Fungal endophytes and their role as protective agents against herbivores

Background/Question/Methods

Endophytes are defined to be fungi or bacteria that live within asymptomatic plant tissue for all or part of their life cycle without causing detectable damage to its host. More specifically, fungal endophytes started being studied extensively in the last decade and since then different ecological roles have been attributed to them. Some of these include: being dormant saprobes and/or dormant pathogens, micorrhizal associates and protective agents against biotic and abiotic stresses. Our interest is to explore the protective agent ecological role fungal endophytes play when in association with plants and investigate the effects these might have on insect herbivores. First off we were able to artificially inoculate cultivated cotton, Gossypium hirsutum with two different fungal endophytes in greenhouse conditions. Then these inoculated plants were exposed to two different insect pests: Aphis gossypii and Helicoverpa zea; both insects from different feeding guilds and economically important pests in cultivated cotton.

Results/Conclusions

Our studies results indicated a significant reduction on the reproduction of cotton aphid after these fed on plants inoculated with the two different endophytes (P=0.002).  These data encouraged us to continue our investigation only this time in a field setting where we followed the same methods used in our greenhouse study. Our field study results indicated that one of the fungal endophytes tested also had a negative reproduction effect on the cotton aphid (P=0.034). Our next project is being analyzed at the moment where the insect pest H. zea was tested in a non-choice in planta feeding assay against the same two fungal endophytes used in the cotton aphid experiment. We hope to elucidate in future studies the mechanism underlying this insect-fungal endophyte-plant interaction since these fungal endophytes can potentially be integrated into pest management control approaches.