Background: Zooprophylaxis is a technique in which blood-seeking vectors are diverted to non-host animals in order to lower blood-feeding rates on human hosts. The success of this technique depends on the host preference of the vector being targeted. The objective of this study was to evaluate the effect of l-lactic acid (Abate) to divert malaria mosquito, Anopheles gambiae from feeding on human host.Methods: A 14-month-old female goat was treated with Abate, a formulation incorporating l-lactic acid into a slowrelease matrix. This formulation was applied on the fur of the goat's back and neck. The treated animal was then presented to Anopheles gambiae sensu stricto (s.s.) as a prospective host in a semi-field environment ('mosquito sphere') together with either an untreated animal or a human. The number of mosquitoes caught to each host choice offered were compared.
Results:Goat treated with the l-lactic acid formulation successfully attracted An. gambiae at higher rates (70.2%) than the untreated ones (29.8%). Furthermore, An. gambiae s.s. were attracted to a treated goat at an equivalent degree (47.3%) as to their preferred human host (52.7%), even when the preferred host was present in the same environment.
Conclusions:The findings indicate that human host-seeking mosquitoes can be diverted into feeding on nonpreferred hosts despite the close proximity of their favoured host, hence reducing chances for the transmission of blood-borne parasites.
The disjunct Eastern Ribbonsnake (Thamnophis sauritus) population in southwest Nova Scotia is listed as “threatened” by the committee on the Status of Endangered Wildlife in Canada. A study of the movements of the species at two lakeshore locations known to support a high density of Eastern Ribbonsnakes was undertaken in 2007 and 2008. Average seasonal movements at both sites ranged from 17 m to 84 m for juvenile snakes and 21 m to 130 m for adults; one neonate was recaptured during the study after travelling 32 m. The maximum distance travelled by an individual snake was 391 m in one season. The best-fit model to explain differences in daily movement patterns included year (P = 0.041), indicating that there is annual variation in the movements of this species. Low recapture rates precluded accurate estimates of home-range size, which varied roughly from 0.16 ha to 0.78 ha. Both movements and home ranges were larger than previously documented in Nova Scotia, but maximum distances travelled were consistent with a previous study in Michigan. Most documented movements were along the lakeshore within contiguous, suitable habitat. More work is needed to understand the frequency of large movements and triggers that initiate movements, e.g., changes in water levels, habitat suitability, or prey availability.
Background: Mosquitoes use odours to find energy resources, blood hosts and oviposition sites. While these odour sources are normally spatio-temporally segregated in a mosquito's life history, here this study explored to what extent a combination of flower-and human-mimicking synthetic volatiles would attract the malaria vector Anopheles gambiae sensu stricto (s.s.) Methods: In the laboratory and in large (80 m 2) outdoor cages in Tanzania, nulliparous and parous A. gambiae s.s. were offered choices between a blend of human skin volatiles (Skin Lure), a blend of floral volatiles (Vectrax), or a combination thereof. The blends consisted of odours that induce distinct, non-overlapping activation patterns in the olfactory circuitry, in sensory neurons expressing olfactory receptors (ORs) and ionotropic receptors (IRs), respectively. Catches were compared between treatments. Results: In the laboratory nulliparous and parous mosquitoes preferred skin odours and combinations thereof over floral odours. However, in semi-field settings nulliparous were significantly more caught with floral odours, whereas no differences were observed for parous females. Combining floral and human volatiles did not augment attractiveness. Conclusions: Nulliparous and parous A. gambiae s.s. are attracted to combinations of odours derived from spatiotemporally segregated resources in mosquito life-history (floral and human volatiles). This is favourable as mosquito populations are comprised of individuals whose nutritional and developmental state steer them to diverging odours sources, baits that attract irrespective of mosquito status could enhance overall effectiveness and use in monitoring and control. However, combinations of floral and skin odours did not augment attraction in semi-field settings, in spite of the fact that these blends activate distinct sets of sensory neurons. Instead, mosquito preference appeared to be modulated by blood meal experience from floral to a more generic attraction to odour blends. Results are discussed both from an odour coding, as well as from an application perspective.
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