Exploring the Nature of Arhopalus ferus (Coleoptera: Cerambycidae: Spondylidinae) Pheromone Attraction.

Cerambycid species of the Spondylidinae subfamily are distributed worldwide and are known for being prolific invaders that infest conifers. In New Zealand, Arhopalus ferus (Mulsant), the burnt pine longhorn beetle, is well-established and requires monitoring at high-risk sites such as ports, airports, and sawmills as part of the requirements to meet pine log export standards set by the New Zealand Ministry of Primary Industries (MPI). Currently, its surveillance relies on traps baited with host volatiles (i.e., ethanol and α-pinene). We used volatile collections from adult beetles, electroantennograms, and field trapping bioassays to identify the pheromones emitted by the burnt pine longhorn beetle A. ferus and their effects on its behaviour. We show that A. ferus males emit mainly (E)-fuscumol and geranylacetone, as well as the minor components, α-terpinene and p-mentha-1,3,8-triene, and that all four compounds elicit a dose-dependent response in antennae of both sexes. Traps baited with the binary combination of geranylacetone plus fuscumol captured significantly more female A. ferus than did unbaited traps in two of three field experiments. α-Terpinene did not affect A. ferus trap catches and effects of p-mentha-1,3,8-triene on trap catch were not determined. Our findings provide further evidence of the use of fuscumol and geranylacetone as aggregation-sex pheromones by longhorn beetles in the Spondylidinae subfamily, and suggest that their deployment in survey traps may improve the efficacy of A. ferus monitoring in New Zealand and elsewhere.

Identification of herbivore-induced plant volatiles from selected Rubus species fed upon by raspberry bud moth (Heterocrossa rubophaga) larvae.

Heterocrossa rubophaga (raspberry bud moth) feed on a range of Rubus species, including commercial berryfruit crops where they are a pest. This study aimed to characterize the responses of native and non-native Rubus species to feeding by raspberry bud moth larvae. In a laboratory environment, in situ headspace volatiles of three Rubus species were collected from healthy plants and those fed upon by raspberry bud moth. Rubus cissoides (bush lawyer), the native host of raspberry bud moth, gave a limited response to larval feeding with green leaf volatiles (GLVs) representing the only new headspace constituents of the infested plants. The non-native hosts, Rubus ursinus var. loganobaccus cv Boysenberry (Boysenberry), and Rubus fruticosus (blackberry), gave strong responses to raspberry bud moth herbivory, releasing a number of unique nitrogenous compounds in conjunction with the GLVs. The nitrogenous compounds were identified as 2-methylbutanenitrile, (Z)- and (E)- 2-methylbutanal O-methyloxime, benzyl nitrile, (Z)- and (E)- phenylacetaldehyde O-methyloxime and indole. The four methyloximes and 2-methylbutanenitrile were confirmed by synthesis. Field collected phenology data showed that raspberry bud moth were active year round on both bush lawyer and blackberry.

Synthesis and Electrophysiological Testing of Carbonyl Pheromone Analogues for Carposinid Moths.

Sex pheromone analogues were synthesized and tested on two pest carposinid moth species: the guava moth, Coscinoptycha improbana, and the raspberry bud moth, Heterocrossa rubophaga. The pheromone analogues used for the electroantennogram testing included (Z)-11-methylenenonadec-7-ene, (Z)-nonadec-12-en-9-amine, (Z)-11-methoxynonadec-7-ene, (Z)-1-(octylsulfinyl)-dec-3-ene, and (Z)-nonadec-12-en-9-ol. An imine analogue, N-((Z)-nonadec-12-en-9-ylidene)cyclopropanamine, was also synthesized but was too unstable for testing with the moths. None of the analogue compounds elicited significant responses from the male moth antennae.

Synthesis and Biological Testing of Ester Pheromone Analogues for Two Fruitworm Moths (Carposinidae).

A range of ester pheromone analogues for carposinid moths were synthesized and evaluated for biological activity. The analogues aimed to take advantage of the structural commonality of (7Z)-alken-11-ones found in this family. Analogues were tested on two pest species: Heterocrossa rubophaga and Coscinoptycha improbana. Two of the analogues, (2Z)-nonenyl nonanoate and (4Z)-heptyl undecenoate, elicited significant electroantennogram responses. Only (4Z)-heptyl undecenoate gave consistent responses with both moth species in single sensillum recording. Field trapping trials were conducted with these two analogues both individually and in combination with the pheromone of each of the two moth species. No attraction was observed to either of the analogues alone, by either moth species. However, when (4Z)-heptyl undecenoate was coupled with the pheromone, it produced a strong inhibitory effect in H. rubophaga, reducing male moth trap catch by over 95%. No inhibitory effect on male moth trap catch was observed in C. improbana.

(7Z)-Tricosene Improves Pheromone Trap Catch of Raspberry Bud Moth, Heterocrossa rubophaga.

Heterocrossa rubophaga, the raspberry bud moth, is a pest of commercial Rubus berry crops and wild Rubus species. Its pheromone was initially identified as a single component, (7Z)-nonadecen-11-one. Here we report further investigation of this carposinid pheromone including volatile collection, gland extraction, mass spectrometry, microchemical analysis, electrophysiology and field testing. The alkene (7Z)-tricosene was identified from female gland extracts and the synthetic compound gave antennal responses from the male moth. Field testing of (7Z)-tricosene showed that it was unattractive alone but in combination with (7Z)-nonadecen-11-one it more than doubled male moth trap catch for all doses tested compared to that of (7Z)-nonadecen-11-one alone. We recommend a blend of 300 µg of (7Z)-nonadecen-11-one and 300 µg of (7Z)-tricosene as an improved monitoring tool for raspberry bud moth for use by berry growers. This is the second report of the Z-alkene as a pheromone component in the Carposinidae family among the three carposisnid pheromones identified to date.

Associative Learning of Food Odor by Social Wasps in a Natural Ecosystem.

The ability of insects to associate olfactory cues with food from their environment has been well documented with various insect orders. However, these studies were based on prior training of insects to associate odors with food sources in the laboratory or in the field with almost no evidence for the development of this phenomenon in natural ecosystems. In New Zealand's ancient Fuscospora spp. or beech forests, invasive Vespula social wasps were attracted to odor from honeydew (benzaldehyde and n-octanol) but did not respond to a known wasp attractant (isobutanol and acetic acid). On the other hand, wasps in a rural/suburban area in New Zealand did not respond to honeydew odor but responded instead to the known wasp attractant. Similarly, social wasps in Hungary did not respond to honeydew odor, but responded to the known wasp attractant. DNA sequences of Vespula vulgaris from the two locations in New Zealand were 100% identical. Similarly, DNA sequences of V. germanica from the two locations in New Zealand were 100% identical, indicating little or no intra-specific variation. On the other hand, DNA sequences of V. vulgaris and V. germanica from New Zealand were 99.56 and 99.78% matches with V. vulgaris and V. germanica samples from Hungary, respectively. Electroantennogram (EAG) response profiles of wasps from the three locations to benzaldehyde, isobutanol, acetic acid, n-octanol and heptyl butyrate were similar. The high similarity in DNA sequences and EAG profiles, with only a behavioral difference in the response to odor sources, suggests that social wasps in New Zealand's beech forest have naturally developed associative learning for the odor of the carbohydrate-rich honeydew. This is the first study to provide conclusive evidence of the occurrence and the development of associative learning of food odor by social insects in a natural ecosystem free of human interference. The ability of social wasps to naturally develop associative learning of food odor might in part explain why they are extremely successful invaders of new ecosystems, especially those with rich honeydew resources. The finding of our study will have significant implications for the use of attractants in wasp monitoring and control in different habitats.

Identification of in situ flower volatiles from kiwifruit (Actinidia chinensis var. deliciosa) cultivars and their male pollenisers in a New Zealand orchard.

In situ flower volatiles from six kiwifruit cultivars (Actinidia chinensis var. deliciosa); 'Hayward', 'Chieftain', 'M56', 'Zes007' (Green11), 'M36', and 'M43' were collected by dynamic headspace sampling. Forty-five compounds were detected in the headspace of the flowers, with straight chain hydrocarbons and terpenes accounting for >98% of the volatiles emitted quantitatively across the six cultivars. Of these hydrocarbons, (3Z,6Z,9Z)-heptadecatriene is reported for the first time from a floral source while (8Z)-hexadecene and (9Z)-nonadecene are reported for the first time from kiwifruit flowers. All three hydrocarbons were verified by synthesis. Quantitative comparison of the six honey bee perceived compounds from the headspace of the cultivars showed that the males 'M36' and 'M43' closely matched the female cultivar Green11 that they are used to pollinate. Males 'M56' and 'Chieftain' were not as closely matched to the female cultivar 'Hayward' that they are used to pollinate. The male 'M56' in particular differed significantly from the female 'Hayward' in four of the six honey bee perceived compounds.

Enantiospecific Synthesis of Both Enantiomers of the Longtailed Mealybug Pheromone and Their Evaluation in a New Zealand Vineyard.

The irregular monoterpenoid sex pheromone of Pseudococcus longispinus and its enantiomer were prepared from the corresponding bornyl acetates. The use of readily accessible chiral starting materials and lactone-lactone rearrangement are the highlights of the present synthesis. The biological activities of the two enantiomers and racemic mixture were tested in a New Zealand vineyard. The (S)-(+)-enantiomer was significantly more attractive to P. longispinus males than the racemic mixture or the (R)-(-)-enantiomer.

Kiwifruit Flower Odor Perception and Recognition by Honey Bees, Apis mellifera.

Volatile organic compounds (VOCs) from male and female kiwifruit (Actinidia deliciosa 'Hayward') flowers were collected by dynamic headspace sampling. Honey bee (Apis mellifera) perception of the flower VOCs was tested using gas chromatography coupled to electroantennogram detection. Honey bees consistently responded to six compounds present in the headspace of female kiwifruit flowers and five compounds in the headspace of male flowers. Analysis of the floral volatiles by gas chromatography-mass spectrometry and microscale chemical derivatization showed the compounds to be nonanal, 2-phenylethanol, 4-oxoisophorone, (3E,6E)-α-farnesene, (6Z,9Z)-heptadecadiene, and (8Z)-heptadecene. Bees were then trained via olfactory conditioning of the proboscis extension response (PER) to synthetic mixtures of these compounds using the ratios present in each flower type. Honey bees trained to the synthetic mixtures showed a high response to the natural floral extracts, indicating that these may be the key compounds for honey bee perception of kiwifruit flower odor.

Spatial analysis of mass trapping: how close is close enough?

BACKGROUND: The identification of new attractants can present opportunities for developing mass trapping, but standard screening methods are needed to expedite this. We have developed a simple approach based on quantifying trap interference in 4 × 4 trap arrays with different spacings. We discuss results from sex pheromones in Lepidoptera (light brown apple moth, Epiphyas postvittana), Diptera (apple leaf curling midge, Dasineura mali) and Homoptera (citrophilous mealybug, Pseudococcus calceolariae), compared with a kairomone for New Zealand flower thrips (Thrips obscuratus). RESULTS: The ratio of catch in corner traps to catch in centre traps was 25:1 at 750 D. mali traps ha(-1) , and was still ∼5:1 at 16 traps ha(-1) , suggesting trap interference even at such low trap densities. Trap competition for sex pheromone lures at close spacing (<5 m) was evident in 16-trap arrays of P. calceolariae, but less so for E. postvittana. No trap competition was observed at 4 m spacings with the kairomone for T. obscuratus. CONCLUSIONS: The ratio of catch in traps in the corner and centre of a 16-trap array at different spacings offers a rapid preliminary assessment method for determining the potential for mass trapping. Additional knowledge of vital rates and dispersal is needed for predicting population suppression. Our approach should have value in mass trapping development. © 2014 Society of Chemical Industry.

Apple volatiles synergize the response of codling moth to pear ester.

Codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), is a major cosmopolitan pest of apple and other pome fruits. Ethyl (E,Z)-2,4-decadienoate (pear ester) has been identified as a host-derived kairomone for female and male codling moths. However, pear ester has not performed similarly in different fruit production areas in terms of the relative magnitude of moth catch, especially the proportion of females caught. Our work was undertaken to identify host volatiles from apples, and to investigate whether these volatiles can be used to enhance the efficacy of host kairomone pear ester for monitoring female and male codling moths. Volatiles from immature apple trees were collected in the field using dynamic headspace sampling during the active period of codling moth flight. Using gas chromatography-electroantennogram detector (GC/EAD) analysis, six compounds elicited responses from antennae of females. These compounds were identified by GC/mass spectrometry (MS) and comparisons to authentic standards as nonanal, (E)-4,8-dimethyl-1,3,7-nonatriene, methyl salicylate, decanal, (Z,E)-α-farnesene, and (E,E)-α-farnesene. When the EAD-active compounds were tested individually in the field, no codling moths were caught except for a single male with decanal. However, addition of (E)-4,8-dimethyl-1,3,7-nonatriene, methyl salicylate, decanal, or (E,E)-α-farnesene to pear ester in a binary mixture enhanced the efficacy of pear ester for attracting female codling moths compared to pear ester alone. Addition of the 6-component blend to the pear ester resulted in a significant increase in the number of males attracted, and enhanced the females captured compared to pear ester alone; the number of males and females caught was similar to that with the pear ester plus acetic acid combination lure. Our results demonstrate that it is possible to synergize the response of codling moth to host kairomone by using other host volatiles. The new apple-pear ester host kairomone blend should be helpful for monitoring female codling moth, and may provide the basis for further improvement of codling moth kairomone.

Improving the efficiency of lepidopteran pest detection and surveillance: constraints and opportunities for multiple-species trapping.

Surveillance using attractants for invasive species can allow early detection of new incursions and provide decision support to response programs. Simultaneous trapping for multiple species, by baiting traps with several lures, is expected to increase the number of species that can be targeted in surveillance programs and improve the cost-effectiveness without affecting surveillance coverage. We tested this hypothesis by choosing four potential forest and urban lepidopteran pest species that are present in Europe but not yet in New Zealand and many other countries. We deployed traps in central and southern Europe with single lures or all possible species combinations (up to four lures per trap). There was only limited interference, apparently due to trap saturation, but no evidence for interspecific repellency among lures for gypsy moth, Lymantria dispar, fall webworm, Hyphantria cunea, pine processionary moth, Thaumetopoea pityocampa, and pine shoot moth, Rhyacionia buoliana. To assess what factors may be important in species compatibility/suitability for multiple-species trapping, we combined our results with those of previous studies conducted by the United States Department of Agriculture. For 75 combinations of pheromones, tested singly or in combination, 19 % showed no effect on trap catch for any of the species tested. In the other cases, either one or both species showed a reduction in trap catch. However, few lure combinations caused complete or nearly complete suppression. For most combinations, catches were still sufficiently high for detection purposes. Species from the same superfamily exhibited more interference than more distantly related species. Together, these results suggest that there are opportunities to improve the range of exotic pests under surveillance, at little additional cost, by multiple-species trapping for which compatibility has been demonstrated.

Mobile mating disruption of light-brown apple moths using pheromone-treated sterile Mediterranean fruit flies.

BACKGROUND: Public opposition to aerial application of sex pheromone for mating disruption of light-brown apple moth (LBAM), Epiphyas postvittana (Walk.), in California stopped its further use in the ca $74 million eradication programme in 2008, underscoring the need for other eradication tactics. It is demonstrated that pheromone-treated sterile Mediterranean fruit flies (medflies), Ceratitis capitata Wied., can disrupt communication in male moths. RESULTS: Medflies topically dosed with moth pheromone (E)-11-tetradecenyl acetate showed a no observed effect level (NOEL) of ~10 µg fly(-1) , with increasing toxicity from 30 to 100 µg fly(-1) . Greater potency and longevity of attraction and lower mortality were achieved using microencapsulated pheromone. Releases of 1000 pheromone-treated medflies ha(-1) prevented male moth catch to synthetic lures in treated 4 ha plots for 1 day in suburban Perth, Australia. Releases of ca 3000 pheromone-treated medflies ha(-1) disrupted catch to single female moths in delta traps, and to synthetic pheromone lures. Percentage disruption on the first four nights was 95, 91, 82 and 85%. CONCLUSIONS: Disruption of moth catch using pheromone-treated medflies is a novel development that, with future improvement, might provide a socially acceptable approach for application of the insect mating disruption technique to control invasive insects in urban environments. Adequacy of payload and other issues require resolution.

The absolute configuration of the sex pheromone of the citrophilous mealybug, Pseudococcus calceolariae.

The absolute configuration of the sex pheromone of the citrophilous mealybug, Pseudococcus calceolariae, was determined to be (1R,3R)-[2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropyl]methyl (R)-2-acetoxy-3-methylbutanoate. NMR, derivatization reactions, chiral gas chromatography-mass spectrometry, and comparison with synthetic chiral reference compounds, were used to determine the absolute configuration of this compound. This activity of this compound was further confirmed by testing synthetic stereoisomers of the compound as lures in traps for adult male mealybugs. Traps baited with 1,000 µg of the pheromone compound caught 36 times more males than traps baited with virgin females. A mixture of stereoisomers of the pheromone compound can be used for field trapping without adverse effects on trap catch. A comparison with the structures of other sex pheromones of mealybugs is presented.

Attraction and antennal response of the common wasp, Vespula vulgaris (L.), to selected synthetic chemicals in New Zealand beech forests.

BACKGROUND: The common wasp, Vespula vulgaris (L.), and the German wasp, Vespula germanica (F.), are significant problems in New Zealand beech forests (Nothofagus spp.), adversely affecting native birds and invertebrate biodiversity. This work was undertaken to develop synthetic attractants for these species to enable more efficient monitoring and management. RESULTS: Seven known wasp attractants (acetic acid, butyl butyrate, isobutanol, heptyl butyrate, octyl butyrate and 2,4-hexadienyl butyrate) were field tested, and only heptyl butyrate and octyl butyrate attracted significantly higher numbers of wasps than a non-baited trap. Accordingly, a series of straight-chain esters from methyl to decyl butyrate were prepared and field tested for attraction of social wasps. Peak biological activity occurred with hexyl butyrate, heptyl butyrate, octyl butyrate and nonyl butyrate. Polyethylene bags emitting approximately 18.4-22.6 mg day(-1) of heptyl butyrate were more attractive than polyethylene bags emitting approximately 14.7-16.8 mg day(-1) of heptyl butyrate in the field. Electroantennogram (EAG) studies indicated that queens and workers of V. vulgaris had olfactory receptor neurons responding to various aliphatic butyrates. CONCLUSION: These results are the first to be reported on the EAG response and the attraction of social wasps to synthetic chemicals in New Zealand beech forests and will enable monitoring of social wasp activity in beech forests.