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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 piroplasma 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.

An artificial feeding device was constructed with a Baudruche membrane bearing olfactory and tactile stimuli, to induce voluntary attachment and feeding of the brown ear tick, Rhipicephalus appendiculatus. Preparation of the membrane and experimental conditions used are described. Unfed adults of R. appendiculatus, 2-3 weeks after moulting, were confined on the membrane, which was treated with cattle ear-wash and other stimuli. They attached and commenced sucking blood within 12-48 h. Fully engorged ticks started detaching from the membrane on the 6th day. After a 5-6-day incubation period, they started laying eggs which hatched into normal larvae.

The morphology and iiinervation of sensory rcceptors on tarsus I of the foreleg u i d on the mouthparia o f t he ciittle tick B o o~/ I~/ I L \ iriic.roplu.\ iire described by nie;inb or light microscopy. Sixty six scnsilla :ire loc;ited on each tiirstis I and forty tive o n e;ich palp. Apurt froin the inuliiply innervuted olkictory and gustatory scnsilla already described in other ticks. several new inultiply innervated sensilla ;ire dexritbed. A new p;ipill;i Ii;is been identitied on tlie d i s t~l surface ofeach inner cheliceriil digii. The piipilla ia associated with cell bodies situated i n the cheliceral shaft and may bc ;I coni;ict chemoreceptor. These ohscrv;itionh form ilie basis for ultr;i$truci ur;il ,ind clectrc~pliysiologic~il st~idics.

The persistence of the Bacillus thuringiensis subsp. kurstaki (Btk) toxin (Cry1Ab protein) from Bt maize (MON810, Yieldgard ) residues incorporated in a vertisol (739 g clay kg −1 ) was investigated. The maize residues were incubated in the soil for 4 weeks, and activity of the toxin in the residues was bioassayed using larvae of the diamondback moth, Plutella xylostella (Lepidoptera: Yponomeutidae). Corrected mortality of P. xylostella in the bioassays decreased from 76% to 30% in less than a week of incubation in the soil. In addition to the above observations, the effects of Btk, Bt subsp. israelensis (Bti), and Bt subsp. tenebrionis (Btt) proteins on the soil microbiota were examined using a vertisol, an alfisol, and an oxisol. The pre-incubated soils (7 days after moisture adjustment) were treated with crystal proteins of Btk, Bti, and Btt and incubated for further a 7-day period. Microbial biomass carbon (MBC) and counts of culturable bacteria and fungi were determined. The proteins did not show effects on MBC or bacterial and fungal counts, possibly as a result of adsorption of the proteins on soil particles, which could have rendered the proteins inaccessible for microbial utilization. Microbial biomass carbon and counts arranged in decreasing order were vertisol>oxisol>alfisol, similar to the amounts of organic C and clay in the soils. However, bacteria and fungi counts were higher in the vertisol than in the alfisol and the oxisol soils. Our observations suggest that larvicidal proteins produced by different subspecies of Bt and Bt maize could persist in tropical soils as a result of adsorption on soil clays but that there were no observable effect on the soil microbiota.