Hyalesthes obsoletus Signoret is a univoltine, polyphagous species completing its complex life cycle, including the nymph subterranean cryptic stage, on herbaceous wild plants in European countries. In vineyards, it occasionally transmits ‘Candidatus Phytoplasma solani’, an obligate parasitic bacterium associated with Bois noir disease of grapevine, from its preferred host plants to grapevine. As no effective control measures targeting phytoplasmas are available, main strategies to manage the disease is based on the vector control. In the case of H. obsoletus, insecticide treatments on grapevine canopy are completely inefficient due to its life cycle. Consequently, the control of this planthopper focuses on its nymphs living on the host plant roots. In the present study, the control activity of entomopathogenic nematodes (EPNs; (Steinernema carpocapsae, S. feltiae, Heterorhabditis bacteriophora) and fungi (EPFs; Beauveria bassiana, Metarhizium anisopliae, Paecilomyces fumosoroseus, Lecanicillium muscarium) against H. obsoletus nymphs and adults were evaluated by laboratory bioassays and semi-field trials. Statistical analyses demonstrated that the majority of the examined EPNs and EPFs are able to control H. obsoletus nymphs and adults, exhibiting a range of effectiveness. In all the conducted trials, S. carpocapsae and P. fumosoroseus were found as the most effective biocontrol agents among EPNs and EPFs, respectively. Interestingly, considering their ability to colonize the soil after their inoculation, EPNs and EPFs can reduce the H. obsoletus population density for long time. Ecological competency and conditions that can impede or enhance the EPNs and EPFs performance should be investigated to optimize their performance in field conditions.
Biological control of Hyalesthes obsoletus Signoret, the main insect vector of ‘Candidatus Phytoplasma solani’, using entomopathogenic nematodes and fungi
Mori N
2022-01-01
Abstract
Hyalesthes obsoletus Signoret is a univoltine, polyphagous species completing its complex life cycle, including the nymph subterranean cryptic stage, on herbaceous wild plants in European countries. In vineyards, it occasionally transmits ‘Candidatus Phytoplasma solani’, an obligate parasitic bacterium associated with Bois noir disease of grapevine, from its preferred host plants to grapevine. As no effective control measures targeting phytoplasmas are available, main strategies to manage the disease is based on the vector control. In the case of H. obsoletus, insecticide treatments on grapevine canopy are completely inefficient due to its life cycle. Consequently, the control of this planthopper focuses on its nymphs living on the host plant roots. In the present study, the control activity of entomopathogenic nematodes (EPNs; (Steinernema carpocapsae, S. feltiae, Heterorhabditis bacteriophora) and fungi (EPFs; Beauveria bassiana, Metarhizium anisopliae, Paecilomyces fumosoroseus, Lecanicillium muscarium) against H. obsoletus nymphs and adults were evaluated by laboratory bioassays and semi-field trials. Statistical analyses demonstrated that the majority of the examined EPNs and EPFs are able to control H. obsoletus nymphs and adults, exhibiting a range of effectiveness. In all the conducted trials, S. carpocapsae and P. fumosoroseus were found as the most effective biocontrol agents among EPNs and EPFs, respectively. Interestingly, considering their ability to colonize the soil after their inoculation, EPNs and EPFs can reduce the H. obsoletus population density for long time. Ecological competency and conditions that can impede or enhance the EPNs and EPFs performance should be investigated to optimize their performance in field conditions.
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