Comparison of Commercial Lures and Food Baits for Early Detection of Fruit Infestation Risk by Drosophila suzukii (Diptera: Drosophilidae).

Drosophila suzukii (Matsumura; Diptera: Drosophilidae) is one of the most serious invasive pests of berries and cherries worldwide. Several adult monitoring systems are available to time foliar application of insecticides with the expectation of detecting the presence of D. suzukii before they infest susceptible crops. We tested this by comparing four different trapping systems based on two homemade baits, apple cider vinegar (ACV) or fermenting dough, and two fermentation volatile-based commercial lures, Scentry and Trécé. Traps baited with dough or Scentry captured more D. suzukii than traps baited with ACV or Trécé in blueberries and traps baited with Trécé in raspberries. In blueberries, traps baited with Scentry, Trécé and dough provided 11-21 d of warning prior to first detection of fruit infestation. However, these traps were not as effective in summer floricane raspberries. The Scentry lure baited traps detected D. suzukii on the same week as the first detection of fruit infestation and other trapping systems detected the fly 4 to 11 d after the first detection, suggesting the need for an improved D. suzukii detection system in raspberries. Both synthetic lures (Scentry and Trécé) were significantly more selective for D. suzukii than dough bait, although the selectivity of all four tested lures/baits were relatively low at <20%. Our results suggest that in locations where D. suzukii adults are not trapped in late winter and spring, adult monitoring of D. suzukii using a sensitive trapping system may provide early warning of pending infestation risk thereby potentially reducing unnecessary insecticide applications.

Tempo-Spatial Dynamics of Adult Plum Curculio (Coleoptera: Curculionidae) Based on Semiochemical-Baited Trap Captures in Blueberries.

Plum curculio, Conotrachelus nenuphar (Herbst), has become an important pest of highbush blueberries in the northeastern United States. Here, we conducted experiments in 2010-2013 to compare the efficacy of semiochemical-baited traps for C. nenuphar versus conventional (beating cloth) sampling methods in blueberries, and to understand the seasonal abundance and distribution of C. nenuphar adults within and among blueberry fields using these traps. Black pyramid traps baited with the C. nenuphar aggregation pheromone grandisoic acid and the fruit volatile benzaldehyde caught three to four times more adults than unbaited traps without causing an increase in injury to berries in neighboring bushes. Numbers of adult weevils caught in traps correlated with those on bushes (beating cloth samples), indicating that trap counts can predict C. nenuphar abundance in the field. Early in the season, traps placed 20 m from field edges near a forest caught higher C. nenuphar numbers than traps placed at farther distances, suggesting movement of overwintered weevils from outside fields. Using a trapping network across multiple fields in an organic farm, we found evidence of C. nenuphar aggregation in "hotspots"; early in the season, C. nenuphar numbers in traps were higher in the middle of fields, and there was a correlation between these numbers and distance from the forest in 2013 but not in 2012. These results show that semiochemical-baited traps are effective in capturing C. nenuphar adults in blueberries, and that these traps should be placed in the interior of fields preferably, but not exclusively, near wooded habitats to maximize their efficacy.

Attraction of the Invasive Halyomorpha halys (Hemiptera: Pentatomidae) to Traps Baited with Semiochemical Stimuli Across the United States.

A recent identification of the two-component aggregation pheromone of the invasive stink bug species, Halyomorpha halys (Stål), in association with a synergist, has greatly improved the ability to accurately monitor the seasonal abundance and distribution of this destructive pest. We evaluated the attraction of H. halys to black pyramid traps baited with lures containing the pheromone alone, the synergist methyl (2E,4E,6Z)-decatrienoate (MDT) alone, and the two lures in combination. Traps were deployed around areas of agricultural production including fruit orchards, vegetables, ornamentals, or row crops in Delaware, Maryland, North Carolina, New Jersey, New York, Ohio, Oregon, Pennsylvania, Virginia, and West Virginia from mid-April to mid-October, 2012 and 2013. We confirmed that H. halys adults and nymphs are attracted to the aggregation pheromone season long, but that attraction is significantly increased with the addition of the synergist MDT. H. halys adults were detected in April with peak captures of overwintering adults in mid- to late May. The largest adult captures were late in the summer, typically in early September. Nymphal captures began in late May and continued season long. Total captures declined rapidly in autumn and ceased by mid-October. Captures were greatest at locations in the Eastern Inland region, followed by those in the Eastern Coastal Plain and Pacific Northwest. Importantly, regardless of location in the United States, all mobile life stages of H. halys consistently responded to the combination of H. halys aggregation pheromone and the synergist throughout the entire season, suggesting that these stimuli will be useful tools to monitor for H. halys in managed systems.

Can a specialist parasitoid, Macrocentrus cingulum (Hymenoptera: Braconidae), influence the ecotype structure of its preferred host Ostrinia nubilalis (Lepidoptera: Crambidae)?

Synchronization between a parasitoid and its preferred host is an essential strategy for successful biological control. Two ecotypes of Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) in North America are distinguished by their voltinism. In this study, the differential impact of a specialist parasitoid, Macrocentrus cingulum Brischke (Hymenoptera: Braconidae), on the univoltine and multivoltine populations of O. nubilalis is investigated. Four years of field and laboratory study suggested that M. cingulum emergence was synchronized with the spring emergence of the multivoltine ecotypes of O. nubilalis in Pennsylvania. Univoltine populations experienced minimal parasitism from M. cingulum. Field-collected data suggested that the postdiapause multivoltine O. nubilalis field population was male biased, whereas the univoltine population was female biased. M. cingulum-parasitized postdiapause O. nubilalis larvae were significantly heavier than the male and nonparasitized female larvae. Sex ratio differences observed in overwintered O. nubilalis populations in the presence or absence of M. cingulum parasitism suggested preferential parasitism between male and female O. nubilalis larvae. Correlation between the larger parasitized O. nubilalis larval host and the number of adult parasitoids emerging per host suggested a potential evolutionary advantage to parasitizing female or larger hosts.