CRYPTOPHLEBIA-LEUCOTRETA (LEP, TORTRICIDAE) - A PROMISING ALTERNATE HOST FOR MASS-PRODUCTION OF THE CYDIA-POMONELLA GRANULOSIS-VIRUS (CPGV)FOR BIOLOGICAL PEST-CONTROL

Cydia pomonella (L.) (Lep.: Tortricidae), the codling moth, is an impo rtant pest particularly in apple orchards. Its larvae damage the fruit . The granulosis virus CpGV, which originates in C. pomonella, can be used as biological control agent of this pest with similar efficiency like chemical insecticides. But an in vivo-production of CpGV is insuf ficient with C pomonella, because an effective mass rearing of the hos t is difficult. Therefore, another species of the same family, Cryptop hlebia leucotreta, was studied for its suitability for production of C pGV. C leucotreta was significantly better in rearing than C pomonella : Females deposited on the average 3.9 times more eggs (504 eggs/femal e), egg hatchability was about 10 % better (92.1 % in contrast to 82.4 %) and 10 % more of neonates (80.8 % in contrast to 70.2 %) developed to moths under individual rearing conditions compared with C pomonell a. In mass rearing (rearing trays: 1.8 kg diet), the best yield of mot hs was, with 767.7 moths per kilogram (kg) diet, even 13.4 times highe r than that with C pomonella (57.2 moths). In addition, the time for d evelopment was nearly one third shorter, as it took only 30 (C. leucot reta) instead of 41 (C. pomonella) days from egg to moth at 25-degrees -C. Both species produced similar amounts of CpGV-granula per larva, w hen 5th instar larvae were inoculated with the CpGV working-seed: 1.8 x 10(10) granula for C leucotreta and 1.7 x 10(10) for C pomonella. Th e 10000 fold higher inoculum concentration for C leucotreta was compen sated under simulated mass rearing conditions (Petri dish: 44 g diet) by a 61 % higher granula yield per gram diet than that from C. pomonel la: Maximum yield of CpGV was 6.6 x 10(9) granula against 4.1 x 10(9) granula/g diet. Using the rearing trays, the difference in the virus y ield should be even higher considering the higher yield of moths. In q uality control experiments, it was demonstrated that CpGV raised in th e homologous host C pomonella and in the alternate host C leucotreta w as identical regarding the biological activity, the DNA pattern in res triction enzyme analysis, the banding of granula and virions in sucros e- and CsCl-gradients, the absorption pattern (240-360 nm) and the ele ctron microscopic morphology of negative stained granula. These result s showed, that C leucotreta is a promising candidate for mass producti on of CpGV.