, therefore the hydroxyl groups on the side chain appear to confer activity. Evidence is presented to support three hypotheses which may be advanced to describe the mode of action of the sterols, namely:

(a) Synthesis and/or release of the ‘milk’ secretion from the uterine gland is significantly retarded.

(b) Although the size of the blood-meal is normal, digestion of the in vitro meal is very slow.

(c) Development of the larva itself may be affected by the presence of the hormonally active sterol (or a metabolite) in the ‘milk’.

Effective dose of sterol causing 70% abortion in flies is very much lower than that dose required when injected into the haemolymph. The Malpighian tubules very rapidly excrete the sterol. Therefore, either (1) a slow release of sterol or metabolite into the haemolymph is necessary to disrupt ‘milk’ production, or (2) digestion of the treated in vitro meal itself (and subsequent meals as well) is so retarded that the larva in utero is effectively starved.