Environmental Entomology最新文献

Halyomorpha halys (Stål), an invasive species of Asian origin, has become a key pest of tree fruit in areas of the Eastern and Pacific Northwest United States. This study used a 5-yr dataset of pheromone trap captures from 4 ecoregions (Mountains, Piedmont, Southeastern Plains, and Atlantic Coastal Plain) of North Carolina to validate temperature-driven phenology models previously reported for oviposition by overwintering adults and eclosion of F1 adults using semi-field cage studies. Cumulative proportion of pheromone trap captures of F1 adults and nymphs over cumulative degree days was compared to predictions based on the previously reported models' quadratic equation curves for adult eclosion (y = -0.0000015x2 + 0.004736x - 2.664) and oviposition (y = 0.0000032x2 - 0.010853x + 9.050). The oviposition model was validated using projected oviposition curves to predict nymphal populations over time by using life stage-specific development and mortality rates. Analysis of coefficients of determination (R2) for all regressions showed that F1 adult model predictions varied by region and year. Mean R2 values in the Mountain, Piedmont, and Southeastern Plains ecoregions for F1 adults were 0.88, 0.93, and 0.93, respectively. Nymphal regressions also varied by ecoregion, with mean R2 values of 0.95, 0.86, and 0.88 in the Mountains, Piedmont, and Southeastern Plains, respectively. Differences among regions were mostly associated with lower R2 values at sites with low population densities. Results are discussed in relation to the value of these models in studying the ecology of invasive species and in informing pest management decisions.

Dragonflies and damselflies are exposed to various anthropogenic stressors in the aquatic-terrestrial ecosystem, which can affect their development and fitness. The symmetry of their wings, shaped during the aquatic larval stage, can serve as an indicator of environmental stress during development. Recent advances in computer-vision now provide the opportunity to standardize and enhance the precision of 2D assessments of entire wings, including many structural parameters, enabling a more reliable comparison of the effects of multiple anthropogenic stressors. We investigated the effect of 3 anthropogenic stressors on the fluctuating wing asymmetry of the damselfly Coenagrion puella: (i) Exposure to the agricultural insecticide chlorantraniliprole in a climate chamber experiment, (ii) alteration of the aquatic community with the mosquito control agent Bti (Bacillus thuringiensis israelensis), and (iii) altered hydrological regimes, both of which were applied in a floodplain mesocosm experiment in a full 2-factorial design. We found changes in wing size and several asymmetry parameters in response to the insecticide and altered hydrological regimes, whereas Bti treatment increased the number of cells in front wings. Our results show that damselflies' wing morphology and symmetry can be affected by anthropogenically induced stress in aquatic ecosystems. The intensity of stressor effects varied across treatments, with altered hydrology causing the strongest changes in wing size and asymmetry.

The armyworm, Mythimna unipuncta (Haworth), is a seasonal migrant that travels every spring from the United States towards northern breeding areas, such as Quebec (Canada), to avoid hot summer temperatures. Because of climate change, it could arrive earlier in the province, and the temperatures encountered upon arrival could increasingly vary, possibly influencing the female's reproductive traits. To explore the influence of temperatures on the reproduction and fecundity of M. unipuncta, we investigated the correlation between the number of eggs in egg clusters and their mass (g). Next, sexually mature couples were formed and subjected to constant temperatures of 10, 17, or 25 °C in growth chambers. We evaluated the lifetime fecundity, daily fecundity, delay between couple formation and egg laying, oviposition period (number of days between the first and last days of oviposition), number of oviposition days inside the oviposition period, mating percentage, and lifetime mating frequency. Our results showed that high temperature (25 °C) reduced egg size. Although temperature did not influence the lifetime fecundity of M. unipuncta, high temperature negatively influenced the couples' mating percentage and frequency. The 25 °C treatment also shortened the females' oviposition period. Together, our findings suggest that high temperatures would be more detrimental to the reproductive parameters of M. unipuncta than cooler temperatures. Results are discussed in a context of climate change.

Anoplophora glabripennis Motschulsky is an invasive woodboring beetle in North America and Europe that threatens a broad range of tree genera. Eradication is a costly and time-consuming process that requires visual surveys to detect beetle damage on host trees. Knowing the distribution of beetle damage within trees could directly benefit survey efforts by focusing surveys on high-risk areas and indirectly by identifying habitat factors that structure beetle populations. In the A. glabripennis infestation in South Carolina, we identified an isolated and actively growing subpopulation on an island that had not fully occupied the available host trees. With host resources still abundant for the beetle, the distribution of oviposition pits and exit holes is expected to be the result of habitat preference and (in the case of exit holes) larval performance. We examined the distribution of eggs and emerging adults by cataloging the >14,000 oviposition sites and >1,400 exit holes distributed among the 33 infested and uninfested host trees on the island, documenting the stem height, diameter, surface area, and bark thickness for all damage. Oviposition pits and exit holes were neither randomly nor evenly distributed within tree canopies; however, the distribution of available habitat (ie stem space within the canopy) seemed to drive most of the distribution, and the presence of damage was biased toward larger/taller trees. These results suggest some preference in egg placement with regard to canopy height, stem diameter, and bark thickness within canopies, but the responses are subtle and may have limited utility in guiding visual surveys.

Environmental disturbances have become increasingly frequent in the Amazon region. This study evaluated the potential bees of the Euglossini (Hymenoptera, Apidae) as bioindicators of environmental quality across 3 forest types-native, regenerating, and degraded-and assessed mercury (Hg) contamination in the biomass of Eulaema cingulata. Sampling was conducted between March 2021 and May 2023 in the southern portion of the Brazilian Legal Amazon. A total of 362 males euglossine were collected, representing 29 species: 177 individuals in native forest (22 spp.), 104 in degraded forest (20 spp.), and 81 in regenerating forest (23 spp.). Euglossine abundance differed significantly among forest types and varied in the interaction with seasonality. These results indicate that forest conservation status influences the structure of euglossine assemblages. Based on our findings, species such as Eufriesea ornata, Euglossa ignita, Euglossa orellana, Eulaema bombiformis, and Exaerete frontalis are more abundant in conserved forest environments. Although environmental mercury contamination was confirmed in soil and plant samples, Hg was not detected in Eulaema cingulata biomass. Nevertheless, further studies on mercury bioaccumulation in other euglossine species are warranted, given the persistent anthropogenic pressure in the southern Amazon.

Temperate-zone Geometridae moths, active across seasons, offer an excellent model for investigating how related species respond to varying environmental conditions, particularly photoperiod-a major Zeitgeber regulating biological oscillators. In this study, we examined the daily cycle of sperm release from the testes in 9 geometer moth species, including univoltine and bivoltine taxa, as well as diurnal and nocturnal species. We found that sperm release into the upper vasa deferentia differs consistently between day-flying and night-flying species. Moreover, we observed marked differences in the diel regulation of sperm release between spring and summer generations of the same species. Experimental evidence suggests that these intergenerational differences are photoperiod-dependent. Further manipulation confirmed that a long photoperiod not only abolishes rhythmic sperm release but also significantly reduces the number of eupyrene sperm bundles transferred into the vasa deferentia. This is the first demonstration, under near-natural conditions, of photoperiodic regulation of a physiological rhythm in a peripheral organ via its suppression. These findings underscore the importance of environmental timing cues in reproductive physiology and provide new insights into the temporal plasticity of insect reproductive systems. Importantly, they also highlight the potential for integrating agro-chronobiological knowledge with mechanistic studies of temporal regulation in insect pests. Finally, this work adds to our understanding of how peripheral oscillators may be shaped by selective pressures in closely related species occupying distinct ecological niches, where differences in the timing of life-history processes serve as key axes of divergence.

Osmia lignaria Say, the blue orchard bee is a native managed bee used to pollinate almond orchards and other early-blooming fruit crops. While this pollinator has proven effective for almond pollination, in-orchard propagation of this species has proven difficult. This study analyzed the usefulness of planting early blooming annuals within orchards to enhance on-site propagation of O. lignaria during pollination. Three native species were established between rows (inter-row flower strips, IRFS) in an isolated almond orchard in California's southern Central Valley. Pollination by O. lignaria was provided as a supplement to that provided by recommended levels of honey bee (Apis mellifera) hives. Proportion of supplemental pollen within brood provisions collected during the almond bloom period was analyzed with respect to the distance of nesting domiciles from IRFS and time interval. Maximal use of supplemental pollen occurred within a proximity of 0 to 40 m between th nest box and the IRFS. Activity levels of O. lignaria in the IRFS increased through the almond bloom period, peaking during the last third of the IRFS bloom. At the end of almond bloom, O. lignaria numbers sharply declined as honey bee numbers increased on the IRFS. Other native bee species also utilized the IRFS. This study reveals that 40 m or less between in-orchard floral plantings and nest boxes for O. lignaria optimized IRFS utilization, providing a pathway for determining nest box placement relative to IRFS plantings. Comments are made on practical considerations with respect to orchard management.

Why and how herbivorous insects choose to feed on some plant species and not others can be influenced by many factors; however, it is not always clear why herbivorous insects will choose to lay their eggs on some plants over others. The Hopkins' host selection principle (hereafter HHSP) hypothesizes that female insects prefer to lay eggs on host plants upon which they fed as larvae, but there are studies that both support and refute the hypothesis. Here, we test HHSP in a dietary generalist moth, fall webworm (Hyphantria cunea, hereafter FW). Previously, local host plant abundance has been the only factor found to determine FW host plant use; whether FW exhibit individual host plant preferences is unknown. We conducted preference tests with females of the two FW morphotypes (red-head and black-head), presenting females with four host plants: their one natal host plant, two other potential host plants, and one non-host plant for that morphotype that is a host plant for the other morphotype. Overwhelmingly, females of both morphotypes oviposited on a non-plant surface in the choice arena and those that did oviposit on a plant did not distinguish between host plants and non-host plants. Of the few FW females that oviposited on a host plant, only red-head females showed preference for their natal hosts. Our results support previous findings that HHSP is not a strong driver of host plant selection, suggesting that female FW are not selective in their choice of host plants, which may facilitate generalism in this species.

The use of native plant cultivars in pollinator plantings is somewhat controversial. Although some cultivars originate from wild populations, others are bred for novel ornamental traits, which may have unintended impacts on floral rewards, such as nectar and pollen. It is unclear whether changes in floral displays and/or rewards may alter plant-pollinator relationships. We established an experimental garden of Pacific Northwest native plants and native cultivars to evaluate differences in their floral traits and bee communities. We used a combination of methodologies to quantify variation in plant traits that could influence pollinator foraging, including those associated with floral displays (eg petal color, corolla morphology) and floral rewards (pollen and nectar). We also measured changes in bee community composition (eg species associations, functional diversity) across plant groups. We found that cultivars varied significantly from native plants across multiple floral display or reward traits. No plants were bred for nectar or pollen traits, thus changes in rewards were likely pleiotropic. Nine out of 10 tested cultivars had dissimilar bee communities to their native plant counterpart, though minimally developed cultivars were associated with similar bee species and functional traits. Our results suggest that the development of native plant cultivars can come at the cost of pollinator functional richness, though some variation in bee composition may be expected among wild plant populations with diverse phenotypes. Plants with phenotypes consistent with wild-type plants tended to support functionally rich bee communities and should be emphasized in plantings to maximize potential benefits to pollinators.