Testing the host range of the pestiferous leafminer, Liriomyza langei, and non-pestiferous leafminer species

Liriomyza, an agriculturally important genus of agromyzid leafminers, has been a significant pest of vegetable crops and several ornamental plants for the past 30 years. Pestiferous Liriomyza spp. have consistently and rapidly developed insecticide resistance to the pesticides developed for control and have a high propensity towards pesticide resurgence. Currently L. langei is considered the most difficult to control.  However, nearly all leafminers are attacked by parasitoids, Agromyzidae have been shown to share parasitoids across genus, and parasitism rates are often between 70-90%.  Generalist parasitoids, such as Diglyphus begini and Neochrysocharis arizonensis wasps, attack Liriomyza spp. leafminer larvae in vegetable crops and have been shown to be the dominant parasitoids in natural systems. There is potential for the creation of nursery crops of shared parasitoids using early-season non-perstiferous leafminers. The research presented here shows experimentally that L. langei will not develop on sunflower and conversely that L. helianthi, a native leafminer on sunflower, will not feed or develop on celery. L. langei was reared on fava bean and L. helianthi on sunflower. Each trial had a combination of choice and no-choice treatments in 21- 2 ft³ cages. Ten newly emerged leafminers were released into each cage and left for 10 days, after which, feeding holes, mine exits, mines, pupae and any emerging adults were counted. Our hope is to use this preliminary work to identify early-season leafminer hosts, like L. helianthi, that do not appear to have the potential to become pestiferous. Once identified, we hope to promote high populations of natural enemies early in the season using these alternative hosts and thereby more effectively control pestiferous leafminer species.