Storage Time Effect Of Defibrinated And Irradiated Bovine Blood Feeding On Glossina Pallidipes And Glossina Fuscipes Fuscipes Under Laboratory Conditions For The Purpose Of Sterile Insect Techniques

Abstract

The use of sterile insect techniques in tsetse fly control and eradication campaign depends on mass production of good quality sterile males in laboratory. The mass production of the flies in turn requires a constant supply of blood diet with good quality because both males and females including the larvae within the uterus of pregnant female flies depend on the blood for their survival and reproduction. The aim of this study was to investigate storage time and irradiation effect on reproductive and mortality/ survival rate of G. pallidipes and G. fuscipes fuscipes under laboratory condition. A total of 540 females and males flies randomly sampled from each G. pallidipes and G. fuscipes fuscipes species to investigate both storage and irradiation effect respectively. Flies were fed on different batches of blood collected and stored for three years, two years, one year, and one month fresh blood, fed four times a week. To investigate irradiation effects, two groups again were allocated to feed on both irradiated and non-irradiated fresh one-month blood. Pupae were collected daily and mortality checks were done on weekly basis. The quality of the blood diet was measured by observation of microbial load in blood, tsetse production parameters including mortality/ survival, PPIF, fecundity, pupae production, and weight. One-way analysis of variance was performed to analyze data on storage time effect and the qualities of blood between irradiated and non-irradiated were analyzed by using STATA computer software (version 12). Mean separation was made using Duncan's Multiple Range Test (DMRT). The result revealed that the survival of flies fed on irradiated blood batches stored at -20ºC within two to three years’ time range had lower survival compared to the rest of the irradiated blood batches stored for less than a year. Similarly, lower pupae production was also recorded among these irradiated bloods. The irradiated blood stored for two to three years range had more of small pupae (class A and B) compared to fresh one-month irradiated blood batched stored less than a year in both species. Additionally, our study showed that irradiated defibrinated bovine blood was also found to be suitable to maintain G. pallidipes and G. fuscipes fuscipes colonies compared with non- irradiated bovine blood. The result showed that the efficacy of sterilization of cobalt 60 (1.5. KGy) on blood was high. Both the survival and PPIF of flies fed on non-irradiated fresh one-month blood batches were lower compared to flies fed on fresh one-month irradiated blood in both species. Bacterial isolates of Rhudococcus equi commonly found in both non-irradiated blood feed diets and in sampled dead flies. There was a significant difference between the blood storage time and the production parameters were better among flies fed on fresh one-month blood stored less than a year. Furthermore, this study showed that irradiated defibrinated bovine blood was suitable to maintain G. pallidipes and G. f. fuscipes colonies compared with non-irradiated bovine blood. Both the survival and PPIF of flies fed on non-irradiated fresh one-month blood batches were lower compared to flies fed on fresh one-month irradiated blood in both species. Therefore, it can be recommend that fresh one-month irradiated bovine blood stored for less than a year to be an optimum storage time for rearing of both Tsetse species at KTFRC for the control of the flies using SIT.