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10-Minute Presentation

Plant-Insect Ecosystems

10-min: P-IE, Microbial Control and Microbial Interactions

Effect of synthetic fungicides used in strawberry on Hirsutella sp.: An entomopathogenic fungus of Phytonemus pallidus

Wednesday, November 13, 2024
1:54 PM – 2:06 PM MST
Location: Phoenix Convention Center, 126 C
Oral Presentation
Phytonemus pallidus Banks (Acari: Tarsonemidae) is a mite pest of worldwide importance that affects various crops, including strawberries. Since the withdrawal of endosulfan in Canada in 2016, control strategies for this pest have been limited. In 2018, the first observation of a fungus infecting P. pallidus in Quebec was made in a strawberry field on l’Île d'Orléans. Sequencing of ITS regions has enabled identification of the genus Hirsutella sp. Several species of this genus are known to parasitize insects and arthropods, making them interesting control agents. During an inventory of P. pallidus with mycosis carried out during this project, Hirsutella sp. was found in both organic and conventional strawberry fields. To determine the impact of the main fungicides used in strawberry fields on the growth of this entomopathogenic fungi, in vitro tests were carried out using three isolates of Hirsutella sp. One isolate was isolated from an organic farm and the other two were isolated from conventional farms. When incorporated in culture media at recommended concentrations, most fungicides tested strongly inhibit the growth of Hirsutella sp. Demethylation inhibitor fungicides had the strongest percent inhibition of radial growth. The three strains had similar sensitivity, but some differences were noted depending on the fungicide groups. Studies on the compatibility of fungicides with entomopathogenic fungi are useful to select fungicides that have less impact on the entomopathogenic fungi and to promote their presence. A conservation biological control strategy with Hirsutella sp. could potentially be developed to control P. pallidus in strawberry fields.