Efficacy of alpha-chlorhydrin in sewer rat control

What can pest management learn from laboratory animal ethics?

There remains a lack of a clear overarching policy framework for decision-making in pest control programmes. In comparison, ethical principles have been extensively developed for scientific procedures, such as those underlying the UK's Animals (Scientific Procedures) Act 1986. This paper assesses the extent to which the principles and methodology underlying the act and secondary guidance could be used to provide principles of rodent management. Useful principles include that any programme has a legitimate purpose; that methods are used only if the harms are outweighed by the benefits; that harms are minimised by refinement, replacement and reduction and that there is personal responsibility. The usefulness and implications for pest control of each principle and the overall approach are discussed.

A review of chemical, biological and fertility control options for the camel in Australia

Since their introduction to Australia in 1840 the one-humped camel, Camelus dromedarius, has gone from the colonist’s companion to a conservationist’s conundrum in the fragile arid ecosystems of Australia. Current management techniques are failing to curb present population growth and alternatives must be sought. This review assess the applicability of currently registered and developmental vertebrate pesticides and fertility control agents for camel control, as well as examining the potential usefulness of known C. dromedarius diseases for biological control. Not surprisingly, little is known about the lethality of most vertebrate pesticides used in Australia to camels. More has been published on adverse reactions to pharmaceuticals used in agriculture and the racing industry. An examination of the literature on C. dromedarius diseases, such as camel pox virus, contagious ecthyma and papillomatosis, indicates that the infections generally result in high morbidity but not necessarily mortality and this alone may not justify their consideration for use in Australia. The possibility exists that other undiscovered or unstudied biological control agents from other camilid species may offer greater potential for population control. As a long-lived species the camel is also not ideally suited to fertility control. Notwithstanding, anti-fertility agents may have their place in preventing the re-establishment of camel populations once they have been reduced through mechanical, biological or chemical means. Delivery of any generic chemical or fertility control agent will, however, require a species-tailored pathway and an appropriate large-scale deployment method. Accordingly, we put forward avenues of investigation to yield improved tools for camel control.

Fertility control in vertebrate pest species

The potential of fertility control in the management of pest mammalian and avian species is discussed as a tool additional to the conventional methods based on poisons. There are several advantages in the use fertility control methods, and many chemical compounds are already available that disrupt fertility and act through different mechanisms. The chemicals more effective are those with long-lasting effects acting on both sexes. This article briefly synthesizes the knowledge gathered on the use of chemicals disrupting male fertility. Models suggest that such an approach can be effective for population control of pest vertebrates. However, the efficacy of sterilizing males has been positively tested so far only in species in which females mate with territorial or dominant males.

Species-specific toxic effects of alpha-chlorohydrin and 6-chloro-6-deoxyglucose on astrocytes

In 1969 alpha-chlorohydrin was reported to have a reversible antifertility effect in male rats. It has since been reported to have a reversible antifertility effect in many other species but not in mice and rabbits. In chronic high-dosage regimens it was reported to be neurotoxic to mice. At high doses the 6-chloro-6-deoxysugars were found to have a reversible, complete antifertility effect. 6-Chloro-6-deoxyglucose had an antifertility effect in rats and marmosets but not in mice, hamsters, guinea-pigs or rabbits. However, repeated high doses were found to be neurotoxic in the mouse and marmoset, the most prominent pathological feature being vacuolation of astrocytes. In the studies reported here the ability of alpha-chlorohydrin and 6-chloro-6-deoxyglucose to induce vacuolation of mouse astrocytes has been confirmed in vitro. The failure of either agent to induce vacuolation of rat astrocytes suggests that both the antifertility effect of these agents and their neurotoxic effects are species-specific. The lack of correlation between neurotoxic and antifertility effects of such agents suggests that in vitro techniques may aid the development of a safe, reversible male antifertility agent and also aid in the design of further agents for rodent control.