LIFE-HISTORY STUDIES OF THE LEAFMINER LIRIOMYZA-TRIFOLII ON SUSCEPTIBLE AND RESISTANT CULTIVARS OF DENDRANTHEMA-GRANDIFLORA

The feeding, fecundity, mortality and rate of development of Liriomyza trifolii (Burgess) on 12 cultivars of Dendranthema grandiflora (Tzvel.) (Syn. Chrysanthemum morifolium (Ramat.)) were determined in 'no choice' experiments. Number of feeding punctures, number of eggs laid and total number of larvae varied between cultivars but these characters were not strongly associated with leafminer population increase. Good indicators of host plant resistance were larval mortality, number of pupae and duration of the larval period. Of these three, larval mortality which could be as high as 98% was most suitable. Based on life history data it was predicted that Liriomyza trifolii cannot survive on the resistant cultivar Penny Lane. This prediction was verified experimentally.