Can fungal endophytes be used to control ornamental insect pests?

The floriculture industry generated an estimated $32.1 billion dollars in retail sales in 2011.This number would be higher if not for the damage caused by insect pests and the costs to control them. Chronic pesticide use to control pest insects can be expensive and lead to the evolution of resistance. Biological control approaches have used predators to manage pest populations. Unfortunately, many predators are generalist consumers. Therefore, they do not differentiate between pests and non-pests. Microbial biocontrol agents (entomopathogens) have also been used with varying degrees of success. Our study examined a different approach to control pest insects, the use of fungal entomopathogens as endophytes. Potentially beneficial endophytic fungi can live asymptomatically inside plants. We inoculated Discovery Yellow Marigolds (Tagetes erecta) and Benary’s Giant Formula Mix Zinnias (Zinnia elegans) with one of two species of endophytic entomopathogenic fungi (Beauveria bassiana, and Paecilomyces lilacinus) to control a species of leafminer (Liriomyza trifolii). Successful endophytic establishment was determined by plating surface-sterilized cotyledons on potato dextrose agar petri dishes. Adult leafminers were introduced to inoculated and control plants 14 days after planting. The flies were allowed to oviposit for three hours, and then removed. At five days post-infestation, the plants were analyzed for leafminer damage to leaves, endophyte retention and effects on plant growth.