Abstract We found a presumably new species that is closely related to Lordiphosa collinella but different from it in the range of host plants. Lordiphosa collinella is a generalist breeding on a wide variety of decayed herbaceous plants. In contrast, the new form almost specializes in breeding on Pachysandra terminalis . First, we delineate the latter specialist as a new species, Lordiphosa yuktopakina sp. nov. The hypothesis that they are sibling but distinct species is highly supported by studies of breeding ecology, morphology, genetic differentiation and reproductive isolation. Lordiphosa yuktopakina is estimated to have differentiated from L . collinella approximately 0.121 million years ago. For the ancestor of L . yuktopakina to use P. terminalis as an alternative host plant, the fly should have surmounted the hard texture of the host plant tissue. Lordiphosa yuktopakina has achieved this by making the ovipositor more robust and increasing the size of the cephalopharyngeal skeleton and the allometry of the mouth hook with larger teeth especially in the 1st instar larva. These adaptations to the newly acquired host plant should be reflected in the female reproductive traits. Thus, the two Lordiphosa species studied here provide a new instance of recent speciation with change and specialization to a particular host plant.

Abstract The Darwin wasp Neotypus coreensis Uchida, 1930 (Ichneumonidae: Ichneumoninae) is rediscovered. A female was reared from a pupa of the endangered lycaenid Niphanda fusca (Bremer & Grey, 1853) collected in Oita Prefecture, Kyushu. This represents the first confirmed record of this species from Japan since the records reported by Hirukawa (1985) and the first record from Kyushu. DNA barcoding (658 bp of mt COI ) confirmed the identification and showed close similarity to Neotypus melanocephalus . Although the Japanese and European populations of N. coreensis are morphologically identical, they parasitize different hosts: Niphanda in Japan and Maculinea in Europe. The rediscovery highlights the importance of parasitoids in understanding and conserving endangered insect–parasite interactions.

Abstract Mangrove forests form vital interfaces between aquatic and terrestrial ecosystems, supporting a wide variety of organisms, both vertebrates and invertebrates. Although insects have long been underrepresented in mangrove research, particularly compared with studies on plant biology and ecosystem functioning, recent findings suggest that their diversity and ecological importance are greater than previously recognized. Nevertheless, their roles in trophic interactions, especially as prey, remain poorly understood. Here, we document six instances of insect predation from a mangrove habitat on Iriomote Island, the Yaeyama Islands, Japan. These include predation by fish, crabs, spiders, dragonflies, wasps and flies on various insect taxa, some of which are associated with mangrove environments. Although fragmentary, these records indicate that insects contribute to mangrove food webs not only as herbivores and detritivores but also as an important prey resource for a broad range of predators. Our observations underscore the need for further research into insect‐mediated trophic relationships in mangrove ecosystems.

ABSTRACTAnt nests accommodate a diverse group of strictly associated arthropods. Most of these arthropods are seldom observed outside their host nest, emphasizing significant gaps in our knowledge regarding their biology. We recorded a series of field observations of lepismatid silverfish (Zygentoma: Lepismatidae) moving outside their usual Messor nest habitat in southern Spain and France. We illustrate how they move between different nests and locate nests by closely tracking the foraging trails of their hosts. Additionally, we confirm a prior observation that they can follow their host ants when they migrate to a new nest site. Our observations offer new insights into the hidden biology and the intricate interactions of specialized arthropod symbionts with their hosts within a spatial context.

Abstract Insect community structures and biological interactions vary with the distance from the mainland to islands. Gall inducers are key organisms in local arthropod communities because their galls harbor diverse arthropods. We investigated the parasitoid community of a gall‐inducing cecidomyiid Schizomyia sasakii on the Izu Peninsula and the Izu Islands, Japan. We examined relationships between parasitism by Inostemma sp. and Torymus hirtipennis, and gall characteristics, and analyzed the directional selection on gall characteristics induced by S. sasakii in each locality. The species richness of parasitoids on the Izu Islands decreased with the distance from the Izu Peninsula to each island, and area of respective islands. Inostemma sp. preferably attacked large galls on Ohshima Island, and T. hirtipennis tended to attack relatively small galls in the Izu Peninsula. Directional selection on gall characteristics of S. sasakii favored the induction of larger galls and thicker tissues by S. sasakii on Ohshima Island. In contrast, no directional selection was detected in the gall characteristics on Hachijojima Island. The number of alternative host species of parasitoid may affect variation in parasitoid richness of S. sasakii on distant and small islands, because the species richness of gall midges is necessary to maintain local parasitoid populations. Our study supported the ovipositor limitation hypothesis for the torymid species, related to gall size. The directional selection of parasitoid attacks on the Izu Islands may act to favor the induction of large and hypertrophic galls by S. sasakii to avoid the parasitoids.

Abstract One of the characteristics of the adult eclosion rhythm in Drosophila melanogaster is that adult emergence time differs greatly between the first and second eclosion days. The emergence time is in the middle of the light period on the first eclosion day, but immediately after light‐on on the second day. We hypothesized that incomplete entrainment of the endogenous pacemaker to the light–dark (LD) cycle is responsible for the daily variation. Due to the very short pupal period of this species, adult emergence may occur before complete synchronization of the pacemaker with the external cycle on the first eclosion day. Therefore, the peak time on the first eclosion day may differ significantly from that on the second day. To verify this hypothesis, using pupae that had pupariated within 24 h, the time difference between the first and second peaks was compared in LD 12:12 or constant darkness at five different temperatures from 30 to 15°C. In both light regimes, the time difference decreased with decreasing temperature and extended pupal duration. The interval between the eclosion peaks approached 24 h, supporting this hypothesis. These results can be interpreted by using a two‐oscillator model.

ABSTRACTCrithidia mellificae and Lotmaria passim are trypanosomatids that infect honeybees, and many studies suggest that both parasites contribute to the decline in the honeybee population. The Japanese honeybee (Apis cerana japonica) is a native honeybee that inhabits various areas of Japan and is one of the most important pollinators. Both parasites have been well studied in the western honeybee (Apis mellifera) but have been poorly investigated in A. c. japonica. The present study investigated the presence of C. mellificae and L. passim in one feral and six managed A. c. japonica colonies at three different institutes. Five out of seven colonies were polymerase chain reaction‐positive for L. passim (71.4%); however, C. mellificae was not detected. Four of the five colonies were positive in both the midgut and hindgut, but one was positive only in the hindgut. A homology search and phylogenetic tree of the glycosomal glyceraldehyde‐3‐phosphate dehydrogenase (gGAPDH) and cytochrome b (Cytb) genes obtained in this study indicated that the sequences belonged to L. passim. The results of this study emphasize concerns regarding the health of this ecologically important pollinator and the importance of further investigation of the prevalence of L. passim in A. c. japonica in a wider area of Japan.