The Viability, Fertility and Behaviour of Tsetse Flies (Glossina Morsitans) Sterilized by Irradiation Under Various Conditions

Abstract

Glossina morsitans pupae of known age were irradiated at different times during pupal life. The ages after which irradiation in air did not prevent development and normal eclosion, were identified. Irradiation at the earliest age which allowed normal eclosion of males resulted in decreased adult survival compared with pupae irradiated on the day of eclosion, but in both cases survival was improved by irradiating in an atmosphere of nitrogen. Pupae which had reached the day of peak male eclosion were stored at 10°—11° for 5 days and then produced a predictable flush of adult emergence following irradiation in nitrogen or in air. This technique, or the alternative of irradiation some days before eclosion is expected, would enable several days' collection of pupae to be treated as a single batch for the purposes of release in a sterile male control project. Laboratory measurements of several behavioural parameters showed that adult males, irradiated as pupae, can deviate from normal when compared with unirradiated controls. However, irradiation in nitrogen caused less alteration to behaviour than the lower doses in air required to achieve the same reduction in fertility. Measurements and estimates of the somatic and genetic effects of various irradiation treatments given under described conditions, were used to predict the treatment which would provide the optimal population suppression in a field control project involving the release of sterilized males. Computations have shown that the optimal sterilizing treatment may differ for different target levels of population reduction, and this concept may be of considerable significance in the control of oviparous insects with greater reproductive potential than tsetse flies. Résumé LONGÉVITÉ, FERTILITÉ ET COMPORTEMENT DE MOUCHES TSÉ‐TSÉ (GLOSSINA MORSITANS) STÉRILISÉES PAR IRRADIATION SOUS DIVERSES CONDITIONS Des pupes de Glossina morsitans d'âge connu ont éTÉ irradiées à divers moments de leur développement. On a ainsi précisé les âges auxquels l'irradiation (dans l'air) n'empêche ni le développement, ni l'éclosion de la pupe. La survie des adultes mâles qui éclosent normalement de pupes irradiées à leur plus jeune âge est réduite par rapport à celle des måles provenant de pupes irradiées tardivement, le jour même de l'éclosion. Dans les deux cas cependant la survie est prolongée quand l'irradiation des pupes se fait dans une atmosphère d'azote, plutôt que dans l'air. Les pupes ayant atteint l'âge pour lequel on obtient le maximum d'éclosions d'imagos mâles après irradiation peuvent être stockées à 10°–11° pendant 5 jours, de façon à s'assurer une production en séries de mâles irradiés. Cette technique permettrait d'irradier en un seul lot des pupes collecTÉes au cours de plusieurs jours, ce qui est un avantage certain dans le cas d'un projet de lutte autocide. Plusieurs paramètres relatifs au comportement des mâles adultes peuvent être mesurés en laboratoire et cette étude montre que les mâles issus de pupes irradiées en atmosphère d'azote conservent un comportement p...

Chilling, irradiation and transport of male Glossina palpalis gambiensis pupae: effect on the emergence, flight ability and survival.

“…Similar results were observed for G. tachinoides pupae irradiated with 120 Gy on day 28 post larviposition [25] and for G. p. gambiensis pupae irradiated with 110 Gy [16]. These results were expected since several studies in the past have aimed at optimising the irradiation process in order to induce near 100% sterility while minimising somatic damage [26,27].…”

LABORATORY EVALUATION OF CONTACT SEX PHEROMONE AND BISAZIR FOR AUTOSTERILIZATION OF GLOSSINA MORSITANS

“…It is also apparent that sterilized d' d' can compete with normal d d to secure a mate. However, as shown by Curtis & Langley (1972) a simple test of competitiveness in the laboratory can provide no indication of other behaviourai changes associated with sterilization (Langley et al, 1974) and which may be reflected in an impaired ability to compete with normal <5' d' for mates in the field.…”

Survival and reproductive potential of gamma irradiated male Glossina pallidipes Austen

“…This dose induces a comparable level of sterility in other members of the morsitans group i.e. G. m. morsitans and G. austeni (Curtis, 1968 andLangley et al, 1974), and it is therefore likely that the sterilising dose found with G. pallidipes from Uganda will apply to G. pallidipes from Ethiopia. The survival and mating ability of irradiated males were not significantly compromised under laboratory conditions and even in field cages these males competed very well for mates, although there was a small but significant reduction in the amount of sperm transferred during insemination among females mated to irradiated males (G. Mutika, pers.…”