Placostylus fibratus is an endemic endangered species from New Caledonia. This snail is favoured as food, and the harvests for consumption from the wild population increase alarmingly. Thus, local authorities decided to promote research into the rearing methods for P. fibratus. Sixty-three snails from the Isle of Pines, divided into five groups, were subjected to different temperatures (20, 25, and 30°C) and humidities (80 ± 5% and 95 ± 5%) and constant light conditions (12 h:12 h photoperiod). The variables measured were activity levels (percent active animals, i.e. outside the shell) and daily food intake rate (DFIR, in milligrams dry matter per gram of live snail weight). The average proportion of active animals throughout the experiment amounted to 14.3%, with an average DFIR of 1.61 mg/g. P. fibratus were more active (and consumed more) at lower temperatures and higher humidity levels. From 20 to 30°C the activity level dropped from 24.9 to 6.5% and DFIR from 2.7 to 0.33 mg/g (adjusted averages). Overall, P. fibratus seemed capable of tolerating average temperatures (in the region of 25°C) if humidity was high. However, around 30°C they became almost completely inactive, regardless of humidity. The light/dark regime had a very limited impact on the variables under examination, and P. fibratus' nocturnal behaviour in the wild is likely to be explained by the need for favourable temperature and humidity levels.
Two field experiments were conducted to evaluate the efficiency of Rusa deer in the development of the cattle tick Boaphilus microplus in comparison with that of steers in the same pastures and under the same conditions of infestation. No difference was noted between a mixed steer/deer herd and a pure steer or pure deer herd in the infestation pattern of each host, suggesting that attachment to the alternative host is mechanical and not affected by the simultaneous presence of the primary host on the pasture. Deer are capable of producing engorged viable females, with weight and reproductive performances similar to or even better than females fed on steers. For moderate levels (1 million larvae per hectare) and high levels (32 million larvae per hectare) of pasture infestation, tick burdens on steers were not very different (e.g. average 1,911 and 2,681 ticks per m2 skin, respectively, on day 24). This may be because of saturation of steer skin sites at the moderate larval dose. Deer harboured 2.7-33 times fewer ticks than steers and produce no engorged females at the moderate larval level and 32 times fewer engorged females than steers at the high larval level. Infestation of deer was dose-dependent with averages of 12 and 399 ticks per m2 skin on day 25 at the moderate and high larval levels, respectively. At a high infestation level of the environment, Rusa deer may contribute, but to a limited extent, to infestation of pastures and, consequently, of cattle. However, their role in sustaining a viable tick population requires further investigation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.