Insecticidal activity of Trichoderma harzianum against Xylotrechus arvicola and Acanthoscelides obtectus inmature stages

Xylotrechus arvicola Olivier is an important pest in vineyards (Vitis vinifera L.) in the main wine-producing regions of the Iberian Peninsula, and Acanthoscelides obtectus Say causes severe post-harvest losses in the common bean (Phaseolus vulgaris L.). Trichoderma (Teleomorph: Hypocrea) is a fungal genus found in the soil. It is a secondary fast growing opportunistic invasive, which produces enzymes able to degrade the fungal cell wall and compounds with antimicrobial activity [1]. Strains of Trichoderma spp. have shown good results in the biological control of pests [2]. The objective of this work was to determinate the insecticidal activity of Trichoderma harzianum against the immature stages of X. arvicola and A. obtectus under laboratory conditions. With a spray tower, the susceptibility of the immature stages of X. arvicola and A. obtectus against T. harzianum was evaluated. One mL of spore suspension (1 × 10⁷ spores per mL) of T. harzianum was applied directly to the eggs. Every two days monitoring was carried out after treatment over 14 days, measuring the eggs size, the emergence of larvae and altered metamorphosis. The results (Figure 1A and Figure 1B) showed a good insecticidal activity of T. harzianum against both insect pests. T. harzianum showed peak inhibition in the immature stages of 83% and 88% in X. arvicola and A. obtectus, respectively. The insecticidal ability of T. harzianum to invade the eggs, proliferate inside them, and kill their larvae, make this fungus a potentially effective tool for the control of the immature stages of these species.

Fig. 1: X. arvicola eggs (A) and A. obtectus eggs (B) of different ages inhibited by T. harzianum during 14 days after treatment. Upper and lower error bars are represented. (Fisher's LSD. p < 0.05).

Acknowledgements: [coauthors] I would like to thank the Department of Engineering and Agricultural Sciences of the Higher School and Technical Agricultural Engineering and the Institute of Environment, Natural Resources and Biodiversity of the University of León.

Keywords: Biological control, insecticidal activity, Trichoderma harzianum, insect pest.

References:

[1] Mayo S, Gutiérrez S, Malmierca MG, Lorenzana A, Campelo MP, Hermosa R, Casquero PA. Influence of Rhizoctonia solani and Trichoderma spp. in growth of bean (Phaseolus vulgaris L.) and in the induction of plant defense-related genes. Front Plant Sci 2015; 6: 685

[2] Abdul-Wahid, OA, Elbanna, SM. Evaluation of the insecticidal activity of Fusarium solani and Trichoderma harzianum against cockroaches; Periplaneta americana. Afr J Microbiol Res 2012; 6: 1024 – 1032