Mechanism of Action of Endophytic Fungi Hypocrea lixii and Beauveria bassiana in Phaseolus vulgaris as Biopesticides against Pea Leafminer and Fall Armyworm.

John Onyari Mmari,Komivi Senyo Akutse,Olivia Ngeno Chebet,Vaderament-A Nchiozem-Ngnitedem,Leonidah Kerubo Omosa,Sevgan Subramanian

doi:10.3390/molecules26185694

John Onyari Mmari, Komivi Senyo Akutse + Show 4 more

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https://doi.org/10.3390/molecules26185694

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Abstract

Endophytic fungal isolates Hypocrea lixii F3ST1 and Beauveria bassiana G1LU3 were evaluated for their potential to endophytically colonize and induce active compounds in Phaseolus vulgaris, as a defense mechanism against pea leafminer (Liriomyza huidobrensis) and fall armyworm (Spodoptera frugiperda). Endophytic colonization was achieved through seed inoculation with the volatile emissions from P. vulgaris plants being analyzed using GC-MS. The crude extracts of P. vulgaris obtained using methanol and dichloromethane were assayed against leafminer and fall armyworm larvae using leaf dipping and topical application, respectively. The two isolates successfully colonized the entire host plant (roots, stems, and leaves) with significant variation (p < 0.001) between fungal isolates and the controls. The results showed qualitative differences in the volatile profiles between the control plants, endophytically colonized and insect-damaged plants attributed to fungal inoculation and leafminer damage. The crude methanol extracts significantly reduced the percentage pupation of 2nd instar leafminer larvae (p < 0.001) and adult-flies emergence (p < 0.05). The survival of the 1st instar fall armyworm larvae was also significantly reduced (p < 0.001) compared to the controls. This study demonstrated the high potential of endophytic fungi H. lixii and B. bassiana in inducing mainly specific defense compounds in the common bean P. vulgaris that can be used against pea leafminer and fall armyworm.

Highlights

The common bean, Phaseolus vulgaris (Fabaceae), is one of the most important food legumes worldwide [1]
Hypocrea lixii F3ST1 exhibited the highest percentage of colonization in the leaves (93.3%) and stems (91.6%), while B. bassiana G1LU3 had the highest percentage of colonization in the roots (76.6%), moderate in the stems (68.3%), and lowest in the leaves (55.0%)
H. lixii F3STI exhibited the highest percentage of colonization of the various plant parts as compared to B. bassiana G1LU3

Summary

Introduction

The common bean, Phaseolus vulgaris (Fabaceae), is one of the most important food legumes worldwide [1]. The crops contribute significantly as a valuable source of nutrition and income. The production of the common bean is adversely affected by herbivorous pests and the resulting diseases [2]. Among the insect pests of the bean crops, the most destructive is the Liriomyza leafminers, a polyphagous invasive species, whose larvae mines under leaf surfaces, creating winding trails on the foliage [3]. Oviposition and mining interfere with nutrient transport and creates avenues for the entry of diseases causing severe yield losses [4]. Has caused export restrictions to international markets and, as a result, loss of revenue [5] The quarantine status of Liriomyza sp. has caused export restrictions to international markets and, as a result, loss of revenue [5]

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