The Effect of Temperature and Humidity on the Losses of Nitrogenous Substances from the Skin of Ayrshire Calves

Topically applied myco-acaricides for the control of cattle ticks: overcoming the challenges

In the absence of commercially viable and environmentally friendly options, the management of cattle ticks is heavily dependent on the use of chemical acaricides. Due to recent advances in production, formulation and application technology, commercial fungus-based biological pesticides (myco-insecticides, myco-acaricides) are becoming increasingly popular for the control of plant pests; however, they have not been used against animal ectoparasites. The literature clearly demonstrates that entomopathogenic fungi are pathogenic to ticks under laboratory conditions. Pasture applications have also shown promise while experiments on topical application have had variable results. These results suggest that major research hurdles still exist especially for the latter. Although literature on ticks and their interactions with entomopathogenic fungi exists, there is not a clear understanding on how this can be influenced by the microenvironment of the cattle skin surface. This paper critically reviews pathogen, tick target and host skin microenvironmental factors that potentially affect pathogenicity of the applied entomopathogen. Factors influencing the route of infection for topically applied myco-acaricides are also reviewed. Major researchable constraints and recommendations are identified and prioritized. In particular, there is the need for basic studies to understand the interaction of entomopathogenic fungi with the components of the skin microenvironment, to identify suitable strains, and to develop improved formulations to overcome the various challenges.

Olfactory receptors on the antennae of the malaria mosquito Anopheles gambiae are sensitive to ammonia and other sweat-borne components

Electrophysiological studies on female An. gambiae s.s. mosquitoes revealed a receptor neuron within a subpopulation of the antennal grooved-peg sensilla sensitive to the odour of incubated sweat, but not responding to fresh sweat. This receptor neuron was sensitive to ammonia as well, a sweat-borne component which attracts female An. gambiae in a windtunnel bioassay. Neurons innervating a different subpopulation of grooved-peg sensilla did not show a response to incubated sweat. In the latter sensilla, however, one type of neuron responded to water or water containing solutions, while another receptor neuron was inhibited when stimulated with dry air, ether or ethanol. Neurons innervating sensilla trichodea, a more abundant antennal type of olfactory sensillum, did not respond to fresh or incubated sweat at the doses offered. However, receptor neurons within the sensilla trichodea responded with excitation to several sweat-borne components. A subpopulation of the sensilla trichodea was innervated by neurons sensitive to geranyl acetone. A second subpopulation housed receptor neurons sensitive to indole. 3-Methyl-1-butanol and 6-methyl-5-hepten-2-one evoked excitation of receptor neurons within both subpopulations of sensilla trichodea. Neurons were most sensitive to indole and geranyl acetone with a threshold of 0.01%. These findings are discussed in the context of host-seeking behaviour.