Damage Potential of Rose Chafer and Japanese Beetle (Coleoptera: Scarabaeidae) in Michigan Vineyards

Responses of young non-fruiting grapevines, Vitis labrusca (L.) var. ‘Niagara’, to defoliation were examined at two stages of vine growth when beetles typically infest vineyards. In the first experiment, vines were caged and subjected to two weeks of feeding by 0, 10, 20, or 40 adult Macrodactylus subspinosus Fabricius (Scarabaeidae: Macrodactylini) during bloom, or to the same range of adult Popillia japonica Newman (Scarabaeidae: Anomalini) during veráison, when berries begin changing color. Leaf area removed increased with beetle density, but less than 1% of the leaf area was removed at the highest density of M. subspinosus, and less than 7% at the highest density of P. japonica. Vine growth measurements taken during the year of injury and prior to bloom during the following season indicated no significant impacts of this leaf injury on vegetative growth. In the second experiment, mechanical injury was induced by removing 0, 10, 20, or 30% of the total leaf area of every fully expanded leaf at bloom or veráison. A significant effect of mechanical injury at bloom was found on cane diameters when measured at veráison, indicating that a carbon source limitation was induced in these vines. By the time of leaf loss, cane diameters were not significantly different across treatments, indicating that vines may have been able to compensate for the earlier defoliation. Injury at veráison had no significant effect on vine growth parameters. These results suggest that young ‘Niagara’ vines are able to tolerate foliar injury far exceeding that caused by two weeks of exposure to 40 beetles of either species. Surveys of Michigan vineyards containing different grape varieties indicated that although both beetle species could be found in high abundance, leaf injury levels were low. The implications for management of beetle foliar herbivory in vineyards are discussed

Damage Potential of Rose Chafer and Japanese Beetle (Coleoptera: Scarabaeidae) in Michigan Vineyards

Responses of young non-fruiting grapevines, Vitis labrusca (L.) var. ‘Niagara’, to defoliation were examined at two stages of vine growth when beetles typically infest vineyards. In the first experiment, vines were caged and subjected to two weeks of feeding by 0, 10, 20, or 40 adult Macrodactylus subspinosus Fabricius (Scarabaeidae: Macrodactylini) during bloom, or to the same range of adult Popillia japonica Newman (Scarabaeidae: Anomalini) during veráison, when berries begin changing color. Leaf area removed increased with beetle density, but less than 1% of the leaf area was removed at the highest density of M. subspinosus, and less than 7% at the highest density of P. japonica. Vine growth measurements taken during the year of injury and prior to bloom during the following season indicated no significant impacts of this leaf injury on vegetative growth. In the second experiment, mechanical injury was induced by removing 0, 10, 20, or 30% of the total leaf area of every fully expanded leaf at bloom or veráison. A significant effect of mechanical injury at bloom was found on cane diameters when measured at veráison, indicating that a carbon source limitation was induced in these vines. By the time of leaf loss, cane diameters were not significantly different across treatments, indicating that vines may have been able to compensate for the earlier defoliation. Injury at veráison had no significant effect on vine growth parameters. These results suggest that young ‘Niagara’ vines are able to tolerate foliar injury far exceeding that caused by two weeks of exposure to 40 beetles of either species. Surveys of Michigan vineyards containing different grape varieties indicated that although both beetle species could be found in high abundance, leaf injury levels were low. The implications for management of beetle foliar herbivory in vineyards are discussed

Epeoloides pilosulus (Cresson) Rediscovered in Michigan, with Notes on the Distribution and Status of its Macropis hosts.

Epeoloides pilosulus (Cresson 1878) is one of the rarest bees in North America with only a handful of records since 1960. The last collection in Michigan was made in 1944. Epeoloides pilosulus is a brood parasite of Macropis bees, which until recently had not been collected in Michigan for several decades. Bee surveys in Midland County, Michigan have led to the rediscovery of E. pilosulus in this state – the first record in 74 years. Michigan becomes the fourth state where E. pilosulus has been rediscovered after Connecticut in 2006, New York in 2014 and Maine in 2016, and the sixth region in North America after Nova Scotia in 2002 and Alberta in 2010. State-wide bee surveys have also shown that the principal host, Macropis nuda (Provancher 1882), remains widespread in Michigan, and that Macropis patellata Patton 1880 is newly recorded for the state

Pollen Germination and Tube Growth in Northern Highbush Blueberry are Inhibited by Extreme Heat

The increasing intensity and frequency of extreme heat events threaten crop productivity globally. Certain phases of plant reproduction necessary for fertilization are highly sensitive to extreme heat, particularly during pollen development, germination, and tube elongation. However, few studies have assessed the effects of extreme heat on pollen performance in perennial crop plants. To understand how northern highbush blueberry pollen responds to high temperatures, we quantified pollen germination and pollen tube growth in vitro using four commercially relevant cultivars (Bluecrop, Elliott, Jersey, and Liberty) in climate-controlled chambers. We also tested recovery from high heat in ‘Bluecrop’ to determine whether pollen tubes can still germinate and grow after short bursts of extreme heat. We found the highest proportion of germinated pollen tetrads and the greatest pollen tube growth at 20 and 30 °C, and the lowest levels at 10 and 40 °C, with nearly complete inhibition at 40 °C. Exposure to between 30 and 40 °C revealed significant reduction in pollen germination and tube growth above 35 °C across all cultivars and assessment times. Exposure to 37.5 °C for only 4 hours resulted in substantial reductions in pollen germination and pollen tube growth, even after pollen was moved to optimal conditions of 25 °C. Extreme heat exposure, even for a short duration, significantly limits blueberry pollen germination and tube development. This is expected to have cascading effects on fruit set and crop yield. The nonreversibility of the effects on pollen highlights the need to prevent fields reaching damaging temperatures by developing crop monitoring and management strategies to protect crops during bloom

Mating Disruption of Paralobesia viteana in Vineyards Using Pheromone Deployed in SPLAT-GBM™ Wax Droplets

Abstract A paraffin wax formulation releasing pheromone for mating disruption of insects was tested during 2005 and 2006 in Vitis labrusca vineyards infested by grape berry moth, Paralobesia viteana (Lepidoptera: Tortricidae). In early May of each year, 1-ml droplets of SPLAT-GBM™ wax containing 3% sex pheromone of P. viteana were applied to every wooden post at a rate of 400/ha in replicated 1.3-ha plots. Moth captures in sex pheromone baited traps placed at the vineyard borders and interiors revealed significant disruption of male moth captures in treated plots, with activity of one application lasting over 10 weeks during both years. Treatment with SPLAT-GBM™ did not affect the proportion of clusters infested until the end of the second growing season, when infestation was 27% lower in the treated plots than in the control plots. Comparisons of moth captures in traps placed inside 15.2 × 16.5 m vine plots that were untreated or received varying densities of 0.2-ml wax drops or Isomate-GBM hand-tied dispensers at the recommended rate of 450/ha indicated that orientational disruption increased with droplet density. Similar numbers of moths were captured in plots that received 10 or 30 drops per vine as were trapped in plots with twist ties spaced at 0.4 per vine. Moth captures in monitoring traps baited with increasing sizes of wax droplets (0.2, 0.5, or 1-ml drops) or red septa containing P. viteana sex pheromone suggest decreasing ability of male moths to reach traps with increasing pheromone loading. This study indicates that wax-deployed pheromone can reduce crop infestation by P. viteana after 2 years of deployment, and that the increasing of pheromone release by using application of greater droplet densities or by using larger droplets will improve the level of disruption achieved

Epeoloides pilosulus (Cresson) Rediscovered in Michigan, with Notes on the Distribution and Status of its Macropis hosts.

Epeoloides pilosulus (Cresson 1878) is one of the rarest bees in North America with only a handful of records since 1960. The last collection in Michigan was made in 1944. Epeoloides pilosulus is a brood parasite of Macropis bees, which until recently had not been collected in Michigan for several decades. Bee surveys in Midland County, Michigan have led to the rediscovery of E. pilosulus in this state – the first record in 74 years. Michigan becomes the fourth state where E. pilosulus has been rediscovered after Connecticut in 2006, New York in 2014 and Maine in 2016, and the sixth region in North America after Nova Scotia in 2002 and Alberta in 2010. State-wide bee surveys have also shown that the principal host, Macropis nuda (Provancher 1882), remains widespread in Michigan, and that Macropis patellata Patton 1880 is newly recorded for the state