Evidence for a female sex pheromone in the brassica pod midge Dasineura brassicae

ABSTRACT. The responses of Dasineura brassicae Winn. (Diptera, Cecidomyiidae) to odours from both male and female midges and from their host ( Brassica napus ) and non-host ( Vicia faba ) plants were studied using a Y-tube olfactometer. Female but not male D. brassicae are attracted to crushed B. napus leaves but not to those of V. faba. Males are attracted to live virgin females, to crushed virgin and mated females and to hexane washes of females, suggesting that the female produces a sex pheromone that attracts males. Males were also attracted to hexane washes of female ovipositors, but not to washes of the bodies of females without ovipositors, suggesting that the ovipositor is the site of pheromone release or production. Males were not attracted to live mated females or to other live or crushed males and mated females were not attracted to other mated females.     

Plant volatiles and density-dependent conspecific female odors are used by Asian citrus psyllid to evaluate host suitability on a spatial scale

We investigated how chemical cues derived from female Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae) and their host plants affect host acceptance choices by conspecifics. In four-choice cage and two-choice olfactometer assays, female psyllids avoided conspecific female cues in a density-dependent manner. However, odors from citrus plants actively damaged by psyllid feeding were attractive to conspecific females. When odors from feeding-damaged plants were presented simultaneously with odors from female D. citri, attraction of female conspecifics was no longer observed as compared with a clean air control in olfactometer assays. In subsequent experiments, D. citri females were released within arenas that contained actively feeding-damaged or non-damaged (control) citrus plants, each with previously psyllid-infested and uninfested young leaves. D. citri development is linked to the presence of these newly emerging leaves which is the only site of nymphal development. Female D. citri were initially attracted by the actively damaged plants as compared with non-damaged controls. After acceptance of plants that were actively damaged by feeding, D. citri females preferentially chose and settled on uninfested young leaves as compared with previously infested young leaves. A herbivore-induced plant volatile attractant and a female-specific odor repellent appear to be complementary foraging cues providing psyllids with information at two spatial scales: (1) the whole plant level for choosing a plant potentially harboring male conspecifics for mating, and (2) the within plant level to reduce intra-conspecific competition by identifying previously exploited resources.     

Attraction of pepper weevil to volatiles from damaged pepper plants

Pioneer herbivorous insects may find their host plants through a combination of visual and constitutive host‐plant volatile cues, but once a site has been colonized, feeding damage changes the quantity and quality of plant volatiles released, potentially altering the behavior of conspecifics who detect them. Previous work on the pepper weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae), demonstrated that this insect can detect and orient to constitutive host plant volatiles released from pepper [Capsicum annuum L. (Solanaceae)]. Here we investigated the response of the weevil to whole plants and headspace collections of plants damaged by conspecifics. Mated weevils preferred damaged flowering as well as damaged fruiting plants over undamaged plants in a Y‐tube olfactometer. They also preferred volatiles from flowering and fruiting plants with actively feeding weevils over plants with old feeding damage. Both sexes preferred volatiles from fruiting plants with actively feeding weevils over flowering plants with actively feeding weevils. Females preferred plants with 48 h of prior feeding damage over plants subjected to weevil feeding for only 1 h, whereas males showed no preference. When attraction to male‐ and female‐inflicted feeding damage was compared in the Y‐tube, males and females showed no significant preference. Wind tunnel plant assays and four‐choice olfactometer assays using headspace volatiles confirmed the attraction of weevils to active feeding damage on fruiting plants. In a final four‐choice olfactometer assay using headspace collections, we tested the attraction of mated males and virgin and mated females to male and female feeding damage. In these headspace volatile assays, mated females again showed no preference for male feeding; however, virgin females and males preferred the headspace volatiles of plants fed on by males, which contained the male aggregation pheromone in addition to plant volatiles. The potential for using plant volatile lures to improve pepper weevil monitoring and management is discussed.     

Mating behavior of Diabrotica speciosa (Coleoptera: Chrysomelidae)

Diabrotica speciosa (Germar) is an economically important pest of Neotropical cultures and represents a quarantine risk for Neartic and Paleartic Regions. Despite its agricultural importance, few studies have been done on mating behavior and chemical communication, which has delayed the development of behavioral techniques for population management, such as the use of pheromone traps. In this study, we determined 1) the age at first mating; 2) diel rhythm of matings; 3) number of matings over 7 d; 4) the sequence of D. speciosa activities during premating, mating, and postmating; 5) the duration of each activity; and 6) response to male and female conspecific volatiles in Y-tube olfactometer. The first mating occurred between the third and seventh day after adult emergence and the majority of pairs mated on the fourth day after emergence. Pairs of D. speciosa showed a daily rhythm of mating with greater sexual activity between the end of the photophase and the first half of the scotophase. During the 7 d of observation, most pairs mated only once, although 30% mated two, three, or four times. In a Y-tube olfactometer, males were attracted by virgin females as well as by the volatile compounds emitted by females. Neither males nor their volatiles were attractive to either sex. Our observation provide information about mating behavior of D. speciosa, which will be useful in future research in chemical communication, such as identification of the pheromone and development of management techniques for this species using pheromone traps.     

Male Diachasma alloeum parasitoids from two host species of tephritid fruit flies respond equally to female-produced sex pheromone

Abstract.  Diachasma alloeum is a braconid wasp that parasitizes hawthorn-infesting Rhagoletis pomonella and blueberry-infesting Rhagoletis mendax , both tephritid fruit fly sibling species. The behavioural responses of male D. alloeum originating from both fruit fly host species to hexane extracts of conspecific females originating from both host species and females of various mating status are investigated in a laboratory Y-tube olfactometer. Male D. alloeum originating from either R. mendax or R. pomonella respond to one whole-body, female equivalent hexane extract in equal frequency as to a live, virgin female; this response is at least 7.5-fold greater than to solvent controls. Male D. alloeum originating from R. mendax or R. pomonella are attracted to hexane extracts of female D. alloeum abdomens but not to extracts of the head and thorax regions. Virgin D. alloeum females attract significantly more male D. alloeum originating from either host species compared with mated females of the same age. Copulation behaviour between same host and mixed host pairs appears to be identical. Male D. alloeum are equally responsive to the female-produced sex pheromone of female D. alloeum , irrespective of females' host-species origin, suggesting that these host-specific populations can potentially interbreed.     

Role of the plant–conspecific complex in host location and intra-specific communication of Lygus rugulipennis

Abstract.  Wind tunnel and vertical open Y-shaped olfactometer studies are used to test whether volatile cues from the host plant ( Vicia faba ), from conspecific bugs, and from a plant–conspecifics combination, would elicit behavioural responses in mated males and females of Lygus rugulipennis . In the olfactometer, females move towards volatiles from healthy plants but they do not respond to volatiles released by oviposition- and/or feeding-damaged plants without conspecifics, nor to conspecifics alone. Both in the wind tunnel and olfactometer, females respond to volatiles emitted by the plant–insect complex. By contrast, in the wind tunnel, both sexes move significantly towards damaged host plants, even if the presence of conspecifics on these plants enhances only the female response. However, the presence of eggs from conspecifics on host plants reduces the responses of both sexes in the wind tunnel. Finally, males, as well as females, are less responsive to conspecifics alone compared with damaged plants, especially when conspecifics are present on the host plants (host plant– Lygus complex). The results suggest that volatiles emitted by plants and conspecifics influence L.   rugulipennis behaviour, giving information to both sexes on the presence of suitable host plants that have been colonized by other conspecifics acting as pioneers, or providing information on the presence of an already exploited host plant (presence of eggs), thus preventing competition. Males also can use this information to increase the probability of encountering mature females.     

Repellent effect of guava leaf volatiles on settlement of adults of citrus psylla, Diaphorina citri Kuwayama, on citrus

Abstract  The Asiatic citrus psyllid ( Diaphorina citri Kuwayama [Hemiptera: Sternorrhyncha: Psyllidae]) is a vector of huanglongbing (citrus greening), a devastating disease of citrus caused by phloem-limited bacteria. Growing guava ( Psidium guajava ) as an intercrop appears to be a successful means of reducing psyllid numbers within citrus orchards; however, the mechanism by which such a reduction is achieved is unknown. To determine the repellent effect of guava leaf and factors attributed to this activity, responses of adult psyllids to guava leaf and its odor were evaluated in cage tests and Y-tube olfactometer test. The results showed that guava leaf possessed a repellent effect against the adult citrus psyllids. Fewer psyllids were found on citrus leaves in the presence of guava foliage than in its absence. Young and old guava leaf showed equal repellent activity. By covering the guava shoots with net cloth, it was revealed that the repellent effect of guava leaf against adult psyllids on citrus was attributed to the volatile compounds, rather than physical factors. The olfactometer response of adult psyllids to guava leaf odor was dosage-dependent. Between guava odor and control, only 35.00%, 25.00% and 16.25% of the psyllids moved toward guava odor when presented with 5.0, 10.0 and 15.0 g of guava shoots, respectively. The olfactometer experiments also showed that both male and female psyllids responded similarly to the guava leaf odor.     

雌星豹蛛性信息素的行为学证据

采用星豹蛛(Pardosa astrigera)成熟雄蛛求偶时潜伏时间、静止时间、身体震动和第一墩步足伸展次数等行为参数,利用行为学方法测定了不同性别、日龄和生殖状态的星豹蛛雌蛛释放的拖丝对雄蛛求偶行为的影响。结果表明,雄蛛第一对步足伸展和身体震动等典型求偶行为是进行星豹蛛性信息素生物测定的可靠评价指标。星豹蛛雄蛛能通过拖丝上的性信息素辨别星豹蛛的性别、日龄和生殖状态。雄蛛在成熟3周未交配雌蛛拖丝处理过滤纸上潜伏时间和静止时间都相应最短,在交配未产卵雌蛛、雌亚成蛛和成熟雄蛛拖丝上时间中等,在卵孵化雌蛛拖丝处理滤纸上潜伏时间和静止时间都相应最长。成熟3周未交配雌蛛和交配未产卵雌蛛释放的拖丝都能引起雄蛛第一对步足伸展和身体震动等典型求偶行为,雄蛛对成熟3周未交配雌蛛拖丝典型求偶行为的频率都相应高于交配未产卵雌蛛。卵孵化雌蛛释放的拖丝虽也能引起雄蛛第一对步足伸展行为,但其伸展频率显著降低;而其它拖丝都不能引起雄蛛典型求偶行为。     

Effect of age and time of day on sex attraction and mating of the face fly, Musca autumnalis

A well-defined sexual attraction exists between mature virgin female and mature unmated male face flies, Musca autumnalis, tested in a Y-tube olfactometer. Attraction seems to be maximum when females are 5 to 6 days old and males are 4 to 8 days old post emergence. Gonadotrophic cycles probably play a rôle in the periodicity of the sexual attraction. Attraction as well as insemination reach a peak during the noon hours, gradually decline through the afternoon, and reach a minimum level in the evening. A daily rhythm of sex pheromone release and/or production is most probably present in virgin female flies.     

Behavioral Response of <Emphasis Type="Italic">Tamarixia radiata</Emphasis> (Waterston) (Hymenoptera: Eulophidae) to Volatiles Emanating from <Emphasis Type="Italic">Diaphorina citri</Emphasis> Kuwayama (Hemiptera: Psyllidae) and Citrus

Tamarixia radiata Waterston (Hymenoptera: Eulophidae) is an effective idiobiont ectoparasitoid of the psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae), vector of the huanglongbing (HLB). We examined the olfactory responses of T. radiata to volatiles emanating from D. citri or plant volatiles using a custom designed T-maze olfactometer and open arena bioassays. We also examined the behavioral response of male and female T. radiata to conspecifics of the opposite sex to determine whether olfactory signals mediate mate location. T. radiata adults exhibited a sexually dimorphic response to volatiles emanating from D. citri and citrus. Female T. radiata responded positively to the odors emanating from D. citri nymphs in both olfactometer and open arena bioassays. However, female wasps showed no response to odors emanating from D. citri adults, D. citri honey dew secretions, intact citrus or orange jasmine leaves. Odors emanating from D. citri damaged citrus were not attractive to T. radiata females but stimulated attraction of wasps to D. citri on damaged plants. T. radiata females were not attracted to D. citri immatures when they were presented as visual cues. Male T. radiata did not show attraction to D. citri nymphs or other putative odors that were attractive to female T. radiata. In olfactometer bioassays, more male T. radiata responded to the odor of female conspecifics than blank controls in the absence of associated citrus host plant volatiles. Odors emanating from female T. radiata were not attractive to male T. radiata. Male or female T. radiata were not attracted to the odors emanating from same sex conspecifics. Both male and female T. radiata adults showed positive phototactic behavior. Collectively, our results provide behavioral evidence that: 1) female T. radiata use volatiles emanating from D. citri nymphs to locate its host and: 2) female T. radiata release a volatile pheromone that attracts male conspecifics.     

Communication ecology of webbing clothes moth: attractiveness and characterization of male-produced sonic aggregation signals

Abstract:  We tested the hypothesis that the webbing clothes moth, Tineola bisselliella (Hum.) (Lep., Tineidae), uses sonic signals in addition to pheromonal signals for communication. To record sound from individual or groups of moths of either or both sexes, we used a digital recording system, microphones sensitive to sonic and/or ultrasonic frequencies, and speakers capable of emitting sonic and ultrasonic sound. In a soundproof environment, male T. bisselliella produced sounds of 27 decibels (dB, sound pressure level; 0 dB corresponds to 20  μ Pa), with a base frequency of 40–50 Hz and a harmonic frequency of 80–100 Hz. Sound intensity and frequency increased to 55 dB and 65–75 Hz (with ≥3 harmonic frequencies), respectively, when calling males were near (<2 cm) conspecifics of either sex. There was no evidence that females produce sound and no evidence for ultrasonic sound production by either sex. In Y-tube bioassay experiments, virgin male and female T. bisselliella preferred played-back sonic signals from males to silent control stimuli, whereas mated females showed no preference for either stimulus. In arena bioassay experiments, males as well as virgin and mated females preferred played-back sonic signals from males over a white noise control. Use of pheromonal and sonic signals by T. bisselliella would be adaptive, because the capacity for sonic communication persists even if sensory adaptation or habituation to pheromonal signals occurred. This hypothesis is consistent with the fact that other inhabitants of enclosed microhabitats, such as the greater wax moth, Galleria mellonella L., and Indian meal moth, Plodia interpunctella (Hb.), have also evolved analogous multimodal communication systems.     

Mating Effect on Sex Pheromone Production of the Oriental tobacco budworm,Helicoverpa assulta

This study was undertaken to clarify the suppression phenomenon of sex pheromone production after mating and its relationship to the physiological mechanism in adult females of Helicoverpa assulta, and determine the mating factor from males causing depletion of sex pheromonc production. Sex pheromone production of H. assulta females was mostly terminated in 3 hours after mating. Mated females maintained with a low titer of sex pheromone until 3 days when it started to increase again, which showed a characteristic of species mating more than once. The mated female again produced pheromone upon injection of pheromone biosynthesis activating neuropeptide (PBAN) or extracts of brain-suboesophageal ganglion complexes (Br-Sg) of mated female, which were shown similar pheromonotropic activities as compared with virgin females. These results indicated that the mating did not inhibit the receptivity of pheromone gland itself and PBAN biosynthesis in suboesophageal ganglion of the mated females. And it seems to support that the depletion of sex pheromone production is responsible for blocking of PBAN release from head. To investigate the mating factor from adult males, when extracts of reproductive organs of male were injected into hemocoel of virgin females evoking depletion of sex pheromone production as shown in mated female. The results suggest that a chemical substance(s) from the male reproductive organs could be responsible for the loss of sex pheromone biosynthesis in H. assulta.     

Prey Habitat Location by the Cassava Mealybug Predator Exochomus flaviventris: Olfactory Responses to Odor of Plant, Mealybug, Plant–Mealybug Complex, and Plant–Mealybug–Natural Enemy Complex

Exochomus flaviventris Mader is considered to be the most active predator of the cassava mealybug Phenacoccus manihoti Matile–Ferrero in Central Africa. The response of experienced gravid female coccinellids to the odor of cassava plant (var. Zanaga), unparasitized mealybugs, plant–mealybug complex with or without feeding prey (parasitized or not), and plant–mealybug complex with or without conspecific coccinellids was investigated in a Y-tube olfactometer. The odor of uninfested cassava plants was not more attractive than clean air. Dual-choice tests revealed that mealybug-infested plants were preferred to mealybugs alone and mealybug-damaged plants and were the major sources of volatiles that attract females coccinellids to the microhabitat of its prey. The emission of volatile chemicals did not appear to be limited to the infested parts of the plant but did occur systemically throughout the plant. The presence of conspecific coccinellid larvae or adult males did not modify the attractiveness of the mealybug-infested plants. However, when an infested plant with conspecific predator females (alone or with conspecific males) was compared to an infested plant or infested plant with conspecific males, E. flaviventris females showed a preference for the last two sources of odor. The uninfested plant with conspecific males was also preferred to the uninfested plant with conspecific females. In addition, the odor of conspecific males was preferred over that of conspecific females. Female predators preferred the plant infested with unparasitized mealybugs over the plant infested with mealybugs previously parasitized. These results showed that E. flaviventris females use herbivore-induced plant volatiles during foraging and can detect via olfaction the presence of conspecific gravid females and parasitized prey, thus assessing patch suitability from a distance.     

Sex‐specific responses of Asian citrus psyllid to volatiles of conspecific and host‐plant origin

Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is the primary vector of Candidatus Liberibacter spp. bacteria that cause citrus greening, a disease of worldwide importance. Olfactometry was employed to test responses of D. citri to odours from intact citrus plants (Mexican lime, Citrus aurantifolia, sour orange, Citrus aurantium, Marsh grapefruit, Citrus paradisi and Valencia orange, Citrus sinensis), citrus plants previously infested with D. citri, and odours of conspecifics including nymphs, adult insects of same and opposite sex, and their products (honeydew), both alone and in combination. In contrast to other studies, psyllids of both sexes were attracted to volatiles of undamaged Mexican lime leaves, whereas undamaged grapefruit attracted only females, and leaves of Valencia and sour orange did not attract either sex. All four plant species attracted female psyllids when previously infested, but only Mexican lime and sour orange‐attracted males. Thus, Citrus species appear to vary in the production of both constituitive and induced volatiles that attract adult psyllids. Volatiles emitted by nymphs did not attract either sex, but psyllid honeydew was attractive to males, likely due to female pheromone residues. Males oriented to the odour of females, whereas the reverse was not true, and neither males nor females oriented to same‐sex volatiles. The addition of conspecific cues (adults, nymphs or honeydew) did not increase female attraction to previously infested leaves, but male response was increased by the presence of adults and honeydew, regardless of plant species. Thus, female psyllids appear to orient more strongly to volatiles of plant origin, whereas males respond more strongly to cues emanating from females and conspecific excretions. These results suggest that female psyllids drive the initial colonization of host plants, whereas males orient to females and infested plants. Identification of the specific volatiles involved may permit their use in monitoring and management of this pest.     

Mechanisms of pheromone inactivation in the gut of Periplaneta americana

The sex attractant of the cockroach, Periplaneta americana, has been shown in earlier work to be largely inactivated by dissected midgut from males and from mated females. It is only slightly inactivated by the midgut from virgin females. In this paper, the sex pheromone inactivating system is further studied and shown to be active in late instar larvae of both sexes. In the male this pheromone inactivation is inhibited by piperonyl butoxide, a microsomal oxidase inhibitor. This compound appears to act on the midgut tissue directly. In the mated female, piperonyl butoxide has little effect. When the pheromone inactivating capacity is partitioned into soluble and tissue components, it appears that the soluble component is most active in the male, whereas the tissue component is most active in the female. Evidence from heat inactivation, trichloracetic acid precipitation, and the use of soy bean trypsin inhibitor, as well as the time course of the reaction, suggest that the factor or factors inactivating pheromone are proteins, probably enzymes. Evidence that at least part of the pheromone inactivating capacity is due to microsomal oxidases is considered. It is also observed that both pheromone and piperonyl butoxide absorb to membranes.     

A female‐produced short‐range sex pheromone in the egg parasitoid Trissolcus brochymenae

The potential for short‐range sex pheromone communication by the egg parasitoid wasp Trissolcus brochymenae (Hymenoptera: Platygastridae) was investigated in closed arena bioassays. Males of this parasitoid showed more antennal drumming and more frequent mounting behaviour on 1‐ to 2‐d‐old virgin females compared with 8‐d‐old virgin females. Male copulation attempts were fewer with previously mated females than with virgin females. Males courted and made copulation attempts with 1‐ to 2‐d‐old female cadavers, but not with male cadavers or with female cadavers rinsed in organic solvents of different polarities. Male attraction to female cadavers was re‐established by treating cadavers with acetone extracts of females, but not with ether or hexane extracts. In experiments using female cadavers dissected into head, mesosoma, and gaster, and then reassembled using one unwashed body section and two body sections washed in acetone, males were attracted only to the reassembled cadavers with an unwashed mesosoma. These findings suggest that (1) courtship behaviour in males of T. brochymenae is triggered by a short‐range sex pheromone produced by females; (2) the age and the physiological condition of females (virgin/mated) influence pheromone release or production; (3) the female's mesosoma is the source of the sex pheromone; and (4) polar components of the sex pheromone play a major role in influencing male behaviour. Our results suggest that quasi‐gregarious egg parasitoids are selected for short‐range rather than long‐range sex pheromones.     

Attraction of male winterform pear psylla to female-produced volatiles and to female extracts and evidence of male–male repellency

Pear psylla, Cacopsylla pyricola (Förster) (Homoptera: Psyllidae), is a major pest of commercial pears in North America and Europe. Olfactometer trials have shown that males of both the summer and winter morphotype are attracted to female-infested host material. Additional work with the summer morphotype has shown that males are attracted to females even in the absence of the host plant, which is evidence that female C. pyricola produce a volatile sex attractant. Here, we describe similar results with the winterform, confirming for this morphotype that the female psylla rather than the infested host material is the source of the attractant. Male winterforms displayed attraction to odors from live females in the absence of the host plant, freshly killed females, and female whole body extracts. The female whole body extracts were at least as attractive as a comparable number of live females, suggesting that we were successful at extracting the components of the attractant with this procedure. All previous olfactometer trials with C. pyricola used the insect as the attractant source; the current study is the first to demonstrate that volatile chemicals isolated from the female insect were attractive to male conspecifics. Winterform males were also assayed to odors produced by conspecific males. We found that male psylla avoided volatile odors from live males, freshly killed males, or whole body extracts of males. To our knowledge, these results are the first indication that males of any member of the Psyllidae avoid odors associated with conspecific males.     

Mate Finding Via a Trail Sex Pheromone by <Emphasis Type="Italic">Aphytis melinus</Emphasis> DeBach (Hymenoptera: Aphelinidae) Males

Finding mates is frequently problematic for parasitoid wasps. In some parasitoid species, males rely on volatile, airborne sex pheromones for locating mates, while in others they rely on contact, trail sex pheromones. This study sought to shed light on the mate finding mechanism of males of Aphytis melinus. Specifically, the goal was to determine whether A. melinus males use airborne or contact pheromones, or both, for locating mates. The study showed that A. melinus males rely on a contact, trail sex pheromone for locating mates: A. melinus males responded to substrate-borne cues left by virgin females, while they did not respond to airborne cues from virgin females. Specifically, males more frequently encountered virgin females when the females walked across an arena to a fixed encounter point compared to when they were manually placed at the encounter point, and spent greater than expected time on surfaces previously visited by virgin females compared to control surfaces not visited by females. In contrast, males did not respond to airborne cues from virgin females in an airflow olfactometer nor to traps baited with virgin females in the field, and spent similar lengths of time on surfaces visited by newly-mated or 24-h mated females versus control surfaces not visited by females. The main effect of the trail sex pheromone on the behavior of A. melinus males was to direct their search and, so, increase the likelihood of encountering mates. This effect apparently is not preceded by longer-range attraction of males via an airborne female sex pheromone. Overall, the results of this study support a hypothesis in which A. melinus males searching on substrates on which females may be present rely exclusively on a trail sex pheromone to locate mates.     

Sex attraction in Bactericera cockerelli (Hemiptera: Triozidae)

The potato psyllid, Bactericera (=Paratrioza) cockerelli (?ulc) (Hemiptera: Triozidae), is a major pest of potato. We examined the role of chemical signals in sex attraction, assessing male and female response to male- and female-produced volatile chemicals. In laboratory olfactometer assays, potato psyllid males were attracted to odorants emitted from live females and from solvent extract of females. These results indicate that the female-produced chemicals responsible for attracting males may be isolated by means of insect extractions. Males were also attracted to volatile chemicals from males and extracts of males, providing the first example of male-male attraction in the Psylloidea. Males exposed simultaneously to odorants from conspecific females and males were preferentially attracted to female odorants, suggesting the presence of a female-specific sex attractant for males. Potato psyllid females avoided volatile chemicals emitted by females and extracts of females and by volatile chemicals emitted by males and extracts of males. Possible explanations for avoidance of conspecifics by females are discussed. This study is the first report of male attraction to volatile chemicals emitted by females and female extracts in the Triozidae and more specifically in the potato psyllid.     

Males of Hylamorpha elegans burmeister (Coleoptera: Scarabaeidae) are attracted to odors released from conspecific females

The behavioral responses of Hylamorpha elegans L. (Coleoptera: Scarabaeidae, Rutelinae) to the semiochemicals released from conspecific individual adults were studied, with particular attention paid to female attraction of males. Odors released from virgin females significantly attracted male conspecifics in both the field and laboratory olfactometer and wind tunnel bioassays. However, females did not attract other females, and males attracted no one. The response of male H. elegans to (1) compounds (1,4-hydroquinone and 1,4-benzoquinone) released only by unmated females; (2) the essential oil of the secondary host (Nothofagus obliqua); and (3) the blend of 1,4-hydroquinone and 1,4-benzoquinone with N. obliqua essential oil was studied. The blend of 1,4-benzoquinone mixed with essential oil at the trial concentration was attractive with males. The same response was found with 1,4-hydroquinone alone. The essential oil did not have the expected attractant effect on conspecific males. These results suggest that, when combined with essential oil, 1,4-benzoquinone may function in the sexual behavior of males and females. These findings are discussed in terms of the ecological role of this putative sexual pheromone and its potential use in a strategy of control of this pest.