Fumiaki Mochizuki

Female Sex Pheromone of a Carpenter Moth, Cossus insularis (Lepidoptera: Cossidae)

This study describes the identification of a sex pheromone component of a cossid moth, Cossus insularis. Coupled gas chromatographic–electroantennographic detection (GC–EAD) analysis of solid-phase microextraction (SPME) collections of volatiles released by live female moths showed that two compounds elicited EAG responses from the antennae of male moths. These compounds were identified as (E)-3-tetradecenyl acetate (E3-14:Ac) and (Z)-3-tetradecenyl acetate (Z3-14:Ac) by mass spectral analysis and retention index comparisons with synthetic standards. The ratio of E3-14:Ac and Z3-14:Ac was 95:5 in the effluvia of a female. In field bioassays, sticky traps baited with blends of E3-14:Ac and Z3-14:Ac showed that E3-14:Ac is an essential component of the pheromone. However, the role of Z3-14:Ac is unclear, because E3-14:Ac as a single component was as attractive to male moths as blends of E3-14:Ac and Z3-14:Ac, including the 95:5 blend released by live female moths.

Combined use of a synthetic trail pheromone and insecticidal bait provides effective control of an invasive ant

BACKGROUND Except for sex pheromones, use of pheromones in pest management has been largely unexplored. A high concentration of trail pheromone disrupts ant trail following and foraging, and thus synthetic trail pheromone can be a novel control agent for pest ants. In this study, a year-long treatment of small areas (100 m(2) plots of urban house gardens) with synthetic trail pheromone, insecticidal bait or both was conducted to develop a novel control method of the invasive Argentine ant Linepithema humile (Mayr). RESULTS The ant population could be maintained lower than or similar to the initial level only by combined treatment with synthetic trail pheromone and insecticidal bait. Actually, the ant population was nearly always lowest in combination treatment plots. Throughout the study period, the ant population in plots treated with either one of synthetic trail pheromone or insecticidal bait remained similar to no-treatment plots. CONCLUSIONS Combination treatment may be a more effective and environmentally friendly method for controlling invasive ants than conventional methods. Extermination of ants by insecticidal bait and inhibition of re-infestation by pheromone may be the mechanism of the combination effect. This is the first study to show a significant effect of synthetic trail pheromone on ant population.

Sex pheromone production and perception in the mating disruption‐resistant strain of the smaller tea leafroller moth, Adoxophyes honmai

Mating disruption is an environmentally safe plant protection strategy that uses a synthetic copy of an insect pheromone to interfere with sexual communication and hence reproduction. To date, a number of pest moths have been controlled with applications of formulated pheromones as mating disruptants. Recently, however, the first example of resistance to mating disruption was documented in one of the major tea pests in Japan, the smaller tea leafroller moth, Adoxophyes honmai Yasuda (Lepidoptera: Tortricidae). To avoid other such cases, it is important to elucidate the mechanism(s) by which the disruptant lost its effectiveness. To this end, we imposed further selection by rearing field‐collected resistant insects with a synthetic pheromone in the laboratory. After more than 70 generations of selection, a strain with quite strong resistance was established, males of which could find and copulate with their mates even in the presence of 1 mg l−1 of disruptant. Although the mating ability of this strain was greatly increased, the composition and blend ratio of the sex pheromone produced and emitted by females were not obviously changed in comparison with those of females sensitive to mating disruption. However, male response to the pheromone blend was markedly broadened after selection so that resistant males could locate a synthetic pheromone source even when it lacked a pheromone component that is normally necessary for attraction. Males capable of locking onto off‐ratio pheromone blends may be better able to find calling females in pheromone‐treated environments than narrowly tuned males because of greater capability of overcoming sensory imbalance.

Mating disruption of the Japanese giant looper in tea gardens permeated with synthetic pheromone and related compounds

The Japanese giant looper, Ascotis selenaria cretacea, is a serious defoliator of tea gardens in Japan. The females produce racemic (Z,Z)‐6,9‐cis‐3,4‐epoxynonadecadiene (epo3,Z6,Z9‐19:H, main component) and (Z,Z,Z)‐3,6,9‐nonadecatriene (Z3,Z6,Z9‐19:H, minor component). The orientation of the males to the synthetic pheromone placed in a trap was strongly disrupted by Z3,Z6,Z9‐19:H or a mixture of its monoepoxy derivatives (epoxydiene mixture, EDM) impregnated in septa and placed around the trap. Based on this result, polyethylene tubes containing Z3,Z6,Z9‐19:H or EDM were prepared and effect of these dispensers was examined in a field. Disruption of male orientation to synthetic pheromone traps was achieved in orchards permeated with Z3,Z6,Z9‐19:H at dispenser density of 3000 and 5000 tubes ha−1 (release rate: 0.55–0.61 mg day−1 tube−1) and with EDM at every tested dose, 250–5000 tubes ha−1 (release rate: 0.25–0.39 mg day−1 tube−1). Furthermore, disruption of mating in tethered females was observed in these orchards; particularly, the mating was perfectly inhibited in the areas treated with EDM at 3000 and 5000 tubes ha−1. This is the first formulation for the mating disruption of a geometrid pest.

Mating disruption by a synthetic sex pheromone in the white grub beetle Dasylepida ishigakiensis (Coleoptera: Scarabaeidae) in the laboratory and sugarcane fields.

A serious sugarcane pest, Dasylepida ishigakiensis, remains in the soil during most of its life cycle except for a short period for mating. Mating disruption by an artificial release of the sex pheromone (R)-2-butanol (R2B), therefore, may be a feasible method to control this pest. We examined the effects of artificial release of R2B and its related compounds, (S)-2-butanol (S2B) and the racemic 2-butanol (rac-2B), on the mating success of this beetle both in the laboratory and in the field. In flight tunnel experiments, almost all males orientated towards a R2B-releasing source and 40% of them landed on the source. When the atmosphere was permeated with R2B, the frequency of males landing on the model was significantly reduced. Both rac-2B and S2B were less effective, but substantial reduction in landing success by males was achieved at higher rac-2B concentrations. R2B released from polyethylene dispensers in sugarcane plots greatly reduced not only the proportion of females mated with males but also the number of males caught by R2B-baited traps, indicating that male mate-searching behaviour was strongly affected by the released R2B. Similar inhibitory effects on male behaviour were also observed when tube- or rope-type dispensers released high rac-2B concentrations in the field. These results indicate that it would be highly possible to control D. ishigakiensis through the disruption of the sexual communication by releasing either synthetic R2B or rac-2B.

Identification of the sex pheromone secreted by Synanthedon tenuis (Lepidoptera: Sesiidae)

The Japanese persimmon treeborer, Synanthedon tenuis (Butler) (Lepidoptera: Sesiidae), is a harmful pest of persimmon trees (Diospyros spp.). Because males of this species are known to be attracted by (3Z,13Z)-3,13-octadecadienyl acetate (Z3,Z13-18:OAc), a mating disruptant composed of a 1:1 mixture of Z3,Z13-18:OAc and the (3E,13Z)-isomer, the original target of which is an allied pest, S. hector (Butler), has been diverted to control S. tenuis. However, the sex pheromone secreted by S. tenuis females has not been characterized. Analyses of pheromone gland extracts using gas chromatography (GC) equipped with an electroantennographic detector (GC-EAD) and GC combined with mass spectrometry (GC–MS) detected only Z3,Z13-18:OAc, and no other known sesiid pheromone components were found. In a persimmon orchard, S. tenuis males were selectively attracted by a lure baited with Z3,Z13-18:OAc among four geometrical isomers of 3,13-octadecadienyl acetate, indicating that males strictly discriminated among the configurations of the two double bonds. Lures baited with single Z3,Z13-18:OAc attracted only S. tenuis. Further field experiments revealed that the attractiveness of Z3,Z13-18:OAc is significantly inhibited by the addition of the (3E,13Z) isomer or the parent alcohol.

Age-dependent changes in the ratio of (R)- and (S)-2-butanol released by virgin females of Dasylepida ishigakiensis (Coleoptera: Scarabaeidae).

The females of the white grub beetle, Dasylepida ishigakiensis, release two enantiomers of 2-butanol, (R)-2-butanol and (S)-2-butanol. The ratio describing the relative proportions of these two enantiomers (R/S ratio) has not yet been investigated. (R)-2-Butanol has been shown to attract males in laboratory and field experiments, whereas (S)-2-butanol tends to inhibit them. To determine the R/S ratio of the 2-butanol emitted by virgin females, we collected 2-butanol from young (53 days old), mature (63 days old) and old females (73 days old) using water, extracted with an SPME fibre and subsequently injected into GC-MS. The major component of the 2-butanol emitted by the young females was (R)-2-butanol, but as the females aged, the component ratio favoured (S)-2-butanol. Young females released an 80:20 mixture of (R)- and (S)-2-butanol, whereas old females released a 45:55 mixture. The EAG response of male antennae to a 50:50 ratio (racemic mixture) showed a similar dose-response curve to that of (R)-2-butanol. The male orientation responses to (R)-2-butanol decreased when the relative proportion of (S)-2-butanol increased. An inhibitory and/or masking effect of (S)-2-butanol on male orientation behaviour was also observed in the flight tunnel assay. These results suggest that males are more strongly attracted to young females than to old females. We also discuss the possibility of using 2-butanol isomers as a control or monitoring agent for this insect.

Chemoreception in astigmatid mites

Despite the tremendous importance of chemicals (such as alarm [1], aggregation [21, and sex pheromones [3,4] as well as food attractants [5]) in the ecology of astigmatid mites, little is known about chemoreception in these arthropods. That the external scapular setae (sce) of Caloglyphus polyphyllae are receptors of the male-attracting sex pheromone has been clarified by amputation of the sensilla [3]. The facts that these setae correspond in position to the trichobothria, a conspicuous sense organ of the closely related group of oribatid mites, and that chemoreceptors of other acarines are not present on the dorsum but mainly on the first tarsi and pedipalps prompted us to further investigate the chemical sense of astigmatid mites. Examination of the external morphology of cuticular sensory structures (coupled with behavioral observations) revealed that the principal chemosensory organs are located on both the tarsi I and II and the propodosoma. Two mites were elected as representatives of the group, namely, Rhizoglyphus robini and Tyrophagus putrescentiae, due to their economical importance as agricultural and storedproduct pests, respectively. The sce of R. robini were excised and ten mites set in 4-cm ID Petri dishes containing damp filter paper (FP) and a small amount of wheat germ in the center. After 2h, small pieces of FP impregnated with the alarm pheromone, neryl formate [6] (citral has been reported as the active component [7], but neral and geranial are only minor components [6]), were set either close to mites feeding or in front of walking individuals. With nonexcised mites, escape behavior was observed with the threshold active concentration of 1 ppm, whereas excised ones did not demonstrate the behavior even at 1000 ppm. Investigations