Managed honeybees and South American bumblebees exhibit complementary foraging patterns in highbush blueberry.

Despite Apis mellifera being the most widely managed pollinator to enhance crop production, they are not the most suitable species for highbush blueberries, which possess restrictive floral morphology and require buzz-pollination. Thus, the South American bumblebee Bombus pauloensis is increasingly managed as an alternative species in this crop alongside honeybees. Herein, we evaluated the foraging patterns of the two species, concerning the potential pollen transfer between two blueberry co-blooming cultivars grown under open high tunnels during two seasons considering different colony densities. Both managed pollinators showed different foraging patterns, influenced by the cultivar identity which varied in their floral morphology and nectar production. Our results demonstrate that both species are efficient foragers on highbush blueberry and further suggest that they contribute positively to its pollination in complementary ways: while bumblebees were more effective at the individual level (visited more flowers and carried more pollen), the greater densities of honeybee foragers overcame the difficulties imposed by the flower morphology, irrespective of the stocking rate. This study supports the addition of managed native bumblebees alongside honeybees to enhance pollination services and emphasizes the importance of examining behavioural aspects to optimize management practices in pollinator-dependent crops.

Contamination of fresh produce sold on the Italian market with Cyclospora cayetanensis and Echinococcus multilocularis.

To investigate the presence of Cyclospora cayetanensis, Toxoplasma gondii and Echinococcus spp. in fresh produce sold in Italy, 324 locally produced 'ready-to-eat' (RTE) mixed-salad packages belonging to three brands and 324 berries packages (blueberries and blackberries imported from Peru and Mexico, respectively, and raspberries grown in Italy) were purchased at retail. Nine individual packages from each of the six types of fresh produce were collected monthly for one year, and with the same produce pooled, this resulted in a total of 72 pools for the whole year. Using microscopy (FLOTAC), a Cyclospora-like oocyst was detected in a blueberry sample and a taeniid egg was detected in a RTE-salad sample. Molecular tools confirmed these to be C. cayetanensis and Echinococcus multilocularis, respectively. Toxoplasma gondii was not detected in any of the samples. This study shows for the first time in Europe that imported berries on the Italian market may be contaminated with C. cayetanensis and RTE salads grown in Italy with E. multilocularis. The results indicate a new epidemiological scenario and highlight that current management of fresh produce, locally produced or imported, does not ensure products are free from parasite contamination.

Repellent, oviposition-deterrent, and insecticidal activity of the fungal pathogen Colletotrichum fioriniae on Drosophila suzukii (Diptera: Drosophilidae) in highbush blueberries.

Spotted-wing drosophila, Drosophila suzukii, and the anthracnose pathogen Colletotrichum fioriniae are an important insect pest and fungal disease of highbush blueberries, respectively, in the United States. However, whether C. fioriniae infection affects D. suzukii preference and performance remains unknown. Here, we conducted choice and no-choice studies to determine the repellent, oviposition-deterrent, and insecticidal effects of C. fioriniae on D. suzukii. In choice tests, blueberry fruit treated with anthracnose solutions containing spores from either field-collected infected fruit ('fruit') or a laboratory C. fioriniae culture ('colony') were less attractive to sexually mature D. suzukii females, but not males, than untreated fruit. The plant tissue (fruit or leaves) did not influence C. fioriniae repellency effects on D. suzukii. In no-choice tests, 55% fewer numbers of eggs were laid on, and 65% fewer adults emerged from, blueberry fruit treated with either the 'fruit' or 'colony' anthracnose solution than untreated fruit. Egg-to-adult D. suzukii survival was also 12% lower on C. fioriniae-infected fruit. No repellency or negative effects on survival were observed when C. fioriniae spores were filtered out of the solution. These findings will help efforts towards the discovery of microbial-derived repellent/oviposition-deterrent compounds that could be used in behavior-based management strategies for D. suzukii.

Evaluation of the U.S. Food and Drug Administration validated molecular method for detection of Cyclospora cayetanensis oocysts on fresh and frozen berries.

Outbreaks and sporadic cases of Cyclospora cayetanensis have been linked to consumption of berries. The efficacy of the U.S. Food and Drug Administration (FDA) method for detection of C. cayetanensis was evaluated in fresh berries (blackberries, strawberries, blueberries and mixed berries) and in frozen mixed berries. The protocol included seeding with C. cayetanensis oocysts, produce washing, DNA extraction and a dual TaqMan assay. As few as five oocysts were detected in every type of fresh berry analyzed. All berry samples seeded with 200 oocysts were positive and all unseeded berry samples were negative. No significant differences were observed among any of the berry types analyzed in detection rates, CT values and estimated oocyst recovery percentages. Mixed berries were seeded and frozen for up to seven weeks. As few as five oocysts were also detected. No significant differences were observed in C. cayetanensis CT values between fresh and frozen mixed berries at any seeding level. In conclusion, the FDA BAM Chapter 19B method for the detection of Cyclospora was robust, consistent, and showed high sensitivity in all types of berries analyzed. Evaluation of the FDA detection method in berries will provide reliable laboratory support for surveillance programs and for outbreak investigations.

A novel multiplex real-time PCR for the detection of Echinococcus multilocularis, Toxoplasma gondii, and Cyclospora cayetanensis on berries.

Foodborne parasites (FBP) are of major public health importance and warrant appropriate detection and control strategies. Most of the FBP considered for risk-ranking by a panel of experts are potentially transmitted via consumption of contaminated fresh produce, including berries. In this study we focused on the potential of three FBP, namely Echinococcus multilocularis, Toxoplamsa gondii, and Cyclospora cayetanensis, as contaminants of berries. Surveys to assess these parasites as contaminants of fresh produce in general, and berries in particular, are scanty or non-existent mainly due to the lack of optimized laboratory methods for detection. The aim of the present study was to develop and evaluate a novel multiplex qPCR for the simultaneous detection of E. multilocularis, T. gondii, and C. cayetanensis from berry fruits. The efficiency and linearity of each channel in the multiplex qPCR were within the acceptable limits for the range of concentrations tested. Furthermore, the method was shown to have good repeatability (standard deviation ≤0.2 Cq) and intermediate precision (pooled standard deviation of 0.3-0.6 Cq). The limit of detection was estimated to 10 oocysts for Toxoplasma and Cyclospora, and 5 eggs for Echinococcus per 30 g of raspberries or blueberries. In conclusion, evaluation of the present method showed that the newly developed multiplex qPCR is highly specific, precise, and robust method that has potential for application in food-testing laboratories.

Differential Susceptibility of Wild and Cultivated Blueberries to an Invasive Frugivorous Pest.

Highbush blueberry is a crop native to the northeast USA that has been domesticated for about 100 years. This study compared the susceptibility of wild and domesticated/cultivated highbush blueberries to an invasive frugivorous pest, the spotted wing drosophila (Drosophila suzukii). We hypothesized that: 1) cultivated fruits are preferred by D. suzukii for oviposition and better hosts for its offspring than wild fruits; and, 2) wild and cultivated fruits differ in physico-chemical traits. Fruits from wild and cultivated blueberries were collected from June through August of 2015 and 2016 from 10 to 12 sites in New Jersey (USA); with each site having wild and cultivated blueberries growing in close proximity. The preference and performance of D. suzukii on wild and cultivated blueberries were studied in choice and no-choice bioassays. In addition, we compared size, firmness, acidity (pH), total soluble solids (°Brix), and nutrient, phenolic, and anthocyanin content between wild and cultivated berries. In choice and no-choice bioassays, more eggs were oviposited in, and more flies emerged from, cultivated than wild blueberries. Cultivated fruits were 2x bigger, 47% firmer, 14% less acidic, and had lower °Brix, phenolic, and anthocyanin amounts per mass than wild fruits. Levels of potassium and boron were higher in cultivated fruits, while calcium, magnesium, and copper were higher in wild fruits. These results show that domestication and/or agronomic practices have made blueberries more susceptible to D. suzukii, which was associated with several physico-chemical changes in fruits. Our study documents the positive effects of crop domestication/cultivation on an invasive insect pest.

Development of Anastrepha fraterculus (Diptera: Tephritidae) Related to the Phenology of Blueberry, Blackberry, Strawberry Guava, and Surinam Cherry Fruits.

Anastrepha fraterculus (Wiedemann, 1830) is the main pest of temperate climate orcharding. The study investigated the development of A. fraterculus related to phenological stage of blueberry, blackberry, strawberry guava, and Surinam cherry trees. The phenological stages I (green fruits), II (intermediate ripening stage of fruits), and III (fruits close to harvesting) were determined, and they are from 8th, 10th, and 11th week; 6th, 8th, and 9th week; 8th, 13th, and 16th week; and 5th, 6th, and 7th week after the first flowering of blueberry, blackberry, strawberry guava, and Surinam cherry trees, respectively. We collected fruits from orchards to determine the infestation index using the formula: number of pupa/fruit weight. To investigate the development of A. fraterculus, we determined the following biological parameters: egg-to-adult period, weight of pupae, oviposition period, fecundity, number of pupae, and number of infested fruits. The infestation index for the fruits collected in the field was greater in strawberry guava and Surinam cherry fruits. In the laboratory, the development of A. fraterculus occurred in stage III of blueberry. In blackberry, besides stage III, we also observed the development in stage II, however, at lower infestation. In strawberry guava, the development of A. fraterulus occurred in stages II and III, and the development in both stages was similar. For Surinam cherry, the development occurred in the three phenological stages with similar values for biological parameters. Overall, of the four hosts studied, the strawberry guava and Surinam cherry fruits allowed a better biological development of A. fraterculus, corroborating its preference for fruits native to Brazil.

Temperature-related development and population parameters for Drosophila suzukii (Diptera: Drosophilidae) on cherry and blueberry.

Temperature-related studies were conducted on Drosophila suzukii Matsumura (Diptera: Drosophilidae: Drosophilini). From 10-28°C, temperature had a significant impact on blueberries, Vaccinium corymbosum L. (Ericales: Ericaceae), and cherries, Prunus avium (L.) L. 1755 (Rosales: Rosaceae), important commercial hosts of D. suzukii. Temperature had a significant influence on D. suzukii developmental period, survival, and fecundity, with decreasing developmental periods as temperatures increased to 28°C. At 30°C, the highest temperature tested, development periods increased, indicating that above this temperature the developmental extremes for the species were approached. D. suzukii reared on blueberries had lower fecundity than reared on cherries at all temperatures where reproduction occurred. The highest net reproductive rate (R(o)) and intrinsic rate of population increase (r(m)) were recorded on cherries at 22°C and was 195.1 and 0.22, respectively. Estimations using linear and nonlinear fit for the minimum, optimal, and maximum temperatures where development can take place were respectively, 7.2, 28.1, and 42.1°C. The r(m) values were minimal, optimal, and maximal at 13.4, 21.0, and 29.3°C, respectively. Our laboratory cultures of D. suzukii displayed high rates of infection for Wolbachia spp. (Rickettsiales: Rickettsiaceae), and this infection may have impacted fecundity found in this study. A temperature-dependent matrix population estimation model using fecundity and survival data were run to determine whether these data could predict D. suzukii pressure based on environmental conditions. The model was applied to compare the 2011 and 2012 crop seasons in an important cherry production region. Population estimates using the model explained different risk levels during the key cherry harvest period between these seasons.

Field type, trap type and field-edge characteristics affect Rhagoletis mendax captures in lowbush blueberries.

BACKGROUND: Blueberry maggot, Rhagoletis mendax Curran (Diptera: Tephritidae), is the most important pest of blueberries in eastern North America. Insecticide use in fruit-bearing lowbush blueberry fields could be reduced with management strategies focused on vegetative fields. Fly distribution and fruit infestation levels were assessed where fruit-bearing and vegetative fields adjoin and along forested edges of vegetative fields. RESULTS: Along adjoining edges, immature female flies were captured in fruiting fields and mature females in vegetative fields throughout the season. Male fly captures and fruit infestation levels were greater at 5 m than at 30 m from the edge. Along forested edges, fly captures were best predicted by densities of ripe lowbush blueberries and large coniferous trees. Maggot infestation level in lowbush blueberries was best predicted by blueberry density and small deciduous trees. Bunchberry, Cornus canadensis L., was the only non-crop host in which blueberry maggot was found. CONCLUSIONS: We have shown that relatively high numbers of flies occur in vegetative fields and at edges of fruiting fields. Ripe blueberries and certain vegetation in forested edges affect fly distribution and probably maintain populations. These results may help to predict where controls for blueberry maggot should be targeted and suggest that management strategies focused on vegetative fields and field edges may be worthwhile.

Sending mixed messages: a trophic cascade produced by a belowground herbivore-induced cue.

Plants defend themselves against herbivores both directly (chemical toxins and physical barriers) and indirectly (attracting natural enemies of their herbivores). Previous work has shown that plant roots of citrus defend against root herbivores by releasing an herbivore-induced plant volatile (HIPV), pregeijerene (1,5-dimethylcyclodeca-1,5,7-triene), that attracts naturally occurring entomopathogenic nematodes (EPNs) to Diaprepes abbreviatus larvae when applied in the field. However, the soil community is complex and contains a diversity of interspecific relationships that modulate food web assemblages. Herein, we tested the hypothesis that other nematode types beyond EPNs, as well as, nematophagous fungi are affected by the same HIPV that attracts EPNs to herbivore-damaged roots. We employed molecular probes designed to detect and quantify nematodes from the Acrobeloides-group (free-living bacterivorous nematodes, FLBNs), some of which compete with EPNs by 'hyperparasitizing' insect cadavers, and five species of nematophagous fungi (NF), which attack and kill EPNs. In two different agricultural systems (citrus and blueberry), we detected diverse species of nematodes and fungi; however, only the behavior of FLBNs was affected in a manner similar to that reported previously for EPNs. Although detected, NF abundance was not statistically affected by the presence of the belowground HIPV. We provide the first evidence showing subterranean HIPVs behave much the same as those aboveground, attracting not only parasitoids, but also hyperparasites and other food web members.

Lethality of reduced-risk insecticides against plum curculio (Coleoptera: Curculionidae) in blueberries, with emphasis on their curative activity.

BACKGROUND: Historically, management of plum curculio, Conotrachelus nenuphar (Herbst), in highbush blueberries has focused on post-bloom broad-spectrum insecticide applications targeting the adults. Here, the efficacy of different classes of insecticides against various stages of C. nenuphar was compared, and a prebloom treatment with the chitin synthesis inhibitor novaluron in combination with a post-bloom insecticide application was tested. RESULTS: Novaluron decreased the number of oviposition scars and eggs on fruit and reduced larval emergence by >60% when applied prebloom. Post-bloom applications of the oxadiazine indoxacarb and the organophosphate phosmet, but not the neonicotinoid acetamiprid, showed significant adulticidal activity. The neonicotinoids acetamiprid and thiamethoxam and phosmet showed significant curative activity on C. nenuphar larvae when applied topically to infested fruit, whereas the pyrethroid fenpropathrin, indoxacarb and novaluron were weaker curative agents. Residue profiles showed that acetamiprid and phosmet residues had the highest levels while fenpropathrin and novaluron had the lowest levels of fruit penetration. CONCLUSIONS: In blueberries, novaluron showed anti-ovipositional/ovicidal activity, indoxacarb and phosmet showed adulticidal activity, while the neonicotinoids and phosmet showed best curative (larvicidal) control on C. nenuphar. A prebloom novaluron application in combination with a post-bloom treatment with an adulticidal/larvicidal insecticide is recommended for optimal multi-life-stage management of C. nenuphar. © 2013 Society of Chemical Industry.

Biology and efficacy of Aprostocetus (Eulophidae: Hymenoptera) as a parasitoid of the blueberry gall midge complex: Dasineura oxycoccana and Prodiplosis vaccinii (Diptera: Cecidomyiidae).

In the southeastern United States, bud-infesting larvae of two gall midge species, Dasineura oxycoccana (Johnson) and Prodiplosis vaccinii (Felt), destroy from 20 to 80% of the rabbiteye blueberry crop, Vaccinium virgatum Aiton (syn. V. ashei Reade). These midge larvae are attacked by five species of parasitoid wasps. The most effective of these is the bivoltine eulophid Aprostocetus sp. nr. marylandensis (Eulophidae), whose adults constitute one-third of the gall midge parasitoids, active in both conventional and organic blueberry fields. Broods of Aprostocetus use several reproductive strategies to keep sole possession of their larval hosts. As solitary endoparasitoids as well as facultative hyperparasitoids, precocial larvae of Aprostocetus devour hosts organs along with any younger siblings and rival parasitoid broods. Although larger hosts are preferred, any sized larvae can be parasitized, which reduces brood congestion and infanticide. An Aprostocetus female spends an hour or more in a systematic hunt for hosts, during which time 40 to 100% of midge larvae encountered are parasitized. Aprostocetus females could have located hosts more quickly had they recognized host-feeding scars as cues. Even so, high rates of larval parasitism achieved by Aprostocetus may kill as many midges as insecticides do.

Phenology of Dasineura oxycoccana (Diptera: Cecidomyiidae) on cranberry and blueberry indicates potential for gene flow.

Dasineura oxycoccana (Johnson) (Diptera: Cecidomyiidae) is a pest of cranberry, Vaccinium macrocarpon (Aiton) (Ericales: Ericaceae), and highbush blueberry, Vaccinium corymbosum (L.) (Ericales: Ericaceae), in North America. In British Columbia, Canada, D. oxycoccana was first found on highbush blueberry in 1991 and then on cranberry seven years later. Because many cranberry and highbush blueberry farms are adjacent to one another, we hypothesized that D. oxycoccana was moving from highbush blueberry onto cranberry. Cranberry and highbush blueberry differ in phenology, and adaptation to these different phenologies may result in host races or cryptic species on these two crops. We recognized the alternative hypothesis that D. oxycoccana had arrived as immature stages with cranberry vines imported from another region of North America. During spring and summer, we recorded the phenology of D. oxycoccana and the development of plant shoots from three cranberry and three highbush blueberry farms to determine whether the opportunity exists for successful movement of D. oxycoccana between the two crops. Our results show that D. oxycoccana from cranberry and highbush blueberry overlap in phenology for much of the season, indicating a high potential for movement and gene flow. However, differences were seen in number of larvae per shoot, location of pupae, and heat unit accumulation during larval development suggesting that instead there may be the potential for host race or cryptic species formation.

Susceptibility of low-chill blueberry cultivars to Mediterranean fruit fly, oriental fruit fly, and melon fly (Diptera: Tephritidae).

No-choice tests were conducted to determine whether fruit of southern highbush blueberry, Vaccinium corymbosum L., hybrids are hosts for three invasive tephritid fruit flies in Hawaii. Fruit of various blueberry cultivars was exposed to gravid female flies of Bactrocera dorsalis Hendel (oriental fruit fly), Ceratitis capitata (Wiedemann) (Mediterranean fruit fly), or Bactrocera cucurbitae Coquillet (melon fly) in screen cages outdoors for 6 h and then held on sand in the laboratory for 2 wk for pupal development and adult emergence. Each of the 15 blueberry cultivars tested were infested by oriental fruit fly and Mediterranean fruit fly, confirming that these fruit flies will oviposit on blueberry fruit and that blueberry is a suitable host for fly development. However, there was significant cultivar variation in susceptibility to fruit fly infestation. For oriental fruit fly, 'Sapphire' fruit produced an average of 1.42 puparia per g, twice as high as that of the next most susceptible cultivar 'Emerald' (0.70 puparia per g). 'Legacy', 'Biloxi', and 'Spring High' were least susceptible to infestation, producing only 0.20-0.25 oriental fruit fly puparia per g of fruit. For Mediterranean fruit fly, 'Blue Crisp' produced 0.50 puparia per g of fruit, whereas 'Sharpblue' produced only 0.03 puparia per g of fruit. Blueberry was a marginal host for melon fly. This information will aid in development of pest management recommendations for blueberry cultivars as planting of low-chill cultivars expands to areas with subtropical and tropical fruit flies. Planting of fruit fly resistant cultivars may result in lower infestation levels and less crop loss.

Examining the spatial distribution of flower thrips in southern highbush blueberries by utilizing geostatistical methods.

Flower thrips (Frankliniella spp.) are one of the key pests of southern highbush blueberries (Vaccinium corymbosum L. x V. darrowii Camp), a high-value crop in Florida. Thrips' feeding and oviposition injury to flowers can result in fruit scarring that renders the fruit unmarketable. Flower thrips often form areas of high population, termed "hot spots", in blueberry plantings. The objective of this study was to model thrips spatial distribution patterns with geostatistical techniques. Semivariogram models were used to determine optimum trap spacing and two commonly used interpolation methods, inverse distance weighting (IDW) and ordinary kriging (OK), were compared for their ability to model thrips spatial patterns. The experimental design consisted of a grid of 100 white sticky traps spaced at 15.24-m and 7.61-m intervals in 2008 and 2009, respectively. Thirty additional traps were placed randomly throughout the sampling area to collect information on distances shorter than the grid spacing. The semivariogram analysis indicated that, in most cases, spacing traps at least 28.8 m apart would result in spatially independent samples. Also, the 7.61-m grid spacing captured more of the thrips spatial variability than the 15.24-m grid spacing. IDW and OK produced maps with similar accuracy in both years, which indicates that thrips spatial distribution patterns, including "hot spots," can be modeled using either interpolation method. Future studies can use this information to determine if the formation of "hot spots" can be predicted using flower density, temperature, and other environmental factors. If so, this development would allow growers to spot treat the "hot spots" rather than their entire field.

Evaluation of emergence traps for monitoring blueberry gall midge (Diptera: Cecidomyiidae) adults and within field distribution of midge infestation.

The blueberry gall midge, Dasineura oxycoccana (Johnson) (Diptera: Cecidomyiidae), is a key pest of rabbiteye blueberry, Vaccinium virgatum Aiton, in the southeastern United States, but it has not been studied extensively and little is known about its ecology and management. Studies were conducted to develop an improved method for monitoring D. oxycoccana adults and to determine the within-field distribution of infestation. Four emergence traps were evaluated in an organic rabbiteye blueberry planting for their effectiveness in capturing D. oxycoccana adults early in the season. These traps included a jar trap, wheat blossom midge trap, petri dish trap, and bucket trap. The petri dish and bucket traps captured the highest numbers of adults in 2007 and 2008, respectively. Both traps had a clear plastic panel coated with adhesive. Adult midges emerging from the soil beneath the traps were caught in the adhesive as they flew up toward the light. Emergence traps are useful for detecting the presence of adults early in the season before larval infestation is apparent in the flower buds. To determine the pattern of midge infestation, flower buds were collected weekly from January to March in 2006 from rabbiteye blueberry plants located in a plot at the southwest border of an existing blueberry planting. There were no differences found in the number of larvae collected from various distances within blueberry rows. However, when flower buds were collected from an isolated rabbiteye plot in 2007 and 2008, D. oxycoccana infestation was not uniform. In both years, the southern border row had a significantly higher number of midge larvae per bud compared with the other rows.

Seasonal abundance, life history, and parasitism of Caloptilia porphyretica (Lepidoptera: Gracillariidae), a leafminer of highbush blueberry.

The leafminer Caloptilia porphyretica Braun (Lepidoptera: Gracillariidae), has become a frequent pest in commercial highbush blueberries, Vaccinium corymbosum L., in New Jersey, but little is known about its seasonal abundance, life history, and parasitism rates. Monitoring programs were conducted from 2003 to 2006 on seven blueberry farms to determine the relative abundance of this leafminer by using pheromone-baited traps and by sampling vegetative and flower/fruit clusters and new shoot growth. We found at least three distinct generations per year, with populations reaching their highest peak in the second generation. Laboratory studies characterized the life history of C. porphyretica and its parasitoid Pholetesor sp. prob. salalicus (Mason). The developmental period of C. porphyretica, from egg to adult, took 927, 838, and 912 degree-days (DD) at 20, 25, and 30 degrees C, respectively, by using a developmental threshold of 4.8 degrees C. This was equivalent to an average of 892 DD to complete development to adult, which compared with 870 and 880 DD between the first and second, and second and third generations, respectively, by using pheromone trap data averaged from 2004 to 2006. Although C. porphyretica populations varied greatly, the number of larvae in cluster and new shoot samples was highly correlated with the number of adults in traps. Field parasitism rate was -29%, with the braconid Pholetesor sp. the most abundant parasitoid. Ten of the 13 parasitoid species collected belonged to the family Eulophidae. When different ages of leafminers were exposed to Pholetesor sp., we found that the parasitoid attacks 9-15-d-old instars that reside in the mines of leaves.

SPLAT-OrB reveals competitive attraction as a mechanism of mating disruption in oriental beetle (Coleoptera: Scarabaeidae).

This study compared the efficacy of SPLAT-OrB, a new pheromone formulation for oriental beetle mating disruption that can be mechanically applied, with hand-applied plastic dispensers in commercial blueberry fields. Both formulations were tested at 2.5 and 5 g of the major sex pheromone component (Z)-7-tetradecen-2-one per hectare, and evaluated by measuring trap shut-down, mating success of caged females, and the number of grubs in sentinel blueberry pots baited with tethered females. All pheromone-treated plots had fewer male captures in traps and lower mating success of caged females compared with untreated plots. SPLAT-OrB, and plastic dispensers at the higher rate, also reduced the number of grubs in sentinel pots. To understand the mechanism of mating disruption in oriental beetle, males were observed approaching the pheromone sources in disrupted plots. In addition, male oriental beetle captures were quantified in plots treated with varying SPLAT-OrB dollop densities per ha. Consistent with predictions for competitive attraction, field observations revealed males approaching the pheromone source and male captures decreasing concavely with increasing dollop density. In a mark-release-recapture study, male oriental beetles responded to SPLAT-OrB dollops and plastic dispensers at least 60 m from the source. Additionally, SPLAT-OrB emitted pheromone that was attractive to male oriental beetles for >5 wk; however, emission rates and attraction dropped rapidly during the first 3-4 wk. This study demonstrates the feasibility of using SPLAT-OrB for oriental beetle mating disruption as an alternative to hand-applied plastic dispensers, and conclusively reveals that a principal mechanism is the competitive attraction of males.

Host status of blueberry to invasive tephritid fruit flies in Hawaii.

Forced infestation studies were conducted to determine whether northern or southern highbush blueberries, Vaccinium corymbosum L., are hosts for the invasive tephritid fruit flies in Hawaii. Fruit were exposed to gravid female flies of Bactrocera dorsalis Hendel (oriental fruit fly), Ceratitis capitata (Wiedemann) (Mediterranean fruit fly), or Bactrocera cucurbitae Coquillet (melon fly) in screen cages outdoors for 6 h and then held on sand in the laboratory for 2 wk for pupal and adult emergence. The number of puparia, number of puparia per gram, and percentage of adult emergence on 'Bluecrop' blueberry were significantly higher for B. dorsalis and C. capitata than B. cucurbitae; B. dorsalis, C. capitata, and B. cucurbitae produced an average of 1.06, 0.60, and 0.09 pupae per g fruit and had 5.8, 54.1, and 12.7% adult emergence, respectively. 'Berkeley' blueberries produced an average of only 0.06, 0.02, and 0.0 pupae per g fruit for B. dorsalis, C. capitata, and B. cucurbitae, respectively. Similarly, six blueberry cultivars were harvested weekly for 10 wk, exposed to Bactrocera latifrons (Hendel) in cages, and held for pupal and adult emergence on either sand or artificial diet. In total, 2,677 blueberries were exposed to 2681 B. latifons and held on sand, and no pupariation or adult emergence was observed. Small numbers of B. latifrons puparia and adults emerged from the artificial diet treatment in all cultivars. Results from rearing on sand and diet indicate that blueberry is an acceptable oviposition host for B. latifrons but not an adequate developmental host. These data suggest blueberry is potentially a good host for B. dorsalis and C. capitata, and an adequate host for Bactrocera cucurbitae, but that there may be significant variation in resistance among cultivars. Blueberry seems to be a nonhost for B. latifrons.

Monitoring and temperature-based prediction of the whitemarked tussock moth (Lepidoptera: Lymantriidae) in blueberry.

Larvae of the whitemarked tussock moth, Orgyia leucostigma (J.E. Smith) (Lepidoptera: Lymantriidae), defoliate and contaminate blueberries, Vaccinium corymbosum L., in eastern North America, but infestations are often not detected until economic damage has been caused. To improve monitoring techniques and understand the phenology of the whitemarked tussock moth in blueberry, we compared four trap types and determined temperature-based phenology of this pest over two growing seasons. Large delta traps captured the greatest number of male moths, and similar moth captures were found with or without monthly lure changing. Traps placed at field perimeters adjacent to woods trapped significantly more moths than those inside fields, whereas position in the canopy (high versus low) did not affect captures. Under laboratory conditions, the lower developmental threshold for larvae was 12.3 degrees C, in close agreement with field studies indicating a 12.8 degrees C threshold. Using the 12.8 degrees C threshold, monitoring of O. leucostigma cohorts on caged blueberry plants revealed a spring generation with egg hatch starting at 206 +/- 3 growing degree-days (GDD) and a late-summer generation with egg hatch starting at 1,157 +/- 52 GDD. Combined use of optimized monitoring methods and the phenology model for O. leucostigma is expected to improve integrated management of this pest in blueberry.