Initial characterisation of Metarhizium anisopliae CPMA1502 for the development of a biopesticide against the oil palm fruit scraper Demotispa neivai (Coleoptera: Chrysomelidae)

Abstract

Entomopathogenic fungi are key components of biological pest control programs. Among these, Metarhizium anisopliae is one of the best-studied and has been demonstrated to be particularly effective against coleopterans. The native M. anisopliae CPMa1502, previously selected for its insecticidal activity against Demotispa neivai (oil palm fruit scraper), was studied to establish its growth parameters under several culture conditions and its virulence on different stages of D. neivai. Considerable conidia production of CPMa1502 on MAYP (Maltose Agar Yeast with Potato Extract) and SMAYR (Sabouraud Maltose Agar with yeast extract and rice extract) agar was observed (1×109 conidia cm–2 at 14 days). The isolate was highly tolerant to a wide range of pH (5-9; germination >90%; radial growth rate: 0.95-1.02 mm day–1) but moderately tolerant to high temperatures (>35°C). Additionally, the adhesion capacity to D. neivai cuticle and conidial hydrophobicity was strong (114 conidia mm–2: 72%). Finally, the insecticidal activity of CPMa1502 was greater on larvae than on adults, with a mean lethal concentration (LC50) of 1.8×104 conidia mL–1 and a mean lethal time (LT50) of 4.3 days, than on adults. These findings show that CPMa1502 is a promising candidate for further development as a biopesticide against D. neivai