COMPARISON OF 2 POTENTIAL METHODS TO DETECT BACTROCERA-TRYONI (DIPTERA, TEPHRITIDAE) GAMMA-IRRADIATED FOR QUARANTINE PURPOSES

We examined use of both biochemical and anatomical techniques to detec t irradiated larvae and pupae of the Tephritid fruit fly Bactrocera tr yoni (Froggatt). Electrophoretic protein profiles for control and irra diated larvae were similar, irrespective of the age at which irradiati on occurred. Protein profiles for control and irradiated pupae were al so similar for the first 2 d of pupation. A new protein band was detec ted in control pupae 3 d after pupation began. This band was not obser ved in any irradiated pupae. However, because pupae cannot be aged mor phologically, the absence of this protein band cannot be used to disti nguish between irradiated and nonirradiated pupae of unknown age. Diss ections of pupae indicated that the new protein band was not present b ecause irradiated pupae died during the first days of pupation. No irr adiated pupae survived to emergence. Electrophoretic techniques did no t identify consistently either irradiated larvae or pupae of B. tryoni . The corrected size of the supraesophageal ganglion in irradiated mat ure larvae was significantly smaller than in untreated larvae, regardl ess of the age at which irradiation occurred. This reduction was appro ximate to 64% in samples treated as eggs (26 h), first (72 h), and sec ond (96 h) instars and 34% in third instars. A significant reduction i n size of the supraesophageal ganglion of mature third instars from al l irradiation treatments suggests that this character may be successfu lly used to detect B. tryoni irradiated at quarantine dose rates. Irra diated samples had a significantly longer larval and pupation period, possibly because of the inability of irradiated larvae to feed normall y. We also observed a significant increase in larval mortality with de creasing age at irradiation.