Environmental Entomology最新文献

Potato leafhopper (PLH), Empoasca fabae Harris (Hemiptera: Cicadellidae), is an economic pest of a variety of crops that migrates between overwintering sites in the southern United States and northern breeding grounds. Since 2005, the Midwest Suction Trap Network (STN) has monitored the magnitude and timing of aerially dispersing aphids' activity, but the potential of the network to monitor other taxa is only beginning to be explored. Here, we use the Midwest STN to examine how the magnitude and timing of PLH activity vary with weather, cropland cover, and time of year. We found that weekly PLH activity increased early in the season (May-June) with increasing degree day accumulation and decreased mid-season (July-August) with increasing occurrence of rain. The first detections occurred earlier in southern latitudes, while the last detections occurred sooner, when there was more surrounding potato land cover, and later over time between 2018 and 2021 and in southern latitudes. PLH activity was thus longer in duration in southern latitudes and has continued to extend later into the year overall. Resolving uncertainty about how well the Midwest STN captures migratory activity and how closely suction trap detections reflect local population densities in crop fields remain important research priorities before the potential of the Midwest STN for PLH monitoring can be realized. Still, observed patterns suggest that PLH could increase in economic importance as insects disperse over larger portions of the growing season in the warming, agriculturally productive US Midwest and that the STN can become a useful tool to monitor these changes.

Eucryptorrhynchus scrobiculatus (Motschulsky) (Coleoptera: Curculionidae) is a notorious pest of Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae). E. scrobiculatus adults typically aggregate under leaves and in soil crevices at the base of A. altissima in the field. We hypothesize that the environmental factors and conspecific signals determine their aggregation behavior. To test this, we investigated adult numbers in light-exposed and shaded areas of the sample trees and conducted experiments in both field and lab settings. Results revealed that (i) greater adult distribution in shaded areas; (ii) significant influence of temperature and illumination on aggregation tendency in the field; (iii) no gender-based difference in aggregation degree and maximum aggregation between light and dark; (iv) the host plant triggering the aggregation tendency, negatively affected in the absence; (v) the aggregation tendency of E. scrobiculatus weakened with the temperature gradually changing to ordinary temperature; and (vi) mutual attraction and chemical attraction between males and females. Thus, the aggregation behavior was influenced by factors including temperature, light intensity, host plant, and conspecific signals, but light's role was not obvious in the lab.

The avian vampire fly Philornis downsi (Dodge & Aitken) (Diptera: Muscidae) is native to continental South America and the Caribbean, but invasive in the Galapagos Archipelago. The larvae of P. downsi feed on the blood and tissues of the nestlings of 75% of the small land bird species that are endemic or native to Galapagos, causing high in-nest mortality and severe population declines in some species. Efficient trapping techniques are vital to safeguarding these birds in the short term as well as for monitoring fly populations, but basic information about the ecology of the fly is still needed to help develop a species-appropriate trapping method. In this study, we used a novel trapping regime with a vertical distribution to make inferences about P. downsi's behavioral and spatial ecology and to optimize trap catch. Our results showed that male and female P. downsi were trapped in greater numbers below the canopy (3.1-7.5 m), lower down than other commonly caught insect species (5.1-11.5 m). Notably, the effect of trap height remained consistent across seasons and different weather conditions. These findings suggest that P. downsi tend to move at heights where their hosts nest (at or below the canopy) and do not spend time above the canopy. This also makes it unlikely that strategies such as hill-topping or aerial swarming are being used to locate mates. As such, trapping and control efforts should be focused below the canopy in forests with similar canopy heights to effectively capture P. downsi and reduce bycatch of other insects.

During the eradication program undertaken against Anoplophora glabripennis (Motschulsky) in the Greater Toronto Area, information was collected on the numerous signs of injury found on wounded trees. Herein, we used a portion of this information to assess the characteristics of logs with signs of oviposition (i.e., pits). Specifically, we related the basal diameter, type (log bole vs. log branch), height above ground, and branch hierarchy level of logs with pits to tree size (i.e., height and diameter at breast height) and level of infestation intensity. In general, pits were concentrated on logs from the bole and branches that were 8-14 cm in diameter in the lower 8 m of the bole and in the first 2 levels of the branching hierarchy. Oviposition pit location was strongly influenced by tree size-both height and diameter at breast height, with more pits on the lower bole in small trees and then higher on the bole and into the branches as tree size increased. As tree-level infestation intensity increased, pits were found on both larger and smaller diameter portions of the trees, presumably as preferred oviposition sites became saturated. These findings can improve the efficacy of surveillance activities for A. glabripennis.

The overabundance of large herbivores can have detrimental effects on the local environment due to overgrazing. Culling is a common management practice implemented globally that can effectively control herbivore populations and allow vegetation communities to recover. However, the broader indirect effects of culling large herbivores remain relatively unknown, particularly on insect species such as ground-dwelling beetles that perform key ecosystem processes such as decomposition. Here we undertook a preliminary investigation to determine how culling sika deer on an island in North Japan impacted ground-beetle community dynamics. We conducted pitfall trapping in July and September in 2012 (before culling) and again in 2019 (after culling). We compared beetle abundance and community composition within 4 beetle families (Carabidae, Scarabaeidae, Geotrupidae, and Silphidae), across seasons and culling treatments. We found each family responded differently to deer culling. Scarabaeidae displayed the greatest decline in abundance after culling. Silphidae also had reduced abundance but to a lesser extent compared to Scarabaeidae. Carabidae had both higher and lower abundance after culling, depending on the season. We found beetle community composition differed between culling and season, but seasonal variability was reduced after culling. Overall, the culling of large herbivores resulted in a reduction of ground-dwelling beetle populations, particularly necrophagous species dependent on dung and carrion for survival. Our preliminary research highlights the need for long-term and large-scale experiments to understand the indirect ecological implications of culling programs on ecosystem processes.

Terminalia argentea Mart. (Combretaceae), native to Brazil, is used in habitat restoration programs. Arthropods are bioindicators because their populations reflect changes in the environment. We evaluated the recovery of a degraded area by using ecological indices and analyzing arthropod interactions on T. argentea plants. The richness and diversity of sap-sucking Hemiptera and the abundance of tending ants and Sternorrhyncha predators increased with the number of T. argentea leaves. The correlation of the abundance of tending ants and Sternorrhyncha predators was positive with that of the sap-sucking Hemiptera, and the abundance of Sternorrhyncha predators was negative with that of tending ants and sap-sucking Hemiptera. The positive correlation between the abundance, richness, and diversity of insect groups and numbers of T. argentea leaves is an example of the bottom-up regulation mechanism, with the population dynamics of the lower trophic levels dictating those of higher trophic levels. The contribution of T. argentea, a host plant of many arthropods, to the recovery of ecological relationships between organisms in degraded ecosystems is important.

The polyphagous pest, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), damages fruit in orchards and field crops and is often found within nearby woodlands. Pheromone-baited traps can be used to monitor H. halys. However, the efficiency of trapping H. halys may vary depending on trapping strategy (live vs. dead capture), location (ground or canopy), and diel periodicity of captures. We compared H. halys capture within fruiting hosts for: (i) live and kill traps on the ground vs. traps in the canopy of black cherry (Prunus serotina Ehrh.) (Rosales: Rosaceae), sugarberry (Celtis laevigata Willdenow) (Rosales: Cannabaceae), and pecan (Carya illinoinensis (Wangenh.) K. Koch) (Fagales: Juglandaceae) trees, (ii) ground and canopy-live traps in sassafras (Sassafras albidum (Nutt.) Nees) (Laurales: Lauraceae), and (iii) whether diel periodicity was detected for live capture in sassafras and cotton. More H. halys adults and nymphs were captured in kill traps than in live traps. More nymphs were captured in kill traps in black cherry and sugarberry on the ground than in the canopy. Live adult capture was significantly greater in sassafras and pecan canopies than on the ground. In cotton and sassafras, more live adults were captured from 8 PM-noon, with the fewest captured from noon-6 PM. A better understanding of stink bug activity in the field allows for improved trapping and, possibly, improved timing of treatment applications.