Morphological and molecular identification of the entomopathogenic fungus Purpureocillium lilacinum and its virulence against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) larvae and pupae

Abstract

Background The tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a serious pest of solanaceous plant species, mainly Solanum lycopersicum L. The entomopathogenic fungi, an alternative to chemical insecticides, proved to be an efficient biocontrol agent in reducing pest population density. In the present study, an entomopathogenic fungus, Purpureocillium lilacinum isolated from soil was identified based on the morphological and molecular characteristics and its pathogenicity was tested against target pest. Results The micromorphological characters showed variations in growth pattern, shape and colour on different cultural media. For molecular analysis, a phylogenetic tree based on ITS/LSU and ITS/β-tubulin (benA) gene regions was constructed which revealed the isolate (FC18) as P. lilacinum (Thom) Luangsa-ard, Houbraken, Hywel-Jones and Samson (Family: Ophiocordycipitaceae). Further, the pathogenicity of P. lilacinum was tested using different spore concentrations (1 × 108, 1 × 107, 1 × 106, 1 × 105 and 1 × 104 spores/ml) on larval and pupal stages of T. absoluta, which showed a dose-dependent mortality. At the highest concentration (1 × 108 spores/ml), the mean mortality of 92.99, 83.05, 72.0% of second, third and fourth instar was observed, respectively. Pupal mortality also showed significant differences at different spore concentrations. Conclusion Obtained results showed that the virulence of the indigenous strain of P. lilacinum on T. absoluta can be utilized in the field suppression of the pest as a potent biocontrol agent.

<em>Purpureocillium lilacinum </em>for Biocontrol, Bioremediation and Biofertilization

“…The fungus P. lilacinum has proven to be a highly effective biocontrol agent against a broad spectrum of insects, including the tomato leafminer pest. This is an interesting finding that highlights the potential of this fungus as a natural solution for pest management [32].…”

Protein Levels in Metarhizium anisopliae (Metschn.) Sorokīn Infested Tomato Fruit Borer Helicoverpa armigera Hubner (Lepidoptera; Noctuidae)

“…Higher proteases in the M. anisopliae increase its efficacy against host insect [25]. The initial point of fungal infection depends on protease activity [26]. The virulent strain ICAR SBI VS 8 infected H. armigera recorded lower protein levels even at lower conidial concentrations, demonstrating its potential to produce more protease to defend the host immune system.…”

Purpureocillium lilacinum SBF054: Endophytic in Phaseolus vulgaris, Glycine max, and Helianthus annuus; Antagonistic to Rhizoctonia solani; and Virulent to Euschistus heros

“…Furthermore, the bioinsecticide activity of these propagules is also distinct and complex among fungi, and there are few studies on the virulence of P. lilacinum blastospores in insects. Most studies report the effectiveness of only aerial conidia in soft-bodied or larval-stage insects [ 8 , 10 , 17 , 19 ]. The results from different studies may not be directly comparable, as fungal isolates, insect populations, and experimental protocols are variable.…”

“…In this scenario, using microorganisms beneficial to agriculture has become an increasingly frequent management strategy to reduce the amount of chemical inputs used without losses in productivity [ 6 ]. When established in the environment, these microorganisms can act as a biocontrol agent for pests and diseases, growth promoters, and resistance inducers, as well as increase fertilization and promote soil correction [ 6 , 7 , 8 , 9 , 10 ]. One of the species used to formulate biological products based on microorganisms is the fungus Purpureocillium lilacinum (Thom.)…”

“…It is considered a biocontrol agent for plant-parasitic nematodes, especially the species Meloidogyne incognita and Tylenchulus semipenetrans [ 14 , 15 ]. In addition to its ability to biocontrol nematodes, this species parasitizes insect pests, including the citrus blackfly ( Aleurocanthus woglumi ), pepper thrips ( Scirtothrips dorsalis ), tomato leafminer ( Tuta absoluta ), whitefly ( Bemisia tabaci ), earworm ( Helicoverpa zea ), and leaf-cutter ant ( Acromyrmex lundii ) [ 8 , 10 , 16 , 17 , 18 , 19 ]. Purpureocillium lilacinum contains endophytic strains that bring benefits to the plant, both for promoting growth and inducing resistance to herbivorous insects [ 7 , 16 , 20 ].…”