Lethality of the entomogenous fungus Beauveria bassiana strain NI8 on Lygus lineolaris (Hemiptera: Miridae) and its possible impact on beneficial arthropods

Authors: Portilla, Maribel; Luttrell, Randall; Snodgrass, Gordon; Zhu, Yu Cheng; Riddick, Eric

Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/11/2017
Publication Date: 12/11/2017
Citation: Portilla, M., Luttrell, R.G., Snodgrass, G.L., Zhu, Y., Riddick, E.W. 2017. Lethality of the entomogenous fungus Beauveria bassiana strain NI8 on Lygus lineolaris (Hemiptera: Miridae) and its possible impact on beneficial arthropods. Journal of Entomological Science. 52(4):352-369. https://doi.org/10.18474/JES17-15.1.
DOI: https://doi.org/10.18474/JES17-15.1

Interpretive Summary: The entomopathogenic fungus Beauveria bassiana strain NI8 is a potential candidate for biological control of tarnished plant bug (TPB), in the Mississippi Delta. Decisions to deploy NI8 as a biological control require significant ecological understanding of the interactions among the targeted host, fungal isolate, and the environment. This research examined the effect of B. bassiana sprays targeted at TPB and on adults of the key beneficial insects including honey bees, green lacewings, minute pirate bug, convergent lady beetle, Asian lady beetle, and pink lady beetle. This research also examined the effect of NI8 on field collections of jumping spiders and crab spiders that were broadly categorized into family and may have included a number of different spider species. Results indicate that the Mississippi Delta native strain NI8 may be suitable for control of, not only because it is high pathogenic against the targeted pest, but also for selectivity and low virulence against some beneficial arthropods. NI8 does potentially impact other species including green lacewings.

Technical Abstract: Bioassays were conducted to examine the pathogenicity of the fungus Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) strain NI8 against Lygus lineolaris (Palisot de Beauvois) and its impact on natural enemies including Apis mellifera L., Crysoperla rufrilabris Burmeister, Orius insidiosus Say, Hippodamia convergens Guérin-Méneville, Harmonia axyridis (Pallas), Coleomegilla maculata De Geer, and field collections of jumping spiders (Aranea: Salticidae), and crab spiders (Aranea: Thomisidae). Insects were treated with four concentrations of NI8 (7 x 104, 105, 106 and 107 spores/ mL) directly via topical spray. LD50 and LS50 were estimated for all species except for the collective field samples of jumping and crab spiders. From the resulting data, no significant differences in mortality were observed among L. lineolaris, A. mellifera and C. rufilabris. All three species were highly affected when exposed to the highest test concentrations of B. bassiana with 99.0%, 98.2%, and 90.0% mortality, respectively. Between 35 and 45% of the tested populations of O. insidiosus, H. convergens, field collected crab spiders, and C. maculata were infected at 7 x 107 spores / mL; whereas only 22% and 27%, respectively of the field collected jumping spiders and H. axyridis were killed at 10-d with the same concentration. No significant differences were found between the LD50s measured for L. lineolaris (2.75 viable spores per mm2) and C. rufilabris (2.11 viable spores per mm2). Results indicate that C. rufilabris will be highly affected by the NI8 strain of B. bassiana when applied for control of L. lineolaris. In contrast, B. bassiana appeared to have little to limited effects on the other beneficial arthropods assayed at the test concentrations targeted for L. lineolaris control.