A SIMPLE METHOD FOR ARTIFICIAL INFECTION OF TSETSE, GLOSSINA-MORSITANS-MORSITANS LARVAE WITH THE DNA VIRUS OF GLOSSINA-PALLIDIPES

Newly deposited Glossina morsitans morsitans larvae were chilled over ice and inoculated with 1 mul of either virus suspension derived from Glossina pallidipes salivary gland homogenate or sterile tsetse physiological saline. They were allowed to pupariate and then maintained at 25-degrees-C, 70% r.h. until soon after emergence when their salivary glands were examined for enlargement and presence of virus particles. Teneral G. m. morsitans which received the virus inoculum (n = 135) as larvae all became infected as revealed by gross hypertrophy of their salivary glands and ultrastructural manifestation of virus particles within the glandular epithelial cells and lumina. In the control group, which received the tsetse physiological saline (n = 91), only 1.1% of the flies showed the salivary gland enlargement, a level equivalent to the prevalence of virus infection normally detectable in the G. morsitans colony. This technique opens the way for testing the biocontrol potential of this virus. The DNA virus from G. pallidipes is clearly infective to G. morsitans morsitans, suggesting that the hypertrophied, chalky-white salivary glands, reported in various Glossina spp., are a manifestation of infection by one and the same virus.