Christopher J. Moore

Male-specific volatiles from nearctic and Australasian true bugs (Heteroptera: Coreidae and Alydidae)

Aeration and exocrine gland extracts were analyzed for three Coreidae and two Alydidae. Males of all the species studied emit volatile blends that are probably pheromones, but sexual communication in these insects evolved differently. In the alydids,Riptortus serripes andMirperus scutellaris, the metathoracic scent glands are sexually dimorphic, and the dimorphisms are expressed chemically. Secretions from the male alydids contain high concentrations of esters or alcohols [e.g., (E)-2-hexenyl (Z)-3-hexenoate, (E)-2-hexenyl butyrate, and (E)-2-octenol], while females produce mainly acids and aldehydes [e.g., butyric and hexanoic acids, and (E)-2-hexenal]. In the coreids,Amblypelta lutescens lutescens, Amblypelta nitida, andLeptoglossus phyllopus, the metathoracic scent glands are not sexually dimorphic, but male- and species-specific volatiles are released, apparently from cells in the cuticular epidermis. The coreid male-specific volatiles are primarily monoterpenes and sesquiterpenes, including (−)-(3R)-(E)-nerolidol as the major component fromA. lutescens lutescens (an Australasian species) andL. phyllopus (a Nearctic species). Only (+)-(3S)-(E)-nerolidol is commonly found in plants so (E)-nerolidol from these coreids is environmentally unique because of its chirality.

Mass-trapping ofCarpophilus spp. (Coleoptera: Nitidulidae) in stone fruit orchards using synthetic aggregation pheromones and a coattractant: Development of a strategy for population suppression.

Experiments were conducted in southern New South Wales to evaluate the potential of mass-trapping using synthetic aggregation pheromones and a coattractant as a control option forCarpophilus spp. in stone fruit orchards. A cordon of 54 pipe and 54 funnel traps (one trap of each type per perimeter tree) baited with pheromones ofC. mutilatus andC. davidsoni and coattractant (fermenting bread dough) was maintained around an apricot orchard for three weeks prior to harvest. The incidence ofCarpophilus spp. in ripe fruit in the center of the orchard was significantly reduced compared to a nearby orchard or the perimeter trees containing traps. A cordon of 16 water-filled Magnet funnel traps baited with pheromones ofC. mutilatus andC. davidsoni and coattractant was placed around a 9 × 9 block of trees in a peach orchard (single traps on alternate perimeter trees). This trapping regime significantly reduced infestation of fruit baits byCarpophilus spp. in the center tree over a period of six weeks compared to fruit baits in trap trees and distant (100 m) control trees. However, cordons of eight pheromone traps within 1 m of single trees or a single trap adjacent to a tree increasedCarpophilus spp. infestation of fruit baits by up to 7.5 × compared to trees without pheromone traps. Mass-trapping based on perimeter positioning of pheromone traps (at a yet to be determined distance from protected trees) appears to show potential as a control strategy forCarpophilus spp. in stone fruit orchards during fruit ripening and harvest but traps too close to trees must be avoided. Development of a strategy for population suppression is discussed with respect to trap type, efficacy, positioning, and density; pheromone and coattractant delivery systems; and orchard sanitation.

Cuticular hydrocarbons of buffalo fly, Haematobia exigua, and chemotaxonomic differentiation from horn fly, H. irritans.

We determined the quantity and chemical composition of cuticular hydrocarbons of different strains, sexes, and ages of buffalo flies, Haematobia exigua. The quantity of cuticular hydrocarbons increased from less than 1xa0μg/fly for newly emerged flies to over 11xa0μg/fly in 13-d-old flies. The hydrocarbon chain length varied from C21 to C29, with unbranched alkanes and monounsaturated alkenes the major components. Newly emerged flies contained almost exclusively C27 hydrocarbons. Increasing age was accompanied by the appearance of hydrocarbons with shorter carbon chains and an increase in the proportion of alkenes. 11-Tricosene and 7-tricosene were the most abundant hydrocarbons in mature H. exigua. Cuticular hydrocarbons of H. exigua are distinctly different from those of horn flies, Haematobia irritans. The most noticeable differences were in the C23 alkenes, with the major isomers 11- and 7-tricosene in H. exigua and (Z)-9- and (Z)-5-tricosene in H. irritans, respectively. Cuticular hydrocarbon analysis provides a reliable method to differentiate the two species, which are morphologically difficult to separate. The differences in cuticular hydrocarbons also support their recognition as separate species, H. exigua and H. irritans, rather than as subspecies.

Identification, synthesis, and bioactivity of a male-produced aggregation pheromone in assassin bug,Pristhesancus Plagipennis (Hemiptera: Reduviidae)

Pristhesancus plagipennis, a large Australian assassin bug, possesses three pairs of dorsal abdominal glands (DAGs). In the male, the anterior and posterior glands are hypertrophied and secrete an attractant pheromone. Gas chromatography-mass spectrometry (GC-MS) analyses of male DAG extracts and airborne volatiles emitted from calling males showed the pheromone signature to be dominated by a novel component. Subsequent chemical manipulations, GC-MS, and chiral-column analyses established its identity as (Z)-3-hexenyl (R)-2-hydroxy-3-methylbutyrate. Minor components included 3-methylbutanol, 2-phenylethanol, (Z)-3-hexenol, decanal, (E)-2-hexenoic acid, and three minor hexenyl esters. Bioactivity studies using laboratory olfactometers and outdoor flight cages demonstrated attraction by femaleP. plagipennis to calling males, heptane extracts of male posterior DAGs and a synthetic formulation of the (Z)R enantiomer of the major ester, alone or in combination with other components of male anterior and posterior DAGs. Males were also attracted to the major ester. The racemate andS enantiomer of the ester were not attractive. Contamination of the (Z)R enantiomer with 30–60% of theE isomer also made the compound nonattractive. This is the first report of an aggregation pheromone in the Reduviidae. The prospects for pheromonal manipulation ofP. plagipennis populations to enhance the value of this predator in horticultural ecosystems, are discussed.

Discrepancy Between Antennal and Behavioral Responses for Enantiomers of α-Pinene: Electrophysiology and Behavior of Helicoverpa armigera (Lepidoptera)

The ability of adult cotton bollworm, Helicoverpa armigera (Hübner), to distinguish and respond to enantiomers of α-pinene was investigated with electrophysiological and behavioral methods. Electroantennogram recordings using mixtures of the enantiomers at saturating dose levels, and single unit electrophysiology, indicated that the two forms were detected by the same receptor neurons. The relative size of the electroantennogram response was higher for the (−) compared to the (+) form, indicating greater affinity for the (−) form at the level of the dendrites. Behavioral assays investigated the ability of moths to discriminate between, and respond to the (+) and (−) forms of α-pinene. Moths with no odor conditioning showed an innate preference for (+)-α-pinene. This preference displayed by naïve moths was not significantly different from the preferences of moths conditioned on (+)-α-pinene. However, we found a significant difference in preference between moths conditioned on the (−) enantiomer compared to naïve moths and moths conditioned on (+)-α-pinene, showing that learning plays an important role in the behavioral response. Moths are less able to distinguish between enantiomers of α-pinene than different odors (e.g., phenylacetaldehyde versus (−)-α-pinene) in learning experiments. The relevance of receptor discrimination of enantiomers and learning ability of the moths in host plant choice is discussed.

Chemical Characterization of Urinary Pheromones in Brown Antechinus, Antechinus stuartii

In the small dasyurid marsupial, Antechinus stuartii, males exhibit scent-marking in the form of cloacal marking of nesting areas during the breeding season. Females of this species show no such behavior. To characterize the potential male pheromonal scent signal, urine-derived volatiles from sexually active males were analyzed by GC-MS and compared to that of females and a castrated male. More than 10 urinary compounds were identified. A series of homologous methylketones was observed in both males and females, whereas aldehydes were present only in female urine. Urine from the castrate was virtually compound-free except for minute concentrations of a compound tentatively identified as 2,4-dithiapentane. This compound was also found in one of the sexually active males. The GC profiles of the sexually active males contained high concentrations of two pyrazine derivatives and four methylketones that were not detected in the profiles of either females or the castrate. These compounds may influence social communication in the brown antechinus, Antechinus stuartii.

Identification of presumed pheromone blend from australasian predaceous bug,Oechalia schellenbergii (Heteroptera: Pentatomidae)

Oechalia schellenbergii is one of the most common predatory insects in Australia and the islands of the South Pacific. Adult males of this predaceous “true bug” collected during March near Gatton, Queensland, Australia, had a pair of enlarged exocrine glands opening underneath their wings that presumably produce an attractant pheromone. The two major components of the secretion are 3-methylenehexyl acetate and 9-hydroxygeranyl diacetate [2,6-dimethyl-2(E),6(E)-octadien-1,8-diol diacetate].

Pheromone-mediated mass trapping and population diversion as strategies for suppressing Carpophilus spp. (Coleoptera: Nitidulidae) in Australian stone fruit orchards

1u2003Five experiments were conducted during 1995–99 in stone fruit orchards on the Central Coast and in inland New South Wales, Australia, on the use of synthetic aggregation pheromones and a coattractant to suppress populations of the ripening fruit pests Carpophilus spp. (Coleoptera: Nitidulidae).