Identification of major components of larviposition pheromone from larvae of tsetse fliesGlossina morsitans morsitans Westwood andGlossina morsitans centralis Machado

The presence of pheromones produced by larvae ofGlossina morsitans morsitans andG. m. centralis, respectively, which attract gravid females and result in aggregation of pupae, is confirmed. Behavioral experiments indicated that females preferred to larviposit over moist sand conditioned by previously allowing larvae to pupariate in it. Similar results were obtained with filter papers contaminated with the prepupariation excretions of larvae and with volatiles collected from larvae prior to pupariation.n-Pentadecane andn-dodecane were identified as the dominant electrophysiologically active components of the larviposition pheromones ofG. m. morsitans andG. m. centralis, respectively, by GC-EAD and GC-MS analysis of the trapped larval volatiles. Both identified compounds were shown to significantly attract gravid females to larviposition sites in laboratory behavioral assays.     

Synthesis of diastereomeric mixture of 15,19,23-trimethylheptatriacontane,contact sex pheromone of tsetse fly,Glossina morsitans morsitans westwood

A nine-step synthesis is described for a diastereomeric mixture of 15,19,23-trimethylheptatriacontane, a contact sex pheromone ofGlossina morsitans morsitans Westwood. The compound has been synthesized by means of double alkylation of diethyl 3-oxoglutarate (DEOG) with 3-methyl-2-heptadecenyl methanesulfonate, which was readily prepared from 1-hexadecene, as the key step.This study constitutes Part XII of Selective Alkylation of Diethyl 3-Oxoglutarate. Part XI of this series, see Naoshima et al. (1984).     

Responses of Glossina morsitans morsitans to Blends of Electroantennographically Active Compounds in the Odors of Its Preferred (Buffalo and Ox) and Nonpreferred (Waterbuck) Hosts

In a previous study, comparison of the behavior of teneral Glossina morsitans morsitans on waterbuck, Kobus defassa (a refractory host), and on two preferred hosts, buffalo, Syncerus caffer, and ox, Bos indicus, suggested the presence of allomones in the waterbuck odor. Examination of the volatile odors by coupled gas chromatography–electroantennographic detection showed that the antennal receptors of the flies detected constituents common to the three bovids (phenols and aldehydes), as well as a series of compounds specific to waterbuck, including C₈C₁₃ methyl ketones, -octalactone, and phenols. In this study, behavioral respones of teneral G. m. morsitans to different blends of these compounds were evaluated in a choice wind tunnel. The flies' responses to known or putative attractant blends (the latter comprising EAG-active constituents common to all three animals and those common to buffalo and ox, excluding the known tseste attractants, 4-methylphenol and 3-n-propylphenol), and to putative repellent (the blend of EAG-active compounds specific to the waterbuck volatiles), were different. A major difference related to their initial and final behaviors. When a choice of attractant blends (known or putative) and clean air was presented, flies initially responded by flying upwind toward the odor source, but later moved downwind and rested on either side of the tunnel, with some preference for the side with the odor treatments. However, when presented with a choice of waterbuck-specific blend (putative repellent) and clean air, the flies' initial reaction appeared random; flies flew upwind on either side, but eventually settled down on the odorless side of the tunnel. Flies that flew up the odor plume showed an aversion behavior to the blend. The results lend further support to previous indications for the existence of a tsetse repellent blend in waterbuck body odor and additional attractive constituents in buffalo and ox body odors.     

Unusual polymethyl alkenes in tsetse flies acting as abstinon inGlossina morsitans

The major alkene of the male tsetse fly,Glossina morsitans morsitans, was isolated for characterization by thin-layer and gas chromatography (GC). The mass spectra of the alkene and the alkene DMDS derivative indicated one isomer, 19,23-dimethyltritriacont-1-ene. The material is present at 1–2g/male fly and is partially transferred to the female preparatory to or during mating. A dose-dependent antiaphrodisiac effect was seen with exposed male flies using the isolated natural product, with 2 and 4g causing 80% loss of copulatory attempts, and 10g extinguishing the attempts. This effect was increased by addition of male-produced alkane. This compound and a 31-carbon homolog also appear inG. m. submorsitans. Similar quantities of alkenes that are species-specific appear in all tsetse males. Structures of male-produced trimethylalkenes that appear in two other species,G. palpalis palpalis andG. fuscipes fuscipes, were investigated.     

Odor composition of preferred (buffalo and ox) and nonpreferred (waterbuck) hosts of some Savanna tsetse flies

A previous study on the feeding responses of tsetse flies, Glossina morsitans morsitans, implicated the existence of allomonal barriers, both volatile and nonvolatile, on the nonpreferred host, waterbuck, Kobus defassa. In the present study, electroantennogram-active compounds in odors from waterbuck were compared with those of two preferred hosts of tsetse flies, buffalo, Syncerus caffer, and ox, Bos indicus. Odors from the three bovids were trapped on activated charcoal and/or reverse-phase (octadecyl bonded) silica and analyzed with a gas chromatography-linked electroantennographic detector (GC-EAD) and, where possible, identified by using gas chromatography-linked mass spectrometry (GC-MS) and chromatographic comparisons with authentic samples. The GC-EAD profiles (with G. m. morsitans antennae) of the odors of the two preferred hosts were comparable, comprising medium-chain, saturated or unsaturated aldehydes and phenols, with buffalo emitting a few more EAG-active aldehydes. Waterbuck odor gave a richer profile, consisting of fewer aldehydes but more phenolic components and a series of 2-ketones (C₈–C₁₃) and -octalactone. This bovid also emits moderate amounts of C₅–C₉ straight-chain fatty acids, some of which were detected in buffalo and ox only in trace amounts. However, these did not elicit significant GC-EAD responses. Waterbuck profiles from the antennae of G. pallidipes showed broad similarity to those from G. m. morsitans, although the composition of aldehydes and ketones was somewhat different, indicating species-specific difference in the detection of host odors. Certain waterbuck-specific EAG-active components, particularly the 2-ketones and lactone, constitute a candidate allomonal blend in waterbuck odor.     

Demonstration of sex pheromones in caddisflies (Trichoptera)

Field tests with live, caged females and whole-body extracts of females of the caddisflyGumaga griseola (McLachlan) (Trichoptera: Sericostomatidae) demonstrate, for the first time, the existence of a chemically mediated sexual communication system in this insect order. Both live females and extracts are significantly more attractive to conspecific males than either empty control traps or traps baited withGumaga nigricula (McLachlan) females. Anatomical structures suggest that semiochemicals are widespread in Trichoptera.     

Cuticular hydrocarbons of tsetse flies II:Glossina fuscipes fuscipes,G. palpalis palpalis,G. p. gambiensis,G. tachinoides,andG. brevipalpis

The alkanes (methylalkanes) were analyzed from both sexes of four members of thepalpalis group of tsetse flies,Glossina fuscipes fuscipes, G. palpalis gambiensis, G. palpalis palpalis, G. tachinoides plus onefusca group member, G. brevipalpis, to determine structures, abundances, and the presence of unique or specific methylalkanes. These insects are unique in that trimethylalkanes were major components except in femaleG. tachinoides and both sexes ofG. brevipalpis where 2-methylalkanes were the major components. The identification of novel long-chain tetramethylalkanes, including 11,15,19,23-tetramethylpentatriacontane, a minor component of femaleG. f. fuscipes, G. p. gambiensis, andG. p. palpalis, is reported here. Tetramethylalkanes were significant components of both sexes ofG. brevipalpis. The major tetramethylalkane in G.brevipalpis is 3,7,11,15-tetramethylhen-triacontane. The use of the methylalkanes as taxonomic indicators in tsetse is discussed.     

A 4-Alkyl-substituted Analogue Of Guaiacol Shows Greater Repellency To Savannah Tsetse (Glossina spp.)

The responses of Glossina morsitans morsitans Westwood to guaiacol (2-methoxyphenol), a mild repellent constituent of bovid odors, and seven analogues comprising 2-methoxyfuran, 2,4-dimethylphenol, 2-methoxy-4-methylphenol (4-methylguaiacol), 4-ethyl-2-methoxyphenol (4-ethylguaiacol), 4-allyl-2-methoxyphenol (4-allylguaiacol; eugenol), 3,4-methylenedioxytoluene, and 3,4-dimethoxystyrene were compared in a two-choice wind tunnel. The 4-methyl-substituted derivative (2-methoxy-4-methylphenol) was found to elicit stronger repellent responses from the flies compared with guaiacol. None of the other analogues showed significant repellent effects on flies. 4-Methylguaiacol, guaiacol, and eugenol (which was included because of previous reports of its repellency against a number of arthropods) were further evaluated in the field with wild populations of predominantly Glossina pallidipes Austen. The presence of guaiacol or eugenol near odor-baited traps caused some nonsignificant reduction in the number of tsetse catches at relatively high release rates (∼50 mg/hr). In contrast, the 4-methyl derivative at three different release rates (2.2, 4.5, and 9.0 mg/hr) reduced trap catches of baited traps in a dose-response manner. At 10 mg/hr release rate, it reduced the catches of baited and unbaited traps by ∼80 and ∼70%, respectively. In addition, the compound not only reduced the number of tsetse attracted to natural ox odor (∼ 80%), but also had an effect on their feeding responses, reducing the proportion that fed on an ox by more than 80%. Our study shows that the presence of a methyl substituent at the 4-position of guaiacol enhances the repellency of the molecule to savannah tsetse and suggests that 4-methylguaiacol may represent a promising additional tool in the arsenal of techniques in trypanosomiasis control.     

Effect of steam distillate extracts of selected resistant cultivated and wild rices on behavior of leaffolderCnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae)

Rice plant volatiles extracted as steam distillates significantly affected the behavior of the rice leaffolder,Cnaphalocrocis medinalis (Guenée). Leaffolder moths laid significantly fewer eggs on TN1 rice plants treated with extracts of resistant wild species of rice,Oryza officinalis andOryza punctata, than on TN1 plants treated with extracts of resistant cultivated rices. Extracts ofO. officinalis andO. punctata adversely affected egg hatchability.O. officinalis andO. punctata extracts were more toxic to first-instar larvae than extracts of other resistant varieties. Leaf area consumed by the larvae was reduced on TN1 plants treated withO. officinalis andO. punctata extracts compared with that on plants treated with extracts of resistant cultivated rice varieties.     

Growth inhibition ofMusca domestica L. andCulex quinquefasciatus (say) by (−)-3-epicaryoptin isolated from leaves ofClerodendron inerme (Gaertn) (Verbenaceae)

The petroleum ether extract ofClerodendron inerme leaves afforded a compound that matched the clerodane compound (–)-3-epicaryoptin in physical and spectral characteristics. The test compound inhibited the development ofMusca domestica andCulex quinquefasciatus larvae. First- and third-instar fly larvae reared on 3-epicaryoptin-treated diet pupariated later and earlier than their respective controls and adult emergence from puparia was inhibited. Apart from larval mortality, exposure of fourth-instar mosquito larvae to 3-epicaryoptin resulted in death at larval-pupal molt and pupaladult eclosion, indicating inhibition of the molting process.     

Use of chemical variation and predation as plant defenses byEncelia farinosa against a specialist herbivore

Larvae of the monophagous herbivore,Trirhabda geminata, selectively eat particular plants and plant parts of its natural host,Encelia farinosa. Measurements of leaf damage and larval positions on branches through time support this observation. Time-lapse movie photography revealed that larvae are sufficiently mobile to search most of a plant in a 48-hr period and that aggregations were the result of larval activity and not directly the result of oviposition. Experiments withT. geminata larvae on artificial diets containing a range of natural concentrations of chemical extracts fromE. farinosa leaves showed that the larvae grew significantly slower and had a lower overall survivorship at the high concentration. Combining the results of all choice tests, larvae appeared unable to distinguish between high- and low-concentration agar diets. Considered individually, larval preferences for natural production concentrations changed as the season progressed. Early-season larvae preferred low-concentration leaves, while late-season larvae preferred high-concentrations. Measurements of chemical and nitrogen content of leaves selected by larvae in the field confirmed this pattern. Percent parasitism in field-collected larvae increased with season as the larval population decreased. This combination of slowed growth and increasing parasitism and predation is a putative defense strategy ofEncelia farinosa to prevent adaptation by a specialist herbivore to the total range of compounds elaborated.     

Beneficial arthropod behavior mediated by airborne semiochemicals

Heliothis zea (Boddie) larvae fed cowpea seedlings produced volatile semiochemicals to whichMicroplitis demolitor Wilkinson responded in a wind tunnel. However, mostM. demolitor females reared fromH. zea larvae fed an artificial diet were not responsive at emergence to the same volatile semiochemicals. A preflight contact with frass fromH. zea fed cowpea was needed to stimulate a response of sustained flight in a wind tunnel. The most consistent flight response was 7–10 days postemergence. Response resulting from both antennal and ovipositor contact with host frass during preflight stimulation was no better than from antennal contact alone. Chilling the parasitoid pupae rendered most of the emerging females unresponsive to volatile semiochemicals.Hymenoptera: Braconidae.     

Effect of steam distillate extract of resistant wild riceOryza officinalis on behavior of brown planthopperNilaparvata lugens (Stal) (Homoptera: Delphacidae)

Rice plant volatiles extracted as steam distillates significantly affected the behavior of the brown planthopperNilaparvata lugens (Stal). In a choice test, significantly more females settled and fed on tillers of a susceptible rice variety, Taichung Native 1 (TN 1), sprayed with acetone or untreated TN 1 plants than on TN 1 tillers sprayed with the extracts of resistant wild riceOryza officinalis. O. officinalis steam distillate was highly toxic to first-instar nymphs ofN. lugens. Ingestion and assimilation of food by females was significantly reduced on TN 1 plants sprayed withO. officinalis distillate compared to TN 1 plants sprayed with acetone. Application of0. officinalis distillate on TN 1 plants adversely affected hatchability of eggs ofN. lugens.     

Production of pheromone by hairpencil glands of males obtained from interspecific hybridization betweenHeliothis virescens andH. subflexa (Lepidoptera: Noctuidae)

Pheromone produced by the hairpencil glands of interspecific hybrid- and backcross-generation males from crosses betweenHeliothis virescens (F.) withH. subflexa (Gn.) was studied. Males of reciprocal F₁ hybrids, all of which had hairpencil glands morphologically similar to those ofH. virescens, produced neither the same pheromone blend nor amounts of pheromone that were produced by males ofH. virescens. Instead, these hybrid males produced pheromone that was quantitatively and qualitatively similar to that produced byH. subflexa. Hairpencil gland extracts from males obtained from backcrossing F₁ females of either cross to males ofH. subflexa were the same as those ofH. subflexa. However, extracts from backcross males of crosses between F₁ females andH. virescens were variable. Some extracts from these backcross males were like those ofH. virescens while others were either likeH. subflexa or were intermediate between those of the parent species. These results showed that the production of pheromone by the hairpencil glands of hybrid and backcross males is under the dominant regulation of autosomal genes of theH. subflexa genome.     

Multifunctional communication inRiptortus clavatus (Heteroptera: Alydidae): Conspecific nymphs and egg parasitoidOoencyrtus nezarae use the same adult attractant pheromone as chemical cue

The bean bug,Riptortus clavatus lays scattered eggs (as opposed to the egg masses of pentatomids) on host as well as nonhost plants. Therefore, the first feeding stage (second-instar) nymphs emerging from eggs laid on nonhost plants need a signal that enables them to locate a food source at the lowest energy cost. Male-released (E)-2-hexenyl (E)-2-hexenoate, (E)-2-hexenyl (Z)-3-hexenoate, and myristyl isobutyrate play the double role of attractant pheromone for adults as well as aggregation pheromone, which enables the second-instar nymphs to find the host food plant. These male-specific semiochemicals are released only when foodstuff is available. On the other hand, females ofOoencyrtus nezarae, the most effective parasitoid of the host in Kumamoto, Japan (where the field experiments were conducted), utilize these semiochemicals as kairomones in order to locate the potential host community. Field experiments revealed that the synthetic pheromone rivaled 10 live males in the attraction of adults and second-instar nymphs. Captures of the egg parasitoidO. nezarae females in cylindrical sticky traps were significantly higher in traps baited with the synthetic semiochemicals than in control traps. The number of females captured was significantly higher than the number of males, although the captures in the sticky suction trap system revealed that the populations of male and female were not significantly different.     

Receptors of sex pheromones and abstinons inMusca domestica andGlossina morsitans

Receptors arranged in two pairs on the inner and outer sides of the proximal end of the tibia of legs ofMusca domestica L. andGlossina morsitans morsitans Westwood are described here for the first time. In the male fly, these receptors function in perception of sex pheromones, as demonstrated in experiments in which the sense organs were coated with paraffin. Similar techniques showed that sense organs for abstinon are located on the tarsi. Scanning electron microscopy and light microscopy show that the tibial sense organs ofMusca may be sensilla of the coeloconic type.     

Cross-attraction between two species ofMatsucoccus

In laboratory bioassays, males ofMatsucoccus resinosae fromPinus resinosa in New York andMatsucoccus n. sp. fromPinus thunbergiana in Korea were strongly attracted to crude hexane extracts ofM. resinosae females, andM. resinosae males responded strongly to extracts ofMatsucoccus n. sp. females. Males of the two species responded similarly to gas chromatographic fractions and subfractions of a pentane extract ofM. resinosae females. Sex pheromones of these two species appear to be the same or very similar.Homoptera: Coccoidea: Margarodidae.     

Communication ecology of webbing clothes moth: 2. Identification of semiochemicals mediating attraction of adults to larval habitat

Our objective was to identify the semiochemicals that mediate attraction of the webbing clothes moth (WCM), Tineola bisselliella (Lepidoptera: Tineidae), to suitable larval habitat. Coupled gas chromatographic-electroantennographic detection (GC-EAD) analyses of Porapak Q-captured bioactive volatiles from horseshoe crab, and dried but untanned vertebrate pelts revealed numerous EAD-active volatiles. These volatiles were identified by comparative GC-mass spectrometry and GC-EAD analyses of natural and synthetic compounds. A blend of 28 synthetic candidate semiochemicals attracted both male and female WCM. Experiments deleting various components determined that saturated aldehydes—but not unsaturated aldehydes, saturated hydrocarbons, saturated alcohols, or ketones—were essential for blend attractiveness. A blend of nonanal, the single most attractive aldehyde, in combination with geranylacetone was more attractive to WCM than the 28-component blend or dried, untanned animal pelt. Selection of larval habitat resides more with male than female WCM, as indicated by stronger EAD responses from male than female antennae to habitat-derived semiochemicals, and more selective and early response to habitat cues by males than females. Exploitation of nonanal and geranylacetone as resource-derived semiochemicals by both adult WCM and its larval parasitoid, Apanteles carpatus, is an example of convergent semiochemical parsimony.     

Search for tsetse attractants: A structure-activity study on 1-octen-3-ol inGlossina fuscipes fuscipes (Diptera: Glossinidae)

Trapping tsetse flies belonging to thepalpalis group still relies totally upon luring by visual cues even though odor-baited trapping is used effectively against themorsitans-group species. Forty-three percent of the antennal olfactory cells ofGlossina f. fuscipes, a member of thepalpalis group, respond to 1-octen-3-ol. For this species we report a structure-activity relationship between 1-octen-3-ol analogs, in which carbon chain length and the configuration of the hydroxyl and -bond moieties are varied, and biological activity. Although the optimum chain length for all cells sensitive to 1-octen-3-ol is eight and most cells give lower responses when the hydroxyl function is omitted, there is a clear division into two groups. One group is diverse and represents cells that appear indifferent to the presence or position of the bond; many will respond to such disparate structures as acetone and 3-methylphenol as well as to 1-octen-3-ol. In the other group, the structural requirements for the stimulus are more stringent; the cells appear to be specifically tuned to 1-octen-3-ol. Their thresholds are three orders of magnitude lower than those of the former group. The existence of two clusters points to a functional division in the olfactory sense. We suggest that the latter low-threshold group is involved in host detection from a distance while the former diverse group is involved in host discrimination at close range. Trap harvests with 1-octen-3-ol as a bait may have been disappointing because the appropriate mixture for generating a landing response on the traps is still lacking.     

Crude extracts of asteraceous weeds

Petrol and ethanolic extracts of six asteraceous weeds were added to artificial diets to screen for growth inhibition and mortality of the variegated cutworm,Peridroma saucia (Hbn). Petrol and ethanolic extracts ofArtemisia tridentata andChamomilla suaveolens and ethanolic extracts ofChrysothamnus nauseosus andCentaurea diffusa severely inhibited larval growth at five times the natural concentrations. The twoC. suaveolens extracts and the ethanol extract ofA. tridentata were active at the natural concentration (100%) and were further examined at 20, 40, 60, and 80% of this level. Inhibition of larval growth was directly related to concentration for each of the three extracts tested. EC₅₀s (effective concentration to inhibit growth by 50% relative to controls) for the three extracts were 36–42% of the naturally occurring level in the plants. Nutritional indices were calculated for secondinstarP. saucia feeding on the activeA. tridentata EtOH extract and the petrol extract fromC. suaveolens. Addition of the activeA. tridentata EtOH or theC. suaveolens petrol extract to the diet resulted in significant reduction in the relative growth rate of larvae, although theA. tridentata extract was much more inhibitory. Dietary utilization was significantly lower for larvae fed theA. tridentata EtOH extract.