Usun Shimizu-kaya

Various chemical strategies to deceive ants in three Arhopala species (lepidoptera: Lycaenidae) exploiting Macaranga myrmecophytes.

Macaranga myrmecophytes (ant-plants) are generally well protected from herbivore attacks by their symbiotic ants (plant-ants). However, larvae of Arhopala (Lepidoptera: Lycaenidae) species survive and develop on specific Macaranga ant-plant species without being attacked by the plant-ants of their host species. We hypothesized that Arhopala larvae chemically mimic or camouflage themselves with the ants on their host plant so that the larvae are accepted by the plant-ant species of their host. Chemical analyses of cuticular hydrocarbons showed that chemical congruency varied among Arhopala species; A. dajagaka matched well the host plant-ants, A. amphimuta did not match, and unexpectedly, A. zylda lacked hydrocarbons. Behaviorally, the larvae and dummies coated with cuticular chemicals of A. dajagaka were well attended by the plant-ants, especially by those of the host. A. amphimuta was often attacked by all plant-ants except for the host plant-ants toward the larvae, and those of A. zylda were ignored by all plant-ants. Our results suggested that conspicuous variations exist in the chemical strategies used by the myrmecophilous butterflies that allow them to avoid ant attack and be accepted by the plant-ant colonies.

Congruence of Microsatellite and Mitochondrial DNA Variation in Acrobat Ants (Crematogaster Subgenus Decacrema, Formicidae: Myrmicinae) Inhabiting Macaranga (Euphorbiaceae) Myrmecophytes

A previously reported mitochondrial DNA (mtDNA) phylogeny of Crematogaster (subgenus Decacrema) ants inhabiting Macaranga myrmecophytes indicated that the partners diversified synchronously and their specific association has been maintained for 20 million years. However, the mtDNA clades did not exactly match morphological species, probably owing to introgressive hybridization among younger species. In this study, we determined the congruence between nuclear simple sequence repeat (SSR, also called microsatellite) genotyping and mtDNA phylogeny to confirm the suitability of the mtDNA phylogeny for inferring the evolutionary history of Decacrema ants. Analyses of ant samples from Lambir Hills National park, northeastern Borneo, showed overall congruence between the SSR and mtDNA groupings, indicating that mtDNA markers are useful for delimiting species, at least at the local level. We also found overall high host-plant specificity of the SSR genotypes of Decacrema ants, consistent with the specificity based on the mtDNA phylogeny. Further, we detected cryptic genetic assemblages exhibiting high specificity toward particular plant species within a single mtDNA clade. This finding, which may be evidence for rapid ecological and genetic differentiation following a host shift, is a new insight into the previously suggested long-term codiversification of Decacrema ants and Macaranga plants.

Potential host range of myrmecophilous Arhopala butterflies (Lepidoptera: Lycaenidae) feeding on Macaranga myrmecophytes

“Plant-ants”, i.e. those symbiotic with myrmecophyte plants, defend their hosts against herbivores. Plant-ants are expected to affect the host-plant ranges of herbivores that feed on myrmecophytes. This study aimed to experimentally determine whether anti-herbivore defences by plant-ants restrict the larval host-plant ranges of four Arhopala (Lycaenidae) butterflies that feed on Macaranga (Euphorbiaceae) trees, some of which are myrmecophytes. We fed Arhopala larvae with the leaves of five Macaranga species under ant-excluded conditions to examine their potential host-plant ranges. Under ant-excluded conditions, three Arhopala species survived to the pupal stage when fed species not used in the field as well as their normal host species. Our data suggested that the aggressive behaviours of plant-ants towards leaf-feeding insects restrict the potential host-plant ranges of some Macaranga-feeding Arhopala butterflies.

Myrmecoxeny in Arhopala zylda (Lepidoptera, Lycaenidae) Larvae Feeding on Macaranga Myrmecophytes

ABSTRACT Some species in the tree genus Macaranga (Euphorbiaceae) in the Southeast Asian tropics are myrmecophytic; they have highly species-specific mutualisms with symbiotic ants (plant-ants), which defend them from herbivores. However, larvae of some Arhopala (Lycaenidae, Lycaeninae) species can elude the ants. Here we demonstrated that Arhopala zylda larvae showed myrmecoxeny on their myrmecophytic Macaranga host plants; they had no stable association with the plant-ants. Despite the presence of many plant-ants, A. zylda larvae were rarely attended or attacked by ants on their host plants. The plant-ants of three other myrmecophytic Macaranga species (non-hosts to A. zylda) also paid little attention to experimentally introduced A. zylda larvae. The myrmecoxeny seen in A. zylda is notable among lycaenid larvae that feed on myrmecophytes, because almost all are obligate intimate myrmecophiles.

Host-plant use by two Orthomeria (Phasmida: Aschiphasmatini) species feeding on Macaranga myrmecophytes

Myrmecophytes depend on symbiotic ants (plant‐ants) to defend against herbivores. Although these defensive mechanisms are highly effective, some herbivorous insects can use myrmecophytes as their host‐plants. The feeding habits of these phytophages on myrmecophytes and the impacts of the plant‐ants on their feeding behavior have been poorly studied. We examined two phasmid species, Orthomeria alexis and O. cuprinus, which are known to feed on Macaranga (Euphorbiaceae) myrmecophytes in a Bornean primary forest. Our observations revealed that: (i) each phasmid species relied on two closely‐related myrmecophytic Macaranga species for its host‐plants in spite of their normal plant‐ant symbioses; and (ii) there was little overlap between their host‐plant preferences. More O. cuprinus adults and nymphs were found on new leaves, which were attended by more plant‐ants than mature leaves, while most adults and nymphs of O. alexis tended to avoid new leaves. In a feeding choice experiment under ant‐excluded conditions, O. alexis adults chose a non‐host Macaranga myrmecophyte that was more intensively defended by plant‐ants and was more palatable than their usual host‐plants almost as frequently as their usual host‐plant, suggesting that the host‐plant range of O. alexis was restricted by the presence of plant‐ants on non‐host‐plants. Phasmid behavior that appeared to minimize plant‐ant attacks is described.

New Pilophorus species associated with myrmecophilous Macaranga trees from the Malay Peninsula and Borneo (Heteroptera: Miridae: Phylinae)

Seven new species of the phyline plant bug genus Pilophorus Hahn, 1926, namely, P. aurifasciatus Nakatani & Komatsu, P. gracilipennis Nakatani & Komatsu, P. lambirensis Nakatani & Komatsu, P. laticollaris Nakatani & Komatsu, P. longirostris Nakatani & Komatsu, P. multivillus Nakatani & Komatsu, and P. unifasciatus Nakatani & Komatsu, are described from the Malay Peninsula and Borneo (Sarawak). These new species are associated with myrmecophilous Macaranga spp. (Euphorbiaceae), which are well-known as myrmecophytes. All the new species have a uniquely protruded scutellum; the phylogenetic significance of this modification is discussed.

Reduced ant defenses in Macaranga myrmecophytes (Euphorbiaceae) infested with a winged phasmid Orthomeria cuprinus

Macaranga is a tree genus that includes many species of myrmecophytes, which are plants that harbor ant colonies within hollow structures known as domatia. The symbiotic ants (plant–ants) protect their host plants against herbivores; this defense mechanism is called ‘ant defense’. A Bornean phasmid species Orthomeriacuprinus feeds on two myrmecophytic Macaranga species, Macaranga beccariana and Macaranga hypoleuca, which are obligately associated with Crematogaster ant species. The phasmids elude the ant defense using specialized behavior. However, the mechanisms used by the phasmid to overcome ant defenses have been insufficiently elucidated. We hypothesized that O.cuprinus only feeds on individual plants with weakened ant defenses. To test the hypothesis, we compared the ant defense intensity in phasmid-infested and non-infested M. beccariana trees. The number of plant–ants on the plant surface, the ratio of plant–ant biomass to tree biomass, and the aggressiveness of plant–ants towards experimentally introduced herbivores were significantly lower on the phasmid-infested trees than on the non-infested trees. The phasmid nymphs experimentally introduced into non-infested trees, compared with those experimentally introduced into phasmid-infested trees, were more active on the plant surface, avoiding the plant–ants. These results support the hypothesis and suggest that ant defenses on non-infested trees effectively prevent the phasmids from remaining on the plants. Thus, we suggest that O.cuprinus feeds only on the individual M. beccariana trees having decreased ant defenses, although the factors that reduce the intensity of the ant defenses remain unclear.

Differences in the fruit maturation stages at which oviposition occurs among insect seed predators feeding on the fruits of five dipterocarp tree species: Seed predators of Dipterocarpaceae

The seeds of dipterocarp trees are the main food resources for many species of weevils, bark beetles and small moths; however, for most seed‐eating insects on dipterocarp tropical trees, seed utilization patterns remain poorly investigated. This study aimed to determine the fruit maturation stages at which eggs are laid by different insect seed predators feeding on the seeds or fruits of the following five dipterocarp species: Dipterocarpus globosus, Dryobalanops aromatica, Shorea beccariana, S. acuta and S. curtisii, which reproduced during the same period. We investigated the occurrence frequencies of the insect seed predators at various growth stages by collecting both unfallen and fallen fruit on several occasions during the period of seed/fruit maturation in a tropical rainforest in Borneo from September to December 2013. Weevils and bark beetles were the dominant insect seed predators of the five tree species. One or two weevil species of Alcidodes, Damnux and/or Nanophyes preyed on the seeds of each of the five tree species, and one bark beetle species, Coccotrypes gedeanus, preyed on the seeds of all five tree species. Many larvae, pupae and adults of each weevil species were found in pre‐dispersal (unfallen) fruit, whereas bark beetles at various growth stages were found in post‐dispersal (fallen) fruit. These results suggested that, among the dominant insect seed predators of the five dipterocarp species, weevil species oviposit on pre‐dispersal fruit and begin their larval growth before seed dispersal, whereas the oviposition and larval development of bark beetle species occurs in post‐dispersal fruit.

Additional species and records of the “horn-backed” Pilophorus plant bugs in Southeast Asia (Heteroptera: Miridae: Phylinae)

Three new species of the “horn-backed” phyline plant bug genus Pilophorus Hahn, namely, P. erinaceulus , P. maruyamai and P. parvolus , are described from Borneo, Malaysia and Sumatra, Indonesia. The following species are newly recorded within Southeast Asia: P. lambirensis from the Malay Peninsula; P. laticollaris from Sumatra; P. longirostris and P. multivillus from Borneo. A supplementary key to the key by Nakatani et al. (2013) is provided.Y. Nakatani * , Natural Resources Inventory Center, National Institute for Agro-Environmental Sciences, Kannondai, 3-1-3, Tsukuba, Ibaraki, 305-8604, Japan. nakatany@affrc.go.jpT. Komatsu, Institute of Tropical Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan. corocoro1232000@yahoo.co.jpU. Shimizu-kaya, Center for Ecological Research, Kyoto University, Hirano, Otsu, Shiga 520-2113, Japan. shimizu.kaya.55c@st.kyoto-u.ac.jpT. Itioka, Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-nihonmatsu-cho, Sakyo-ku, Kyoto 606-8501, Japan. ichioka.takao.5m@kyoto-u.ac.jpT. Itino, S. Ueda, Department of Biology, Faculty of Science, Shinshu University 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan. ueda32@shinshu-u.ac.jpR. Hashim, Institute of Biological Science, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia. rh4758@gmail.comW. Asfiya, S. Hartini, Division of Zoology, Research Center for Biology, Indonesian Institute of Sciences, Jl. Raya Jakarta-Bogor Km. 46, Cibinong, Bogor, 16911, Indonesia. wara.asfiya@lipi.go.idH. Herwina, Laboratorium Riset Taksonomi Hewan, Jurusan Biologi, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Andalas, Kampus UNAND Limau Manis, Padang, 25163, Indonesia. hennyf91@gmail.com

A new genus and species of myrmecophilous brentid beetle (Coleoptera: Brentidae) inhabiting the myrmecophytic epiphytes in the Bornean rainforest canopy.

Pycnotarsobrentus inuiae Maruyama & Bartolozzi, gen. nov. and sp. nov. (Brentinae: Eremoxenini) is described from the Lambir Hills National Park, Borneo (Sarawak, Malaysia) based on specimens collected from Crematogaster difformis F. Smith, 1857 ant nests in the myrmecophytic epiphytic ferns Platycerium crustacea Copel. and Lecanopteris ridleyi H. Christ. A second species of Pycnotarsobrentus is known from Malaysia but is represented by only one female and consequently not yet described pending discovery of a male. Pycnotarsobrentus belongs to the tribe Eremoxenini and shares some character states with the African genus Pericordus Kolbe, 1883. No species of Eremoxenini with similar morphological modifications are known from the Oriental region.