INFLUENCE OF IRRADIATION ON DEVELOPMENT OF CARIBBEAN FRUIT-FLY (DIPTERA, TEPHRITIDAE) LARVAE

Larvae of the Caribbean fruit fly, Anastrepha suspensa (Loew), were ir radiated at hatching with 0, 5, 10, 20, 50, 75, 100, and 150 Gy doses from a Cesium-137 source and dissected for measurements of the supraes ophageal ganglion (brain) and proventriculus (B/Pry) as mature third i nstars, Cross-sectional area of a plane through the brain and proventr iculus, and simple dorsal width measurements of the two organs were ev aluated as indicators of radiation exposure. Brain area, brain width, and brain/proventriculus (B/Prv) ratios were significantly different f rom controls in insects treated with a dose greater than or equal to 2 0 Gy. Detailed dissections of hatching larvae exposed to 50 Gy reveale d reductions in brain growth small and misshapen compound eye and leg imaginal disks, and a ventral nerve cord that was elongated and sinuou s. Larvae irradiated on the 1st d of each of the three instars had sma ller brains, with the percentage of reduction in brain size being grea ter the younger the larvae were at the time of exposure. Brain and pro ventriculus measurements and calculated B/Prv values are indicative of irradiation in Caribbean fruit fly larvae, but the procedure may not be adaptable for routine use by quarantine inspectors.