Environmental Entomology最新文献

The eastern larch beetle, Dendroctonus simplex LeConte, is a North American species of bark beetle that shares the distribution of its host, Larix laricina (Du Roi) K. Koch. A recent outbreak in the Great Lakes region has prompted renewed interest in the chemical ecology of eastern larch beetle and its natural enemies. Here, we describe field assays elucidating these insects' flight responses to host resin odors and pheromone components in Minnesota and laboratory olfactometer assays illustrating walking responses by eastern larch beetle to pheromone components produced by female beetles. In field trials, the addition of host monoterpenes ∆-3-carene and α-pinene to seudenol lures increased trap captures of eastern larch beetles. Similarly, α-pinene increased captures of Thanasimus spp. predators in seudenol-baited funnel traps. Frontalin release rates between 0.014-3.3 mg/day did not significantly alter catches of eastern larch beetles with seudenol alone, however, still higher concentrations of frontalin (24 mg/day) decreased catches. In contrast, increasing frontalin release rates increased attraction of Thanasimus spp. to seudenol. In a laboratory olfactometer assay, a combination of frontalin and seudenol released at rates comparable to those of a solitary, mining female arrested walking male eastern larch beetles whereas either compound alone did not. Insights into the eastern larch beetle's chemical ecology will improve understanding of cues in host and mate location that may be exploited for management.

Pesticides released into the environment are increasingly recognized as a global threat to freshwater ecosystems because of their adverse effects on non-target organisms, particularly aquatic insects and other arthropods. Superoxide dismutases (SODs) are important antioxidant enzymes that play a crucial role in protecting organisms from oxidative stress induced by harmful materials. In this study, we identified 2 cellular SODs (PxSOD1 and PxSOD2) in Protohermes xanthodes Navás (Megaloptera: Corydalidae), an freshwater predatory insect, and determined the oxidative stress induced in P. xanthodes larvae by sublethal exposure to chlorpyrifos (CPF). PxSOD1 and PxSOD2 are members of the cytoplasmic Cu/ZnSODs and mitochondrial MnSODs, respectively, and differ substantially in protein structure. Both PxSOD1 and PxSOD2 recombinant proteins demonstrated catalytic activity toward O2•- in the activity assays. After exposure to sublethal concentrations of CPF, malondialdehyde (MDA) content and SOD activities were increased in P. xanthodes larvae in a dose-dependent manner. PxSOD1 expression was decreased in the 0.42 and 4.2 μg/L CPF groups and increased in the 4.2 μg/L CPF group. PxSOD2 was upregulated by 0.42, 4.2, and 8.4 μg/L CPF treatments and the expression levels in the 4.2 and 8.4 μg/L CPF groups were significantly higher than that in the no CPF control. Our results suggest that sublethal concentrations of CPF can induce oxidative stress in P. xanthodes larvae, and the cellular SODs in P. xanthodes larvae may contribute to the protection against CPF-induced oxidative stress.

Colonizing aphids play an important role in the transmission of RNA phytoviruses in the family Solemoviridae. According to "host manipulation hypothesis," phloem limited and persistently transmitted Solemoviridae viruses modulate host physiology that positively affects vector behavior and fitness and facilitates virus spread. However, it is unclear if virus-modulated host effects on vectors across pathosystems involving Solemoviridae members are always positive. Cotton leafroll dwarf virus (CLRDV) is a recently introduced Solemoviridae member in the United States, and it is transmitted by the cotton aphid (Aphis gossypii). Effects of CLRDV infection on vector behavior and fitness were evaluated on its primary host plant, cotton (Gossypium hirsutum), and an alternate host plant, hibiscus (Hibiscus acetosella). In this study, changes to viruliferous and non-viruliferous aphid preference and aphid fitness on virus-infected and non-infected hosts were examined. In contrast to the hypothesized preference of non-viruliferous aphids for infected plants and vice-versa, both viruliferous and non-viruliferous A. gossypii preferred non-infected cotton and hibiscus plants over CLRDV-infected plants. This suggested that the preference of non-viruliferous vectors to non-infected plants might negatively impact virus acquisition, whereas the preference of viruliferous vectors toward non-infected plants could positively facilitate virus inoculation. The total fecundity and intrinsic rate of increase of aphids were higher on non-infected plants compared with CLRDV-infected plants. The lack of enhanced fitness benefits on CLRDV-infected hosts also could negatively impact virus spread. Overall, this study suggested that "host manipulation hypothesis" favoring vector attraction and enhanced fitness on infected plants does not apply to all pathosystems involving Solemoviridae members.

Nectar is an important source of food for adult mosquitoes, influencing their biological characteristics including longevity, fecundity, and flight range. Consequently, it can impact mosquitoes' survival and efficiency in transmitting disease. Different mosquito species are known to show preferences for flower nectar from certain plants, yet despite the importance of these plant-mosquito associations, knowledge of such biotic interactions is sparse. Here, we present a systematic map to address the question: "Which nectar do mosquitoes feed on?." The mapping process identified 49 articles (comprising 51 studies) meeting inclusion criteria, detailing 397 records of 74 mosquito species feeding on nectar from 145 plant species and 109 genera. Data extracted from the map were then analyzed to better understand if mosquitoes showed preferences for specific plant nectar. A key finding from this study is clear evidence supporting the hypothesis that mosquitoes exhibit preferences for nectar from particular plant species, including 77 species of plants and 58 genera for Aedes species, 18 species of plants and 17 genera for Anopheles species, and 16 species of plants and 16 genera for Culex species (all 3 genera belong in Diptera: Culicidae). Our study also highlighted the need for further field and laboratory work in time and space and using methods that randomly selects plant species for investigation. This would facilitate a better understanding of the relationship between mosquito feeding behavior and nectar seasonality and abundance; data that are critical for the development and improvement of new mosquito control methods to tackle vector-borne diseases.

Corn earworm, Helicoverpa zea Boddie (Lepidoptera: Noctuidae), is a common herbivore that causes economic damage to agronomic and specialty crops across North America. The interannual abundance of H. zea is closely linked to climactic variables that influence overwintering survival, as well as within-season host plant availability that drives generational population increases. Although the abiotic and biotic drivers of H. zea populations have been well documented, prior temporal H. zea modeling studies have largely focused on mechanistic/simulation approaches, long term distribution characterization, or degree day-based phenology within the growing season. While these modeling approaches provide insight into H. zea population ecology, growers remain interested in approaches that forecast the interannual magnitude of moth flights which is a key knowledge gap limiting early warning before crops are planted. Our study used trap data from 48 site-by-year combinations distributed across North Carolina between 2008 and 2021 to forecast H. zea abundance in advance of the growing season. To do this, meteorological data from weather stations were combined with crop and soil data to create predictor variables for a random forest H. zea forecasting model. Overall model performance was strong (R2 = 0.92, RMSE = 350) and demonstrates a first step toward development of contemporary model-based forecasting tools that enable proactive approaches in support of integrated pest management plans. Similar methods could be applied at a larger spatial extent by leveraging national gridded climate and crop data paired with trap counts to expand forecasting models throughout the H. zea overwintering range.

Herbivorous insects utilize olfactory and visual cues to orient on suitable host plants, and such cues can be employed to facilitate insect monitoring. Lygus lineolaris Palisot de Beauvois is a polyphagous pest throughout North America. Monitoring this pest as it moves between crop and non-crop hosts remains challenging, and a lack of effective monitoring tools complicates management of this insect. In this study, we examined the electrophysiological and behavioral responses of L. lineolaris to the volatile emissions of 2 crop hosts: alfalfa and strawberry. Gas chromatography with electroantennographic detection was applied to identify antennally active compounds in headspace extracts of flowering host plants, before responses to individual compounds were examined in the field. Five compounds consistently elicited antennal depolarizations in adults of L. lineolaris and, of these, (±)-linalool increased the capture rate of L. lineolaris females in the field. Subsequent experiments examined the influence of visual cues and stereochemistry on capture rate, revealing that lures containing (±)-linalool and (S)-(+)-linalool significantly increased the capture rate of L. lineolaris females compared with traps baited with (R)-(-)-linalool and controls, indicating that L. lineolaris is attracted to (S)-(+)-linalool. While lures increased capture on red traps, this was not the case for white traps, emphasizing the importance of visual cues in the movements and monitoring of L. lineolaris. This study demonstrates that L. lineolaris is attracted to (S)-(+)-linalool in the field, and that attraction depends on trap color. This knowledge is expected to improve monitoring strategies for L. lineolaris in agricultural systems.

A new population of the Asian longhorned beetle (Anoplophora glabripennis Motschulsky), an invasive species in North America since 1996, was discovered in Charleston County, South Carolina, in 2020. This population is the furthest south Asian longhorned beetle has established in North America. Previous models only estimate development time at this latitude; as such, we examined Asian longhorned beetle phenology in this novel climate. Over 24 consecutive months, we collected 153 eggs, 878 larvae, 37 pupae, and 1 unemerged adult (1,009 total specimens) from the federal quarantine zone in South Carolina and used larval head capsule width to determine development rate and voltinism. The presence of Asian longhorned beetle adults was determined via visual field observations. Asian longhorned beetle in South Carolina appears to have a synchronous univoltine life cycle, in contrast to populations in the northern United States and Canada that typically develop in 2-3 yr. This information will be useful for future model development to determine Asian longhorned beetle life cycles, for implementing novel management methods, and will aid in predictions to benefit visual survey efficacy.

The non-native wood-boring and symbiotic fungus-culturing Xylosandrus germanus (Blandford) was first reported in New York apple orchards in 2013. Trapping surveys have been conducted annually since to assist growers in timely applications of preventative control measures. In 2021, a similar-looking introduced species, Anisandrus maiche (Kurentsov), was identified in traps in west central New York. Anisandrus maiche was first recorded in 2005 in Pennsylvania but its history in New York was unclear due to potential misidentification. We collected and identified ambrosia beetles using ethanol-baited bottle traps in 2022 and 2023 in New York at 2 commercial apple orchards near Lake Ontario and 2 cider apple orchards in the lower Finger Lakes district. Traps were placed in a forest interior, the forest edge, and the orchard edge at each site. Xylosandrus germanus was trapped from mid-April into early October; it was abundant in the Lake Ontario region but less so in the Finger Lakes. In contrast, counts of A. maiche were very high in the Finger Lakes but extremely low near Lake Ontario. It was trapped from late-May to mid-September. Most other bark and ambrosia beetle species were uncommon. Captures of X. germanus and A. maiche were generally highest in the forest interior and declined toward the orchard edge, but each species was usually present in traps across habitats at the same time. Thus, the practice of trapping at forest edges should continue. Both species can potentially infest stressed trees, including in orchards, throughout the growing season.

Understanding and optimizing rearing conditions for dragonfly larvae is crucial for ecological research and conservation efforts, yet optimal rearing conditions and general rearing practices are lacking. In this study, we investigated the effect of temperature, amount of oxygen in water, presence of (artificial) plants, and age of eggs on hatchability, survival, and development of dragonfly larvae using the model species Sympetrum striolatum. We conducted three independent experiments and assessed variability between egg clutches of individual females, as well as the occurrence of cannibalism among larvae. Our results showed that egg hatchability varied significantly between individual females and was negatively affected by egg aging and the presence of artificial plants. Larval survival was negatively affected by water temperatures above 24°C, the presence of artificial plants, and egg aging, and positively affected by high feeding frequency, in certain instars. Notably, cannibalism was observed among later instar larvae, especially under higher density conditions. Based on these findings, we provide practical recommendations for optimizing dragonfly larvae rearing protocols, emphasizing the importance of maintaining optimal temperature, appropriate feeding regimes, and managing larval density to reduce cannibalism. This study offers experimental, evidence-based guidelines for dragonfly larvae rearing, contributing to improved research methodologies and conservation efforts.

Wild bee communities are the target of various conservation and ecological restoration programs. Strategic conservation can influence bee communities visiting fields and help mitigate pollinator limitations in fruit production. However, planning compatible conservation strategies and gauging their effectiveness requires understanding how local communities vary across space and time in crops and adjacent semi-natural areas. Here, we assessed the spatiotemporal changes in the composition of wild bee communities in blueberry fields and adjacent forests. In partnership with commercial farms in southeast Georgia, USA, we deployed blue vane traps at the interior and edge of blueberry fields and within adjacent forests of 8 fields, from March to October over 2 yr. We identified 72 wild bee species across 26 genera. The most common were Melissodes communis (Cresson, Hymenoptera: Apidae), Bombus bimaculatus (Cresson, Apidae), Melissodes bimaculatus (Lepeletier), Ceratina floridana (Mitchell, Apidae), Lasioglossum pectorale (Smith, Halictidae), and Lasioglossum nymphale (Smith), which accounted for nearly 60% of the wild bees caught. Bee diversity and richness fluctuated over time, with peaks in all 3 habitat types occurring after the blueberry blooming. Bee abundance in the adjacent forest was relatively constant throughout the season, while in the field interior and edge assemblages, abundance peaked between May and June. We observed dissimilarity in species composition related to month and field location. This difference was explained by fluctuation in the identity and relative abundance of the most abundant species. Together, our study advances foundational knowledge of wild bee community dynamics and species identity in blueberry fields which will help inform and prioritize conservation practices.