DISINFESTATION OF LEAFROLLER AND MITE PESTS USING A HIGH-TEMPERATURE CONTROLLED ATMOSPHERE

Abstract

Mortality responses of 3-d-old eggs and 1st, 3rd and 5th instars of Epiphyas postvittana (Walker), Planotortrix octo Dugdale, Ctenopseustis obliquana (Walker), and diapausing adult Tetranychus urticae Koch to a high-temperature controlled atmosphere (1.2% O 2 with 1% CO 2 at 40°C) were determined in the absence of host fruit. The treatment incorporated a 21 h protocol to serially establish the target controlled atmosphere and temperature conditions. E. postvittana was the most tolerant leafroller to controlled atmosphere treatment. The mean treatment time for 99% mortality (LT 99 ) for life stages of E. postvittana decreased in the following order: 3rd instars ≃ 5th instars > 1st instars ≃ 3-d-old eggs. Controlled atmosphere treatment was more effective against this species than air at 40°C (3th instar LT 99 values of 34.6 and 44.2 h respectively). P. octo and C. obliquana were equally susceptible to the controlled atmosphere treatment, and the life stages tested exhibited similar mortality responses (LT 99 values ranging between a minimum of 18.5 h to a maximum of 21.4 h). Both these leafrollers were more sensitive to air at 40°C than E. postvittana, T. urticae was more tolerant of the controlled atmosphere than the 3 leafroller species (mean LT 99 value of 120.5 h). The mortality responses of diapausing T. urticae were similar under controlled atmosphere or air treatment at 40°C.