Biology subjects

Saga, T.

Publications and source records attributed to Saga, T..

5 recordsLinked to original sources

bioRxiv2025

Feasibility of an eDNA-based educational program for high school students

O_LIEnvironmental education plays a crucial role in raising public awareness of ecosystem conservation. Environmental DNA (eDNA) analysis is a promising environmental education tool because it enables easy and comprehensive biodiversity assessment through simple water sampling. Despite several citizen-based surveys using eDNA analysis, minimal attention has been paid to its educational effectiveness. C_LIO_LIIn this study, we examined the educational feasibility of eDNA analysis by conducting an environmental education program that incorporated eDNA-based local fish surveys in three high schools in Japan. Through detailed questionnaire surveys conducted before and after the program, we verified whether our program increased student interest in biodiversity and ecosystem services. C_LIO_LIIn the program, students proactively identified diverse fish species living in the survey area by simply collecting water. The questionnaire survey results showed that student knowledge of and interest in biodiversity and ecosystem services increased after the program. Students became aware of local fish diversity and expressed their motivation to engage in conservation activities. We confirmed the educational impact of the program not only at the end but also immediately following the water sampling experience. C_LIO_LISynthesis and applications. These results provide the first empirical evidence of the positive effects of eDNA analysis on student environmental awareness and engagement. Our program provides a feasible model for eDNA-based environmental education. Because eDNA analysis can be applied to diverse target taxa that are unique to a given area, similar environmental education programs can be conducted for various citizen groups worldwide. Our research also suggested that eDNA-based environmental education was effective for younger generations with varying levels of interest and experience in nature, showing significant potential for addressing the extinction of natural experiences and motivating citizens to participate in ecosystem conservation activities. C_LI

scientific communication and education↗

bioRxiv2025

Fertilization reduces aphid performance but does not alter competitive exclusion between specialist and generalist species

Understanding how resource availability shapes herbivore competitive interactions is crucial for predicting pest dynamics under changing agricultural practices. Interspecific competition among herbivorous insects is mediated by host plant quality, yet mechanisms underlying competitive outcomes under varying nutrient conditions remain unclear. We investigated how fertilization affects population dynamics and competitive interactions between the legume-specialist Megoura crassicauda and the generalist Aphis craccivora on pea shoots (Pisum sativum) under fertilized and unfertilized conditions. Aphid population dynamics were monitored for 30 days in single-species and mixed-species treatments, and plant survival and biomass changes were assessed. Unexpectedly, fertilization reduced aphid population growth in both species, challenging conventional assumptions about nutrient effects on herbivores. Fertilization significantly affected M. crassicauda population growth but not that of A. craccivora. In mixed treatments, A. craccivora consistently excluded M. crassicauda by day 25, regardless of nutrient status. Plant mortality occurred in all aphid treatments except M. crassicauda under fertilized conditions. Our findings demonstrate that nutrient enrichment reduced herbivore performance but did not alleviate interspecific competition. The consistent competitive dominance of the generalist suggests that intrinsic species traits, rather than resource availability, determine competitive hierarchies. These findings have implications for pest management under changing agricultural practices.

ecology↗

bioRxiv2024

Laboratory observations reveal that mature Vespa mandarinia larvae continue calling at night

Animals produce and perceive vibroacoustic signals. Vespa hornet larvae produce a rhythmic rasping sound by rubbing their mandibles against the cell wall of the nest. The call is thought to be a larval provisioning cue. However, detailed observations of larval calls have been limited to a few species, and it is not known whether the call can be influenced by the external environment, such as light and time of day, or by internal larval states, such as feeding. We conducted laboratory observations of larval calls under workerless conditions to investigate the effects of 1) larval stage, 2) daily variation, 3) light conditions, and 4) feeding treatment. Vespa mandarinia larvae produce sounds regardless of their situation, such as position, light condition, time of day, and worker absence. During mastication, the larvae stopped calling. A key finding of this research is the novel discovery that larvae produce sounds at night, which is a previously undocumented behaviour.

animal behavior and cognition↗

bioRxiv2024

Dietary Analysis of Vespula shidai in Reared and Wild Nests

This study examines the dietary behaviors of both reared and wild nests of Vespula shidai in Central Japan, a region known for its rich biodiversity and unique entomophagy culture, particularly the consumption of wasp larvae and pupae, known locally as "hachinoko." This study reveal that these wasps exhibit remarkable dietary versatility, consuming a wide range of vertebrates--more varied than their counterparts in Hawaii and New Zealand. The study notes that wild nests, unlike their reared nests, consume a significantly greater variety of vertebrate species, even without supplementation. This suggests that vertebrate carcasses provide crucial nutrients that contribute substantially to wasp development. Additionally, this research highlights individual foraging preferences among nests, which are influenced by both the availability and nutritional value of prey, as well as human feeding practices. This variation in prey composition, particularly evident between reared and wild nests, underscores the complex interaction between wasps natural dietary habits and human intervention.

ecology↗

bioRxiv2019

Polyandry and Paternity influence disease resistance in a eusocial wasp - support for the pathogen parasite hypothesis

Polyandry (multiple mating by females) is a central challenge for understanding the evolution of eusociality. Several hypotheses have been proposed to explain its observed benefits in eusocial Hymenoptera, and one, the parasite-pathogen hypothesis, proposes that high genotypic variance among workers for disease resistance prevents catastrophic colony collapse. We tested the parasite-pathogen hypothesis in the polyandrous wasp Vespula shidai. We infected isolated workers with the entomopathogenic fungus Beauveria bassiana and quantified their survival in the laboratory. Additionally, we conducted paternity analysis of the workers using nine microsatellite loci to investigate the relationship between survival and matriline/patriline of the workers. As predicted by the parasite-pathogen hypothesis, nestmate workers of different patrilines showed differential resistance to B. bassiana. We also demonstrated variations in virulence among strains of B. bassiana. Our results are the first to directly support the parasite-pathogen hypothesis in eusocial wasps and suggest that similar evolutionary pressures drove the convergent origin and maintenance of polyandry in ants, bees, and wasps.

animal behavior and cognition↗