Establishment of Beauveria bassiana as a fungal endophyte in potato plants and its virulence against potato tuber moth, Phthorimaea operculella (Lepidoptera: Gelechiidae)

Abstract

The potato tuber moth, Phthorimaea operculella, is the most damaging potato pest in the world and is difficult to control as the larvae are internal feeders in the foliage and tubers. Entomopathogenic fungi that colonize plants as endophytes have lethal and sublethal pathological effects on insect pests. We show that Beauveria bassiana colonizes the aerial parts of potato plants endophytically after inoculation through soil drenching. Endophytic B. bassiana persisted in potato foliage for more than 50 days postinoculation. Bioassays indicated that foliage of B. bassiana-inoculated potato plants were pathogenic against larvae of P. operculella. Sublethal experiments indicated that B. bassiana negatively affected the growth, development, and reproduction of P. operculella. Development experiments showed that the weight of P. operculella pupae reared on B. bassianacolonized potato plants (4.25 mg) was significantly less than that of those reared on uninoculated control plants (8.89 mg). Compared with newly eclosed larvae fed on control plants, those fed on B. bassiana-inoculated plants had significantly lower survivorship, with only 17.8% developing to the adult stage. Oviposition of P. operculella females reared on B. bassiana endophytically colonized plants was significantly lower (35 eggs/female) than of those reared on uninoculated plants (115 eggs/female). This study demonstrates that endophytic B. bassiana can be a potential biological control agent for the control and management of P. operculella. Comparing pupal weights of P. operculella reared on potato plants inoculated with the B. bassiana strain GZGY-1-3 and on untreated control plants, pupae from the control plants were significantly heavier than those from treated plants.

Evaluation of Various Inoculation Methods on the Effect of Beauveria bassiana on the Plant Growth of Kiwi and on Halyomorpha halys Infestation: A Two-Year Field Study

“…The spray application (S) showed lower efficacy compared to the other methods (I, R), probably because the endophytes are affecting stronger when inhabiting the internal tissues of the plant [65,66]. Moreover, the successful endophytic action and colonization of B. bassiana in the root area has also been observed on other commercial crops [61,67]. Of course, the foliar mode of action in other experiments has shown beneficial effects in other plants such as tomato Solanum Lycopersicum L. (Solanales: Solanaceae) [68] and sorghum Sorghum bicolor (Poales: Poaceae) [69], but this was not observed to a significant extent in our experiment.…”

“…Trunk inoculation by injection (also referred to as macro-injection) is not always a costeffective approach because it requires well-trained personnel and it is a time-consuming method [58][59][60], although it may have some benefits for specific plant species [61,62]. Other application methods, such as leaf or trunk spraying, may be easier to use.…”

“…Still, spraying methods sometimes may not demonstrate the same efficiency and residence time in plant tissues, due to various biotic factors, including spore load (CFU mL −1 ) and concentration, dispersal and spore persistence, shelf-life, and virulence [63,64]. Nevertheless, there are cases of crops in which there was no beneficial effect noted from the endophyte application on them with trunk penetration techniques, such as in avocado Persea americana (Laurales: Lauraceae) [58][59][60]; some methods may be species-specific [61].…”

Colonization of Piriformospora indica enhances rice resistance against the brown planthopper Nilaparvata lugens

“…Notably, several fungal species especially entomopathogenic fungi by endophytic colonization exerted effective control on insect pests. [12][13][14][15][16] Piriformospora indica (Hymenomycetes: Basidiomycota) discovered in an Indian desert is a root endophytic fungus that colonizes in the surface, rhizodermal and cortical cells, and intracellular space of plant roots, 17 and establishes beneficial interactions with a variety of plant hosts, including Arabidopsis, rice, wheat, sweet potato, onion, and tomato. 18,19 In most of the hosts, P. indica significantly stimulates the growth and yield.…”