Invasive Ants Affect Spatial Distribution Pattern and Diversity of Arboreal Ant Communities in Fruit Plantations, in Tarakan Island, Borneo

Human activities influence ant community structure. In tropical areas, the habitat characteristics of crop plantations frequently shape the structure of arboreal ant communities. The present study investigated the spatial distribution of arboreal ants dwelling in durian Durio zibethinus and citrus Citrus amblycarpa plantations in the Tarakan Island, North Kalimantan. Specifically, it was investigated whether ant communities are dominated by native or invasive species; and if ant arboreal mosaics occur. This study included two sites (A and C) comprising durian and citrus plantations and one site B with only citrus plantations. Ant workers dwelling on crop trees were collected by branch beating, and subsequently identified and counted. Across all sites, a total of 64,360 workers, from 22 ant species, were collected from 59 durian and 63 citrus trees. In site A, the invasive species Tapinoma melanocephalum and the native species Oecophylla smaragdina were numerically dominant. A null model analysis of species co-occurrence revealed that species segregation existed in this site. Conversely, in sites B and C the invasive species T. melanocephalum and Technomyrmex albipes were dominant, and native arboreal ants almost co-occurred with the two species. Moreover, the number of T. melanocephalum and T. albipes workers was negatively correlated with the species diversity index of arboreal ants. However, the number of O. smaragdina workers showed no significant correlation. The results suggest that the invasion and domination of non-native species dissasemble spatial structures and reduce the species diversity in arboreal ant communities. The community structures of arboreal ants in fruit plantations were varied, depending on the fruit species and the properties of dominant ants

JAS siasat pencemaran

金沢大学理工研究域自然システム学系Certain lapwing species (Vanellus spp.) breed in agricultural habitats, where they are dependent on particular features of such artificial conditions. The breeding behavior and breeding success of the Grey-headed Lapwing Vanellus cinereus were examined on farmland in central Japan. Thirty-five pairs in 2004 and 42 pairs in 2005 were observed nesting on farmland consisting mainly of rice fields. Nests appeared to be distributed such that aggregations seemed to function as semi-colonies. Farming practices seriously affected breeding success: 33 (42.9%) breeding attempts were prevented during farming cultivation and flooding in spring. In 2004, only 16 (45.7%) pairs produced fledglings, and in 2005 only 14 (33.3%) pairs were successful. Territory size was also a factor affecting breeding success; territory area was positively correlated with the number of fledglings produced per nest. Grey-headed Lapwing parents intensively defended their nests and chicks; furthermore, group defense by multiple adults was also observed frequently. Defensive behavior was mainly directed against avian predators such as crows (Corvus spp.) and raptors, with group defense more frequently against raptors. Group defense was also more likely to occur where nests were close together, and it seemed that such defense was effective in increasing the number of chicks hatched. The breeding success of Grey-headed Lapwing was found to be influenced both by environmental and behavioral factors

Musculoskeletal systems that generate extremely fast movements in the trap-jaw ants

The 11th International Symposium on Adaptive Motion of Animals and Machines. Kobe University, Japan. 2023-06-06/09. Adaptive Motion of Animals and Machines Organizing Committee.Poster Session P1

Species composition of herbivorous insects and ants on trees in the plantations of durian Durio zibethinus and citrus fruits Citrus amblycarpa in Tarakan Island of Borneo

In the tropics, the specific insect communities are observed in the fruit plantations asone form of agroforestry systems. The information on the communities of herbivorous insects aspests and ants as pest-control agents could be useful in facilitating effective management ofplantations. Durian Durio zibethinus and citrus fruits Citrus amblycarpa are traditionally grown asagricultural products in the North Kalimantan region of Borneo, though the information onherbivorous insects and ants remains scant. In this study, we assessed the species composition anddensities of herbivorous insects and ants inhabiting on trees in the plantations of durian and citrusfruits in Tarakan Island of North Kalimantan. From 2016 to 2017, 55649 individuals of herbivorescomprised of 61 species and 64360 ant workers comprised of 25 species were collected by treebeatingsampling on 59 durian and 63 citrus trees in three plantation sites (A-C). In citrus fruittrees, aphid Toxoptera citridida was dominant in the herbivore communities. While, in durian trees,more than 80% of herbivores was occupied by various herbivore groups, leaf beetle, moth,mealybug, psyllid and leafhopper. In ants, more than 60% of ants collected in each site wasoccupied by three species Tapinoma melanocephalum, Technomyrmex albipes, and Oecophyllasmaragdina. NMDS analyses showed the patterns of classification in herbivorous insect and antcommunities were similar: the groups in site C could be classified, independent on the groups insite A and B. Probably, it may be caused by the environmental factors in site C. Otherwise, thecharacteristics of herbivores community are possibly affected by any interactions with ants,resulting in the association among the structures of herbivore and ant communities. Our data couldprovide useful information for the pest control activities in the plantations of durian and citrus fruitsin North Kalimantan

Effects of Two Army Ant Species, Dorylus laevigatus and Pheidologeton affinis, on Seed Survival and Germination in Bird-dispersed Plant Dysoxylum alliaceum

熱帯域に分布する木本植物の多くは晴乳類や鳥類を種子散布者として利用し，報酬として種子に栄養価の高い果実を備えている。しかしそれら果実を伴った種子は高密度に分布するアリともまた複雑な関係を持っている。西ジャワ州のポゴール植物園において鳥散布種であるシマセンダン属の1 種Dysoxylum alliaceum の種子とその近隣に生息している2 種の軍隊アリ，サスライアリの1 種印刷Dorylus lavigantusとヨコヅナアリの1 種Pheidologeton affinis との関係を野外観察と実験によって調べた。特にこれらのアリ種が種子の生存率と発芽率に及ぼす影響に着目した。地表に種子を置いた観察では種子100個の内，71 個(71.0%)が2 種のアリによって地面に埋められ，その果肉(ariI)が食べられていた。しかしその種子のほとんどは生存していた。プラスチックの網を使って実験的にアリの埋土を妨げると，配置した全ての種子は果肉部分からカビに感染して死亡した。また果肉をつけたままの種子群と除去した種子群を地面に植えて発芽率を比較したところ，果肉を除去した種子はしなかった種子よりも高い生存率と発芽率を示した。これらのことから2 種の軍隊アリは埋土と果肉の除去によってD. alliaceum の種子の生存，発芽率を上げているものと思われる

Clonal reproduction and genetic caste differences in a queen-polymorphic ant, Vollenhovia emeryi

Most social Hymenoptera are characterized by simple haploid sex determination and environment-based caste differentiation. This appears to be strikingly different in the queen-polymorphic ant Vollenhovia emeryi. Almost all long- and short-winged queens from a population in Central Japan were homozygous at three microsatellite loci, whereas workers were mostly heterozygous, suggesting either a complex system of genetic caste determination or, more likely, the production of female sexuals from unfertilized eggs by thelytokous parthenogenesis and of workers from fertilized eggs. Furthermore, male genotypes were not compatible with those of the queens and had exclusively the paternal allele found in the sterile, heterozygous workers, probably because males are produced from fertilized eggs after the exclusion of maternal nuclear DNA as recently reported for Wasmannia auropunctata. The genus Vollenhovia might provide an interesting model system to trace the evolution of unusual caste and sex determination systems