Activity patterns in pregnant tsetse flies, Glossina morsitans

International audienceThe circadian rhythm of locomotor activity in the parasitoid Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae) varies according to genetic and non-genetic factors. The physiological state of the adult influences the circadian rhythm of locomotor activity. Mating is responsible for a long-term decrease in the activity of males, while an increase in female activity is observed. In females, a previous oviposition reduces the spontaneous activity for 2 days. Food deprivation causes a 2-day increase in daily activity, followed by a strong decrease for both sexes. The daily amount of activity is much more affected by physiological variations of the parasitoid than the temporal distribution of the activity (i.e. phase and pattern of activity). In all experiments, variation in locomotor activity was related to path variations. Furthermore, comparison of inbred lines proved the genetic variability of these behavioural traits and of infestation capacity within a strain. Correlations between successive generations demonstrated their transmissibility. The genetic variability constitutes an evolutionary potential allowing the population to display an adaptive response to predictable (i.e. periodic) environmental variations. The behavioural plasticity resulting from physiological changes allows an individual response to unpredictable variations of the environment. Both mechanisms optimize resource exploitation by insect parasitoids

Section: Discussionmentioning

confidence: 99%

Physiological and genetic factors as sources of variation in locomotion and activity rhythm in a parasitoid wasp (Trichogramma brassicae)

Pompanon

Fouillet

Boulétreau

1999

“…The tubes, held lid-down in a compartmentalized box, were examined daily, shortly after lights on, for newly deposited puparia. As larviposition usually occurs between midday and sunset (Denlinger & Ma, 1974;Brady & Gibson, 1983;Randolph et al, 1991a), the date of larviposition was taken as the previous day and this was designated 'day O', with succeeding days in the pregnancy cycle designated 'day l', 'day 2', etc.…”

Section: Methodsmentioning

confidence: 99%

Reproductive under‐performance of tsetse flies in the laboratory, related to feeding frequency

Gaston¹,

Randolph²

1993

Abstract. The rates of development of the eggs and larvae in utero and the next two developing ovarioles were measured by ovarian dissection on each day of the pregnancy cycle in tsetse, Glossina morsitans, subject to different feeding regimes. Compared with flies fed four times per pregnancy cycle, flies fed three times per cycle showed a lower pupal production rate (70%), the same (zero) adult mortality, a slightly slower growth rate of the larva and second ovariole only from day 8 onwards, but the same growth rate of the first ovariole. Flies fed only twice per pregnancy cycle produced no pupae, suffered 18% adult mortality and showed a significantly slower growth rate of the larva and second ovariole from days 6 and 7 respectively, but still the growth rate of the first ovariole was barely affected. Flies offered food three times or twice per pregnancy cycle engorged fully at every opportunity, but 16.5% of the flies offered food four times per cycle did not feed on every occasion, while 12–22% did not engorge fully on days 3, 5 or 7. In assessing the applicability of these laboratory results to the field situation the following points must be borne in mind: in the laboratory flies take smaller mean blood meals than in the field; during protein production associated with larval growth the proportion of the blood meal lost to transformation and excretory costs is less than during normal lipid metabolism; the balance between the tsetse's known fertility rate and adult and pupal mortality rates reveals that the abortion rate in the field must be extremely low. The high abortion rates usually observed in laboratory colonies, even when flies are offered food dailyl would be quite untenable in the field and indicate that laboratory conditions impose physiological stresses on the flies that are quite different from those in the field. These facts indicate that three field‐sized meals may be sufficient to meet the energy demands of normal larval development in the field.

“…Accepting that laboratory-reared flies fed ad Libitum probably ingest smaller meals than flies in the field, it seems that five or six blood meals per inter-larval period of 9 days may be normal for G.rn.morsitans in the laboratory (Langley & Pimley, 1974;Brady & Gibson, 1983). However, if the opportunities to feed are restricted, flies compensate by ingesting larger meals (L.angley & Pimley, 1975).…”

Section: Introductionmentioning

confidence: 99%

Feeding frequency in relation to reproduction in Glossina morsitans morsitans and G.pallidipes

Langley

Stafford

1990

Measurements of residual haematin in males of Glossina morsitans morsitans Westwood reared in the laboratory at 25oC suggest that blood meal digestion is completed in 4 or 5 days after feeding. However, a high proportion of haematin is present as faecal matter 2 days after feeding and it is concluded that digestion is completed sooner than indicated by the regression of logio haematin on time. Therefore, low levels of residual haematin in field‐caught tsetse provide no indication of the frequency with which they feed. For this reason the effects of feeding frequency upon various reproductive parameters in the laboratory have been examined. It is concluded that the best performance is achieved by G.m. morsitans females which ingest four blood meals per inter‐larval period and that for a similar performance in G.pallidipes five blood meals are required. The extent to which such feeding frequencies are a reflection of feeding activity in the field are discussed in terms of the biochemical requirements to maintain a reproductive adult female tsetse in positive energy balance.