James D. Barbour

Treating Panel Traps with a Fluoropolymer Enhances their Efficiency in Capturing Cerambycid Beetles

ABSTRACT The most effective traps for capturing cerambycids and other saproxylic beetles are intercept designs such as funnel traps and cross-vane panel traps. We have observed that adult cerambycids of many species often alight and walk upon panel traps, and few are actually captured. In an effort to improve trap capture and retention, researchers have treated intercept traps with Rain-X, a polysiloxane formulation that renders surfaces more slippery. Here, we summarize experiments that compared the efficacies of Rain-X and Fluon, a PTFE fluoropolymer dispersion, as surface treatments for panel traps that are deployed to capture cerambycid beetles, using untreated traps as controls. Fluon-treated traps captured on average >14× the total number of beetles, and many more cerambycid species, than were captured by Rain-X-treated or control traps. Beetles captured by Fluon-treated traps ranged in body length by 350%. They could not walk on vertical panels treated with Fluon but easily walked on those treated with Rain-X and on untreated traps. Moreover, a single Fluon treatment remained effective for the entire field season, even in inclement weather. We conclude that treating panel traps with Fluon greatly improves their efficiency in capturing cerambycid beetles. This increased efficacy will be particularly important when traps are deployed to detect very low-density populations, such as incursions of exotic species, or remnant communities of rare and endangered species. The influence of Fluon on trap efficiency may vary with product formulation and its source and also with climatic conditions.

Using Generic Pheromone Lures to Expedite Identification of Aggregation Pheromones for the Cerambycid Beetles Xylotrechus nauticus, Phymatodes lecontei, and Neoclytus modestus modestus

Males of several species of longhorned beetles in the subfamily Cerambycinae produce sex or aggregation pheromones consisting of 2,3-hexanediols and/or hydroxyhexanones. We tested the hypothesis that this diol/hydroxyketone pheromone motif is highly conserved within the subfamily, and the resulting prediction that multiple cerambycine species will be attracted to compounds of this type. We also tested the concept that live traps baited with generic blends of these compounds could be used as a source of live insects from which pheromones could be collected and identified. Traps placed in a mature oak woodland and baited with generic blends of racemic 2-hydroxyhexan-3-one and 3-hydroxyhexan-2-one captured adults of both sexes of three cerambycine species: Xylotrechus nauticus (Mannerheim), Phymatodes lecontei Linsley, and Phymatodes decussatus decussatus (LeConte). Odors collected from male X. nauticus contained a 9:1 ratio of two male-specific compounds, (R)- and (S)-3-hydroxyhexan-2-one. Field trials with synthetic compounds determined that traps baited with (R)-3-hydroxyhexan-2-one (94% ee), alone or in blends with other isomers, attracted similar numbers of X. nauticus of both sexes, whereas (S)-3-hydroxyhexan-2-one (94% ee) attracted significantly fewer beetles. Phymatodes lecontei and P. d. decussatus also were caught in traps baited with hydroxyhexanones, as well as a few specimens of two other cerambycine species, Neoclytus modestus modestus Fall (both sexes) and Brothylus gemmulatus LeConte (only females). Male N. m. modestus produced (R)-3-hydroxyhexan-2-one, which was not present in extracts from females. Neoclytus m. modestus of both sexes also responded to lures that included (R)-3-hydroxyhexan-2-one as one of the components. The only male-specific compound found in extracts from P. lecontei was (R)-2-methylbutan-1-ol, and adults of both sexes were attracted to racemic 2-methylbutan-1-ol in field bioassays. Surprisingly, P. lecontei of both sexes also were attracted to (R)- and (S)-3-hydroxyhexan-2-ones, although neither compound was detected in extracts from this species. Males of all five beetle species had gland pores on their prothoraces that were similar in structure to those that have been associated with volatile pheromone production in other cerambycine species. The attraction of multiple cerambycine species of two tribes to (R)-3-hydroxyhexan-2-one in this study, and in earlier studies with other cerambycine species, suggests that this compound is a widespread aggregation pheromone component in this large and diverse subfamily. Overall, the attraction of multiple species from different cerambycine tribes to this compound at a single field site supports the hypothesis that the hydroxyketone pheromone structural motif is highly conserved within this subfamily.

Male-Produced Aggregation Pheromone of the Cerambycid Beetle Rosalia funebris

We report the identification, synthesis, and field bioassays of a volatile, male-produced aggregation pheromone of a long-horned beetle, the banded alder borer, Rosalia funebris Mots. Headspace collections from males contained a major male-specific compound, (Z)-3-decenyl (E)-2-hexenoate, and several minor components, identified as (Z)-3-decenol, (Z)-3-nonenyl (E)-2-hexenoate, and (Z)-3-decenyl (E)-3-hexenoate. The antennae of both males and females responded strongly to (Z)-3-decenyl (E)-2-hexenoate. We collected significant numbers of adult R. funebris in field bioassays using traps baited with this compound. This pheromone structure is unprecedented in the literature of cerambycid pheromones and distinct from the more common diol/hydroxyketone pheromone motif of many other species of the diverse subfamily Cerambycinae. This is the first pheromone identified for a species in the tribe Rosaliini.

Identification and synthesis of a female-produced sex pheromone for the cerambycid beetle Prionus californicus.

Females of the large cerambycid beetle Prionus californicus produce a powerful sex pheromone that attracts males. The pheromone was adsorbed on solid phase microextraction (SPME) fibers inserted into the ovipositor sheath and analyzed by coupled gas chromatography-electroantennogram detection and GC-mass spectrometry. The pheromone was identified as an isomer of 3,5-dimethyldodecanoic acid by a combination of retention index comparisons and mass spectral interpretation. The mass spectrum was misleading because it exhibited enlarged fragment ions that were not representative of branch points or other obvious stabilizing structural elements. The structure was verified by synthesis of 3,5-dimethyldodecanoic acid as a mixture of all four possible isomers, and this mixture was highly attractive to male beetles in field bioassays. The SPME extracts also contained several other compounds that were tentatively identified as chain-extended homologs of the main pheromone component. This pheromone should prove useful for sampling and management of the beetle, which is an important pest of hops, and an occasional pest in a variety of orchard crops. Although this is the first female-produced pheromone to be identified from the Cerambycidae, there is considerable evidence for pheromone production by females of other species in the subfamily Prioninae. Thus, this pheromone and the associated methodology used in its identification should be useful in the identification of female-produced attractant pheromones from other members of the subfamily.

Synthetic 3,5-Dimethyldodecanoic Acid Serves as a General Attractant for Multiple Species of Prionus (Coleoptera: Cerambycidae)

ABSTRACT Males of the longhorned beetle Prionus californicus Motschulsky (Coleoptera: Cerambycidae) are significantly attracted to the female-produced sex pheromone (3R,5S)-3,5-dimethyldodecanoic acid. Males respond equally well to the synthetic blend of the four stereoisomers of 3,5-dimethyldodecanoic acid as to the single natural enantiomer, suggesting that the unnatural isomers are not inhibitory. Males of the congener Prionus lecontei Lameere also are attracted to the (3R,5S)-enantiomer but not to the (3S,5R)-enantiomer, suggesting that the (3R,5S)-enantiomer is also an important pheromone component of that species. Here, we report the results of field trials that test the hypothesis that synthetic 3,5-dimethyldodecanoic acid will serve as a general attractant for males of other Prionus species. We conducted field bioassays of synthetic 3,5-dimethyldodecanoic acid at study sites in six different regions of North America and one site in the United Kingdom. Traps baited with the synthetic pheromone blend captured males of P. californicus (southwestern Idaho, southern California, and northwestern Utah), P. lecontei (southern California and northwestern Utah), and six additional species of Prionus: Prionus integer LeConte (southwestern Idaho), Prionus imbricornis (L.) (Georgia), Prionus laticollis (Drury) (Georgia), Prionus linsleyi Hovore (north central Arizona), Prionus aztecus Casey (northern Mexico), and Prionus coriarius (L.) (East Anglia, United Kingdom). These findings demonstrate that synthetic 3,5-dimethyldodecanoic acid can be used to assess the geographic distribution and local abundance of many Prionus species and therefore may be of value for monitoring threatened and endangered species of this genus, and for managing those that are pests.

Field evaluation of insect resistance in a wild tomato and its effects on insect parasitoids

Populations of Helicoverpa (= Heliothis) zea (Boddie), Heliothis virescens (F.), Manduca sexta (L.) and M. quinquemaculata (Haw.) and their egg and larval parasitoids were sampled in field plots of the: insect‐resistant wild tomato, Lycopersicon hirsutum f. glabratum C. H. Mull, accession PI 134417; susceptible commercial tomato cultivar ‘Better Boy’ F1 hybrid; and selected, moderately resistant backcross genotype. Densities of H. zea and H. virescens eggs and small larvae were higher on resistant genotypes than on susceptible genotypes, but densities of large larvae were similar on all genotypes. Densities of Manduca spp. larvae were too low to permit similar analyses of the effects of plant genotype. Rates of egg parasitism by Trichogramma spp. and Telenomus sphingis (Ashmead) were reduced on insect‐resistant genotypes. Rates of parasitism by the larval parasitoids Campoletis sonorensis (Cameron) and Cotesia congregata (Say) were reduced on resistant genotypes. No consistent effects on parasitism rates by Cotesia marginiventris (Cresson) were observed and parasitism rates by Cardiochiles nigriceps Viereck were unaffected.

Interaction of fertilizer regime with host-plant resistance in tomato

The effect of fertilizer regime on trichome‐ and lamellar‐based resistance in the wild tomato species, Lycopersicon hirsutum f. glabratum C. H. Mull accession PI 134417, to three insect pests of tomato, the tobacco hornworm, Manduca sexta (L.), the Colorado potato beetle, Leptinotarsa decemlineata (Say), and the tomato fruitworm, Heliocoverpa zea (Boddie), was examined. Increasing the rate at which NPK fertilizer was applied, from 1.8 to 19.6 g/plant/week, reduced the trichome‐based resistance of PI 134417 to M. sexta and L. decemlineata by lowering both the density of type VI (sensu Luckwill, 1943) glandular trichomes and the amount of 2‐tridecanone contained in the tips of these trichomes. 2‐Tridecanone is a toxic methyl‐ketone responsible for glandular trichome‐mediated resistance in PI 134417 to M. sexta and L. decemlineata. A similar increase in the application rate of NPK fertilizer reduced the lamellar‐based resistance of PI 134417 to L. decemlineata and H. zea. The meachanisms for this reduction of resistance are unknown, but may be related to improved nutritional quality of hosts at higher fertilizer regimes.

Interaction of Manduca sexta resistance in tomato with insect predators of Helicoverpa zea

Resistance in accession PI 134417 of Lycopersicon hirsutum f. glabratum to Manduca sexta L. results from the presence of the methyl ketones 2‐tridecanone and 2‐undecanone in the type VI trichome glands on foliage of these plants. Short (24 h) and long term (neonate to adult) laboratory experiments using M. sexta‐resistant and susceptible foliage and methyl ketone treated filter paper disks were conducted to evaluate the direct (plant‐mediated) and indirect (prey‐mediated) effects of this resistance on two predators of Helicoverpa zea eggs, Coleomegilla maculata (DeGeer) and Geocoris punctipes (Say). Direct effects of resistance were manifest as reduced egg consumption and increased mortality for both predators. Indirect effects were manifest as reduced egg consumption by G. punctipes, but were not observed for C. maculata. Results of experiments using methyl ketone‐treated filter paper disks instead of foliage were similar.

Role of steroidal glycoalkaloid α-tomatine in host-plant resistance of tomato to colorado potato beetle

The role of the steroidal glycoalkaloid α-tomatine in the hostplant resistance of tomato to the Colorado potato beetle,Leptinotarsa decemlineata (Say) was examined in short- (24 hr; using first- and fourth-instar larvae) and long-term (first-instar larvae reared through the prepupal stage) feeding experiments. Consumption rate, growth rate, efficiency of conversion of ingested food to body mass, and survival were compared forL. decemlineata provided foliage from susceptible (Lycopersicon esculetum Mill. cv. Walter), resistant (L. hirsutum f.Glabratum C.H. Mull accession PI 134417), and F1 hybrid plants. Values obtained for dietetic indices were regressed against corresponding values for α-tomatine content of foliage provided to larvae. Differences in dietetic indices could not be attributed to variation in foliar α-tomatine content despite a long-standing literature showing theex planta α-tomatine inhibits feeding and growth byL. decemlineata.

Effects of the insect growth regulator, novaluron on immature alfalfa leafcutting bees, Megachile rotundata

Abstract Alfalfa leafcutting bees, Megachile rotundata F. (Hymenoptera: Megachilidae), are the most common pollinators of alfalfa in the Pacific Northwest. Reports from users of M. rotundata in Idaho, Utah and Colorado have indicated exceptionally poor bee return from fields treated with novaluron to control Lygus spp. Our goal was to evaluate novaluron toxicity to immature M. rotundata using two different possible mechanisms of exposure. One goal was to assess immature mortality via treating nectar-pollen provisions and adults with novaluron. Immature M. rotundata mortality in all novaluron provision dosing treatments was significantly higher than the water or blank controls, providing evidence that novaluron is toxic to progeny in nest cells. The mean cumulative frequency showed that more eggs and 1st–2nd instars died compared to older instars. Female M. rotundata nested similarly in field cages during the field cage experiment; however, there was greater immature mortality in cages where females were fed sugar-water + novaluron compared to sugar-water only. Although females provided adequate provisions, there was a low percentage of egg hatch and larval development when females ingested novaluron before mating and nesting. Novaluron was also present in egg provision of bees collecting resources from novaluron-sprayed plants. At least 84% of progeny died when the females were allowed to mate and nest 24 hours after a novaluron application. Novaluron could be contributing to poor bee return in alfalfa grown for seed. Timely insecticide applications to suppress Lygus spp. is an important consideration to improve ongoing bee health.