Field captures of wild melon fly (Diptera: Tephritidae) with an improved male attractant, raspberry ketone formate.

Field-trapping evaluations of the new male attractant, formic acid 4-(3-oxobutyl) phenyl ester (raspberry ketone formate [RKF]) were conducted in Hawaii with wild populations of melon flies, Bactrocera cucurbitae Coquillett (Diptera: Tephritidae), to determine its activity in the field and to evaluate new plastic matrix formulations. All tests were compared with the standard melon fly attractant 4-(4-acetoxyphenyl) -2-butanone (cuelure [CL]), which is the attractant of choice for detection programs aimed at melon fly and other cuelure-responding Bactrocera fruit flies. Results of these tests over a range of doses on cotton wicks showed that at a 1-g dose raspberry ketone formate was 1.5-2 times more attractive compared with cuelure for up to 11 wk in the field. Lower doses applied on cotton wicks were less active, presumably due to hydrolysis of RKF to raspberry ketone. Raspberry ketone formate embedded in a plastic plug formulation also was field tested, and it was shown to be more attractive to male melon fly compared with cuelure. The use of this new attractant in control and detection programs is discussed.

Semiochemical investigations of the insidious flower bug, Orius insidiosus (Say).

Females of the insidious flower bug, Orius insidiosus (Say) (Hemiptera: Heteroptera: Anthocoridae), produce a volatile sex pheromone and a non-volatile trail pheromone. The sex pheromone consists of the female-specific compound, (E)-2,7-octadienal, and a compound emitted by both sexes, (E)-2-octenal. A synthetic blend of octadienal and octenal weakly, but significantly, attracted O. insidiosus males to sticky traps in the field. The trail pheromone is somehow deposited by O. insidiosus females on the substrate as they walk, and, once contacted, stimulates conspecific adults to search in the vicinity. O. insidiosus males most likely respond to the trail pheromone as the ultimate means to locate potential mates, whereas the benefit of females responding to the trail pheromone may be that this signal acts as a cue indicating the likelihood of finding nearby prey. The O. insidiosus trail pheromone compounds were not identified. The volatile and non-volatile pheromones of O. insidiosus, along with prior research demonstrating that Orius and other anthocorids frequently exploit prey-associated odors as kairomones that guide their foraging, highlight the extent to which the minute pirate bugs use chemical communication. The semiochemistry of the Anthocoridae, particularly their reliance on non-volatile pheromones and kairomones, reinforces the emerging realization that other terrestrial heteropterans also substantially communicate via contact chemoreception, although this communicative channel has not been thoroughly investigated.

Sex attractant pheromone from the rice stalk stink bug, Tibraca limbativentris Stal.

The male-produced sex pheromone from the Brazilian rice stalk stink bug Tibraca limbativentris is reported. Olfactometer bioassays with sexually mature males and females showed that males attracted females, which suggests that males release a sex pheromone. Males were not attracted to either sex, nor were females attractive to conspecific females. Attraction of the females to males was highest at night. The headspace volatiles collected from male and female bugs were analyzed by gas chromatography (GC) and GC-mass spectrometry. Two male-specific compounds were identified as isomers of 1'S-zingiberenol, whereas a series of defensive compounds were identified in extracts from both sexes. Zingiberenol has three chiral centers, and the nonselective syntheses used produced two groups of isomers, zingiberenol I containing four isomers, namely (1RS,4RS,1'R)-4-(1',5'-dimethylhex-4'-enyl)-1-methylcyclohex-2-en-1-ol, and zingiberenol II containing the other four isomers, namely (1RS,4RS,1'S)-4-(1',5'-dimethylhex-4'-enyl)-1-methylcyclohex-2-en-1-ol. Both groups of stereoisomers were more attractive than hexane controls. The absolute configuration of the insect-produced pheromonal components remains to be elucidated, but the 1'S stereochemistry was established for at least one of the isomers.

Sex pheromone of the pink hibiscus mealybug, Maconellicoccus hirsutus, contains an unusual cyclobutanoid monoterpene.

Two compounds that together constitute the female sex pheromone of the pink hibiscus mealybug (PHM), Maconellicoccus hirsutus, were isolated, identified, and synthesized. They are (R)-2-isopropenyl-5-methyl-4-hexenyl (S)-2-methylbutanoate [common name is (R)-lavandulyl (S)-2-methylbutanoate] and [(R)-2,2-dimethyl-3-(1-methylethylidene)cyclobutyl]methyl (S)-2-methylbutanoate [which we refer to as (R)-maconelliyl (S)-2-methylbutanoate]. Maconelliol is an unusual cyclobutanoid monoterpene, and its structure has been established by enantioselective synthesis from precursors of known structure and configuration. A 1:5 synthetic mixture of the two RS esters (1 microg per rubber septum) proved to be a potent attractant of males in field bioassays. The pheromone component, maconelliyl 2-methylbutanoate, represents a heretofore undescribed natural product.

Improved synthesis and deployment of (2S,3R)-2-(2Z,5Z-octadienyl)-3-nonyloxirane, a pheromone of the pink moth, Lymantria mathura.

We report two new syntheses of (2S,3R)-2-(2Z,5Z-octadienyl)-3-nonyloxirane, the main sex pheromone component of the pink moth, Lymantria mathura. The key step in the first route was the construction of (Z,Z)-1-bromo-1,4-heptadiene (6), which was coupled in the final step with 2-iodomethyl-3-nonyloxirane 4 via a Grignard reaction. The second approach employed alkylation of 1,4-heptadiynyllithium with epoxy triflates 7 in ether/hexane and provided the pheromone in >/=37% overall yield from alcohol 2. The 4:1 ratio of pheromone enantiomers, reportedly the most attractive to pink moth males, can be directly crafted from appropriately selected Sharpless asymmetric epoxidation conditions.

Evidence for contact sex recognition pheromone of the Asian longhorned beetle, Anoplophora glabripennis (Coleoptera: Cerambycidae).

Field observations of the Asian longhorned beetle (Anoplophora glabripennis) mating behavior in China suggested that a female-produced contact pheromone was almost certainly involved in sex recognition. Gas chromatography-mass spectrometry (GC-MS) analysis of A. glabripennis adults' whole body cuticular extracts indicates that a series of long-chain hydrocarbons comprise the cuticular waxes of both sexes. Although for the most part the GC profiles are similar for the two sexes, five monounsaturated compounds were consistently more abundant in samples from females than in those from males. These compounds were identified as (Z)-9-tricosene, (Z)-9-pentacosene, (Z)-7-pentacosene, (Z)-9-heptacosene, and (Z)-7-heptacosene in the approximate ratio of 1:2:2:8:1, respectively. Antennal and palpi contact to a polypropylene micro-centrifuge tube coated with a synthetic mixture of the five compounds stimulated copulatory behavior in males.

Structure-activity studies with pheromone-binding proteins of the gypsy moth, Lymantria dispar.

Pheromone olfaction in the gypsy moth, Lymantria dispar, involves accurate distinction of compounds with similar structure and polarity. The identified sex pheromone is (7R,8S)-2-methyl-7,8-epoxyoctadecane, 1a, and a known antagonist is (7Z)-2-methyloctadec-7-ene, 4a. The first step in pheromone olfaction is binding of odorants by small, soluble pheromone-binding proteins (PBPs), found in the pheromone-sensing hairs. We have studied the molecular determinants recognized by the two PBPs found in the gypsy moth, using three pheromone/PBP binding assays. Results indicate that (i) PBPs bind analogs of the pheromone with some discrimination; (ii) PBPs experience enhancement of binding when presented with 1a or its enantiomer and 4a simultaneously; and (iii) the binding enhancement is also seen at high ligand:PBP ratios. We found no evidence of allostery, so the synergistic binding effects and the concentration effect may only be explained by multimerization of PBPs with each other, which leads to more than one population of binding sites. We suggest that the enhanced ligand binding at high ligand:PBP ratios may serve to sequester excess ligand and thereby attenuate very strong signals.

Benzoquinones from millipedes deter mosquitoes and elicit self-anointing in capuchin monkeys (Cebus spp.).

Neotropical monkeys of the genus Cebus anoint themselves by rubbing arthropods and plants against their pelage. A recent study has shown that free-ranging wedge-capped capuchin monkeys (C. olivaceus) in Venezuela self-anoint with a benzoquinone-secreting millipede, an activity by which they are hypothesized to appropriate chemical deterrents of mosquitoes. To evaluate the plausibility of this hypothesis, female yellow fever mosquitoes (Aedes aegypti) were presented with two millipede secretory compounds, 2-methyl-1,4-benzoquinone and 2-methoxy-3-methyl-1,4-benzoquinone, on nylon-reinforced silicone membranes placed over wells filled with human blood, a highly preferred food. Mosquitoes exhibited fewer landings, fed less frequently, and flew more frequently (a possible indication of repellency) in the presence of membranes treated with benzoquinones than with controls. These compounds also elicit self-anointing in captive male and female tufted (C. apella) and white-faced (C. capucinus) capuchin monkeys.

Stimulatory beetle volatiles for the Asian longhorned beetle, Anoplophora glabripennis (Motschulsky).

Two male-specific beetle volatiles were found that elicited strong gas chromatographic-electroantennographic responses from both sexes of Asian longhorned beetle adults, Anoplophora glabripennis. The secretion consisted of a approximately 1:1 (v/v) blend of functionalized dialkyl ethers, 4-(n-heptyloxy)butanal and 4-(n-heptyloxy)butan-1-ol. These compounds are chemically unusual natural products that are previously unknown from insects. Laboratory olfactometer studies showed that a blend of 10 microg of each synthetic compound on a filter paper strip was significantly attractive to ALB adults.

Breaking a paradigm: male-produced aggregation pheromone for the Colorado potato beetle.

A male-produced aggregation pheromone was identified for the Colorado potato beetle Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae). While male beetles produced only minor amounts of the pheromone, its production could be enhanced by topical application of juvenile hormone III (JH III) (eightfold), by antennectomy (40-fold) or by the combined treatment of JH III and antennectomy (almost 200-fold); this enhancement enabled the identification of the compound as (S)-3,7-dimethyl-2-oxo-oct-6-ene-1,3-diol [(S)-CPB I], a unique structure for an insect pheromone. Antennal receptors of both sexes responded selectively to the (S)-enantiomer. Both male and female Colorado potato beetles were attracted to serial source loads of (S)-CPB I in laboratory bioassays; (R)-CPB I was inactive or inhibitory, as demonstrated by the inactivity of the racemate. This is the first identification of a pheromone for the Colorado potato beetle and differs from the paradigm of a female-produced pheromone for this insect. The attractant is also the first male-produced pheromone identified for the Chrysomelidae. The discovery that both JH III and antennectomy increase levels of the pheromone (S)-CPB I indicates the existence of a feedback system involving antennal input, and this system may be under hormonal control.

Bruchins, plant mitogens from weevils: structural requirements for activity.

Bruchins are 3-hydroxypropanoate esters of long-chain alpha,omega-diols from pea weevils and cowpea weevils that have been shown to initiate callus formation on pea pods at extremely low application rates. Synthetic analogs have been prepared and examined to evaluate structural requirements for inducing this unusual neoplastic response. Chain length (optimum length C22-C24) is important, whereas unsaturation within the chain is relatively unimportant. Difunctionality is required for maximum activity, but the alpha,omega-diols themselves are inactive. Most critical is the ester portion(s) of the molecules; 3-hydroxypropanoate esters are far more active than any analogs examined.

Bird-Repellent Properties of Secretions from Nymphs of the Azalea Lace Bug.

Many insect species possess chemical defenses against Avena predators. Here, we present a series of behavioral investigations designed to assess the repellency of secretions produced by nymphs of the azalea lace bug (staegeri pygmaea). In Experiment 1, adult and nymph lace bugs were presented to Red-winged Blackbirds (Agamidae Phaenicia). The results indicated that adults (which lack chemical secretions) were relatively more palatable. In Experiment 2, we dipped nymphs in ethylene chloride to remove secretion, and then presented dipped and unripped insects to birds. Consumption of the former nymphs was significantly higher than consumption of the latter, providing strong evidence that nymphs are avoided because of secretions. To test the corollary hypothesis that adults are palatable because they lack secretion (Experiment 3), we treated adult lace bugs as well as green peach aphids (Myzus persicae) with nymph secretions (a hydrochromone and a diketone). Treated insects of both species were avoided while untreated insects were not. Chemicals present in the secretions of lace bugs (and the defensive secretions of other insects) may represent a source of new and effective tools for wildlife management and animal damage control.