Evaluating Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) Response to Methyl Eugenol: Comparison of Three Common Bioassay Methods.

Insect responses to chemical attractants are often measured using olfactory bioassays prior to testing in field experiments. The attraction of sexually mature male Bactrocera dorsalis to methyl eugenol (ME) and the loss of attraction by ME pre-fed males have been demonstrated in laboratory bioassays and field trapping studies. It has been suggested that ME nonresponsiveness can be exploited to improve the effectiveness of B. dorsalis management programs by protecting sterile males from ME-based control measures. Currently, work is underway to identify alternatives that reduce or eliminate ME response. To support the development of compounds and evaluation of their effect on B. dorsalis attraction to ME, we compared the effectiveness of three common bioassay methods that have been used to measure lure response in Bactrocera flies under controlled conditions (choice assays using Y-tube [Y], small-cage arena [SC], and rotating carousel field-cage [RC]) to determine which bioassay method is efficient and reliable. A series of bioassays comparing ME-exposed and ME-naïve wild-type and genetic sexing strain males showed that the RC and SC were effective at both observing attraction to ME and detecting a significant reduction in ME response from ME-exposed males. However, the male attraction to ME and a significant decrease in response to ME after ME feeding was not observed in our Y-tube assays. These suggest that RC and SC are preferable options to evaluate ME non-responsiveness in B. dorsalis, and that Y-tube tests are difficult to administer correctly.

Inter- and Intrasexual Interactions in Anoplophora glabripennis (Coleoptera: Cerambycidae) and the Impact of Different Sex Ratios.

The behaviors of Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) during inter- and intrasexual interactions between both solitary and paired individuals at different sex ratios were observed on Acer platanoides L. (Sapindales: Sapindaceae) branches in the laboratory. Intrasexual contact was generally ignored by females, but between males resulted in battles from which one male ultimately retreated. When male size differed, larger males won battles, whereas equally sized males split the wins and battled longer. When males initiated intersexual contact, they quickly found and mounted the female. The female apparently determined if and how long the male could copulate with her by controlling access to her genital opening and males would eventually dismount if the female remained unreceptive. After successful copulation, males ignored female intruders and fought off male challengers, generally without dismounting. Some males dismounted females without attempting to copulate. Individual age and size were not predictive of either female or male choice in a mate. Mating duration was affected by both female receptivity and sex ratios present. Male interruptions of the pair shortened time in copula. Male-skewed sex ratios (1F:2M) significantly shortened the time a male would stay with an unreceptive female. Female-skewed sex ratios (2F:1M) did not impact mating duration. Probability of dispersal both from and within the branch was greater for smaller individuals of both sexes and for males when sex ratios were male-skewed. This information demonstrates how reproductive activity might be impacted as population densities decline during efforts at eradication of this species in North America.

Reproductive Behaviors of Anoplophora glabripennis (Coleoptera: Cerambycidae) in the Laboratory.

The reproductive behaviors of individual pairs of Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae)-all combinations of three populations and three different ages-were observed in glass jars in the laboratory on Acer saccharum Marshall (Sapindales: Sapindaceae) host material. The virgin female occasionally made first contact, but mounting did not occur until the male antennated or palpated the female. If the female was receptive (older females initially less receptive than younger ones), the male mated with her immediately after mounting and initiated a prolonged pair-bond. When the female was not receptive, some males abandoned the attempt while most performed a short antennal wagging behavior. During the pair-bond, the male continuously grasped the female's elytral margins with his prothoracic tarsi or both pro- and mesothoracic tarsi. The male copulated in a series of three to four bouts (averaging three to five copulations each) during which the female chewed oviposition sites or walked on the host. Between bouts, the female oviposited and fertile eggs were deposited as soon as 43 min after the first copulation. Females became unreceptive again after copulation and the duration of the pair-bond depended on the male's ability to remain mounted. Some population differences were seen which may be climatic adaptations. A single pair-bond was sufficient for the female to achieve ~60% fertility for her lifetime, but female fecundity declined with age at mating. Under eradication conditions, mates will become more difficult to find and females that find mates will likely produce fewer progeny because they will be older at the time of mating.

Inheritance and World Variation in Thermal Requirements for Egg Hatch in Lymantria dispar (Lepidoptera: Erebidae).

Mode of inheritance of hatch traits in Lymantria dispar L. was determined by crossing populations nearly fixed for the phenotypic extremes. The nondiapausing phenotype was inherited via a single recessive gene and the phenotype with reduced low temperature exposure requirements before hatch was inherited via a single dominant gene. There was no evidence for sex-linkage or cytoplasmic effects with either gene. Eggs from 43 geographic populations were evaluated for hatch characteristics after being held for 60 d at 5°C followed by incubation at 25°C. There was considerable variation both within and among the populations in the proportion able to hatch, time to first hatch, and average time to hatch. Egg masses with reduced requirement for low temperatures before the eggs were ready to hatch were present in all subspecies of L. dispar and the phenotype was not fixed in most populations. The populations clustered into three distinct groups, and climatic variables were found to be rough predictors of those groups. Variation in hatch phenotypes between populations is likely an adaptation to local climate and within a population provides a bet-hedging strategy to ensure that at least some hatch synchronizes with host leaf-out. Continued vigilance to prevent movement of populations both within and between countries is warranted, because some of the alleles that confer nondiapause or reduced low temperature requirements before egg hatch are not present in all populations and their introduction would increase variation in egg hatch within a population.

Effects of pheromone and plant volatile release rates and ratios on trapping Anoplophora glabripennis (Coleoptera: Cerambycidae) in China.

Native to China and Korea, the Asian longhorned beetle, Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), is a polyphagous wood-boring pest for which a trapping system would greatly benefit eradication and management programs in both the introduced and native ranges. Over two field seasons, a total of 160 flight intercept panel traps were deployed in Harbin, China, which trapped a total of 65 beetles. In 2012, traps using lures with a 1:1 ratio of the male-produced pheromone components (4-(n-heptyloxy)butanal and 4-(n-heptyloxy)butan-1-ol) designed to release at a rate of 1 or 4 milligram per day per component in conjunction with the plant volatiles (-)-linalool, trans-caryophyllene, and (Z)-3-hexen-1-ol caught significantly more A. glabripennis females than other pheromone release rates, other pheromone ratios, plant volatiles only, and no lure controls. Males were caught primarily in traps baited with plant volatiles only. In 2013, 10× higher release rates of these plant volatiles were tested, and linalool oxide was evaluated as a fourth plant volatile in combination with a 1:1 ratio of the male-produced pheromone components emitted at a rate of 2 milligram per day per component. Significantly more females were trapped using the pheromone with the 10-fold higher three or four plant volatile release rates compared with the plant volatiles only, low four plant volatile + pheromone, and control. Our findings show that the male-produced pheromone in combination with plant volatiles can be used to detect A. glabripennis. Results also indicate that emitters should be monitored during the field season, as release rates fluctuate with environmental conditions and can be strongly influenced by formulation additives.

Development and evaluation of a trapping system for Anoplophora glabripennis (Coleoptera: Cerambycidae) in the United States.

Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), commonly known as the Asian longhorned beetle, is an invasive wood-boring pest that infests a number of hardwood species and causes considerable economic losses in North America, several countries in Europe, and in its native range in Asia. The success of eradication efforts may depend on early detection of introduced populations; however, detection has been limited to identification of tree damage (oviposition pits and exit holes), and the serendipitous collection of adults, often by members of the public. Here we describe the development, deployment, and evaluation of semiochemical-baited traps in the greater Worcester area in Massachusetts. Over 4 yr of trap evaluation (2009-2012), 1013 intercept panel traps were deployed, 876 of which were baited with three different families of lures. The families included lures exhibiting different rates of release of the male-produced A. glabripennis pheromone, lures with various combinations of plant volatiles, and lures with both the pheromone and plant volatiles combined. Overall, 45 individual beetles were captured in 40 different traps. Beetles were found only in traps with lures. In several cases, trap catches led to the more rapid discovery and management of previously unknown areas of infestation in the Worcester county regulated area. Analysis of the spatial distribution of traps and the known infested trees within the regulated area provides an estimate of the relationship between trap catch and beetle pressure exerted on the traps. Studies continue to optimize lure composition and trap placement.

Development of the teneral adult Anoplophora glabripennis (Coleoptera: Cerambycidae): time to initiate and completely bore out of maple wood.

Anoplophora glabripennis (Motschulsky) is an introduced invasive pest with the potential to devastate hardwood forests in North America. Using artificial pupal chambers, we documented the time required by teneral adults at three temperatures (20, 25, and 30 °C), 60-80% RH, and a photoperiod of 16:8 (L:D) h to initiate boring after eclosion and subsequently bore completely through a 7-mm (range, 3-11 mm) layer of Norway maple wood (Acer platanoides L.). In total, 218 laboratory-reared pupae from the Chicago, IL, or Inner Mongolia, China, populations were used in the study. Females (1.54 ± 0.03 g) weighed significantly more than males (1.12 ± 0.03 g), but the average weights of the beetles emerging in each temperature did not differ. Adult weight was positively correlated with exit hole diameter (diameter [mm] = 2.2 * weight [g] + 7.9). The rate at which beetles bored through the wood (136, 178, and 168 mm(3)/d at 20, 25 and 30 °C, respectively) significantly differed between temperatures but did not differ with beetle weight. Temperature had a significant effect on the time it took adults to initiate boring (7, 5, and 4 d at 20, 25, and 30 °C, respectively) and subsequently to complete boring to emerge (5, 4, and 4 d at 20, 25, and 30 °C, respectively). This suggests that beetles require more than a week to progress from eclosion to emergence in wood, even at summer temperatures. This information on A. glabripennis basic biology is critical for developing phenology models that are used to time exclusion and eradication methodologies.

Evaluating the use of male-produced pheromone components and plant volatiles in two trap designs to monitor Anoplophora glabripennis.

Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), commonly known as the Asian longhorned beetle, is a wood-boring invasive species introduced from Asia to North America and Europe in solid wood packing material. Efficient monitoring traps are needed to assess population density and dispersal in the field and to detect new introductions at ports of entry. For this purpose, we conducted field trapping experiments in China in the summers of 2007 and 2008. In 2007, we tested Intercept panel traps hung on poplar trees. In 2008, we used Intercept panel traps hung on poplar trees, screen sleeve traps wrapped around poplar trunks, and Intercept panel traps hung on bamboo poles 20 m away from host trees. Traps were baited with A. glabripennis male-produced pheromone alone or in different combinations with plant volatiles. Traps baited with the male-produced pheromone alone caught significantly more females than control traps in both years. The addition of a mixture of (-)-linalool, (Z)-3-hexen-1-ol, linalool oxide, trans-caryophyllene, and trans-pinocarveol to the pheromone significantly increased trap catches of females, 85% of which were virgin. Screen sleeve traps baited with a combination of (-)-linalool and the pheromone caught the highest number of beetles overall in 2008, whereas traps placed on bamboo polls caught the lowest number. Although the logistics for the most effective implementation of a trapping program using a mixture of the pheromone and plant volatiles require additional studies, these results indicate that this pheromone has considerable promise as a monitoring tool for A. glabripennis in the field.

Effects of temperature on Anoplophora glabripennis (Coleoptera: Cerambycidae) larvae and pupae.

Developmental thresholds, degree-days for development, larval weights, and head capsule widths for each larval instar and the pupal stage of Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) were studied at eight constant temperatures (5, 10, 15, 20, 25, 30, 35, and 40°C) for two source populations (Ravenswood, Chicago, IL [IL], and Bayside, Queens, NY [NY]). The estimated lower threshold temperature for development of instars 1-5 and the pupal stage was near 10°C and was near 12°C for the higher instars. Developmental rate was less temperature sensitive for instars 5-9 compared with instars 1-4. Development for all but the first instar was inhibited at constant temperatures >30°C, and all instars failed to develop at 40°C. Although the two source populations had similar responses to temperature, IL larvae were heavier than those from NY. Temperature and its influence on larval weight had profound impacts on whether a larva proceeded to pupation. Based on the temperature effects detailed here, larval development and pupation should be possible in most of the continental United States where suitable hosts are available. These data can be used to develop a degree-day model to estimate beetle phenology; however, at least 2°C should be added to air temperatures to adjust for the mediation of temperature by the wood. These data provide a basis for predicting the potential geographical range of this species and for developing phenological models to predict the timing of immature stages, both of which are important for management programs.

Attraction of Anoplophora glabripennis to male-produced pheromone and plant volatiles.

The male-produced pheromone of Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), which is an equal blend of 4-(n-heptyloxy)butan-1-ol and 4-(n-heptyloxy)butanal, was used in laboratory bioassays and in the greenhouse to determine its potential for attracting A. glabripennis adults. In modified "walking wind tunnels," virgin females were most attracted to the alcohol component, and virgin males were repelled by the pheromone blend at the lowest and highest amounts offered. Y-tube olfactometer bioassays also showed that females were significantly more attracted to the pheromone and its components than males were. However, males were more attracted to plant volatiles than females. Of 12 plant volatiles tested, delta-3-carene and (E)-caryophyllene were highly attractive to males, whereas (Z)-3-hexenyl acetate was repellent to males. Combining the male pheromone blend with (-)-linalool alone or with (Z)-3-hexen-1-ol attracted significantly more males than did the pheromone alone. We tested four trap designs in our quarantine greenhouse with eight different lures. The Intercept Panel traps and the hand-made screen sleeve traps caught more beetles than the Plum Curculio traps and Lindgren funnel traps. Intercept traps worked best when baited with male blend and (Z)-3-hexen-1-ol, whereas screen sleeve traps were most attractive when baited with (-)-linalool. Our findings provide evidence of the attractiveness of the A. glabripennis male-produced pheromone and suggest that it has a role in mate-finding. It is also a first step toward the development of an efficient trap design and lure combination to monitor A. glabripennis infestations in the field.

World distribution of female flight and genetic variation in Lymantria dispar (Lepidoptera: Lymantriidae).

Female gypsy moths, Lymantria dispar L., from 46 geographic strains were evaluated for flight capability and related traits. Males from 31 of the same strains were evaluated for genetic diversity using two polymorphic cytochrome oxidase I mitochondrial DNA restriction sites, the nuclear FS1 marker, and four microsatellite loci. Females capable of strong directed flight were found in strains that originated from Asia, Siberia, and the northeastern parts of Europe, but flight capability was not fixed in most strains. No flight-capable females were found in strains from the United States or southern and western Europe. Wing size and musculature were shown to correlate with flight capability and potentially could be used in predicting female flight capability. The mtDNA haplotypes broadly separated the gypsy moth strains into three groups: North American, European/Siberian, and Asian. Specific microsatellite or FS1 alleles were only fixed in a few strains, and there was a gradual increase in the frequency of alleles dominant in Asia at both the nuclear and microsatellite loci moving geographically from west to east. When all the genetic marker information was used, 94% of the individuals were accurately assigned to their broad geographic group of origin (North American, European, Siberian, and Asian), but female flight capability could not be predicted accurately. This suggests that gene flow or barriers to it are important in determining the current distribution of flight-capable females and shows the need for added markers when trying to predict female flight capability in introduced populations, especially when a European origin is suspected.

Inheritance of female flight in Lymantria dispar (Lepidoptera: Lymantriidae).

A clinal female flight polymorphism exists in the gypsy moth, Lymantria dispar L., where female flight diminishes from east to west across Eurasia. A Russian population where females are capable of sustained ascending flight and a North American population with females incapable of flight were crossed: parentals, reciprocal F(1) hybrids, double reciprocal F(2) hybrids, and all possible backcrosses to both the parental lines were compared. Heritabilities were estimated using a threshold model, female offspring on female parent regressions, and joint-scaling analyses. Heritability of female flight capability measured using a free flight test was at least 0.60, and variation in wing size, muscle strength, and flight behaviors contributed to the flight polymorphism. Relative wing size varied continuously and had a heritability of 0.70. Environmental variation accounted for >90% of the variation in female preflight weight and relative flight muscle strength, as estimated by an inverted female's ability to right herself. Preflight walking behavior and early deposition of eggs were each inherited through a single gene with two co-dominant alleles. There was no evidence for sex-linkage or maternal effects in female flight capability or associated traits. Continued vigilance to exclude and eradicate introductions of strains capable of female flight in North America is warranted even in areas where no females fly, because some of the alleles needed for full flight capability may not be present in the North American populations, and some flight capability is maintained in the hybrids that could increase the rate of spread of L. dispar.

Assessment of the risk of introduction of Anoplophora glabripennis (Coleoptera: Cerambycidae) in municipal solid waste from the quarantine area of New York City to landfills outside of the quarantine area: a pathway analysis of the risk of spread and establishment.

The risk associated with spread of Asian longhorned beetle, Anoplophora glabripennis (Motschulsky), from infested areas in New York City to the wide array of landfills across the eastern United States contracted by the city since 1997 was unknown, but of great concern. Landfills, some as far as South Carolina, Virginia, and Ohio, occupied forest types and climates at high risk of Asian longhorned beetle establishment. The city proposed a separate waste wood collection known as the "311 System;" this was estimated to cost federal and state agencies $6.1 to $9.1 million per year, including the cost of processing and disposal of the wood. Pathway analysis was used to quantify the probability that Asian longhorned beetle present in wood waste collected at curbside would survive transport, compaction, and burial to form a mated pair. The study found that in seven alternate management scenarios, risks with most pathways are very low, especially given existing mitigations. Mitigations included chemical control, removal of infested trees, and burial of wood waste in managed landfills that involved multiple-layering, compaction, and capping of dumped waste with a 15-cm soil cover at the end of each day. Although the risk of business-as-usual collection and disposal practices was virtually nil, any changes of policy or practice such as illegal dumping or disposal at a single landfill increased the risk many thousandfold. By rigorously maintaining and monitoring existing mitigations, it was estimated that taxpayers would save $75 to $122 million dollars over the next decade.

Survival and development of Lymantria monacha (Lepidoptera: Lymantriidae) on North American and introduced Eurasian tree species.

Lymantria monacha (L.) (Lepidoptera: Lymantriidae), the nun moth, is a Eurasian pest of conifers that has potential for accidental introduction into North America. To project the potential host range of this insect if introduced into North America, survival and development of L. monacha on 26 North American and eight introduced Eurasian tree species were examined. Seven conifer species (Abies concolor, Picea abies, P. glauca, P. pungens, Pinus sylvestris with male cones, P. menziesii variety glance, and Tsuga canadensis) and six broadleaf species (Betula populifolia, Malus x domestica, Prunus serotiaa, Quercus lobata, Q. rubra, and Q. velutina) were suitable for L. monacha survival and development. Eleven of the host species tested were rated as intermediate in suitability, four conifer species (Larix occidentalis, P. nigra, P. ponderosa, P. strobus, and Pseudotsuga menziesii variety menziesii) and six broadleaf species (Carpinus caroliniana, Carya ovata, Fagus grandifolia, Populus grandidentata, Q. alba, and Tilia cordata) and the remaining 10 species tested were rated as poor (Acer rubrum, A. platanoidies, A. saccharum, F. americana, Juniperus virginiana, Larix kaempferi, Liriodendron tulipfera, Morus alba, P. taeda, and P. deltoides). The phenological state of the trees had a major impact on establishment, survival, and development of L. monacha on many of the tree species tested. Several of the deciduous tree species that are suitable for L. monacha also are suitable for L. dispar (L.) and L. mathura Moore. Establishment of L. monacha in North America would be catastrophic because of the large number of economically important tree species on which it can survive and develop, and the ability of mated females to fly and colonize new areas.