Morphological and molecular identification of four isolates of the entomopathogenic fungal genus Akanthomyces and their effects against Bemisia tabaci on cucumber

Abstract

The cotton whitefly, Bemisia tabaci Gen. (Hem., Aleyrodidae), is a key pest of many vegetables. Entomopathogenic fungi are promising microbial control agents against B. tabaci, but limited information is available concerning indigenous Iranian isolates. In this study, three isolates of Akanthomyces lecanii (PAL6, PAL7, and PAL8) and one isolate of A. muscarius (AGM5) were obtained from citrus hemipteran pests, Pulvinaria aurantii Cock. and Aphis gossypii Glover, in Mazandaran province, northern Iran. The isolates were then morphologically and molecularly identified. The efficacies of five different agar media for vegetative growth and conidiation of each isolate were determined. Potato dextrose agar was the medium on which the fungal mycelia developed at a relatively high rate. However, the highest rate of conidiation was found on Sabouraud dextrose agar. To determine the effects of the isolates on B. tabaci, a dose–response bioassay was carried out to estimate lethal concentration (LC50) and lethal time (LT50) values of each fungal isolate to second instar nymphs. The mean LC50 values of A. lecanii isolates ranged from 4.22 × 106 to 7.35 × 1013 conidia ml−1 at 5 to 7 days after the treatment. For A. muscarius, the values varied from 9.2 × 104 to 8.7 × 1010 conidia ml−1 at 5 to 7 days after the treatment. The lowest and the highest mean LC50 values were observed for A. mucarius (AGM5) and A. lecanii (isolate PAL6), respectively. The mean LT50 values of A. lecanii and A. muscarius isolates were 7.1–9.0 and 4.9–7.2 days, respectively. The LT50 values of A. muscarius were significantly lower than the other isolates. Overall, all isolates, especially A. muscarius (AGM5), exhibited appropriate potential as a biological control agent against B. tabaci.

First Description of Akanthomyces uredinophilus comb. nov. from Hemipteran Insects in America

“…These authors observed that strains may have potential for development as a single microbial control agent effective against several plant diseases, pest insects and plant parasitic nematodes due to their antagonistic, parasitic and disease resistance-inducing characteristics. Broumandnia et al [56] studied the potentials of four Iranian isolates of A. lecanii and A. muscarius to control B. tabaci on cucumber under laboratory conditions. The authors found that all isolates, especially A. muscarius (AGM5), exhibited appropriate potential as a biological control agent against B. tabaci.…”

Biological and molecular characterization of Cladosporium sp. and Acremonium zeylanicum as biocontrol agents of Aphis fabae in a tri‐trophic system

“…Furthermore, the compatibility of microbiological control agents with other potential natural enemies is crucial for developing appropriate IPM programs (Lacey & Shapiro‐Ilan, 2008). There is limited information on EPF of hemipteran pests in Iran (Broumandnia et al, 2021). In this study, two novel Iranian EPF were isolated and their pathogenicity to A. fabae and their compatibility with L. fabarum release are evaluated.…”

“…The mycelia of EPF can penetrate the insect integument directly, whereas other entomopathogens, including bacteria, viruses, and protozoa, need to be ingested to infect insects (Lovett & Leger, 2017). Thus, EPF can play an important role in controlling sap-feeding insects, such as hemipterans, in microbiological control programs (Broumandnia et al, 2021). Aphids are important sap-feeding pests in many crops (Blackman & Eastop, 2008).…”