Monitoring plum curculio, Conotrachelus nenuphar (Coleoptera: Curculionidae), populations in apple and peach orchards in the mid-Atlantic

We evaluated responses of plum curculio, Conotrachelus nenuphar (Herbst), to four trap types in commercial and unsprayed apple and peach orchards. Trap types included black pyramid and clear Plexiglas panel traps deployed outside the orchard 2 m from the border row, and branch-mimicking cylinder and trunk-mounted screen traps attached to trees in the border row. Bait treatments evaluated in conjunction with each trap type included the synthetic fruit volatile benzaldehyde, the aggregation pheromone grandisoic acid (GA), benzaldehyde in combination with GA, and an unbaited control treatment. In commercial apple orchards, significantly more plum curculio were captured in traps baited with benzaldehyde + GA compared with traps baited with other treatments. Furthermore, significantly more plum curculio were captured by screen traps baited with benzaldehyde + GA compared with unbaited control traps. Significantly more plum curculio were captured by screen traps compared with other trap types in an unsprayed apple orchard. Very few captures were recorded in commercial peach orchards. Dissections of trapped females indicate that bivoltine populations are present in the mid-Atlantic. In general, correlations between timing and amount of trap captures and timing and amount of fruit injury inflicted concurrently or 1 wk after trap captures were very weak for all trap types and bait combinations. Our results agree with previous studies in the northeastern United States in which trap captures are increased by presence of semiochemical baits but fail to serve as reliable tools to determine need for and timing of insecticide application against plum curculio.     

Odor-baited trap trees: a new approach to monitoring plum curculio (Coleoptera: Curculionidae)

We compared a trap approach with a trap-tree approach to determine the need and timing of insecticide applications against overwintered adult plum curculios, Conotrachelus nenuphar (Herbst.), in commercial apple orchards in Massachusetts in 2002. All traps and trap trees were baited with benzaldehyde (attractive fruit odor) plus grandisoic acid (attractive pheromone). Sticky clear Plexiglas panel traps placed at orchard borders, designed to intercept adults immigrating from border areas by flight, captured significantly more adults than similarly placed black pyramid traps, which are designed to capture adults immigrating primarily by crawling, or Circle traps wrapped around trunks of perimeter-row trees, which are designed to intercept adults crawling up tree trunks. None of these trap types, however, exhibited amounts of captures that correlated significantly with either weekly or season-long amounts of fresh ovipositional injury to fruit by adults. Hence, none appears to offer high promise as a tool for effectively monitoring the seasonal course of plum curculio injury to apples in commercial orchards in Massachusetts. In contrast, baiting branches of selected perimeter-row trees with benzaldehyde plus grandisoic acid led to significant aggregation (14-15-fold) of ovipositional injury, markedly facilitating monitoring of the seasonal course of injury to apples. A concurrent experiment revealed that addition of other synthetic fruit odor attractants to apple trees baited with benzaldehyde plus grandisoic acid did not enhance aggregation of ovipositional injury above that of this dual combination. We conclude that monitoring apples on odor-baited trap trees for fresh ovipositional injury could be a useful new approach for determining need and timing of insecticide application against plum curculio in commercial orchards.     

Impact of temperature on plum curculio (Coleoptera: Curculionidae) responses to odor-baited traps

In 2005, captures of overwintered adult plum curculios, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), in standard black masonite pyramid traps deployed in apple (Malus spp.) orchards from half-inch green until fruit reached 7 mm and baited with known attractants did not result in significant captures compared with unbaited traps as they had in 2003 and 2004. These baits included the synthetic aggregation pheromone, grandisoic acid (GA) alone, a six-component synthetic host plant volatile combination (6-Tree) identified from foliar and woody tissues of a Stanley plum tree in combination with GA (6-Tree+GA), and the synthetic fruit volatile benzaldehyde (BEN) in combination with GA (BEN+GA). In 2005, the average daily temperature was below 13 degrees C, much cooler than in 2003 and 2004. We hypothesized that plum curculio could not discriminate between baited and unbaited traps because of reduced release rates of odor-bait stimuli due to their temperature-driven release system. From data collected from 2003 to 2005, we found that plum curculio captures in traps baited with GA alone, 6-Tree+GA, and BEN+GA were significantly related to temperature. We created a predictive model to determine the level of activity, i.e., trap captures in baited traps compared with unbaited traps, we would expect to observe at a particular temperature for these same odor stimuli. Our models predicts that at temperatures between approximately 11 to 13 degrees C we would expect to see no difference between captures in baited and unbaited traps. For captures in odor-baited traps to reach twice those in unbaited traps, our model predicts that temperatures must reach 19.2 degrees C for GA alone, 18.5 degrees C for 6-Tree+GA, and 15.8 degrees C for BEN+GA.     

3 using odor-baited trap trees as sentinels to monitor plum curculio (Coleoptera: Curculionidae) in apple orchards

In commercial orchards in Massachusetts in 2003, we conducted experiments aimed at developing guidelines for use of perimeter-row trap trees baited with grandisoic acid plus benzaldehyde as sentinels in a practical approach to determining need and timing of insecticide applications against overwintered plum curculios, Conotrachelus nenuphar (Herbst). Evaluations were based on percentages of sampled fruit injured by plum curculio. Trap trees baited with grandisoic acid released at approximately 1 mg/d plus benzaldehyde released at approximately 40 mg/d performed as well as or better than trap trees baited with greater or lesser amounts of these attractants in combination. The distance over which a trap tree baited with such odor was effective in aggregating damage to fruit extended to at least 31-33 m (maximum evaluated) along a perimeter row. Trap trees at corners of orchard blocks were as effective as perimeter-row trap trees midway between corner trees. Within the canopy of a trap tree, damage did not tend significantly to be localized in the vicinity of the odor source but tended to be rather evenly distributed among various sectors of the canopy. Finally, among three candidate thresholds evaluated as a trigger for insecticide application, a threshold of one freshly injured fruit proved better than thresholds of two or four freshly injured fruit out of 50 fruit sampled on a trap tree in assuring that orchard-wide damage would remain below a preset economic injury level of 1%. Our findings lead us to suggest that after a whole-orchard application of insecticide to apple trees in Massachusetts orchards shortly after petal fall, subsequent applications of insecticide against plum curculio can be confined to peripheral-row trees and be driven by a provisional threshold of one freshly injured fruit out of 50 fruit sampled on a perimeter-row trap tree baited with the above-mentioned odor.     

Monitoring stink bugs (Hemiptera: Pentatomidae) in mid-Atlantic apple and peach orchards

Pyramid traps coated with "industrial safety yellow" exterior latex gloss enamel paint and baited with Euschistus spp. aggregation pheromone, methyl (2E,4Z)-decadienoate captured more stink bugs than all other baited and unbaited trap types in both apple and peach orchards in 2002 and 2003. Commercial sources of dispensers of methyl (2E,4Z)-decadienoate deployed in association with pyramid traps had a significant impact on trap captures. Captures in pyramid traps were four-fold greater when baited with lures from IPM Technologies, Inc. (Portland, OR) than with lures from Suterra (Bend, OR). Variation in yellow pyramid trap color ("industrial safety yellow" and "standard coroplast yellow") and material (plywood, plastic, and masonite) did not affect trap captures. Brown stink bug was the predominant species captured (58%), followed by dusky stink bug, Euschistus tristigmus (Say) (20%); green stink bug, Acrosternum hilare (Say) (14%); and other stink bugs (Brochymena spp. and unidentified nymphs) (8%). Captures in baited pyramid traps were significantly correlated with tree beating samples in both managed and unmanaged apple orchards and with sweep netting samples in the unmanaged apple orchard. However, problems associated with trapping mechanisms of pyramid trap jar tops and jar traps likely resulted in reduced captures in baited traps. Improved trapping mechanisms must be established to develop an effective monitoring tool for stink bugs in mid-Atlantic orchards.     

Olfactometer Responses of Plum Curculio <Emphasis Type="Italic">Conotrachelus nenuphar</Emphasis> (Herbst) (Coleoptera: Curculionidae) to Host Plant Volatiles,Synthetic Grandisoic Acid,and Live Conspecifics

The plum curculio Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae) is a major pest of pome and stone fruit, but will also attack other fruits. Males produce the aggregation pheromone grandisoic acid; emitting only the (+)-enantiomer which is attractive to both sexes of the univoltine and multivoltine strains, while the synthetic racemic mixture contains optical isomers with equal amounts of (+)- and (?)-enantiomers. Synergy between odours can increase trap captures and improve monitoring techniques, therefore tests were performed in a dual-choice olfactometer with odours attractive to plum curculios according to literature to determine 1) under what physiological conditions (mating status, age, starvation period) these odours are attractive or repulsive, 2) if the (+)-enantiomer or the odour of live males synergizes with host plant volatiles, and 3) if there is a difference in response between plum curculio strains. Females were exposed to: benzaldehyde; trans-2-hexenal; apples; extracts of: plums, apples, blueberries; grandisoic acid; and live males. Plum essence was found to be the most attractive host-plant odour for both immature and mature virgin females, and immature whole apples were attractive to starved females, while trans-2-hexenal, McIntosh apple essence, benzaldehyde along with the combination of benzaldehyde and plume essence was found to be repulsive. Starvation, age, and mated status all influence response to odours. No synergistic or additive affects were observed between any of the odour combinations tested, including the combination of both the natural and synthetic pheromone and plum essence or apples.     

An effective strategy for trapping Douglas-fir beetle, Dendroctonus pseudotsugae (Col., Scolytidae) using combinations of unbaited and pheromone baited funnel traps

Experiments were conducted to confirm and quantify earlier observations that unbaited funnel traps in conjunction with pheromone baited funnel traps may substantially increase trap catches of Douglas-fir beetles, Dendroctonus pseudotsugae . In 12 replicates of one of these experiments during 1998 and 1999, the catches of a single baited control trap were compared to those of a set of four traps where the central trap was baited and a ring of three traps, 1 m from the central trap arranged in a star configuration, were unbaited. In the second experiment conducted during 1999, a ring of three unbaited traps was placed at 2 m and a second at 5 m from the central baited trap. Statistically robust results demonstrated clearly that the configuration of one central baited trap plus three unbaited satellite traps collected twice as many beetles on average over the season compared to the baited control trap. Addition of a second ring of unbaited traps increased collections by only about 20%, but this experiment indicated that trap catches dropped off exponentially with distance from the centre. The number of beetles caught in the baited traps was essentially the same in all 3 arrangements, suggesting that the additional unbaited traps captured beetles that otherwise may not have been captured.     

Movement of plum curculio adults toward host trees and traps: flight versus walking

Adult plum curculios, Conotrachelus nenuphar (Herbst), were dislodged from branches of apple trees by tapping on 14 days between blossom petal fall and 3 weeks thereafter. They fell onto a small square of framed white cloth that was quickly but carefully moved to a position beneath or adjacent to the canopy of another apple tree.There, adults were observed for 50-min periods from 0800–1950 h for propensity to fly from or walk off the cloth or move to hide beneath foliage on the cloth. At each position, the mean time from observation initiation until flight, walking off or hiding did not differ significantly among these behaviors (averaging 21–30 min), but significantly more flew (31–40%) than crawled off (16–19%) or hid (18–20%). Substantial walking off but no flights occurred at air temperatures below 20 °C, whereas at temperatures of 20 °C or greater, propensity for flight was usually significantly greater than that for walking off.Flights were predominantly toward the tree canopy or inter-tree space, with only a small proportion (17% or less) toward the tree trunk or (in a parallel study) toward an unbaited black pyramid trap (mimicking a tree trunk). Walking was overwhelmingly toward the tree trunk or a black pyramid trap adjacent to the trunk. Our observations lead us to conclude that unbaited black pyramid traps next to trunks of host trees (the most attractive position) can be effective at air temperatures below 20 °C by attracting plum curculio adults that would have entered host trees by walking toward and up tree trunks.Such traps appear to be less effective at 20 °C or greater because under such conditions, adults tend to enter host trees by flight into the canopy.     

Monitoring grape berry moth (Paralobesia viteana: Lepidoptera) in commercial vineyards using a host plant based synthetic lure

For some Lepidopteran pests, such as the grape berry moth Paralobesia viteana (Clemens), poor correlation between males captured in traps baited with sex pheromone and oviposition activities of female moths has called into question the value of pheromone-based monitoring for these species. As an alternative, we compared the capture of female and male grape berry moth in panel traps baited with synthetic host volatiles with captures of males in pheromone-baited wing traps over two growing seasons in two blocks of grapes in a commercial vineyard in central New York. Lures formulated in hexane to release either 7-component or 13-component host volatile blends captured significantly more male and female grape berry moth on panel traps compared with the numbers captured on panel traps with hexane-only lures. For both sexes over both years, the same or more moths were captured in panel traps along the forest edge compared with the vineyard edge early in the season but this pattern was reversed by mid-season. Male moths captured in pheromone-baited wing traps also displayed this temporal shift in location. There was a significant positive correlation between captured males and females on panel traps although not between females captured on panel traps and males captured in pheromone-baited traps for both years suggesting pheromone traps do not accurately reflect either female or male activity. Male moths captured in pheromone traps indicated a large peak early in each season corresponding to first flight followed by lower and variable numbers that did not clearly indicate second and third flights. Panel trap data, combining males and females, indicated three distinct flights, with some overlap between the second and third flights. Peak numbers of moths captured on panel traps matched well with predictions of a temperature-based phenology model, especially in 2008. Although effective, panel traps baited with synthetic host lures were time consuming to deploy and maintain and captured relatively few moths making them impractical, in the current design, for commercial purposes.     

Spotted cutworm,Xestia c‐nigrum (L.) (Lepidoptera: Noctuidae) responses to sex pheromone and blacklight

Traps baited with the sex pheromone blend of (Z7)‐ and (Z5)‐tetradecenyl acetate captured significant numbers of male spotted cutworm moths, Xestia c‐nigrum (L.) compared to unbaited traps. Nearly no males were captured in traps baited with (Z7)‐tetradecenyl acetate, the major pheromone component. Antennae of spotted cutworm males responded to (Z7)‐, (E7)‐, (Z5)‐ and (E5)‐tetradecenyl acetate in the laboratory; however there was no response by moths in the field to the E isomers when presented in traps as major and minor components respectively of a binary blend or to the (E7) isomer as a single component. These findings clarify the makeup of a sex attractant that can be used for monitoring X. c‐nigrum on agricultural crops in Washington. However, multi‐year season‐long monitoring of spotted cutworm moths in Yakima Valley apple orchards revealed differential responses to pheromone and blacklight traps. A spring flight period showed a strong moth response to the pheromone compared to blacklight, while a later summer flight period showed a weak moth response to the pheromone relative to blacklight. At this time, we do not know which trap type might best indicate spotted cutworm abundance and risk to crops.     

Impact of trap architecture, adjacent habitats, abiotic factors, and host plant phenology on captures of plum curculio (Coleoptera: Curculionidae) adults

Pyramid traps, 2.44 m and 3.66 m in height, were compared with standard-sized pyramid traps, 1.22 m in height, to assess the impact of trap architecture on captures of adult plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), in two apple (Malus spp.) orchards and a blueberry (Vaccinium spp.) planting. The effects of adjacent habitat (organic orchard versus wooded areas), abiotic factors, and phenological stages of apple also were assessed to determine whether these variables influenced trap captures. Standard-sized pyramidal traps captured significantly more adults than larger trap variants. In the apple orchards, most adults (70-80%) were captured before petal fall with the exception of blocks adjacent to the organic orchard (25%). Significantly more adults were captured along the edge of an apple orchard (managed using an integrated pest management strategy) facing an organic apple orchard (76%) than along the edge facing wooded areas (24%). There was a significant positive correlation between daily trap captures and mean daily temperatures before petal fall in apple orchards.     

Phenology and infestation patterns of plum curculio (Coleoptera: Curculionidae) on four highbush blueberry cultivars

The plum curculio, Conotrachelus nenuphar (Herbst), is a well known pest in apple and peach orchards, but it also is capable of having an economic impact in highbush blueberries. Host phenology and plum curculio oviposition patterns were determined on four highbush blueberry cultivars differing in fruit maturation period. Numbers of oviposition scars were higher on early- ('Weymouth') and mid-season ('Duke' and 'Bluecrop') blueberries than on late-season 'Elliott' in 2001, 2002, and 2003. In 2002, eggs were first present on the three earliest cultivars 21 d before those on 'Elliott', whereas eggs were found on 'Elliott' >40 d after the last sample with eggs for the other three cultivars. The pattern of host phenology and infestation levels suggested that plum curculio oviposition synchronizes well with the availability of suitable fruit for oviposition on early and mid-season cultivars compared with a late-season cultivar of highbush blueberries. The implications of a transition to use of reduced-risk insecticides are discussed in relation to plum curculio management.     

Effectiveness of odor-baited trap trees for plum curculio (Coleoptera: Curculionidae) monitoring in commercial apple orchards in the northeast

The plum curculio, Conotrachelus nenuphar (Herbst), is a key pest of pome and stone fruit in eastern and central North America. For effective management of this insect pest in commercial apple (Malus spp.) orchards in the northeastern United States and Canada, one of the greatest challenges has been to determine the need for and timing of insecticide applications that will protect apple fruit from injury by adults. In a 2004-2005 study, we assessed the efficacy and economic viability of a reduced-risk integrated pest management strategy involving an odor-baited trap tree approach to determine need for and timing of insecticide use against plum curculio based on appearance of fresh egg-laying scars. Evaluations took place in commercial apple orchards in seven northeastern U.S. states. More specifically, we compared the trap-tree approach with three calendar-driven whole-block sprays and with heat-unit accumulation models that predict how long insecticide should be applied to orchard trees to prevent injury by plum curculio late in the season. Trap tree plots received a whole-plot insecticide spray by the time of petal fall, and succeeding sprays (if needed) were applied to peripheral-row trees only, depending on a threshold of one fresh plum curculio egg-laying scar out of 25 fruit sampled from a single trap tree. In both years, level of plum curculio injury to fruit sampled from perimeter-row, the most interior-row trees and whole-plot injury in trap tree plots did not differ significantly from that recorded in plots subject to conventional management or in plots managed using the heat-unit accumulation approach. The amount of insecticide used in trap tree plots was reduced at least by 43% compared with plots managed with the conventional approach. Advantages and potential pitfalls of the bio-based trap tree approach to plum curculio monitoring in apple orchards are discussed.     

Characterizing spring emergence of adult Halyomorpha halys using experimental overwintering shelters and commercial pheromone traps

To improve our understanding of adult Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) overwintering biology and to better inform models of its population dynamics, its temporal pattern of spring emergence was investigated using experimental overwintering shelters in screened cages within protective structures. In 2012, plastic shelters containing 100 adults were deployed in unheated, unlighted buildings, and adjacent woodlots in Virginia, USA. In 2013 and 2014, wooden shelters containing 300 paint‐marked adults were deployed in pairs in six woodlots across Virginia, West Virginia, and Maryland, USA; one in a closed cage and one in a cage with the top removed, enabling emerged adults to be counted or to disperse, respectively. In 2013 and 2014, pheromone‐baited and non‐baited pyramid traps encircled the shelters at each site. Regular counts of adults that emerged into the closed cage and of marked and ‘wild’ (unmarked) adults captured in traps were conducted from February or March through early July. In 2012, emergence patterns from shelters in buildings and woodlots were very similar and matched those recorded from woodlots in 2013 and 2014. In all years, a small peak of emergence occurred in about mid‐April, a larger and more prolonged peak was observed between mid‐May and early June, and emergence ended by early July. Of the 449 H. halys adults captured in traps between 2013 and 2014, only three were marked individuals from shelters in the open cage, suggesting that adults emerging from overwintering sites may require a dispersal flight before responding to pheromone‐baited traps. In 2013 and 2014, respectively, 98 and 93% of captures were in pheromone‐baited traps, but there was no correlation between the weekly number of adults that emerged from shelters in the closed cages and captures in traps.     

Use of residue profile analysis to identify modes of insecticide activity contributing to control of plum curculio in apples

Residue profile analysis techniques were developed, along with laboratory and field-based bioassays to describe the modes of insecticidal activity responsible for the control of the plum curculio, Conotrachelus nenuphar (Herbst), in apples (Malus spp.). Adult plum curculios were treated in laboratory topical bioassays to determine acute contact activity and lethal time for five insecticides. Azinphosmethyl had the highest levels of toxicity and shortest lethal time values, followed by the neonicotinoids thiacloprid, thiamethoxam, and imidacloprid, whereas indoxacarb had the highest LD50 and LT50 values for topical exposure. Field-based residual activity bioassays assessed adult mortality, and fruit and leaf injury from plum curculio exposed to 4 h, 7 d, and 14 d field-aged residues. All compounds caused significant levels of mortality to plum curculio when adults were exposed to fruit clusters 4 h post-application. Thiacloprid, thiamethoxam, and imidacloprid showed oviposition deterrence, antifeedant, and repellency effects in the 7- and/or 14 d residual bioassays and protected fruit in the absence of significant lethal activity. Indoxacarb maintained lethal activity throughout the study intervals, with the incidence of plum curculio feeding, suggesting that ingestion is an important mode of entry. For the neonicotinoids thiacloprid, thiamethoxam and imidacloprid plum curculio mortality was highly correlated with fruit and leaf surface residues. As surface residues declined, sublethal effects such as oviposition deterrence and antifeedant effect remained. The value of the plant-insect-chemistry triad model for describing the temporal dimensions of insecticidal modes of activity and understanding a compound's critical performance characteristics is discussed.     

Discrimination by male dogwood borer, Synanthedon scitula (Lepidoptera: Sesiidae), among traps baited with commercially available pheromone lures

The response of male dogwood borer, Synanthedon scitula (Harris) (Lepidoptera: Sesiidae), to four commercially available pheromone lures and to pheromone source concentration was evaluated in field trapping studies in commercial apple orchards in Virginia and West Virginia Male peachtree borer, Synanthedon exitiosa (Say), lesser peachtree borer, Synanthedon pictipes (Grote & Robinson), and lilac borer, Podosesia syringae (Harris), were also captured in traps baited with all lures tested. Among the lures used, the Scenturion dogwood borer lure was the most attractive to and selective for dogwood borer. Male dogwood borer showed a concentration-dependent response to traps baited with different source concentrations of the pheromone from Scenturion. Chemical analyses revealed that all lures contained principally (Z,Z)-3,13-octadecadien-1-ol acetate (ODDA) but that a significantly higher percentage of (Z,E) plus (E,Z)-3,13-ODDA was present in the Scenturion lure, compared with the others. Weekly collections of fresh male and female dogwood borer pupal exuviae from April until October in 2002 and 2003 suggested that traps baited with Scenturion lures significantly underestimated the size of populations in commercial apple orchards.     

Ionizing irradiation quarantine treatment against plum curculio (Coleoptera: Curculionidae)

Plum curculio, Conotrachelus nenuphar (Herbst), is a quarantine pest of many temperate fruits, such as pomes, Malus spp.; stone fruits, Prunus spp.; and blueberries, Vaccinium spp.; in North America east of the Rocky Mountains and a small area in Utah. There are two strains, a northern univoltine one that undergoes obligate diapause as an adult and a southern multivoltine strain that usually has facultative diapause. Current quarantine treatments for shipment to areas that do not have the pest include methyl bromide fumigation and cold storage for several weeks. The cold storage treatment may not be effective against northern strain adults in diapause. The objective of this research was to develop an irradiation quarantine treatment against plum curculio. The estimated dose to kill southern strain plum curculio adults in one day is approximately 4 kGy. Diapausing northern strain plum curculios were prevented from reproducing with 40 Gy. Reproduction of southern strain plum curculios was prevented with a target dose of 80 Gy, and the dose recommended as a quarantine treatment, that would prevent adults from reproducing, is 92 Gy, the maximum absorbed dose measured when a target dose of 80 Gy was sought. At that dose, oviposition may still occur for up to 1 wk and some of the eggs may hatch, but there is no development beyond the first instar. Hosts of the plum curculio would tolerate that dose well. Immature plum curculios were prevented from reproducing with lower doses.     

Monitoring oriental fruit moth (Lepidoptera: Tortricidae) with sticky traps baited with terpinyl acetate and sex pheromone

Studies in Argentina and Chile during 2010–2011 evaluated a new trap (Ajar) for monitoring the oriental fruit moth, Grapholita molesta (Busck). The Ajar trap was delta‐shaped with a jar filled with a terpinyl acetate plus brown sugar bait attached to the bottom centre of the trap. The screened lid of the jar was inserted inside the trap, and moths were caught on a sticky insert surrounding the lid. The Ajar trap was evaluated with and without the addition of a sex pheromone lure and compared with delta traps left unbaited or baited with a sex pheromone lure and a bucket trap filled with the same liquid bait. Studies were conducted in a sex pheromone‐treated orchard in Argentina and an untreated orchard in Chile. In Chile, the Ajar trap without the sex pheromone lure caught significantly fewer males, females and total moths than the bucket trap, and fewer males and more females than the sex pheromone‐baited delta trap. Total moth catch did not differ between the Ajar trap without a sex pheromone lure and the sex pheromone‐baited trap. Adding a sex pheromone lure to the Ajar trap significantly increased total moth catches to levels not different from those in the bucket trap. However, the Ajar trap with the sex pheromone lure caught significantly more males and fewer females than the bucket trap. In Argentina, the Ajar trap with or without the addition of a sex pheromone lure caught similar numbers of both sexes and total moths as the bucket trap. The sex pheromone‐baited delta trap caught <4% of the number of moths as these three traps. The bucket trap in both studies caught significantly more non‐targets than the delta and Ajar traps. Moth catches in the Ajar trap declined significantly after 2–3 weeks when the bait was not replaced.     

Comparison of male and female emerald ash borer (Coleoptera: Buprestidae) responses to phoebe oil and (Z)-3-hexenol lures in light green prism traps

We conducted trapping experiments for the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) in Michigan, U.S.A., and Ontario, Canada, to compare unbaited light green sticky prism traps with traps baited with phoebe oil, (Z)-3-hexenol (Z3-6:OH), or blends of other green leaf volatiles (GLVs) with Z3-6:OH. Traps were placed in the lower canopy of ash trees (Fraxinus spp.). Catches with Z3-6:OH-baited traps showed a significant male bias and these traps caught significantly more males than the unbaited controls at both sites. They were also superior to phoebe oil-baited traps and those baited with GLV blends. Catches with phoebe oil showed a significant female bias but there was no difference in the number of females captured between traps baited with phoebe oil or Z3-6:OH lures. Catches were analyzed at regular time intervals to examine the response of A. planipennis to the lures over the course of the flight season. Z3-6:OH-baited traps consistently caught more males than the controls at each interval throughout the flight season. Catches of females with Z3-6:OH and phoebe oil were significantly better than the controls early in the flight season but declined to control levels by midseason. Our results suggest that Z3-6:OH-baited green traps placed in the ash canopy would be a superior lure for detecting and monitoring A. planipennis throughout the flight season.     

Early detection and population monitoring of Ceratitis capitata (Diptera: Tephritidae) in a mixed-fruit orchard in northern Greece

Population monitoring of the Mediterranean fruit fly,Ceratitis capitata (Wiedemann), was studied in 1998 in a mixed-fruit orchard in northern Greece, using International Pheromone McPhail traps (IPMT) baited with the female targeted attractants ammonium acetate, putrescine, and trimethylamine, and Jackson traps baited with the male specific parapheromone trimedlure. Special emphasis was placed on detecting the low initial adult population resulting from surviving overwintering larvae as early as possible in the spring and early summer. Traps were suspended on various host trees, using trap grid densities of either 15 or 1.5 traps per hectare. The first adults detected were females captured on 24 June in IPMT traps suspended on apricot trees, which are among the earliest maturing hosts in the area. From the end of July, the most effective trap was the IPMT trap placed on peaches, which followed apricots in the fruit ripening sequence. IPMT traps captured predominately females (approximately 80% of the total captures) and by far outperformed Jackson traps in early detection (the first males in Jackson traps were captured in August) as well as in total captures until mid-October. After mid-October, however, more flies were captured in Jackson traps. Comparing the performance of two trap grid densities on apple trees (the common host in the two grids), we found that in the high-density trap grid the first adults were detected 1 wk earlier than in the low-density trap grid. Our findings for this locality suggest that trap type and plant species on which traps are suspended are of key importance in early detection and population monitoring of C. capitata.