The two reindeer parasites,Hypoderma tarandi andCephenemyia trompe (Oestridae), have evolved similar olfactory receptor abilities to volatiles from their common host

Summary Using the linked gas chromatographical/electroantennogram (GC/EAG) technique it was revealed that the reindeer warble fly (H. tarandi) was specifically able to sense the same components from reindeer interdigital pheromone gland as the reindeer nose bot fly (C. trompe) another reindeer endoparasite. These two species belong to the same family (Oestridae), but different subfamilies, and the evolution towards an endoparasitic life cycle is thought to have been independent. The development of olfactory abilities to find reindeer from long distances is hypothesized to have taken place through convergent evolution or exists because of their common ancestry.     

Neocembrene A, a major component of the trail-following pheromone in the genus Prorhinotermes (Insecta, Isoptera, Rhinotermitidae)

Summary. The diterpene neocembrene A or (1E,5E,9E,12R)-1,5,9-trimethyl-12-(1-methylethenyl)-1,5,9-cyclotetradecatriene, known as the trail-following pheromone of the advanced Termitidae Nasutitermitinae Nasutitermes exitiosus and Trinervitermes bettonianus, has been identified after SPME-GC/MS as the major component of the trail-following pheromone of the Rhinotermitidae Prorhinotermitinae, Prorhinotermes canalifrons and P. simplex. In all the other Rhinotermitidae studied until now, the major component of their trail pheromones is dodecatrienol ((3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol). This biochemical data further add to the anatomical and molecular characteristics that give a special status to the taxon Prorhinotermes among Rhinotermitidae. In Prorhinotermes canalifrons and P. simplex, neocembrene A was the only secretory compound specific to the sternal gland surface that could be detected after SPME. It elicited orientation as well as recruitment behavioral effects. However, the comparison of the respective biological activities triggered by neocembrene A and by sternal gland secretion suggests that minor components of the latter are acting in synergy with neocembrene A.     

Temporal accumulation of phenylpropanoids in male fruit flies, <Emphasis Type="Italic">Bactrocera dorsalis</Emphasis> and <Emphasis Type="Italic">B. carambolae</Emphasis> (Diptera: Tephritidae) following methyl eugenol consumption

Summary. Males of dacine tephritids, Bactrocera carambolae and B. dorsalis are strongly attracted to, and compulsively feed on methyl eugenol (ME), a potent attractant for many Bactrocera species. While ME was shown to be biotransformed into phenylpropanoids, 2-allyl-4,5-dimethoxyphenol and (E)-coniferyl alcohol, and temporarily stored in the rectal gland of male B. dorsalis prior to release during courtship at dusk, B. carambolae male produces only the latter compound along with its de novo synthesized pheromone components. Both species were also shown to have different age-related response, sensitivity and consumption levels of ME. Here, we monitored and compared temporal changes in the accumulation profiles of these phenylpropanoids by the two sibling species, with male rectal glands being individually excised at different time intervals from 15 minutes to 20 days after initial ME feeding and analysed quantitatively. Results are discussed in light of plant-fruit fly co-evolution relationship.     

Sex pheromone of the large aspen tortrix, Choristoneura conflictana(Lepidoptera: Tortricidae)

Summary. Three components that elicited antennal response from male Choristoneura conflictana were found from female gland extracts analyzed using a coupled gas chromatographic-electroantennographic detector system. The main component in gland extracts was (Z)-11-tetradecenal (Z11-14:Ald). Two minor components also elicited antennal response: (E)11-tetradecenal (E11-14:Ald) and (Z)-11- tetradecen-1-ol (Z11-14:OH). Analysis of effluvia indicated that calling virgin females release mostly Z11-14:Ald and trace amounts of Z11-14:OH. Field and wind tunnel behavioral studies showed that Z11-14:Ald alone attracted male moths in a dose response pattern. Tests comparing male response to blends of components detected in gland extracts showed that addition of 1.8% of E11-14:Ald to Z11-14:Ald did not influence male moths in the wind tunnel, but resulted in significantly lower trap captures in the field. The threecomponent blend [Z11-14:Ald (100), E11-14:Ald (1.8), Z11-14:OH (11)], was less attractive than Z11-14:Ald alone in both field and wind tunnel studies. Traps baited with two virgin female moths were equally attractive to males as traps baited with the three-component synthetic blend but less attractive than traps baited with Z11-14:Ald alone. Field tests of various blends of the two components (Z11-14:Ald, Z11-14:OH) detected in the females’ effluvia showed that the addition of 1–10% Z11-14:OH to Z11-14:Ald did not affect the males’ response to Z11-14:Ald. Our data demonstrate that female C. conflictana release sex pheromone components in a different ratio than they are stored in the pheromone gland. The sex pheromone is comprised of a single component, Z11-14:Ald, that can be used to monitor mated and virgin male C. conflictana throughout their flight period.     

Heritable pheromone blend variation in a local population of the butterbur borer moth Ostrinia zaguliaevi (Lepidoptera: Crambidae)

Summary. In a local population of Ostrinia zaguliaevi Mutuura & Munroe (Lepidoptera: Crambidae), extensive variation was found in the blend ratio of three sex pheromone components, (Z)-9-tetradecenyl acetate (Z9-14:OAc, 10.2-63.8%), (Z)-11-tetradecenyl acetate (Z11-14:OAc, 32.2-86.8%), and (E)-11-tetradecenyl acetate (E11-14:OAc, 2.1-11.9%). The variation was observed over a three-year period (2002-2004). Mother-daughter regression analyses have shown that although the heritability of the minor component E11-14:OAc was not significant, the heritability of the proportions of Z9-14:OAc and Z11-14:OAc were substantial (0.5–0.6). In artificial selection experiments, the mean % Z9-14:OAc in the sex pheromone changed significantly within three generations (37% in the control line, 48 and 52% for two lines selected for increase, and 23 and 30% for two lines selected for decrease). Despite these changes, the amounts of fatty acyl pheromone precursors, (Z)-9-, (Z)-11- and (E)-11-tetradecenoate, in the pheromone gland were not significantly affected by the selection. Taken together, variation in the pheromone blend of O. zaguliaevi is likely to be attributable to a few genes involved in the reduction or acetylation of fatty acyl pheromone precursors, the last two steps in pheromone biosynthesis.     

Identification and biological activity of sex pheromone components from females of the plum moth Illiberis rotundata Jordan (Lepidoptera: Zygaenidae: Procridinae)

The plum moth, Illiberis rotundata Jordan (Lepidoptera: Zygaenidae: Procridinae), is a pest of orchards in Japan and China. Few chemical ecological studies have been directed towards the Zygaenidae and particularly the Procridinae. To investigate the sex pheromone of this species, extracts of pheromone glands from adult female I. rotundata were analyzed by coupled gas chromatography-electroantennography (GC-EAG) and coupled gas chromatography-mass spectrometry (GC-MS). Whilst GC-EAG on male moths showed an active peak, identified as 2-butyl (7Z)-dodecenoate, GC-MS also revealed the presence of the homologue 2-butyl (9Z)-tetradecenoate. Electroantennographic investigations, as well as field tests, strongly suggested the natural compounds to have the (R)-configuration at the stereogenic centre. Field results demonstrate 0.2 mg of a 1:1-mixture of (2R)-butyl (7Z)-dodecenoate and (2R)-butyl (9Z)-tetradecenoate to be a powerful lure that may be used in pest control measures against I. rotundata. The chemical structures of the new pheromone components show the same features as those of other zygaenid species: unsaturated fatty acids esterified with a short chain chiral alcohol. This is the first example of a two-component blend constituting the pheromone of a procridinid species.     

Structure and function of Dufour gland pheromones from the crazy ant <Emphasis Type="Italic">Paratrechina longicornis</Emphasis>

Summary. Dufour glands of Paratrechina longicornis were analyzed chemically using GC-MS techniques. The glands contained twelve alkanes between C₉ and C₂₀ chain length with undecane and tridecane as the main components, six alkenes (1- and 4-undecene, 1-, 4-, and 6- tridecene, and heptadecadiene), two alkyl formates (C₁₁ and C₁₃), and saturated and polyunsaturated acids. Many of the alkanes and alkenes were behaviorally active causing a short lasting attraction of ants with different intensity. Detection of the major gland compound undecane in recruitment trails by in vivo SPME sampling provided evidence for its use as a recruitment pheromone. Both poison gland (formic acid) and Dufour gland (undecane) contents were detected on SPME fibers which had been attacked by the ants.     

Localized defecation by pike: a response to labelling by cyprinid alarm pheromone?

Fathead minnows (Pimephales promelas) that have never encountered a predatory pike (Esox lucius), are able to detect conspecific alarm pheromone in a pike's diet if the pike has recently consumed minnows. It remains unclear how this minnow alarm pheromone is secreted by pike and if a pike is able to avoid being labelled as a potential predator by localizing these cues away from its foraging range. The first experiment determined that minnow alarm pheromone is present in pike feces when pike are fed minnows. Individual fathead minnows exhibited a fright response to a stimulus of pike feces if the pike had been fed minnows, but not if the pike had been fed swordtails, which lack alarm pheromone. Individual minnows also exhibited a fright reaction to alarm pheromone in the water (which contained no feces) housing pike which had been fed minnows, suggesting that alarm pheromone is also released in urine, mucous secretions and/or via respiration. The second experiment determined that test pike spent a significantly greater proportion of time in the home area of the test tanks (i.e. where they were fed) but the majority of feces were deposited in the opposite end of the test tank. By localizing their defecation away from the home or foraging area, pike may be able to counter the effects of being labelled as a predator by the alarm pheromone of the prey species.     

Species-specificity in trail pheromones and Dufour's gland contents ofCamponotus atriceps andC. floridanus (Hymenoptera: Formicidae)

Summary By means of gas chromatography, gas chromatographic coupled mass spectrometry, trail-following experiments and electrophysiological recordings from worker antennae, the major trail pheromone components from the hindgut of the formicine speciesCamponotus atriceps andC. floridanus were identified as 3,5-dimethyl-6-(1-methylpropyl)-tetrahydropyran-2-one and nerolic acid, respectively. The Dufour's gland contents of both species, investigated by gas chromatographic coupled mass spectrometry, show significant differences.Pheromones 104: Janssen E, Übler E, Bauriegel L, Kern F, Bestmann H-J, Attygalle AB, Steghaus-Kovacs S, Maschwitz U: Trail pheromone of the Ponerinae antLeptogenys peuqueti (Hymenoptera: Formicidae): a multicomponent mixture of related compounds     

Complex chemical communication in the crazy ant <Emphasis Type="Italic">Paratrechina longicornis</Emphasis> Latreille (Hymenoptera: Formicidae)

Summary. The formicine ant Paratrechina longicornis is known for its extremely opportunistic foraging behaviour. Only a single trail pheromone source, the rectum, was previously described from this ant. Our detailed examination of this ant’s chemical communication system revealed the presence of at least four sources of pheromones. Rectum, poison sac, and Dufour gland contain orientation components with decreasing effectiveness and persistence (in the sequence mentioned) as well as attractants with increasing effectiveness. Furthermore, the mandibular gland contains repellents, and a releaser of defensive behaviour. This set of various signals of different strength and persistence allows an extraordinary degree of flexibility and efficiency in the collective behaviour of P. longicornis, especially food exploitation, and thus may contribute to this insect’s overall ecological success.     

(<Emphasis Type="Italic">Z,Z</Emphasis>)-11,13-Hexadecadienyl acetate and (<Emphasis Type="Italic">Z,E</Emphasis>)-11,13,15-hexadecatrienyl acetate: synergistic sex pheromone components of oak processionary moth,Thaumetopoea processionea (Lepidoptera: Thaumetopoeidae)

Summary. Our objective was to identify sex pheromone components of the oak processionary moth, Thaumetopoea processionea (Lepidoptera: Thaumetopoeidae), whose larvae defoliate oak, Quercus spp., forests in Eurasia and impact human health. Coupled gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometric (MS) analyses of pheromone gland extract of female T. processionea revealed two consistently EAD-active compounds. They were identified as (Z,Z)-11,13-hexadecadienyl acetate (Z11,Z13-16:OAc) and (Z,E)-11,13,15-hexadecatrienyl acetate (Z11,E13,15-16:OAc) by comparative GC, GC-MS and GC-EAD analyses of insect-produced compounds and authentic standards. In replicated field experiments (2000, 2001) in Nordbaden, Südbaden and Sachsen-Anhalt (Germany), Z11,Z13-16:OAc and Z11,E13,15-16:OAc in combination, but not singly, attracted significant numbers of male moths. It will now be intriguing to investigate whether Z11,E13,15-16:OAc, or its corresponding alcohol or aldehyde, serves as a pheromone component also in other species of the Thaumetopoeidae.     

Identification of polyenic hydrocarbons from the northern winter moth, Operophtera fagata, and development of a species specific lure for pheromone traps

Summary. In order to elucidate the composition of the female sex pheromone of the northern (beech) winter moth, Operophtera fagata Scharf. (Lepidoptera: Geometridae), ovipositor extracts of unmated, calling females were analysed by gas chromatography with simultaneous electroantennographic and flame ionization detection (GC-EAD/FID). Male antennal responses indicated three active components, two of which had distinct matching peaks in the FID trace. Using coupled gas chromatography- mass spectrometry (GC-MS), these two compounds were identified as (9Z)-nonadecene (9Z-19:Hy), and (6Z,9Z)-nonadecadiene (6Z9Z-19:Hy), respectively. The third component, present in very small amounts only, was identified as (1,3Z,6Z,9Z)-nonadecatetraene (1,3Z6Z9Z-19:Hy), known as the sex pheromone of the common winter moth, O. brumata. Field tests revealed that traps baited with 6Z9Z-19:Hy and 1,3Z6Z9Z-19:Hy caugth large numbers of male O. fagata. Both compounds were found to be essential for attraction of O. fagata. In addition, the diene prevented captures of co-occurring O. brumata. In contrast, 9Z-19:Hy neither influenced the attractiveness of the two-component mixture towards O. fagata nor contributed to bait specificity. A binary mixture of 6Z9Z-19:Hy and 1,3Z6Z9Z-19:Hy in a ratio of 10:1, applied to pieces of rubber tubing, constituted a highly attractive and species-specific bait for O. fagata, which can be used for monitoring of the flight of this defoliator pest of deciduous forests.     

Behavioural and electrophysiological responses of the olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), to male- and female-borne sex attractants

In the olive fruit fly, Bactrocera oleae, females attract males by producing 1,7-dioxaspiro[5.5]undecane (olean), the main component of the sex pheromone secreted by rectal glands. It has been recently demonstrated that males are able to produce (Z)-9-tricosene (muscalure) in rectal glands, a compound that selectively attracts females. In this study, a male grooming reaction that may transfer the male-borne compounds from rectal to urotergal glands was observed, suggesting that urotergal glands could be involved in B. oleae sexual communication. GC/MS, EAG, GC/EAD analyses and behavioural assays were carried out to compare the role of male rectal and urotergal glands during courtship. In both male glands, olean and muscalure amounts were age dependent. Extracts of rectal glands contained higher amounts of olean and/or muscalure than urotergal ones. Extracts of rectal and urotergal glands of males and females elicited EAG responses in both sexes. GC/EAD showed that female EAG response to male rectal extracts was mainly due to olean and muscalure. Synthetic compounds evoked EAG dose-dependent responses in both sexes, and the EAG response to muscalure was higher as compared to olean. Rectal and urotergal glands from old males were able to attract females, while urotergal glands from young males attracted only males. Overall, our results add knowledge to the mating system of B. oleae, giving first evidences on the electrophysiological activity of muscalure towards both sexes, as well as on the involvement of male urotergal glands in the chemical sexual communication of this pest.     

Female sex pheromone of Ostrinia orientalis – throwing a light on the relationship between O. orientalis and the European corn borer, O. nubilalis

Summary. The sex pheromone of Ostrinia orientalis (Lepidoptera: Crambidae) was analyzed by gas chromatography–electroantennographic detection (GC–EAD), GC–mass spectrometry and a series of bioassays. Three EAD-active compounds were detected in the female sex pheromone gland extract, and identified as tetradecyl acetate (14:OAc), (Z)-11-tetradecenyl acetate (Z11-14:OAc) and (E)-11-tetradecenyl acetate (E11-14:OAc). The titers (ratio) of 14:OAc, Z11-14:OAc and E11-14:OAc in 3-day-old virgin females were 0.49 ng (10), 4.86 ng (98) and 0.10 ng (2), respectively. In a wind-tunnel bioassay, the 98:2 blend of Z11- and E11-14:OAc, but not Z11-14:OAc alone, elicited the same male behavioral responses as virgin females and crude gland extracts. 14:OAc was inactive by itself, and did not show any synergistic effect on the binary blend. Field trapping experiments also confirmed the attractiveness of the binary blend to O. orientalis males. Based on these results, we concluded that the sex pheromone of O. orientalis is a 98:2 mixture of Z11-14:OAc and E11-14:OAc. This sex pheromone is very similar to that of the Z-type European corn borer, O. nubilalis. The present finding raises the question of whether O. orientalis , which is indistinguishable from O. nubilalis based on external morphology, is a biologically distinct species independent from O. nubilalis.     

Sex pheromones and their potential role in the evolution of reproductive isolation in small ermine moths (Yponomeutidae)

Summary Sex pheromone communication in the nine European species of small ermine moths (Yponomeuta) is reviewed in regard to the potential role of pheromones in the speciation process. Six of the nine species studied (viz.,Y. evonymellus, Y. cagnagellus, Y. padellus, Y. irrorellus, Y. plumbellus, andY. vigintipunctatus) use a mixture of (E)-11-and (Z)-11-tetradecenyl acetate in different ratios as primary pheromone components, with combinations of tetradecyl acetate, (Z)-9-tetradecenyl acetate, (Z)-11-hexadecenyl acetate and the corresponding alcohols of the acetates as additional pheromone components. Analysis of (Z)- to (E)-11-tetradecenyl acetate ratios produced by individual females of these species demonstrated significant variation among females of all species. However, the ranges of ratios produced byY. cagnagellus, Y. irrorellus, andY. plumbellus, sharing the same host-plant species, spindle tree, did not overlap. Niche separation of all six species mentioned required consideration of at least one additional pheromone component or of temporal aspects. The remaining three species,i.e. Y. malinellus, Y. mahalebellus andY. rorellus, have pheromones that differ qualitatively.Biosynthetic routes to the pheromone components identified are proposed on the basis of fatty acid pheromone precursors found in the pheromone glands. A phylogenetic tree for the genus is constructed based on allozyme frequency data and changes in pheromone composition are superimposed on this tree. We suggest that the ancestral ermine moth pheromone is a mixture of (Z)-11- and (E)-11-tetradecenyl acetate and the corresponding alcohols, and a scenario of how present-day patterns evolved is outlined. The pheromone differences among the three species using spindle tree as their host-plant might have evolved throughreproductive character displacement upon secondary contact between populations that had already diverged genetically in allopatry. Pheromone differences within the so-calledpadellus-complex (includingY. cagnagellus, Y. mahalebellus, Y. malinellus, Y. padellus, andY. rorellus) in which species might have originated sympatrically, may have evolved byreinforcing selection as these species still hybridise and produce viable offspring when confined in cages. The role of pheromones in reproductive isolation amongYponomeuta species is emphasised by (1) the function of pheromone components of some of the species as behavioural antagonists to other species, (2) the cross-attraction under experimental conditions between allochronic species with similar pheromones, and (3) the formation of hybrids in the laboratory between species that are isolated in nature by pheromone differences.     

Attraction of field-flying aphid males to synthetic sex pheromone

Summary Transparent plastic water traps, baited with the synthetic aphid sex pheromone components (4aS,7S,7aR)-nepetalactone and (1R,4aS,7S,7aR)-nepetalactol or control lures, were placed in four semi-sheltered field sites at a height of 1.1 m. Although males of twenty-one aphid species were collected from the water traps, onlySitobion fragariae (Walker) was abundant. In total, 8 pheromone traps produced 102 males compared with only 10 males in 8 control traps. The sex pheromone released by sexual femaleS. fragariae was identified as the nepetalactone used in the lures. Aphid sex pheromones may be more species-specific than previously thought and the presence of a host plant is not essential for males to locate sexual females.     

Identification of trail pheromone compounds from the labial glands of the stingless bee Geotrigona mombuca

Foragers of several species of stingless bees deposit pheromone spots in the vegetation to guide recruited nestmates to a rich food source. Recent studies have shown that Trigona and Scaptotrigona workers secrete these pheromones from their labial glands. An earlier report stated that species within the genus Geotrigona use citral from their mandibular glands for scent marking. Since convincing experimental proof for this conjecture is lacking, we studied the glandular origin of the trail pheromone of Geotrigona mombuca. In field bioassays, newly recruited bees were diverted by artificial scent trails that branched off from the natural scent trail deposited by their nestmates only when they were baited with extracts from the foragers’ labial glands. Compounds extracted from the mandibular glands, however, did not release trail following behavior. This demonstrates that the trail pheromone of G. mombuca is produced in the labial glands, as in Trigona and Scaptotrigona. Furthermore, in chemical analyses citral was identified exclusively in the foragers’ mandibular glands, which disproves its supposed role as a trail pheromone. The labial glands contained a series of terpene- and wax type esters, with farnesyl butanoate as major constituent. We, therefore, postulate that the trail pheromone of G. mombuca is composed of a blend of esters.     

Sex pheromone communication of tentiform leaf-miners <Emphasis Type="Italic">Phyllonorycter insignitella</Emphasis> and <Emphasis Type="Italic">Ph. nigrescentella</Emphasis> from two related species groups

Summary.  Females of both species start their pheromone-releasing activity on the second day after emergence at the beginning of the photophase. During the present work, a peak of calling activity with close to 100% of active Ph. nigrescentella females was registered 1.5 hour after the light had been put on. The high pheromone release behaviour with 50% active females lasted for 3 hours. The calling activity of the group of females was about 6 h/day. The beginning of a photophase under laboratory conditions or an early morning in nature is a common period for sex pheromone release in the genus Phyllonorycter. (8Z,10E)-tetradecadien-1-yl acetate (8Z,10E-14:Ac), (8Z,10E)-tetradecadien-1-ol (8Z,10E-14:OH) and (8E,10Z)-tetradecadien-1-yl acetate (8E,10Z-14:Ac) in the ratio 96:4:traces as well as 8Z,10E-14:Ac and 8Z,10E-14:OH in the ratio 88:12 collected by Solid Phase Micro Extraction (SPME) were found to be specific for the calling periods of virgin Phyllonorycter insignitella and Ph. nigrescentella females respectively. Field trapping experiments demonstrated that all three compounds are important for the attraction of Ph. insignitella males while only 8Z,10E-14:Ac is the essential sex pheromone component for Ph. nigrescentella. The pheromone activity of all three compounds is reported for the first time. Addition of either 8Z,10E-14:OH or 8E,10Z-14:Ac to 8Z,10E-14:Ac did not have a significant effect on the attraction of Ph. nigrescentella males, while the efficiency of the three component blend was 5 times lower as compared to that of 8Z,10E-14:Ac. Our data demonstrate that 8Z,10E-14:OH and 8E,10Z-14:Ac play a dual function, they are minor sex pheromone components of Ph. insignitella essential for attraction of conspecific males and show an allelochemical, antagonistic effect on Ph. nigrescentella males and, thus, ensuring specificity of the mate location signal in two related Phyllonorycter species.     

Optimal harvesting of a plant-hervibore system: lichen and reindeer in northern Finland

The optimal harvesting policy for a plant-herbivore system consisting of lichen and reindeer in Finnish Lapland is investigated. Using a discrete time model with no age structure it is shown that the optimal procedure to reach target levels for lichen and reindeer involves a possible initial harvest of reindeer and then a sequence of no-harvesting years until the lichen has recovered. After two adjusting harvests the system will settle to an equilibrium. The optimal solution is compared with the fastest possible approach to the target levels. The two solutions coincide if future yields are sufficiently discounted. With a discount factor near one there will be a heavier initial harvest in the optimal solution. It is seen that allowing some harvesting also in the no-harvesting years has no marked effect on the total yield. The target levels for lichen and reindeer are not unique but depend both on discounting and on the length of the planning period.     

Male age structure influences females’ mass change during rut in a polygynous ungulate: the reindeer (Rangifer tarandus)

The manipulation of the sex ratio and age structure in many managed ungulate populations calls for a better understanding of their potential consequences on females’ condition and behavior during rut. During 1996–2002, we manipulated the male age structure and male percentage (nine treatments during 7 years) within an experimental herd of semidomestic reindeer (Rangifer tarandus) and investigated their influence on both the body mass change and the behavior of females during rut. On average, the females lost body mass (−0.95±SE 0.18 kg) during rut, which we contend to reflect somatic costs. The females’ losses increased as the percentage of male decreased, but this was certainly ascribed to one treatment with high male percentage (27.7%) as compared to the others (ranging from 3.9 to 12.2%). Female losses were highest for treatments including both young and adult males as compared to only adult or only young males, and higher for treatments including only young compared to only adult males. This is supported by (1) the higher female harassment frequency when females are exposed to only young or a mixture of young and adult males as compared to only adults, (2) the higher female harassment frequency by young males as compared to adults in the mixed treatments, and (3) the reduced females’ feeding activity in treatments including both young and adult males. We conclude that the male age structure during rut will influence the females’ behavior and mass change and may have implications for females’ life history and for population dynamics.