Circadian activity patterns in three species of tsetse fly: Glossina palpalis, austeni and morsitans

ABSTRACT. Observations on the nature and control of spontaneous flight activity in tsetse flies have so far been made only on G. m. morsitans Westw. This paper reports preliminary observations of the same kind on two other species: G. p. palpalis (R.-D.) and G. austeni Newst. The flight pattern of all three species consisted of short bursts of activity (usually lasting <1 min) separated by long intervals of rest, changes in activity level occurring exclusively as changes in the frequency of these flight bursts. In constant conditions in LD 12:12, G. palpalis and G. austeni were almost totally diurnal, with strongly predominant afternoon activity peaks, but a slight tendency to decrease activity around noon as occurs to a much greater extent in G. morsitans. This rhythm persisted in constant darkness (DD), but whereas in most G. morsitans only the morning peak was retained in DD, in G. palpalis and G. austeni it was only the afternoon peak. The loss of the afternoon peak in G. morsitans may be due to the very low activity levels in DD. Food deprivation led to increased activity in all three species, most markedly so in G. palpalis and G. austeni , in which the amount of activity per day increased c. ten-fold over three days' post-emergence starvation.     

A study on isoenzyme polymorphism in the tsetse fly Glossina morsitans

Polymorphism was studied for a number of enzyme systems in the tsetse fly Glossina morsitans. Enzyme polymorphism was observed for -glycerophospate dehydrogenase, aldehyde oxidase and esterases. For esterases, the operation of null alleles was assumed, as otherwise no explanation could be given for the observed frequencies of the variants.Two laboratory colonies and two field populations were compared with respect to their variation at the leucine aminopeptidase (Lap) loci, for which polymorphism was shown to occur in previous work. Conspicuous differences were found between material originating from Tanzania and from Rhodesia. In addition, allelic relationships were established for the Lap ₃-locus.

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Résumé Faisant suite à des études antérieures, le polymorphisme d'un certain nombre de systèmes enzymatiques a été étudié chez Glossina morsitans. Un polymorphisme a été observé pour l' -glycerophosphate déhydrogénase, pour l'aldéhyde-oxydase et pour les estérases. Pour les estérases, on a supposé l'intervention d'allèles nuls, les fréquences observées chez les variants ne pouvant être expliquées d'autre façon.Deux colonies élevées au laboratoire et deux populations naturelles ont été comparées quant à leur variation au niveau des loci (Lap) pour la leucine aminopeptidase, pour lesquels un travail antérieur avait mis en évidence un polymorphisme. Des différences nettes ont été trouvées entre le matériel provenant de Tanzanie et celui de Rhodésie. En outre des parentés alléliques ont été établies en ce qui concerne le locus Lap ₃.

     

Rhythmic pulses of haemolymph pressure associated with parturition and ovulation in the tsetse fly,Glossina morsitans

Abstract Expulsion of the tsetse larva from the uterus of the female is preceded by 1–2 h of rhythmic pulses of haemolymph pressure that can be detected using a barographic technique. At first baseline pressure is maintained and all pulses are positive in relation to baseline. Then, about 1 h before parturition, baseline pressure increases, pulse intensity increases, and the pulses become both positive and negative in relation to baseline. Each pulse correlates with ‘bobbing’ action of the female's proboscis, the only external indication of this internal activity. A single large pressure pulse is observed at parturition, and thereafter the pressure level returns to the original baseline and pulsing action ceases. Around the presumptive time of ovulation, 1–2 h after parturition, another series of pressure pulses is observed. The pulses are the likely consequence of coordinated waves of muscular contraction that are essential preparation for successful parturition and ovulation.     

Female meiosis in two species of tsetse fly (Genus Glossina)

Supernumerary chromosomes form bivalents during female meiosis in the tsetse fly and it is suggested that this is a control mechanism for their retention in the population. Chiasmata regularly form in the autosome and X chromosome bivalents.     

Diuresis in the tsetse fly Glossina austeni.

After taking a blood meal, the tsetse fly Glossina austeni excretes the excess water and salts of the meal in approximately 30 min. During this period a volume of fluid equivalent to 80% of the unfed weight of the fly passes through the haemolymph, whose composition nevertheless remains almost constant. The fluid excreted has a higher sodium and lower potassium concentration than the haemolymph, indicating that sodium may be the prime mover in urine formation in Glossina.     

Octopamine distribution in the tsetse fly Glossina morsitans

Tissues of Glossina morsitans were assayed for octopamine using an enzymatic technique. Octopamine was detected at the highest concentration in the brain (7.06-7.99 ng mg-1 tissue protein) and thoracic ganglion (10.9-13.89 ng mg-1 tissue protein). Octopamine was present in haemolymph at a concentration of 1.0-1.27 X 10(-7) M. This was not found to vary when insects were flown or mechanically stressed. Nervous tissue, flight muscle and haemolymph showed a significant ability to metabolize octopamine. The greatest enzyme activity was present in the haemolymph.     

Lipophorin from the tsetse fly, Glossina morsitans morsitans.

1. Lipophorin was isolated from the haemolymph of adult tsetse fly, Glossina morsitans morsitans, by ultracentrifugation in a potassium bromide density gradient. 2. The tsetse fly lipophorin (Mr congruent to 600,000) has a density of congruent to 1.11 g/ml and consists of two apoproteins, apolipophorin-I (apoLp-I, Mr congruent to 250,000) and apolipophorin-II (apoLp-II, Mr congruent to 80,000), both of which are glycosylated as shown by staining with periodate-Schiff reagent. The protein complex is composed of 49% protein and 51% lipids. 3. The finding of lipophorin in tsetse fly haemolymph suggests that, although these flies primarily utilize proline for their energy needs, there is an active transport mechanism for the supply of lipid requirements.     

Ovulation, insemination and mating in the tsetse fly Glossina pallidipes

ABSTRACT. Analyses of the ovulation, insemination and mating of female Glossina pallidipes Austen, were carried out in the field and laboratory. In unmated females, ovulation was delayed until at least the fifteenth day of adult life. The predictable pattern of growth and development of eggs was used to age nulliparous females to the nearest day in the field. Inseminated females first appeared at 5–6 days old and most females became inseminated at 8–10 days of age. There were no significant differences in the age at insemination in Zimbabwe or Kenya. Ovulation had occurred in the field by 10–11 days old. Mating therefore occurs at or just before ovulation. Females were able to mate at up to 12 days old and still produce a viable larva from their first egg. In laboratory flies originating from Uganda, factors which reduced and minimized the effects of disturbance, maximized insemination rate, so that under the best conditions the age at mating was identical to that found in the field. Nevertheless, the insemination rate of Fl generation Zimbabwe flies reared from wild-caught females was negligible. The differences in the laboratory mating behaviour of the Zimbabwe flies and the flies from the long-established colony of Uganda origin, are considered to be due to wild G. pallidipes being easily disturbed under laboratory conditions, whereas colony breeding rapidly selects for passivity. The concept of gross differences in G. pallidipes mating behaviour between geographic areas in thus rejected.     

Oxidation of proline by sarcosomes of the tsetse fly,Glossina morsitans

Mitochondria isolated from the flight muscles of tsetse flies are capable of oxidizing proline at rates commensurate with the requirements of the flight system. The rate of oxidation of other substrates is negligible by comparison. In the presence of phosphate, the oxidation of proline is completely controlled by ADP, acting at the level of the respiratory chain and not at the level of the dehydrogenases. The amount of alanine formed during the in vitro oxidation of ¹⁴C-proline is substantially less than the amount of proline used. The result is interpreted on the basis of a branching of the metabolic pathway at the level of glutamate, with the aminotransferase accounting for approximately 80% of the flux, and glutamic dehydrogenase for the remainder.     

The control of receptivity and ovulation in the tsetse fly, Glossina morsitans

ABSTRACT. A rapid decline in receptivity of mated female Glossina morsitans morsitans Westwood is shown to depend on both physical and chemical stimuli associated with copulation. Radiolabelling revealed the transfer of substances from the male to the haemolymph of the female during copulation. Implantation of male tissues or their injection as homogenates into virgin females showed the chemical stimulus to come from the male accessory glands. Receptivity decreased in females mated to males with ejaculatory ducts severed or testes removed and also in females which had a glass bead inserted into their uterus and/or the tip of their abdomen covered with wax, suggesting that a physical stimulus inducing refractoriness is provided by distension of the uterus and/or stimulation of their terminalial setae. Exposing virgin females to daily short matings in which no male materials were transferred, confirmed this. Receptivity also declined slowly with age in unexposed virgin females. Transfusion of haemolymph from mated females (up to 11 days old) into virgins did not indicate the existence of a haemolymph-borne ovulation-inducing factor; apparently only physical stimuli from mating are involved in the induction of ovulation, and somehow prime the ovarian tissue so that it responds appropriately later when the egg has matured. Whether the stimulus is transmitted to the ovary neurally or hormonally is unknown.