The susceptibility of tsetse flies to topical applications of insecticides. I.—Young adults of <i>Glossina morsitans</i> Westw. and chlorinated hydrocarbons

As part of a programme to test the sterile insect technique against Glossina morsitans morsitans Westw. in Tanzania, two aerial applications of endosulfan were applied to a 195-km 2 test area. The applications were made with a 28-day interval to provide an initial reduction in the target species prior to the release of sterile males. A Cessna 310 aircraft equipped with a rotary atomiser and operating at night was used to apply the insecticide at a dosage of about 20 g/ha. Flyround surveys within 48 h following the spraying operations indicated that a 100% reduction of G. m. morsitans adults was achieved in both applications, while G. pallidipes Aust. was reduced by 91 5% in the first and 100% in the second.

Section: Resultssupporting

confidence: 53%

Integration of insect sterility and insecticides for control of Glossina morsitans morsitans Westwood (Diptera: Glossinidae) in Tanzania. IV. Application of endosulfan as an aerosol prior to release of sterile males

Williamson¹,

Dame²,

Lee³

et al. 1983

“…The effects of sex ratio distortion in G. m. submorsitans may have had some bearing on the success of the insecticide control programme which has been carried out against this species in Northern Nigeria (Davies, 1964(Davies, ,1971. A shortfall of males in wild populations may be exacerbated by selective mortality of males because of their greater susceptibility to insecticides (Burnett, 1961(Burnett, ,1962. This may push the population over the threshold beyond which insufficient females are mated during the initial days of life when they are receptive to mating (Gillott & Langley, 1981).…”

Section: Discussionmentioning

confidence: 99%

Sex ratio distortion inGlossina morsitans submorsitansNewstead (Diptera: Glossinidae)

Rawlings

Maudlin

1984

A laboratory colony of Glossina morsitans submorsitans Newst. originating from Nigeria exhibits an excess of females over males. The sex ratio distortion of more than two females to one male was studied by the maintenance of individual flies. Five males sired more than ten daughters without producing any sons when mated to several females, whilst other males fathered approximately equal numbers of male and female offspring; there was no evidence for selective abortion of male embryos. The presence of these 'distorter' males, which produce only female offspring, was found to cause the sex ratio distortion. The results are discussed with reference to data from the field which indicate that this genetic aberration is not confined to the laboratory; possible implications for chemical control programmes are assessed.

“…Tsetse flies have been shown to be extremely susceptible to certain insecticides (Burnett, 1961;Hadaway, 1972), which accounts for the very high levels of kill attained in some field trials (Kendrick & Alsop, 1974) and for the complete eradication of tsetse in certain areas (Davies, 1964(Davies, , 1971. Insecticide resistance has never been demonstrated in the field and because of the outstanding success of some control operations has never been seen as a serious threat to future operations.…”

Section: Discussionmentioning

confidence: 99%

The potential for insecticide resistance in Glossina (Diptera: Glossinidae)— an investigation by computer simulation and chemical analysis

Maudlin

Green

Barlow

1981

A computer model of a tsetse population was developed to determine whether insecticide resistance could evolve as a result of current tsetse control programmes. Chemical analyses were also carried out which showed that Glossina morsitans morsitans Westw. can metabolise DDT to DDE, indicating a potential for insecticide resistance in this species. The model showed that a completely isolated tsetse population stands little chance of surviving attacks with insecticides repeated at short intervals. However, when sufficient time is allowed between applications, such a population may survive and evolution of resistance take place. Given a small amount of immigration, the evolution of resistance is retarded, but population extinction is prevented. The degree of resistance developed by a population also depends on the dominance relationship of a resistant gene with its wild-type allele and on the reproductive fitness of the mutant. It is suggested that control strategies are adopted which would minimise the risk of insecticide resistance becoming a problem in tsetse and that susceptibility studies are carried out both before spraying operations and on any residual population post-spraying.