Survival of Liriomyza trifolii (Diptera: Agromyzidae) in detached chrysanthemum leaves

The influence of leaf detachment and leaf storage conditions on survival of Liriomyza trifolii (Burgess) eggs, larvae, and reared pupae was studied. When kept at 26 +/- 1 degree C and at approximately 100% relative humidity (RH) so that leaf fresh weight and turgidity were maintained, chrysanthemum (Dendranthema grandiflora Tzvelev. cv. Iceberg) leaves that were detached immediately after oviposition yielded as many leafminers as did leaves left on plants. Detached foliage kept at 26 degrees C but at a lower and fluctuating relative humidity (80 +/- 20%) did not yield leafminers if harvested immediately after oviposition. If, however, leaves were detached two days after oviposition (first instars present) and stored at 26 +/- 1 degree C and approximately 80% RH, the leafminer yield was comparable to that from undetached leaves. When stored on or under greenhouse benches (8-32 degrees C, 10-80% RH), leaves that were detached three days after oviposition (second instars present) yielded as many leafminers as leaves on plants. The results emphasize the importance of maintaining greenhouses that are free of plant litter as part of a leafminer control program. For the researcher, the study indicates that L. trifolii can be reared experimentally by using detached leaves rather than whole plants.