Prostephanus truncatus mate choice on contact: does pheromone signalling by males affect their mating success? (original) (raw)
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Contact pheromones of 2 sympatric beetles are modified by the host plant and affect mate choice
Behavioral Ecology, 2016
Host-plant shifts have significantly contributed to the diversification of phytophagous insects. The contact sex pheromones of such insects may be modified by the plant they feed on, thereby contributing to the formation/maintenance of sister species on different plants. Here, we addressed this issue using 2 sister species of specialist phytophagous flea beetles Altica fragaria and Altica viridicyanea, and their oligophagous F 1 hybrids. Specifically, we tested 1) if males from these Altica species recognize conspecific females based on their cuticular hydrocarbon (CHC) profile, 2) if the host plant affects the CHC profile of hybrid females, and 3) whether hybrid males distinguish between hybrid females raised on different host plants. Mate choice tests revealed that males use CHCs to identify conspecific mates. We then identified different CHC profiles in females of the 2 species and showed that the profile of CHCs in hybrids is modified by the host plant in which the beetles develop. Finally, we found that hybrid males raised on one host plant choose females with a matching profile, but this is not the case for males raised on the other plant. Our results suggest that plasticity in the expression of CHCs may have contributed to the original speciation process between the parental species. This reinforces the key role of host plants in shaping the evolution of reproductive isolation among herbivore populations.
2000
The ability of both male and female Prostephanus truncatus beetles to distinguish between the aggregation pheromone signals of two closely located conspecific male beetles was investigated by using an olfactometer. Beetles detected variation between male signalers and visited some signalers more than others. Beetles of both sexes were found to make the same choices. These patterns of preference were found to be mirrored in trap catches of dispersing beetles when single males were used to bait flight traps that were placed in pairs in a woodland habitat in Ghana. The results are discussed with reference to the hypothesis that males signal primarily to attract mates and, therefore, features of the aggregation-pheromone signal may be sexually selected. The implications of the results for current and possible future pest-management tools are also explored.
Environmental Entomology, 2018
Dendroctonus rufipennis (Kirby, Coleoptera: Curculionidae) uses pheromone blends containing aggregative components (frontalin, verbenene, 1-methyl-2-cyclohexen-1-ol [MCOL], and seudenol) and an anti-aggregative component (3-methyl-2-cyclohexen-1-one [MCH]) to coordinate attacks against host trees, but little is known about the influence of external stimuli on pheromone production. We conducted feeding experiments followed by pheromone extractions to determine if feeding duration and mate presence affected pheromone production in D. rufipennis. Unfed beetles of both sexes produced very little of any pheromone component. Females fed for 48 h produced significantly more MCH and MCOL compared to those which fed for 24 h. Males fed for 48 h produced significantly less seudenol than those which fed for 24 h. Male presence did not significantly affect female pheromone production. We propose that the pheromone blend produced by beetles transitions from aggregative to anti-aggregative shortly after colonizing a host, regardless of mate presence.
Journal of Stored Products Research, 1996
Studies were conducted on the effect of age and sex on the response of Prostephunus truncatus (Horn) to its male-produced pheromone using a laboratory walking bioassay. P. truncatus adults responded to pheromone from two days of age, but the level of response significantly decreased gradually from 2-10 days of age: newly-emerged, younger beetles seemed to respond more quickly and stay longer in the vicinity of pheromone soorce than older beetles. There was no significant effect of sex in the level of response to pheromone. The results are discussed in relation to the function of the pheromone: a feeding-based role. The practical implications of the findings on the pest's monitoring using pheromone-baited traps are also highlighted. Copyright 0 1996 Elsevier Science Ltd Key &to&-larger grain borer, Prostephunus truncutus, aggregation pheromone, response, walking bioassay
Animal Behaviour, 2004
Males of many insect species, including beetles, choose their mates according to their reproductive status. However, the ways in which male beetles evaluate female reproductive status have received little attention. We tested the existence of male mate choice in the mealworm beetle, Tenebrio molitor, by observing mating and courtship behaviour of males given simultaneous access to pairs of females differing in their reproductive status: (1) mature versus immature; (2) virgin versus previously mated; (3) familiar (mated with the experimental male) versus unfamiliar (mated with a different male). Males courted and mated preferentially with mature and virgin females. To determine whether chemical cues played a role in these discriminations, we exposed males to filter paper squares bearing chemical cues from different types of females: (1) virgin versus mated; (2) mature versus immature. Males were significantly more attracted to those squares bearing chemical cues from virgin and mature females, suggesting that males can assess female reproductive status on the basis of chemical cues alone.
Rival male chemical cues evoke changes in male pre- and post-copulatory investment in a flour beetle
Behavioral Ecology, 2015
Males can gather information on the risk and intensity of sperm competition from their social environment. Recent studies have implicated chemosensory cues, for instance cuticular hydrocarbons (CHCs) in insects, as a key source of this information. Here, using the broad-horned flour beetle (Gnatocerus cornutus), we investigated the importance of contact-derived rival male CHCs in informing male perception of sperm competition risk and intensity. We experimentally perfumed virgin females with male CHCs via direct intersexual contact and measured male pre-and post-copulatory investment in response to this manipulation. Using chemical analysis, we verified that this treatment engendered changes to perfumed female CHC profiles, but did not make perfumed females "smell" mated. Despite this, males responded to these chemical changes. Males increased courtship effort under low levels of perceived competition (from 1-3 rivals), but significantly decreased courtship effort as perceived competition rose (from 3-5 rivals). Furthermore, our measurement of ejaculate investment showed that males allocated significantly more sperm to perfumed females than to control females. Together, these results suggest that changes in female chemical profile elicited by contact with rival males do not provide males with information on female mating status, but rather inform males of the presence of rivals within the population and thus provide a means for males to indirectly assess the risk of sperm competition.
Insect Science, 2020
Longhorn beetles are among the most important groups of invasive forest insects worldwide. In parallel, they represent one of the most well-studied insect groups in terms of chemical ecology. Longhorn beetle aggregation-sex pheromones are commonly used as trap lures for specific and generic surveillance programs at points of entry and may play a key role in determining the success or failure of exotic species establishment. An exotic species might be more likely to establish in a novel habitat if it relies on a pheromone channel that is different to that of native species active at the same time of year and day, allowing for unhindered mate location (i.e., pheromone-free space hypothesis). In this study, we first tested the attractiveness of single pheromone components (i.e., racemic 3-hydroxyhexan-2-one, racemic 3-hydroxyoctan-2-one, and syn-2,3-hexanediol), and their binary and tertiary combinations, to native and exotic longhorn beetle species in Canada and Italy. Second, we exploited trap catches to determine their seasonal flight activity. Third, we used pheromone-baited "timer traps" to determine longhorn beetle daily flight activity. The response to single pheromones and their combinations was mostly species specific but the combination of more than one pheromone component allowed catch of multiple species simultaneously in Italy. The response of the exotic species to pheromone components, coupled with results on seasonal and daily flight activity, provided partial support for the pheromone-free space hypothesis. This study aids in the understanding of longhorn beetle chemical ecology and confirms that pheromones can play a key role in longhorn beetle invasions.
Over the past decade, volatile sex and/or aggregation pheromones and pheromone candidates have been identified for well over 100 species in the large beetle family Cerambycidae, demonstrating that pheromone-based communication is crucial for effective mate location by these insects. Despite this rapid progress in elucidating the chemical ecology of the Cerambycidae, most research to date has focused on species from North America, Europe, and Asia, with almost nothing known about species native to Africa, Australia, and South America. Here, we report the identification and field assessment of aggregation-sex pheromones produced by adult males of Ambonus distinctus (Newman) and Ambonus electus (Gahan), two sympatric and synchronic
Sex Pheromone Reception in the Scarab Beetle Phyllophaga anxia (Coleoptera: Scarabaeidae)
Annals of the Entomological Society of America, 2002
Antennal olfactory receptor neuron responses in the scarab beetle Phyllophaga anxia (LeConte) were investigated using tungsten microelectrodes Morphological investigations revealed that antennal sensilla are distributed on the entire antennal club lamellae. The female-produced pheromones, L-valine and L-isoleucine methyl esters, were shown to affect two types of olfactory receptor neurons differently One type of olfactory receptor neurons was excited with increasing pheromone concentrations at low doses (0 01-1 pg), but inhibited at higher doses. The second type was excited only at the high pheromone doses (100-1,000 us, stimulus loading) Both receptor neuron types were affected in the same way by the two pheromone components KEY WORDS Phyllophaga anxia, sex pheromone, single cell recording, L-valine methyl ester, L-isoleucine methyl ester THE SCEABAETOAE IS a large family of beetles containing nearly 1,500 species in North America Scarabs are costly economic pests, both in the larval and adult stage, due to the damage they inflict below ground on roots and above ground on crops, plants, and trees The cranberry white grub, Phyllophaga anxia (Le-Conte) , also known as May or June beetles due to their flight period, is a serious pest damaging important pheromone components in P anxia populations as well as over 40 other species of Phyllophuga (P S R.
Japan Agricultural Research Quarterly: JARQ, 2003
Anoplophora malasiaca (Thomson) (Coleoptera: Cerambycidae) male approached the female, touched her with his antennae or tarsi, and then held and mounted her by touching her elytra and pronotum with his palpae. Similar mating attempts by males were confirmed on a glass dummy treated with the solvent extract of female elytra, indicating the presence of a female sex pheromone perceptible by direct contact. When the extract was chromatographed on silica gel, only the hexane fraction showed a weak activity. The activity was apparently enhanced when polar fractions were subsequently mixed with this fraction. Therefore, the sex pheromone consisted of hydrocarbons and polar compounds that operated synergistically. Among more than 40 hydrocarbons identified by GC-MS analysis, only saturated hydrocarbons induced the mating behavior in males. When 8 major authentic hydrocarbons were mixed together with the polar compounds, the blend induced a series of precopulative behaviors in males. Thus, these hydrocarbons were considered to be the components of the sex pheromone in this beetle. Sexual dimorphism was observed in the hydrocarbon profiles. Some hydrocarbons were common between the sexes while others were sexually specific. A blend of male hydrocarbons and female polar components was still active but the opposite combination was inactive. Therefore, polar femalespecific components were critical for revealing the sex pheromonal activity.