The yield of polyhedra per larva with the different forms of phathological midguts in the different generations

The sixth stadium larvae of massonpine caterpillar in the overwintered,first and third generationswere infected with CPV of Dendrolimus spectabilis at the same ineeulation of 1×107 PIB/ml in forest.The results suggested that the larvae of overwintered generation could be chosen as the best carrier forvirus large preduction, and the stage, when the midgut was fully infected and became yellow or whitein color,was the optimum poried for collection.