Radio frequency treatments to control codling moth in in-shell walnuts

'Diamond' Walnuts (Juglans regia L.) in the shell were treated with radio frequency (RF) energy in a 27 MHz pilot-scale system to determine the treatment effect on third- and fourth-instar codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), mortality and walnut quality. After 2 and 3 min of RF treatments, infested in-shell walnuts were heated to 43 and 53 degreesC. The corresponding insect mortality reached 78.6 and 100%. The fatty acid (FA) concentration of treated walnuts was not affected by RF treatments. The FA Values were < 0.1% after accelerated storage times up to 30 days at 35<degrees>C, simulating storage at 4 degreesC for up to 3 years. The effect of RF treatments on walnut oil peroxide values (PV) was not significant. The PV value of walnuts was less than 1.0 meq/kg (the upper limit for good quality walnuts), after 20 days storage at 35 degreesC that simulated 2 year storage at 4 degreesC. The PV was about 1.2 meg/kg after 30 days storage at 35 degreesC. RF treatments can, therefore, potentially provide an effective and rapid quarantine security protocol against codling moth larvae in walnuts as an alternative to methyl bromide fumigation. (C) 2001 Elsevier Science B.V. All rights reserved.