Seasonal Activity of Listronotus maculicollis (Coleoptera: Curculionidae) on Annual Bluegrass

AbstractThe annual bluegrass weevil (ABW), Listronotus maculicollis Kirby, is an economically important pest of short-cut turfgrass in Eastern North America. Wide spread insecticide resistance warrants the development of alternative management strategies for this pest. ABW damage typically occurs in areas with a high percentage of annual bluegrass, Poa annua L., the preferred ABW host. Damage to bentgrasses, Agrostis spp., is much rarer and usually less severe. To aid the implementation of host plant resistance as an alternative ABW management strategy we investigated the tolerance of three bentgrass species to ABW feeding. Responses of P. annua, creeping bentgrass, Agrostis stolonifera L., colonial bentgrass, Agrostis capillaris L., and velvet bentgrass, Agrostis canina L., to adult and larval feeding were compared in greenhouse experiments. Grass responses were measured as visual damage, dry weight of the grass stems and leaves, color, density and overall grass quality. To determine possible mechanisms of grass tolerance constitutive fiber and silicon content were also determined. The three bentgrass species tolerated 2–3 times higher numbers of ABW adults and larvae than P. annua before displaying any significant quality decrease. Creeping bentgrass had the lowest damage ratings. ABW infestation caused higher plant yield reduction in P. annua (up to 42%) than in bentgrasses. Observed differences among the grass species in fiber and silicon content in the plant tissue are unlikely to play a role in the resistance of bentgrasses to ABW. Our findings clearly show that A. stolonifera is the best grass species for the implementation of host plant resistance in ABW management.

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Microsclerotial Granular Formulation of the Entomopathogenic Fungus Metarhizium brunneum and Its Combinations With Hydrogel and Imidacloprid Against the Annual Bluegrass Weevil (Coleoptera: Curculionidae)

Journal of Economic Entomology ◽

10.1093/jee/toaa052 ◽

2020 ◽

Vol 113 (3) ◽

pp. 1118-1128 ◽

Cited By ~ 2

Author(s):

Albrecht M Koppenhӧfer ◽

Shaohui Wu ◽

Olga S Kostromytska

Keyword(s):

Entomopathogenic Fungus ◽

Field Trials ◽

Annual Bluegrass ◽

Significant Control ◽

Metarhizium Brunneum ◽

Listronotus Maculicollis ◽

Moist Sand ◽

Field Efficacy ◽

Neonicotinoid Insecticide ◽

Annual Bluegrass Weevil

Abstract We determined the potential of the entomopathogenic fungus Metarhizium brunneum Petch (Hypocreales: Clavicipitaceae) F52 strain, and of a microsclerotial formulation, for the control of the annual bluegrass weevil, Listronotus maculicollis Kirby, which is a major pest of golf course turf in eastern North America with widespread insecticide resistance. Under laboratory conditions in Petri dishes with moist sand, the microsclerotia (23–46 kg granules/ha) caused high rates of mortality (85–100%) and infection (67–80%) in annual bluegrass weevil adults, but these levels did not occur until after 9 d at constant 26°C and 12–15 d at 14 h at 23°C and 10 h at 17°C. Production of viable conidia was marginally higher at the higher temperature regime (7.3 vs. 5.2 × 109 per gram of granules). Application of microsclerotia did not provide significant control and infection of adults in pots with grass in the greenhouse. In field trials targeting spring generation larvae, microsclerotia application (50–100 kg granules/ha) was ineffective, and coapplication of hydrogel to stabilize soil moisture did not increase larval control. A liquid M. brunneum F52 conidial formulation (4.75–9.5 × 1013 colony forming units/ha) provided up to 51% control. Combinations of M. brunneum F52 with the neonicotinoid insecticide imidacloprid provided additive control with up to 70% control with the conidial formulation. Field efficacy was probably limited by suboptimal temperatures for the fungus, and future tests need to examine whether higher control rates can be achieved in applications targeting the summer generation larvae.

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