Comparing production and efficacy of Cordyceps javanica with Cordyceps fumosorosea

Authors: Behle, Robert; WU, SHAOHUI - University Of Georgia; TOEWS, MICHAEL - University Of Georgia; Duffield, Kristin; Shapiro Ilan, David

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2021
Publication Date: 1/28/2022
Citation: Behle, R.W., Wu, S., Toews, M.D., Duffield, K.R., Shapiro-Ilan, D.I. 2022. Comparing production and efficacy of Cordyceps javanica with Cordyceps fumosorosea. Journal of Economic Entomology. 115(2):455-461. https://doi.org/10.1093/jee/toac002.
DOI: https://doi.org/10.1093/jee/toac002

Interpretive Summary: Biological insecticides based on fungi are commercially available and provide environmentally friendly pest control substitutes for chemical insecticides. New strains of insect killing fungi are regularly collected form naturally infected insects and preliminary research often concludes that they could be suitable for use as bioinsecticides. Unfortunately, these conclusions are often based on only a few of the many beneficial characteristics needed for commercial development. Here, a new isolate of fungus (Cordyceps genus) was directly compared with a commercial Cordyceps strain. The two stains were compared for production of spores when using a variety of nutrient media, for spore survival through drying, formulation processing and storage of prototype samples, for insecticidal efficacy of the final formulated samples, and for evaluating variable production costs in order to provide a “start to finish” comparison between the two isolates. Higher spore production by the commercial isolate resulted in a lower production cost compared with the new isolate. Also, the cost of the media used to maximize production of fungal spores was sufficiently expensive to suggest that a less expensive media yielding fewer spores could be more cost effective for a final product. This study illustrates the need to conduct comprehensive research to support development of microbial agents into commercial pest control products.

Technical Abstract: A newly discovered entomopathogenic fungus (EPF) Cordyceps javanica strain Wf GA17 was compared with the commercial Cordyceps fumosorosea Apopka 97 strain for liquid culture production, formulation, insecticidal efficacy, and storage stability under laboratory conditions. We compared liquid media culture with increasing carbon:nitrogen (C:N) ratios of 10:1, 30:1, and 50:1 for Wf GA17 and Apopka 97 isolates. A third strain, C. fumosorosea strain ARSEF 3581, had previously been optimized for liquid culture production of blastospores and was cultured at 10:1 C:N for a total of seven treatments. Cultures were processed by spray drying with skim milk powder, stored at 25o C to evaluate storage stability and assayed for insecticidal activity against Trichoplusia ni (Lepidoptera: Noctuidae) neonates. Final counts of blastospores for the seven culture treatments were not significantly different, ranging from 4.47 to 9.88 × 108 spores mL-1. Fungal biomass decreased and final glucose concentrations increased with increasing C:N ratios, indicating better fungal growth with higher nitrogen concentrations. Product yields from the spray dryer (grams per L culture) increased with increased C:N ratios while spore concentrations in the powders decreased, ranging from 2.27 to 7.17 × 109 spores g-1. There were no significant differences for insecticidal efficacy among the seven treatments. Spore viability decreased rapidly during storage at 25o C, though spores from 10:1 C:N ratio media retained viability longer than spores produced in media with 30:1 or 50:1 C:N ratios. Cost of ingredients for culture media and formulation decreased with increasing C:N ratios, such that the 30:1 media may yield the most economical product. Between the Wf GA17 and Apopka 97 isolates, the calculated cost of raw material needed for application was 1.4× greater for Wf GA17, a difference that could be erased by optimization of culture conditions.