Abstract Oviposition preference for spherical substrates has been reported in some insects but not in Drosophila species until the recent finding that Drosophila suzukii preferentially lays eggs on spherical surfaces with a smaller radius, whereas D. melanogaster does not. This finding raised two questions: (i) Was this trait specifically acquired in D. suzukii or lost in D. melanogaster? (ii) In the latter case, is it due to the long‐term laboratory culture using oviposition substrates with flat surfaces? To answer these questions, we examined the oviposition preference of three Drosophila species using the stocks recently established from wild individuals. As with D. suzukii, D. simulans and D. takahashii showed significant preference for spherical surfaces with a smaller radius, suggesting that this trait is shared by multiple Drosophila species. In contrast, D. melanogaster did not show any preference for either smaller or larger radii, showing that the preference already has been lost in the natural population of D. melanogaster. It may be possible that the loss of oviposition preference for spherical surfaces is involved in the evolutionary process of D. melanogaster becoming a human commensal.

Abstract Mimicry with warning colors includes Batesian and Müllerian mimicries. If we divide mimicry by sex, there are theoretically four types of mimicry: unimodal, female‐limited, male‐limited and dual mimicry. The latter three cases cause sexual dimorphism in body color and marking pattern but are rarely reported. In this study, we show that the tussock moth Numenes albofascia is possibly a dual mimic. The wing color and marking pattern of male and female N. albofascia are completely different, with the male's pattern resembling that of the smoky moth Pidorus atratus, while the female pattern resembles that of the tiger moth Arctia caja. Body size also differs greatly between the sexes of N. albofascia, matching the mimicry model species of each sex. These moths are distributed sympatrically in Japan, and their adult seasons overlap with each other. According to lizard feeding experiments, N. albofascia is palatable, while both male and female model species are unpalatable. Actograms in the laboratory and the light trapping in the field suggest that females of N. albofascia fly actively from sunset to midnight, while males fly during the twilight period around dawn. Therefore, male and female N. albofascia might be Batesian mimics of diurnally active P. atratus and nocturnally active A. caja, respectively, and the great sexual dimorphism of this moth could be caused by dual mimicry.

Abstract Wetland biodiversity is currently declining on a global scale. Wetland biodiversity understanding is critical for determining the wetlands' conservation value. In this study, Macroplea Samouelle, 1819 (Coleoptera: Chrysomelidae) was discovered in Aomori Prefecture, Honshu Island, Japan. Only two Macroplea species have been recorded in Japan, M. japana (Jacoby, 1885) and M. mutica (Fabricius, 1792). Macroplea japana had been unrecorded for 60 years before being rediscovered in Honshu Island in 2022, and a single adult M. mutica female was discovered in Hokkaido Prefecture in 2003. The discovered individuals were concluded to be M. mutica based on morphological and molecular analyses. Although morphological differences were observed with the Eurasian M. mutica individuals, the male genitalia was nearly identical to M. mutica. For the molecular phylogenetic analysis based on COI and 28S sequences, Macroplea individuals in Japan were clustered with M. mutica on the Eurasian Continent. This is the first record of this species on Honshu Island (and the second in Japan), as well as the first record of adult males. This species would require conservation policies and additional distributional surveys.

Abstract The biology of Horniolus fortunatus (Lewis, 1896) has been fragmentarily reported, but what the larvae and adults feed on and the immature stages are still unknown. In this article, I report that this coccinellid adult and larva feed on mealybugs (Planococcus sp.) living in the nest of the ant Crematogaster matsumurai Forel, 1901.

Abstract The evolution of exaggerated sexual traits may be possible by the relaxation of various constraints on exaggeration. Functional constraints refer to the reduced performance of exaggerated traitsper seor increased survival costs by holding the exaggerated traits. Genetic constraints, such as genetic correlations or pleiotropy, may hinder the independent evolution and exaggeration of traits. Structural constraints, such as competition for space and resources among traits, may require the coordination of the exaggerated trait with surrounding structures. The remarkable diversity of male genital morphology provides an ideal opportunity for examining constraints on sexual trait exaggeration. In this study, we addressed the constraints on the evolution of exaggerated male genital morphology based on a comparative analysis of phenotypic covariation between the genitalia and other body parts usingOhomopterusground beetles. We found that exaggerated male genitalia were related to a relaxation of functional constraint, as revealed by a steeper allometric slope in the species with exaggerated male genitalia. By contrast, genetic constraint based on a shared genetic basis for the male genitalia and other appendages may have little effect on diversification in male genitalia. Structural constraints were strongest in the species with the most exaggerated male genitalia, suggesting that the observed constraint was a result of exaggeration. These findings improve our understanding of sexual trait exaggeration and underlying constraints.

Abstract In the beetle family Carabidae, feeding habits are important life history traits that determine their role in ecosystems and suitability as bioindicators. However, they have not been elucidated for most species, especially in the larval stages. Using laboratory‐rearing experiments, this study examined the larval feeding habits of two large carabid species: Lesticus magnus (tribe Pterostichini) and Chlaenius costiger (tribe Chlaeniini). Although previous studies failed to rear these larvae on insect larva diets, the mandible morphology of the first instars described in those studies, together with subsequently obtained knowledge of the relationship between mandible morphology and feeding habits in other carabid larvae, suggests that they are earthworm feeders. Rearing experiments with three types of animal diet (insect larvae, mixed snail and slug, and earthworm diets) showed that as expected, their larvae are earthworm feeders. In L. magnus, although the larvae accepted the mixed snail and slug diet and the earthworm diet, only larvae reared on the earthworm diet reached adulthood. In C. costiger, the larvae accepted only the earthworm diet and reached adulthood. This is the first report of earthworm feeding during the larval stage for the genus Lesticus (tribe Pterostichini) and tribe Chlaeniini. The importance of these results is discussed from ecological and evolutionary perspectives.

Abstract Altitudinal distribution and seasonal life cycle of drosophilid flies (Diptera) were studied on the southwestern slope of Mt. Higashi‐Kagonoto in Tomi and at Ishi‐no‐yu in Shiga Heights, Nagano, central Japan. Collections of flies were carried out from early spring to late autumn using traps baited with fermenting banana. Based on the present results and previous faunal reports from central Japan, major native drosophilid species collected in this study were classified into migratory (5 species), high‐altitude (6), mid‐altitude (14) and low‐altitude (14) species. The migratory species are assumed to perform extensive seasonal migration between low‐ and high‐altitude areas. Among these native species,Drosophila alpina(a high‐altitude species) andD. moriwakii(a mid‐altitude species) are assumed to pass only one generation in a year, while the others pass two or more generations. Five of the six high‐altitude species are assigned as the Palearctic elements, while four of the five migratory species and 12 of the 14 low‐altitude species are assigned as the Sino‐Japanese elements. The mid‐altitude species consist of approximately equal numbers of the Palearctic and Sino‐Japanese elements. Among the high‐altitude species,D. alpinaandHirtodrosophila makinoiare also distributed in high‐altitude areas in Hokkaido, northern Japan. The other high‐altitude species and most of the mid‐altitude species generally occur in low‐altitude areas in Hokkaido or the further north. The Sino‐Japanese elements occurring at high and mid altitudes in central Japan are also distributed at high altitudes in southern and southwestern China.

The lawn ground cricket, Polionemobius mikado, has protogynous tendencies and protogyny is regulated by photoperiod: shorter photoperiods reduced female development (red) more than male development (blue).

Abstract Rove beetles (Staphylinidae) are one of the largest families in Coleoptera. Although the ecological features of rove beetles are important subjects in terms of understanding their diversification processes, laboratory‐rearing studies have only been conducted for a few species to date. In this study, we established a continuous rearing method for Anotylus amicus (Bernhauer, 1923) (Staphylinidae: Oxytelinae) using bell cricket food. In addition, its life cycle, behavior and morphological variations were investigated using the rearing technique. The mean duration of egg, first, second and third instars, prepupa and pupa were 4.3, 4.0, 4.0, 7.8, 1.7 and 4.7 days at 24°C, respectively. Adults and larvae used substrate, food and excrement for nesting. Mate guarding by males and associated male–male combat were observed. Head width and body size sexually varied; most males were larger than females, but some were comparable to females. Many individuals possessed undeveloped short hindwings, while some, especially large females, had long ones. As A. amicus can be reared simply, have a fairly short generation period, and exhibit interesting behavioral and morphological characteristics, A. amicus is suitable for clarifying the ecological aspects of rove beetles.

Abstract Herbivore outbreaks cause serious damage to forest trees. In recent decades, outbreaks of the gall midge Schizomyia castanopsisae (Diptera: Cecidomyiidae) inducing inflorescence galls on Castanopsis sieboldii (Fagaceae) occurred in the Izu Islands, Tokyo, Japan. We investigated the gall density on the islands and estimated the larval population on Miyakejima Island. We also surveyed seasonal changes in larval age structure, presence of natural enemies, larval cold tolerance, and thermal effects on the adult emergence. In addition, we conducted molecular phylogenetic analyses of S. castanopsisae populations among different localities. The gall density was particularly high in southern parts (from Miyakejima to Aogashima) of the Izu Islands. The gall midge seemed to have been expanding its range toward northern parts in recent years. On Miyakejima, the larval population was estimated to be approximately 158 and 36 bn in 2017 and 2018, respectively. Parasitoids were not found in the dissection of galls. A cold temperature treatment did not affect the percentage of adult emergence. Developmental zero and thermal constant during the period from larval departure to adult emergence were estimated to be 4.7°C and 588.2°C‐days in males and 7.4°C and 476.2°C‐days in females, and the adults were predicted to emerge in April. Populations in Kyushu were genetically distinct from those in Okinawajima and the Izu Islands, but a common haplotype was found between the latter two localities. These imply that S. castanopsisae on the Izu Islands may be a recent invasion, and the absence of natural enemies causes its outbreaks.