Citrus Leafminer Biological Control Agents

Figure 1. Pnigalio spp. (http://kcc-weslaco.tamu.edu/oldwww/webpages/leafminer.htm)

Figure 2. Closterocerus spp. (http://kcc-weslaco.tamu.edu/oldwww/webpages/leafminer.htm)

Biological control of the citrus leafminer is one of the key tools to controlling it. In Southern California there are many generalist parasitoids that typically attack the citrus leafminer. Nine species in five genera including; Closterocerus spp., Cirrospilius spp., Pnigalio spp., Chrysocharis spp., and Sympieses spp. have been found helpful in the control of leafminer. These parasitoids generally attack the gracillariid leafminer which is native to California and lives in oaks. Euderus spp., Zagrammosoma spp.,Sympieis spp., and Chryonotomyia spp., are four genera associated with the gracillariid in the San Joaquin Valley.

As the population of citrus leafminer become larger it will be important to manage and conserve these natural enemies. Things like not spraying citrus with broad-spectrum insecticides and avoiding other practices that disrupt natural enemies will be imperative. There are a number of parasites around the world that may be implemented in California at some time to help the native natural enemies. These natural enemies include Ageniaspis and Citrostichus spp. which have been used in Florida but have a hard time spreading in high enough densities to be comparable to the native parasitoids. Their host range is much smaller than the natives, which limits the colonization during times when leafminer is not in high densities. On the central coast of California where native natural enemies have trouble controlling the leafminer because citrus have multiple flushes of new growth a year, the Ageniaspis and Citrostichus may be more effective.