Ide, J.-Y. (2014) European Journal of Entomology 111: 417-420. (doi: 10.14411/eje.2014.037)
Mated females of the small copper butterfly Lycaena phlaeas avoid harassment by males by closing their wings and concealing themselves when in the proximity of a con-specific butterfly. This wing-closing behaviour is less frequently exhibited by virgin females that are two days old or older (i.e., potentially receptive) than by mated females. During the first 2 days after emergence, females of L. phlaeas are sexually immature and unreceptive. To determine whether recently emerged virgin females try to avoid male harassment, age-related changes in the frequency of harassment-avoidance behaviour of virgin females were investigated. On the day of emergence, a high percentage of virgin females exhibited wing-closing behaviour. Over the following 2 days, however, the frequency of this behaviour declined sharply and then reached a constant low level. This observation supports the idea that the harassment-avoidance behaviour exhibited by virgin females of L. phlaeas depends on their receptivity.
Key words. Immature adult, Lycaena phlaeas, receptivity, sexual conflict, virgin, wing-closing behaviour.
Ide, J.-Y. (2011) Ethology 117: 630-637. (doi: 10.1111/j.1439-0310.2011.01912.x)
Males of many butterfly species persistently court and attempt to mate with females even if the females reject courtship. This male harassment almost certainly has negative effects on female fitness. Therefore, females have likely evolved strategies to avoid such encounters. To investigate the harassment avoidance strategy of females of the small copper butterfly, Lycaena phlaeas daimio, I observed the reactions of females to other individuals flying nearby in the field. In response to the conspecific butterflies, females closed their wings if they had previously been open and did not exhibit any action if the wings had been closed. Females that closed their open wings in response to a conspecific received fewer mating attempts than did females that held their wings open. These results indicate that the wing-closing behaviour of L. phlaeas females functions to deter male mating attempts. The wing-closing reaction occurred primarily in mated females. Because females of L. phlaeas copulate only once during their lives, this behaviour is not considered an indirect mate choice but rather an attempt to avoid persistent mating attempts (i.e. sexual harassment) by males.
Ide, J.-Y. (2010) European Journal of Entomology 107: 369-376. (Journal)
Males of the small copper butterfly, Lycaena phlaeas daimio, exhibit two mate-locating tactics: patrolling and perching. I conducted a field investigation to determine the biotic and abiotic factors affecting the choice of male mate-locating behaviour of L. phlaeas. Patrolling was often observed at high light intensity. Perching was performed throughout the day regardless of environmental conditions, but the chasing reaction to passing insects increased at high light intensity. The activity patterns of neither tactic were affected by the activity patterns of females. Patrolling males had lower thoracic temperatures than did perching males under cool conditions, suggesting that patrolling males lose heat more easily. In contrast, perching males may more easily regulate their body temperature to a suitable level, as they fly for shorter durations and can bask while waiting for mates. These results highlight several reasons (i.e., heat loss, energetic costs) for males to adopt a patrolling tactic under only favourable weather conditions.
Key words: activity pattern, Lycaena phlaeas daimio, mate-locating tactics, patrolling, perching, thermoregulation, weather.
Ide, J.-Y. (2009) Entomologia Experimentalis et Applicata 130: 181-190. (doi: 10.1111/j.1570-7458.2008.00809.x)
Factors responsible for ontogenetic habitat shifts were examined using larvae of the Indian red admiral butterfly, Vanessa indica (Herbst) (Lepidoptera: Nymphalidae). The larvae of V. indica fold leaves of China ramie, Boehmeria nipononivea Koidz. (Urticaceae), to form shelters that also serve as food. When constructing shelters, old larvae (usually third instar or older) frequently cut trenches at the bases of the leaves, whereas younger larvae do not. This trenching behaviour reduces the force required to fold large ramie leaves. Young larvae used small apical leaves as shelter sites. Once larvae were capable of cutting trenches, they moved proximally on the host plant and used middle leaves that either had completed or were about to complete expansion. Results of bioassays revealed that, for young larvae, apical and middle leaves did not differ in food quality. In contrast, for older larvae, the quality of middle leaves was higher than that of apical leaves. These observations suggest that young larvae decrease the risk of predation during shelter construction by using apical leaves that are relatively easy to fold, and that old larvae employ trenching to decrease the duration of leaf folding and improve growth rate by using middle leaves that are of high quality. Thus, the facilitation of leaf-folding by trenching is considered to reduce the necessity of using apical leaves, and the acquisition of the trenching ability triggers an ontogenetic shift in the selection of larval shelter sites.
Key words: feeding-site preference, leaf age, leaf position, China ramie, trenching behaviour, within-plant movement, Lepidoptera, Nymphalidae, Boehmeria nipononivea, performance.
Ide, J.-Y. (2006b) Ecological Research 21: 453-459. (doi: 10.1007/s11284-005-0140-z)
To assess bird predation pressure on butterflies, I investigated beak marks on the wings of two Lethe butterflies for three years in secondary temperate forests. If bird predation had significant effects on average longevity of butterflies, and if the number of specimens preyed upon was proportionate to the number of beak-marked specimens, the beak mark frequency would be negatively correlated with average longevity of a butterfly. Bird predation pressure is generally thought to influence average longevity of butterflies. Therefore, if there is a negative correlation between beak mark frequency and average longevity, bird predation pressure would be reflected in beak mark frequency. Beak mark frequency was negatively correlated with longevity in L. diana (Butler), the more abundant of the two species; thus, the beak mark frequency was considered to be a suitable index of bird predation pressure on the butterflies investigated in this study. In both Lethe species, beak mark frequency was higher in females than in males. Because female butterflies have a relatively smaller thorax and flight muscles and a larger abdomen that contains eggs, they are presumably weaker or less agile fliers than males, and are probably attacked more easily by birds. In autumn, butterflies were heavily attacked by birds irrespective of sex and species. Because the numbers of lepidopteran larvae, which are the preferred prey of many birds, decreased in autumn, birds were thought to shift their diets to alternative prey such as adult butterflies.
Key words: bird predation, lepidopteran larvae, longevity, relative thoracic mass, symmetrical mark.
Ide, J.-Y. (2006a) Applied Entomology and Zoology 41: 49-55. (Journal site)
I investigated inter- and intra-shoot distributions of the caterpillars of the ramie moth Arcte coerulea in shrubs of the host plant China ramie, Boehmeria nipononivea. The caterpillars were distributed on long shoots in the canopy of ramie, and caterpillar performance was better when they fed on leaves of the canopy shoots rather than those of the understory shoots. This was probably because the caterpillars could overcome the host plant defense to obtain nutrition from the sunlit shoots, which often contain higher concentrations of chemical defenses. Within a shoot, caterpillars were found on leaves that had just completed expansion. This leaf preference was probably affected by the change in food quality with leaf age. Caterpillars were never observed on buds, and their performances were poor when they fed on buds. This suggests that the chemical defense is heavily concentrated in buds. Outbreaks of A. coerulea frequently occur and cause defoliation of host plant shrubs; this may have resulted in accelerated evolution of host plant defense for rapid regrowth of the foliage, which contributes to the plantŐs tolerance of these moth caterpillars.
Key words: leaf position, outbreak, plant defense, relative growth rate, specialist herbivore.
Ide, J.-Y. (2004c) Population Ecology 46: 275-280. (doi: 10.1007/s10144-004-0194-8)
Many folivorous insects sever leaf veins, trench across leaf blades, or girdle the petioles prior to feeding on leaves. The purpose of these behaviours is generally thought to be sabotage of the anti-herbivore chemical defences of host plants. For insects that construct leaf shelters, these behaviours may make leaves easier to roll or fold. Larvae of the Indian red admiral butterfly, Vanessa indica (Herbst), cut trenches at the base of host plant leaves and construct leaf-fold shelters. I attempted to determine which of the above functions the trenching behaviour of V. indica larvae performs. If the function of trenching is to facilitate leaf-folding, then larvae should cut trenches before folding leaves. When the larvae used larger leaves, they tended to trench them prior to folding them. This suggests that the function of trenching behaviour is to make leaves easier to fold. However, larvae sometimes cut trenches after folding the leaves, suggesting that this behaviour has additional functions. When the larvae were about to moult or pupate, they did not cut trenches, suggesting that trenching behaviour may also be involved in feeding.
Key words: anti-herbivore defence, leaf-fold shelter, moult, trenching, Vanessa indica.
Ide, J.-Y. (2004b) Ecological Research 19: 189-196. (doi: 10.1111/j.1440-1703.2003.00623.x)
The time schedule of mate-locating behavior in the male satyrine butterfly Lethe diana was studied. Males displayed territorial behavior only in the afternoon, but it was not known whether they attempted to locate mates in the morning. In order for males of most butterfly species to mate with a virgin female, it would be most effective to initiate mate-locating behavior in the morning, when synchronous eclosions occur. Males of L. diana flew patrols in the morning and displayed territorial behavior in the afternoon. The cost of territorial behavior is probably less than that of patrolling, as territorial flights are shorter than those when patrolling. The temporal switching of mate-locating behavior is theoretically favored, since the reproductive value of females decreases later in the day, when males perform the less costly mate-locating behavior. Thus, the diurnal switching of male mate-locating behavior may be an adaptive strategy in response to the rapid decline in the reproductive value of females over the course of a day.
Key words: Lethe diana, mate-locating, patrol, diurnal switching, territorial behaviour.
Ide, J.-Y. (2004a) Journal of Ethology 22: 99-103. (doi: 10.1007/s10164-003-0110-2)
A blade of the bamboo grass Sasa veitchii var. hirsuta (Koidzumi) typically has a lifespan of 2-4 years. After winter, the edge of the blade dies and a white margin is drawn on the blade. Such an albo-marginated blade is thought to be of relatively low quality as food for insects. Caterpillars of the skipper butterfly Thoressa varia (Murray) (Lepidoptera: Hesperiidae) that fed on blades of S. veitchii, almost always utilized current-year blades. The mechanism by which they discriminate between age classes of blades was studied. The caterpillars did not choose albo-marginated blades, but they chose overwintered blades whose margins had been removed. This indicates that they use albo-margination as evidence of the age of a blade.
Key words: albo-marginated blade, current-year blade, discrimination of age classes of blades, feeding preference, overwintered blade, Sasa veitchii var. hirsuta, Thoressa varia.
Kondoh, M. & Ide, J.-Y. (2003) Animal Behaviour 65: 1013-1020. (doi: 10.1006/anbe.2003.2147)
It is widely observed that mate-seeking behaviour in insects starts suddenly at a species-specific time and lasts at most for a few hours (i.e. periodic). Although several hypotheses have been proposed to explain why periodicity occurs, none has incorporated a game-theoretical situation within and between the sexes at the same time. Using a theoretical model, we show that the coevolution of mating strategies can result in the emergence of two distinct population level phases: with and without mate seeking. In the mate-seeking phase, all individuals (male or female) search for mates, whereas no individuals seek mates in the phase without mate seeking. If there are individuals that do not seek mates in the mate-seeking phase, the model predicts that these should be of the sex with (1) lower survivorship during mate-seeking behaviour; (2) higher survivorship during nonmate-seeking behaviour; (3) higher expected future reproductive potential or (4) the sex towards which the sex ratio is biased. Furthermore, the model predicts that the mate-seeking phase is favoured when individuals have (1) high searching efficiency, (2) high survivorship during mate-seeking behaviour of either males or females, (3) low survivorship during nonmate-seeking behaviour of either males or females, or (4) low future reproductive potential for either males or females. In addition, the model suggests the existence of a critical environmental condition that divides these two phases, predicting that gradual changes in this condition trigger a sudden transition between the mate-seeking and nonmate-seeking phases.
Ide, J.-Y. (2003) Transactions of the Lepidopterological Society of Japan 54: 40-46.
Larvae of the satyrine butterfly Lethe diana feed on blades of bamboo grass Sasa veitchii var. hirsuta whose blades have a two-to-four-year life span. I studied age class preference by L. diana. Both current-year blades and blades from previous years were used as oviposition sites by adult L. diana and as food by larvae. The ratio of young to old blades used changed seasonally, and these ratio were consistent with theratio of young to oldblades in available bamboo grass bushes during each season, i.e., neither adults nor larvae showed a preference for any age class of blades. Larvae grew better when they were fed young blades compared to old blades, so the fitness of L. diana would increase if young blades were selected. It is thought that L. diana is not particular about leaf age because it cannot discriminate between young blades and old blades.
Key words: blade age, head-capsule width, larval performance, Lethe diana.
Ide, J.-Y. (2002b) Journal of Ethology 20: 71-78. (doi: 10.1007/s10164-002-0056-9)
The territorial behaviour of butterflies often changes with temperature. The satyrine butterfly Lethe diana has three generations a year, and males display territorial behaviour in the May-June and September-October generations, but not in the July-August generation. This study investigated the relationship between this seasonal change in mate-locating behaviour and thermoregulation. When L. diana was able to hold a territory, thoracic temperature ranged from 23.8 to 33.6ˇC. This temperature was mainly influenced by environmental temperature based on air temperature, solar radiation, and wind, and metabolic heat was estimated to increase thoracic temperature by about 5ˇC in the May-June generation. When environmental temperature at a territorial site was within this range of the thoracic temperature minus the metabolic heat (approximately 5ˇC), L. diana males held territories. Since territorial sites were selected irrespective of the temperature, L. diana could not hold a territory when the temperature of the territorial site exceeded the threshold. In July-August, the temperature of the territorial site was almost always above the suitable range. These results suggest that seasonal change in territoriality of L. diana is due to behavioural thermoregulation.
Key words: Lethe diana, operative temperature, seasonal change, territorial behaviour, thermoregulation.
Ide, J.-Y. (2002a) Ecological Entomology 27: 33-40. (doi: 10.1046/j.1365-2311.2002.0372a.x)
1. The spatial arrangement of resources and climatically favourable sites affects the dispersal pattern of butterflies.
2. The microdistribution of the satyrine butterfly Lethe diana changes seasonally, meaning that the relative spatial arrangement of resources also changes seasonally. The seasonal change in the dispersal pattern of this butterfly was studied.
3. Males of the May-June generation tended to stay in a restricted habitat patch while females of the same generation did not. A number of the May-June generation males became resident at prime forest edge sites, where a territorial behaviour that was rarely seen in other generations was prevalent. Females of the May-June generation moved to these territorial sites for mating but left after copulation to avoid male harassment; their residency was therefore weak.
4. In both sexes, the July-August generation tended to be more mobile than the September-October generation. This was because the July-August generation butterflies utilised dark environments for thermoregulation and, because these conditions were widespread throughout the forest, the butterflies were able to move widely. The September-October generation, however, preferred intermediate light conditions, which tended to be restricted to the forest edge; as this was a relatively small area, butterfly movement was restricted.
Key words: dispersal pattern, forest edge, Lethe diana, light condition, seasonal change, territory.
Ide, J.-Y. (2001b) Entomological Science 4: 279-285. (Journal site)
Closely related species that have similar ecological requirements often vary slightly in their preferences for abiotic environments. In poikilothermal animals, closely related species often utilize different thermal habitats. The congeneric satyrine butterflies Lethe sicelis and L. diana coexist in similar environments and feed on similar foods; however, L. diana tends to inhabit higher altitudes than L. sicelis. This study investigated the microhabitats of the two Lethe butterflies for three years to know whether these butterflies are segregated according to light intensity. When resting or flying, L. sicelis occupied sites that received slightly more sunlight than L. diana did, as predicted; however, the territorial sites of L. sicelis were darker than those of L. diana. L. sicelis had higher thoracic temperatures than L. diana when air temperatures were low. These results suggest that L. sicelis selects better-lit sites in order to use solar radiation to maintain the higher thoracic temperature in flight.
Key words: Lethe diana, Lethe sicelis, light intensity, microhabitat, thermoregulation, thoracic temperature.
Ide, J.-Y. (2001a) Transactions of the Lepidopterological Society of Japan 52: 168-170.
Lethe sicelis displays territorial behaviour related to mating. Territorial behaviour was observed in June and September, but not in July and August, although L. sicelis was observed. It is suggested that high air temperatures prevent L. sicelis from holding territory in summer.
Key words: air temperature, Lethe sicelis, seasonal change, territorial behaviour.
Ide, J.-Y. (2000b) Transactions of the Lepidopterological Society of Japan 52: 13-24.
The microdistribution of butterflies may be affected by food distribution, microclimatically favourable spots, or mate-locating sites. When butterflies' needs for these factors change, their microdistribution may change. In the satyrine butterfly, Lethe diana, a multivoltine species, a seasonal change was observed in the factors that determine the microdistribution of adult butterflies. The microdistribution of every generation was mainly affected by the distribution of sap fluxes, resulting in a patchy butterfly population. The spatial arrangement of habitat patches also changed seasonally. Patches extended into the forest only for the July-August generation, due to seasonal changes in preferred light conditions. To avoid excessive increases in body temperature, the July-August generation of butterflies preferred dark sites within the forest. Generations from other months preferred more sunny sites, so their distribution was limited to near the forest edge. The microdistribution of males of the May-June generation was also affected by territoriality: territories were settled at relatively open sites along the forest edge.
Key words: microdistribution, seasonality, Lethe diana, sap flux, light-condition, territory.
Ide, J.-Y. (2000a) Entomological Science 3: 591-596. (Journal site)
Seasonal change in the flight behaviour of the satyrine butterfly Lethe diana was studied. The flight activity of this species had two peaks a day, with one peak in the morning and the other in the afternoon. The time of the peaks changed seasonally. L. diana flew late morning and early afternoon in spring and autumn, whereas early morning and late afternoon in summer. Consequently, flight occurred at the time of moderate temperature. The seasonal difference in temperatures at peaks of flight activity was slight. However, the temperatures at peaks in spring and autumn were still lower than those recorded in summer. The flight courses of the butterflies covered sunlit areas in spring but were limited to shaded areas in summer. Basking occurred in spring and autumn in order to increase body temperature by absorbing solar radiation. Changes in the time of flight activity and utilization of the solar radiation ensured thermoregulation under seasonally changing thermal conditions.
Key words: Lethe diana, thermoregulation, seasonality, daily activity pattern, flight courses.
Ide, J.-Y. and Kondoh, M. (2000) Ecology Letters 3: 433-440. (doi: 10.1046/j.1461-0248.2000.00169.x)
We present a model of a male-female evolutionary game on mate-locating behaviour. Two major mating systems are considered: "lek polygyny" (in which males aggregate to wait for females searching for males) and "searching polygyny" (in which males search for females emerging or waiting for males). The model predicts that lek polygyny is favoured (i) when male survivorship during lekking is sufficiently higher than that during mate searching, (ii) when female survivorship while visiting a lek is sufficiently higher than at the emergence site, or (iii) when searching efficiency is higher at a lek than at an emergence site. Furthermore, the model shows that a reduction in the reproductive value of females later in the day, which prevents males from performing riskier mate-locating behaviour, can result in a change of mating system. In addition, mixed mating systems can be realized as transient states during this shift.
Key words: lek polygyny, male-female game, mating system, mixed mating system, residual reproductive value, searching efficiency, searching polygyny.