Population growth of the greenhouse whitefly, Trialeurodes vaporariorum Westwood, on greenhouse cucumber
Yamada, H.; Koshihara, T.; Tanaka, K.
Bulletin of the Vegetable and Ornamental Crops Research Station 5: 191-199
1979
Document Number: 382884
Studies were carried out in Japan on the population growth of Trialeurodes vaporariorum (Westw.), which has become a major greenhouse pest in this country in recent years. The distribution pattern of adults, eggs and larvae of T. vaporariorum on cucumber plants was investigated, and it was found that adults occurred only on the apical and adjacent leaves of the plants about 30 days after planting. Eggs were found at the same time as adults, and both showed a strong tendency to aggregate. Larvae, however, were found to be distributed less aggregatively on leaves below those infested by adults and eggs. The pest multiplied rapidly and sooty moulds were observed on the leaves 60-90 days after planting. Threshold density for the occurrence of the fungi was calculated to be approximately 200 adult T. vaporariorum per plant and/or 15-20 mature larvae per 3.14 cm2 of the underside of the leaf. It was calculated that severe infestation would occur about 60 days after planting when initial infestation occurred at the rate of 2-10 adults of T. vaporariorum/plant.