Takac, P. | bioRxiv Science

bioRxiv2020

Three-dimensional analysis and visualization of morphological adaptations associated with viviparity in the Tsetse fly (Glossina morsitans).

Tsetse flies (genus Glossina), the sole vectors of African trypanosomiasis, are distinct from other disease vectors, and most other insects, due to dramatic evolutionary adaptations required to support their unique life history. These morphological and physiological adaptations are driven by demands associated with their strict dietary and reproductive requirements. Tsetse reproduce by obligate viviparity which entails obligate intrauterine larval development and provisioning of nutrients for the developing larvae. Viviparous reproduction reduces reproductive capacity/rate which also drives increased inter- and intra-sexual competition. This work describes three-dimensional (3D) analysis of viviparity associated morphological adaptations of tsetse female reproductive tract as well as that of male seminal secretions by phase contrast microcomputed tomography (pcMicroCT). Structural features of note include abdominal modifications facilitating the extreme abdominal distention required during blood feeding and pregnancy; abdominal and uterine musculature required for parturition of developed larvae; reduction of ovarian structure and capacity; structural features of the male seminal spermatophore that enhance sperm delivery and inhibition of insemination by competing males; uterine morphological features facilitating expansion and contraction before, during and after pregnancy; analysis of structural optimizations of the milk gland facilitating nutrient incorporation and transfer into the uterus. The use of pcMicroCT provides unprecedented opportunities for examination and discovery of internal morphological features not possible with traditional microscopy techniques and new opportunities for comparative morphological analyses over time and between species.Competing Interest StatementThe authors have declared no competing interest.View Full Text

physiology↗

bioRxiv2018

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

BackgroundThe sterile insect technique (SIT) requires mass-rearing of the target species, irradiation to induce sexual sterility and transportation from the mass-rearing facility to the target site. Those treatments require several steps that may affect the biological quality of sterile males. This study has been carried out to evaluate the relative impact of the chilling, irradiation and transport on emergence rate, flight ability and survival of sterile male tsetse flies Glossina palpalis gambiensis.\n\nResultsChilling, irradiation and transport all affected the quality control parameters studied. The emergence rate was significantly reduced by long chilling periods and transport, i.e. from 92% at the source insectary to 78% upon arrival in Dakar. Flight ability was affected by all three parameters with 31% operational flies lossed between the source and arrival insectaries. Only survival under stress was not affected by any of the treatments.\n\nConclusionThe chilling period and transport were the main treatments which impacted significantly the quality of sterile male pupae. Therefore, the delivery of sterile males was divided over two shipments per week in order to reduce the chilling time and improve the quality of the sterile males. Quality of the male pupae may further be improved by reducing the transport time and vibration during transport.\n\nAuthor summaryTsetse fly and the disease it transmits, trypanosomosis, remain an enormous challenge in several countries in sub-Saharan Africa. The use of the Sterile Insect Technique (SIT) has become one of the components of the eradication of tsetse fly in Africa. The sterile insect technique (SIT) requires mass-rearing of the target species, irradiation to induce sexual sterility and transportation from the mass-rearing facility to the target site. In this study, we demonstrate the relative impact of the chilling, irradiation and transport on the emergence rate, the flight ability and the survival of sterile male tsetse flies Glossina palpalis gambiensis. We found that the chilling, irradiation and transport affected the emergence rate and flight ability. But the survival of the sterile male under stress was not affected by any of the treatments. Hence, the quality of the male pupae may further be improved by reducing the transport time and vibration during transport.

physiology↗