Tsetse fly control (1988) Pt. 2 of 2

in the center of the island an experiment has been set up to study certain aspects of tsti behavior there's a Target and an observation pit with cattle on the island there's a natural source of ox odor so the cattle are LED into a water cooled tent and their odor is piped away to a point just below the target human odor from the observation pit that might distract the Flies is extracted and vented well away from the target with this basic setup experiments are underway using decoys impregnated with male sterilance the subject we'll return to later odors that attract tsif flies have been isolated by Chemists in the laboratory and evaluated by insect behaviorists in the field some half dozen compounds that are very attractive to the tsti have been identified so far and most of them can be conveniently dispensed in the field in ways that ensure that they need only be replenished every 3 months or so in this case two glass bottles with Wicks are partly buried near the screen the larger one contains acetone and the smaller one octanol new attractants are being being developed methy ethy Ketone is more effective than acetone simple targets like this with odor attractants are being used successfully in several African countries in setti control campaigns although care has to be taken to ensure the correct location of these devices they have the advantage over other methods of control in that they're relatively cheap they're non-polluting to the environment and can with assistance be maintained by local people if sprayed with Delta methine this only has to be renewed every 6 months or so developments in Target and trap technology have produced exciting improvements in setti control but many questions remain to be answered in this experiment a ring of electrified screens with calculated gaps surrounds a trap so that the number of flies attracted to it can be estimated by catching and Counting a representative sample and here at Langford tsti Pupi are being prepared for sterilization by exposure to radiation from a Cobalt Source when the flyes hatch the males will be selected and released in Africa they will compete with nor noral males for the available females but no Offspring will be produced irradiation techniques like this are often beyond the resources of developing countries but there are other methods of sterilizing tetti we can sterilize mssi selectively on a Target by providing small inanimate objects similar in size and shape to a female on the target these decoys are visually attractive to the males and if they're don't with the female sex pheromone of the species the males will be induced to attempt to mate with them if these pheromone baited decoys are also dosed with a chemical sterilant we have the means of sterilizing the males but they will not sterilize the females and most chemical sterilants are dangerous and highly toxic to other life forms safer chemicals for insect Pest Control are often based on the insect's own hormones new very potent analoges and mimics of insect juvenile hormones are now available they cause development to be arrested at the pupil stage when applied to at setti Pupa development will be arrested after 20 days and it will die but setti Pupi are buried in the ground and therefore cannot be treated directly however the tsti reproductive system comes to our rescue because treat treatment of the adult female with an appropriate formulation of a juvenile hormone results in entry of the hormone into the female's body she transfers the substance to the lava developing in her uterus the lava grows and is born normally but after 20 days in the ground at 25° C development ceases and the puper dies All The Offspring she produces are similarly affected targets and traps can now be adapted so that female flies attracted to them will pick up enough of the compound to sterilize them in this trap the setti passed through a cone of mesh impregnated with synthetic juvenile hormone juvenile hormones have no effect on maled setti but males that make brief contact with them can pick up sufficient material so that when they mate enough is transferred to the female to affect the lvy she produces as the graph shows the sterilization of 1% per day of the males in a ssti population by exposing them to irradiation or a chemical on a Target or in a trap would not produce such a rapid decline in the population as killing 1% per day of both sexes however sterilizing 1% per day of both sexes produces ultimately a greater population decline targets and traps provide the means of either killing or chemically sterilizing tsti selectively since not many other insects are attracted by such devices attempts are being made to exploit Target and trap technology to increase trap efficiency and to use espcially formulated volatile attractive pheromones and juvenile hormone compounds at a level of tech technology suitable for self-help campaigns in Africa but there are plenty of problems spraying from the air in carefully designed and monitored campaigns Remains the most effective method of setti control but it's expensive and requires skilled operators and reinvasion takes place from neighboring unsprayed areas targets screens and traps add a valuable bonus but the materials from which they're made can be used for other purposes and they often disappear the new methods based on pheromones and hormones have yet to be evaluated the search goes on [Music]