The use of fungal entomopathogens as endophytes in biological control: a review

Authors: Vega, Fernando

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2017
Publication Date: 6/1/2018
Citation: Vega, F.E. 2018. The use of fungal entomopathogens as endophytes in biological control: a review. Mycologia. 110:4-30.

Interpretive Summary: Insect pests cause enormous economic losses to agricultural crops worldwide and the use of fungal insect pathogens has been studied for more than 100 years as a pest control alternative. Unfortunately, their potential has been limited by their susceptibility to ultraviolet light and low moisture levels. In this paper we present an overview of a novel method for using fungal insect pathogens which overcomes these environmental constrains and involves their introduction into plants by various inoculation methods. This information will be highly valuable to entomologists and mycologists worldwide, as well as to practitioners of biological control programs against insect pests.

Technical Abstract: Fungal entomopathogens have been proposed as environmentally friendly alternatives to chemical control. Unfortunately, their effectiveness continues to be limited by their susceptibility to UV light, low moisture, etc. A relatively recent development, the use of fungal entomopathogens as endophytes, might overcome the traditional obstacles impeding the widespread adoption of fungal entomopathogens and also provide a novel alternative for management of insect pests and plant pathogens. In addition, some fungal entomopathogens could also function as biofertilizers. A total of 85 papers covering 109 individual fungal entomopathogen studies involving 12 species in six genera are reviewed. A total of 38 plant species in 19 families have been studied, with maize, common bean, and tomato being the most investigated. Of the 85 papers, 39 (46%) have examined the effects of fungal entomopathogen endophytism on 33 insect species in 17 families and eight orders. Thirty-four of the 85 papers (40%) have examined the plant response to endophytism, corresponding to 20 plant species. Various inoculation techniques (e.g., foliar sprays, soil drenching, seed soaking, injections, etc.) have been shown to be effective in introducing fungal entomopathogens as endophytes, but colonization appears to be localized and ephemeral. The field of insect pathology won’t substantially profit from dozens of additional studies attempting to introduce fungal entomopathogens into a wider array of plants, without attempting to understand the mechanisms underlying endophytism, the responses of the plant to such endophytism, and the consequent responses of insect pests and plant pathogens. This review presents several areas that should receive increased attention in order to increase the probability of success for making this technology an effective alternative to chemical control.