Influence of Landscape Factors and Abiotic Conditions on Dispersal Behavior and Overwintering Site Selection by Halyomorpha halys (Hemiptera: Pentatomidae)

Since the initial detection of the invasive Halyomorpha halys (Stål) in the United States in the late 1990s, this insect has emerged as a severe agricultural and nuisance pest. Nuisance problems are due to adult dispersal to overwintering sites in the fall at which time they alight onto and eventually settle within human-made structures in addition to natural harborage. This study examined how three factors, elevation, light, and moisture affected overwintering site selection by H. halys in the mid-Atlantic. Observational counts performed along elevational transects revealed elevation was significant predictor of H. halys abundance during both years of the study in 2014 and 2015 with more adults observed at higher elevations. Choice tests examining effects of moisture and light on settling behavior demonstrated H. halys settled within overwintering shelter boxes in significantly greater numbers when shelters were dry compared with those having moist conditions, and in darkened shelters compared with those augmented with LED lights. Our findings indicate that H. halys use cues at both landscape and very localized levels when seeking and selecting overwintering sites.

Dispersal From Overwintering Sites, Action Thresholds for Blueberry Maggot Fly (Diptera: Tephritidae), and Factors That Can Influence Variation in Predicted Fruit Infestation Levels in Maine Wild Blueberry: Part I

Between 1996 and 2003 field studies were conducted in wild blueberry, Vaccinium angustifolium Aiton (Ericales: Ericaceae) to determine action thresholds for the blueberry maggot fly, Rhagoletis mendax Curran (Diptera: Tephritidae). Thresholds were based upon cumulative fly trap captures on baited Pherocon AM traps. The cumulative numbers of R. mendax flies captured over time was a significant predictor of infested fruit levels (maggots/liter blueberries). Fifty percent of the variance in fruit infestation is explained by fly captures. Based upon this relationship, the University of Maine Cooperative Extension has recommended action threshold of 10 cumulative fly captures/trap. However, this threshold is liberal in terms of risk as only 50% of the variance in fruit infestation is explained by fly captures. The dynamics of colonization rate and fly physiological status entering fruit-bearing fields might partially explain the variance in the action threshold. The majority of flies emerge from pruned fields or along forest scrub/shrub field edges, and it takes between 1 and 10 d (mean = 4.1 ± 0.9 d) for the populations to enter adjacent fruit-bearing fields. Flies dispersed from pruned fields at a decreasing rate the farther they dispersed. The rate of dispersal into fruit-bearing wild blueberry fields also depends upon the overwintering site quality. Sites with fruit exhibited both delayed colonization and lower colonization rates into fruit-bearing fields than adjacent pruned fields with no fruit. We also found that as the season progressed the proportion of flies capable of laying eggs varied greatly by location and year.

Leukocyte profiles vary with breeding latitude and infection status in a seasonally sympatric songbird

Billions of animals migrate annually in pursuit of food, safety, and reproduction. Long-distance migration can be energetically expensive, which can force tradeoffs with investment in other physiological systems (e.g., suppressing immunity). Understanding the physiological impacts of migration is important to predict when and where such animals may be vulnerable to parasites and how changes to migration might affect infectious disease risks. To isolate relationships between migration and physiology from energetic tradeoffs and hormonal shifts associated with spring reproduction, we assessed differences in leukocyte profiles between seasonally sympatric resident and recently arrived fall migrant dark-eyed juncos (Junco hyemalis) in the Appalachian Mountains. When examining heterophil:lymphocyte (HL) ratios, which can elevate for long durations after even mild stressors, we found weak associations with migratory strategy (resident or migrant subspecies). In contrast, feather δ2H values showed that HL ratios were highest for juncos breeding at more northern latitudes, and this relationship was strongest for birds that arrived at the overwintering site infected with haemosporidian parasites (Plasmodium and Haemoproteus spp.). These patterns were more pronounced and better indicated hematological responses to stressors when using multivariate analyses. Our findings suggest that short- and long-distance migration may be more energetically costly in the presence of infection and highlight how approximating breeding latitude and using multivariate analyses can help understand host physiology.

Where does Grapholita molesta (Busck) (Lepidoptera: Tortricidae) overwinter in adjacent peach, pear and apple orchards?

The Oriental fruit moth, Grapholita molesta (Lepidoptera: Tortricidae), is a major pest of tree fruits worldwide, and the diapausing larvae overwinter in cryptic habitats. Investigations of overwintering G. molesta were conducted in adjacent peach, pear and apple orchards in Northern China over three consecutive winters to determine the overwintering site and habitat preferences of the moth. Counts of overwintering larvae in the different orchards demonstrated that the late-maturing peach orchard (‘Shenzhou honey peach’) was the most preferred overwintering habitat with more than 90% of the collected larvae. Larvae were more abundant in host trees, and they very rarely overwintered in the soil. The overwintering site preferences on the host trees were significantly different; over 50% larvae were located in the tree trunks, and followed by main branches. Most of the G. molesta overwintered on the sunny side of the host trees at or below 60 cm from the ground; a few were cocooned on the shaded sides of the trees or greater than 60 cm from the ground. G. molesta began overwintering between August and October, mid- to late September was the peak period for entering winter diapause during 2011–2013 (77.78, 67.59 and 71.15%, respectively). Our findings improve understanding of the orchard habitat and overwintering site preferences of G. molesta and would be useful in the development of efficient forecasting and pest-management strategies for orchards during the winter and early spring.

Genetic diversity of highly pathogenic H5N8 avian influenza viruses at a single overwintering site of migratory birds in Japan, 2014/15

We isolated eight highly pathogenic H5N8 avian influenza viruses (H5N8 HPAIVs) in the 2014/15 winter season at an overwintering site of migratory birds in Japan. Genetic analyses revealed that these isolates were divided into three groups, indicating the co-circulation of three genetic groups of H5N8 HPAIV among these migratory birds. These results also imply the possibility of global redistribution of the H5N8 HPAIVs via the migration of these birds next winter.