Entomopathogenic fungi in Portuguese vineyards soils: suggesting a ‘Galleria-Tenebrio-bait method’ as bait-insects Galleria and Tenebrio significantly underestimate the respective recoveries of Metarhizium (robertsii) and Beauveria (bassiana)

Abstract

Entomopathogenic fungi (EPF) are the natural enemies of insect-pests. However, EPF recoveries can be influenced by the soil habitat-type(s) incorporated and/or the bait-insect(s) used. Galleria mellonella (GM) as bait-insect, i.e. 'Galleria-bait', is arguably the most common methodology, which is sometimes used solely, to isolate EPF from soils. Insect baiting using Tenebrio molitor (TM) has also been employed occasionally. Here 183 soils were used to estimate the functional diversity of EPF in Portuguese Douro vineyards (cultivated habitat) and adjacent hedgerows (semi-natural habitat), using the TM bait method. Moreover, to study the effect of insect baiting on EPF recovery, 81 of these 183 soil samples were also tested for EPF occurrences using the GM bait method. Twelve species were found in 44.26% ± 3.67% of the total of 183 soils. Clonostachys rosea f. rosea was found in maximum soils (30.05% ± 3.38%), followed by Beauveria bassiana (12.57% ± 2.37%), Purpureocillium lilacinum (9.29% ± 2.14%) and Metarhizium robertsii (6.01% ± 1.75%). Beauveria pseudobassiana (P < 0.001), C. rosea f. rosea (P = 0.006) and RESEARCH ARTICLELav Sharma et al. / MycoKeys 38: 1-23 (2018) 2 Cordyceps cicadae (P=0.023) were isolated significantly more from hedgerows, highlighting their sensitivities towards agricultural disturbances. Beauveria bassiana (P = 0.038) and M. robertsii (P = 0.003) were isolated significantly more using GM and TM, respectively. Principal component analysis revealed that M. robertsii was associated both with TM baiting and cultivated habitats, however, B. bassiana was slightly linked with GM baiting only. Ecological profiles of B. bassiana and P. lilacinum were quite similar while M. robertsii and C. rosea f. rosea were relatively distant and distinct. To us, this is the first report on (a) C. cicadae isolation from Mediterranean soils, (b) Purpureocillium lavendulum as an EPF worldwide; and (c) significant recoveries of M. robertsii using TM over GM. Overall, a 'Galleria-Tenebrio-bait method' is advocated to study the functional diversity of EPF in agroecosystems.

Exploring entomopathogenic fungi from South Sumatra (Indonesia) soil and their pathogenicity against a new invasive maize pest, Spodoptera frugiperda

“…The entomopathogenic fungi infecting the Tenebrio bait and growing on the surface of the integument were isolated and cultured in the SDA media. The surface of the larvae infected with the entomopathogenic fungi was first sterilized by modifying the method of Sharma et al (2018) by rinsing with 1% NaOCl for 1 minute, then rinsing with 100 mL of distilled water for 3 times. The surface larvae sterilization was carried out to obtain the fungus that was in the hemocoel or the one that already penetrated the larvae cuticle and prevented the presence of the air fungus.…”

Agroforestry coffee soils increase the insect‐suppressive potential offered by entomopathogenic fungi over full‐sun soils: A case proposing a “bait survival technique”

“…was the most frequently isolated of the fungi. This fungus has been reported to be more abundant in cultivated soils than in surrounding noncultivated soils from temperate regions (Bidochka et al, ; Jabbour & Barbercheck, ; Meyling & Eilenberg, ; Sanchez‐Pena et al, ; Sharma, Oliveira, Torres, et al, ; Sun & Liu, ; Vanninen, ). It is possible that this fungus is quite well‐adapted to survive in agricultural soils; however, even in agricultural soils there may be variability in the suitability of conditions.…”

“…It is possible that this fungus is quite well‐adapted to survive in agricultural soils; however, even in agricultural soils there may be variability in the suitability of conditions. The use of T. molitor as bait could be another possible explanation for the frequency of Metarhizium spp., since Sharma, Oliveira, Torres, et al () report that this bait insect is biased to recover Metarhizium robertsii rather B. bassiana .…”

“…The genus Fusarium has previously been recovered with the insect bait method in soil samples in Palestine (Ali‐Shtayeh et al, ), Norway (Klingen et al, ), China (Sun & Liu, ), and Portugal (Sharma, Oliveira, Torres, et al, ). Although Fusarium species have been reported infecting several insect orders (Sharma & Marques, ; Teetorbarsch & Roberts, ), it was for long consider as a saprophyte rather than a true entomopathogen.…”

“…The hypocrealean fungi Metarhizium and Beauveria have been subjected to intense study over the last 200 years, largely aimed at their use as bioinsecticides in inundative biological control programs (Vega et al, ). More recently, the importance of their ecology, occurrence and abundance (Kepler, Ugine, Maul, Cavigelli, & Rehner, ; Meyling & Eilenberg, , ; Sharma, Oliveira, Torres, & Marques, ), and as plant mutualists has come to the fore (Barelli, Moreira, & Bidochka, ; Behie et al, ; Behie, Zelisko, & Bidochka, ; Bruck, ; Elliot et al, ).…”