Feasibility of controlling Ixodes scapularis ticks (Acari: Ixodidae), the vector of Lyme disease, by parasitoid augmentation.

A theoretical analysis of the feasibility of controlling tick populations (Ixodidae) by the release of reared Ixodiphagus parasitoids in tick ecosystems yielded promising results. The analysis suggested that if reasonable progress could be made in mass-rearing the parasitoids, it would be possible to control the blacklegged tick, Ixodes scapularis (Say), the vector of Lyme disease, by this biological control procedure. Lyme disease has become the most important vector-borne disease in the United States. In a field-release experiment conducted in Africa by members of the International Center for Insect Physiology and Ecology, effective control of Amblyomma variegatum (F.) was obtained by the release of Ixodiphagus parasitoids in tick habitats. Encouraging theoretical results along with the encouraging results of a field-release experiment indicate the need for civil and political leaders in countries where ticks are a major problem to sponsor strong and well-coordinated research initiatives focused on the development of this new method of dealing with tick problems.

Role of phermones and kairmones for insect suppression systems and their possible health and environmental impacts.

Insects produce pheromones as a chemical communication system to facilitate reproduction. These highly active chemical attractants have been synthesized for some of the most important insect pests, including the boll weevil, gypsy moth, codling moth, tobacco budworm, European corn borer, and several bark beetles. While none of the synthetic sex attractants have yet been developed for use in insect control, they offer opportunities for the future both as control agents and to greatly improved insect detection. Investigations are underway on insect trapping systems employing the phermones and on air permeation techniques to disrupt insect reproduction. The pheromones are generally highly species-specific and are not likely to pose hazards to nontarget organisms in the environment. Toxicological studies indicate that they are low in toxicity to mammals, birds, and fish, but adequate toxicological data are necessary before they can be registered for use in insect control. Another new class of compounds called kaironomes has been discovered. These chemicals are involved in the detection of hosts or prey by insect parasites and predators. Kairomones may prove useful in manipulating natural or released biological agents for more effective biological control of insect pests. No information is yet available on the toxicology of these chemicals.

PIP: Insects produce pheromones as a chemical communication system to facilitate reproduction. Synthetic replicas of the natural attractants are available for many of the nation's more important insect pests. Most of these pests are not adequately controlled by natural biological agents. It has been demonstrated that effective control of some insects can be achieved by male annihilation. Kairomones are involved in the detection of hosts or prey by insect parasites or predators. They may prove useful in manipulating natural or released biological agents for control of insect pests. The toxicology of these chemicals is not yet known. Investigations are being made on insect trapping systems to disrupt insect reproduction. Pheromones and kairomones are highly species-specific and are not likely to pose hazards for nontarget organisms. They are low in toxicity to mammals, birds, and fish. However, it seems important that necessary toxicological and environmental studies be undertaken on all compoundC that may prove useful for insect control.

Disruption of gypsy moth mating with microencapsulated disparlure.

Broadcast applications of microencapsulated disparlure at rates of 2.5 to 15.0 grams per hectare are capable of reducing successful mating of wild gypsy moths under field conditions. In test plots, population densities were as high as 32 pairs of pupae in an area of about 700 square meters.

Genetic control of insects of public health importance.

During recent years many advances have been made in the development of insect control by genetic manipulation. These methods include the sterile-male technique, now well known, which depends on ionizing radiation or chemosterilization. The recent field experiment carried out by WHO in Rangoon, Burma, on Culex fatigans has demonstrated that naturally occurring cytogenetic mechanisms such as cytoplasmic incompatibility can be used successfully without the use of radiations or chemosterilants. The paper not only describes the experiment on Culex fatigans but also discusses basic concepts and theoretical considerations involved in genetic control of insects of public health importance. The possibility of using genetic mechanisms for the control of other vector species is also discussed. There are a number of problems which require study before genetic control can be used on an operational scale. These problems and suggestions for future research in this field are also outlined.