Spider mites become easy prey for ants when they leave their protective webs; therefore, the abil... more Spider mites become easy prey for ants when they leave their protective webs; therefore, the ability to avoid traces of ongoing ant activity should confer a selective advantage to mites. We examined avoidance of ant traces by the spider mites Tetranychus kanzawai and Tetranychus urticae. Both mite species avoided host plant leaves with active traces of Pristomyrmex punctatus or Formica japonica ants. Pristomyrmex punctatus trace avoidance by T. kanzawai lasted for more than 1 h, but not more than 3 h. Tetranychus kanzawai also avoided P. punctatus traces on plant stems, along which the mites access leaves. Moreover, T. kanzawai avoided hexane extracts of P. punctatus or F. japonica applied to a filter paper pathway. This study represents the first demonstration of a repellent effect of ant chemical traces on spider mites. Considering the substantial abundance and global distribution of ants in nature, such repellent effects may help to answer the long-standing question of why only a...
The phytophagous spider mites Tetranychus kanzawai and Tetranychus urticae can be as small as <... more The phytophagous spider mites Tetranychus kanzawai and Tetranychus urticae can be as small as <0.5 mm; thus, they are often incidentally consumed along with food plant leaves by voracious lepidopteran larvae (hereafter, ‘caterpillars’). Therefore, the ability to avoid such intraguild predation should confer a selective advantage to mites. We experimentally demonstrated that adult females of both mite species avoided settling on food plant leaves with traces of all tested caterpillar species (Bombyx mori, Papilio xuthus, Spodoptera litura and Theretra oldenlandiae). We examined additional interactions using B. mori and T. kanzawai and found that B. mori trace avoidance by T. kanzawailasted for more than 48 h. Tetranychus kanzawai also avoided B. moritraces on plant stems, along which mites access leaves. Moreover, T. kanzawai avoided acetone extracts of B. mori traces applied to filter paper, indicating that chemical substances of caterpillar traces are responsible for the avoidan...
It has long been hypothesized that the flower-like appearance of the juvenile orchid mantis is us... more It has long been hypothesized that the flower-like appearance of the juvenile orchid mantis is used as visual camouflage to capture flower-visiting insects, although it is doubtful whether such morphological resemblance alone could increase their success in hunting. We confirmed that juvenile female orchid mantes often succeed in capturing oriental honeybees, while adult females often fail. Since most of the honeybees approached the juveniles from the front, we hypothesized that juvenile orchid mantes might attract honeybees by emitting some volatile chemical cues. Gas chromatography-mass spectrometry analyses revealed that the mantes' mandibular adducts contained 3-hydroxyoctanoic acid (3HOA) and 10-hydroxy-(E)-2-decenoic acid (10HDA), both of which are also features of the pheromone communication of the oriental honeybee. We also successfully detected 3HOA emitted in the head space air only at the time when the juvenile mantes were attempting to capture their prey. Field bioas...
ABSTRACT Adults of the white grub beetle Dasylepida ishigakiensis Niijima et Kinoshita (Coleopter... more ABSTRACT Adults of the white grub beetle Dasylepida ishigakiensis Niijima et Kinoshita (Coleoptera: Scarabaeidae) emerge from the soil around dusk for mating on subtropical islands. The present study examines the factors controlling the emergence of males in the laboratory. There are two steps involved. Standby behaviour (i.e. insect head appears at the soil surface) can be observed for several hours before the beetles actually emerge for mating. The standby behaviour is facilitated by warm conditions, although the proportion of standby individuals is influenced not only by the temperature on that day, but also by that on the previous day. Experiments in which beetles are exposed to photoperiod and thermoperiod combinations, in and out of phase, show that temperature is more important in inducing standby and emerging behaviour than light alone. For the second step, factors such as temperature, light and the presence of the female sex pheromone determine whether males will leave the standby position and emerge onto the ground. The female sex pheromone stimulates standby beetles to exhibit emerging and wing vibration behaviours, although the effect depends on when it is presented to beetles. Beetles burrow back into the soil; this behaviour is influenced by illumination and time of the day but not by temperature. The results suggest that D. ishigakiensis possesses a sophisticated mechanism controlling male emergence from the soil.
ABSTRACT Abstract Two active fractions were found during the isolation of contact sex pheromone o... more ABSTRACT Abstract Two active fractions were found during the isolation of contact sex pheromone of female elytra of the white-spotted longicorn beetle, Anoplophora malasiaca (Thomson) (Coleoptera: Cerambycidae), in addition to fraction of hydrocarbons that had previously been identified. One fraction was essential to evoke a series of precopulatory behaviors of males toward a glass dummy when coated together with the hydrocarbon blend. The other fraction enhanced this activity when added to the mixture. From the latter synergistic fraction, we isolated five novel compounds and identified them as 10-heptacosanone, (Z)-18-heptacosen-10-one, (18Z,21Z)-heptacosa-18,21-dien-10-one, (18Z,21Z,24Z)-heptacosa-18,21,24-trien-10-one, and 12-heptacosanone by GC-MS and NMR analyses. A blend of four of these synthetic ketones, without 12-heptacosanone, in the ratio and concentration found in female elytra extract (250 : 400 : 1000 : 180 ng FE−1) showed greater synergistic effect than the natural fraction containing the ketones. This effect was canceled out by further addition of 12-heptacosanone (100 ng FE−1), which was still comparable to the effect of the natural ketone fraction.
Thirteen species of myrmecophilous insects belonging to three orders associated with three specie... more Thirteen species of myrmecophilous insects belonging to three orders associated with three species of Aenictus ants (Aenictus laeviceps, Aenictus gracilis,,Aenictus sp. 18a of SKY) were studied for behavioral observation and cuticular hydrocarbon (CHC) analysis. The myrmecophiles are: Aenictobia thoi, Aenictobia fergusoni, Mimaenictus wilsoni, Aenictoteras malayensis, Rosciszewskia gracilis, Trichotobia gracilis, Aenictoxenus sp., Weissflogia rhopalogaster (Coleoptera: Staphylinidae, rove beetles); Dohrniphora kistneri, Dohrniphora sp. 1, Dohrniphora sp. 2, Vestigipoda maschwitzi (Diptera: Phoridae, scuttle flies); Thysanura fam. gen. sp. (Thysanura, silverfish). Although behaviors of the rove beetles were highly variable by species, i.e., some were carried by ants and some were ignored by ants, the CHC profiles tended to resemble that of the host ants. The generalized scuttle flies Dohrniphora spp. were similar in behavior to each other but the CHC profiles were variable. The legless and wingless scuttle fly Vestigipoda maschwitzi was perfectly integrated into the ant colony as a mimic of ant larvae and also showed CHC profiles common to the ant larvae. The silverfish had very close contact with the ants, but the CHC profiles were quite different from the ants and the quantity itself was very low.
Spider mites become easy prey for ants when they leave their protective webs; therefore, the abil... more Spider mites become easy prey for ants when they leave their protective webs; therefore, the ability to avoid traces of ongoing ant activity should confer a selective advantage to mites. We examined avoidance of ant traces by the spider mites Tetranychus kanzawai and Tetranychus urticae. Both mite species avoided host plant leaves with active traces of Pristomyrmex punctatus or Formica japonica ants. Pristomyrmex punctatus trace avoidance by T. kanzawai lasted for more than 1 h, but not more than 3 h. Tetranychus kanzawai also avoided P. punctatus traces on plant stems, along which the mites access leaves. Moreover, T. kanzawai avoided hexane extracts of P. punctatus or F. japonica applied to a filter paper pathway. This study represents the first demonstration of a repellent effect of ant chemical traces on spider mites. Considering the substantial abundance and global distribution of ants in nature, such repellent effects may help to answer the long-standing question of why only a...
The phytophagous spider mites Tetranychus kanzawai and Tetranychus urticae can be as small as <... more The phytophagous spider mites Tetranychus kanzawai and Tetranychus urticae can be as small as <0.5 mm; thus, they are often incidentally consumed along with food plant leaves by voracious lepidopteran larvae (hereafter, ‘caterpillars’). Therefore, the ability to avoid such intraguild predation should confer a selective advantage to mites. We experimentally demonstrated that adult females of both mite species avoided settling on food plant leaves with traces of all tested caterpillar species (Bombyx mori, Papilio xuthus, Spodoptera litura and Theretra oldenlandiae). We examined additional interactions using B. mori and T. kanzawai and found that B. mori trace avoidance by T. kanzawailasted for more than 48 h. Tetranychus kanzawai also avoided B. moritraces on plant stems, along which mites access leaves. Moreover, T. kanzawai avoided acetone extracts of B. mori traces applied to filter paper, indicating that chemical substances of caterpillar traces are responsible for the avoidan...
It has long been hypothesized that the flower-like appearance of the juvenile orchid mantis is us... more It has long been hypothesized that the flower-like appearance of the juvenile orchid mantis is used as visual camouflage to capture flower-visiting insects, although it is doubtful whether such morphological resemblance alone could increase their success in hunting. We confirmed that juvenile female orchid mantes often succeed in capturing oriental honeybees, while adult females often fail. Since most of the honeybees approached the juveniles from the front, we hypothesized that juvenile orchid mantes might attract honeybees by emitting some volatile chemical cues. Gas chromatography-mass spectrometry analyses revealed that the mantes' mandibular adducts contained 3-hydroxyoctanoic acid (3HOA) and 10-hydroxy-(E)-2-decenoic acid (10HDA), both of which are also features of the pheromone communication of the oriental honeybee. We also successfully detected 3HOA emitted in the head space air only at the time when the juvenile mantes were attempting to capture their prey. Field bioas...
ABSTRACT Adults of the white grub beetle Dasylepida ishigakiensis Niijima et Kinoshita (Coleopter... more ABSTRACT Adults of the white grub beetle Dasylepida ishigakiensis Niijima et Kinoshita (Coleoptera: Scarabaeidae) emerge from the soil around dusk for mating on subtropical islands. The present study examines the factors controlling the emergence of males in the laboratory. There are two steps involved. Standby behaviour (i.e. insect head appears at the soil surface) can be observed for several hours before the beetles actually emerge for mating. The standby behaviour is facilitated by warm conditions, although the proportion of standby individuals is influenced not only by the temperature on that day, but also by that on the previous day. Experiments in which beetles are exposed to photoperiod and thermoperiod combinations, in and out of phase, show that temperature is more important in inducing standby and emerging behaviour than light alone. For the second step, factors such as temperature, light and the presence of the female sex pheromone determine whether males will leave the standby position and emerge onto the ground. The female sex pheromone stimulates standby beetles to exhibit emerging and wing vibration behaviours, although the effect depends on when it is presented to beetles. Beetles burrow back into the soil; this behaviour is influenced by illumination and time of the day but not by temperature. The results suggest that D. ishigakiensis possesses a sophisticated mechanism controlling male emergence from the soil.
ABSTRACT Abstract Two active fractions were found during the isolation of contact sex pheromone o... more ABSTRACT Abstract Two active fractions were found during the isolation of contact sex pheromone of female elytra of the white-spotted longicorn beetle, Anoplophora malasiaca (Thomson) (Coleoptera: Cerambycidae), in addition to fraction of hydrocarbons that had previously been identified. One fraction was essential to evoke a series of precopulatory behaviors of males toward a glass dummy when coated together with the hydrocarbon blend. The other fraction enhanced this activity when added to the mixture. From the latter synergistic fraction, we isolated five novel compounds and identified them as 10-heptacosanone, (Z)-18-heptacosen-10-one, (18Z,21Z)-heptacosa-18,21-dien-10-one, (18Z,21Z,24Z)-heptacosa-18,21,24-trien-10-one, and 12-heptacosanone by GC-MS and NMR analyses. A blend of four of these synthetic ketones, without 12-heptacosanone, in the ratio and concentration found in female elytra extract (250 : 400 : 1000 : 180 ng FE−1) showed greater synergistic effect than the natural fraction containing the ketones. This effect was canceled out by further addition of 12-heptacosanone (100 ng FE−1), which was still comparable to the effect of the natural ketone fraction.
Thirteen species of myrmecophilous insects belonging to three orders associated with three specie... more Thirteen species of myrmecophilous insects belonging to three orders associated with three species of Aenictus ants (Aenictus laeviceps, Aenictus gracilis,,Aenictus sp. 18a of SKY) were studied for behavioral observation and cuticular hydrocarbon (CHC) analysis. The myrmecophiles are: Aenictobia thoi, Aenictobia fergusoni, Mimaenictus wilsoni, Aenictoteras malayensis, Rosciszewskia gracilis, Trichotobia gracilis, Aenictoxenus sp., Weissflogia rhopalogaster (Coleoptera: Staphylinidae, rove beetles); Dohrniphora kistneri, Dohrniphora sp. 1, Dohrniphora sp. 2, Vestigipoda maschwitzi (Diptera: Phoridae, scuttle flies); Thysanura fam. gen. sp. (Thysanura, silverfish). Although behaviors of the rove beetles were highly variable by species, i.e., some were carried by ants and some were ignored by ants, the CHC profiles tended to resemble that of the host ants. The generalized scuttle flies Dohrniphora spp. were similar in behavior to each other but the CHC profiles were variable. The legless and wingless scuttle fly Vestigipoda maschwitzi was perfectly integrated into the ant colony as a mimic of ant larvae and also showed CHC profiles common to the ant larvae. The silverfish had very close contact with the ants, but the CHC profiles were quite different from the ants and the quantity itself was very low.
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