PREDICTION OF APPLE MAGGOT FLY RHAGOLETIS-POMONELLA (DIPTERA, TEPHRITIDAE) EMERGENCE FROM THERMAL UNIT ACCUMULATION

The minimum temperature threshold for the development of apple maggot pupae, Rhagoleiis pomonetla, was 6.4°C. From 1951-75 the 1st flies emerged in cages over infested apples on the avg on June 15 near Highland, NY and on June 23 in Geneva, NY. The avg accumulated air temperature thermal units (T.U.'s) from Mar. 1 using a threshold of 6.4°C until 1st emergence were 614±53 and 641 ±48, respectively, at the 2 locations. The annual deviations between the actual first emergence and the date when the avg T.U.'s were accumulated ranged from 1-8 days with an avg of 3.5 at Geneva and from 1-14 days with an avg of 5.7 days at Highland. From 1975-77 the mean T.U. accumulation and the 99% confidence interval developed at Geneva was used to predict emergence in 5 locations in Wayne Co. The deviations between the observed emergence and dates in which the appropriate number of T.U.'s was accumulated averaged 3.5 and 0.8 days, respectively. © 1979 Entomological Society of America.