The whitefly, Bemisia tabaci, has developed resistance to many insecticides, renewing interest in the biological control of this global pest. Generalist predators might contribute to whitefly suppression if they commonly occur in infested fields and generally complement rather than interfere with specialized natural enemies. Here, we review literature from the last 20 years, across US cropping systems, which considers the impacts of generalist predators on B. tabaci. Laboratory feeding trials and molecular gut content analysis suggest that at least 30 different generalist predator species willingly and/or regularly feed on these whiteflies. Nine of these predators appear to be particularly impactful, and a higher abundance of a few of these predator species has been shown to correlate with greater B. tabaci predation in the field. Predator species often occupy complementary feeding niches, which would be expected to strengthen biocontrol, although intraguild predation is also common and might be disruptive. Overall, our review suggests that a bio-diverse community of generalist predators commonly attacks B. tabaci, with the potential to exert substantial control in the field. The key challenge will be to develop reduced-spray plans so that generalist predators, and other more specialized natural enemies, are abundant enough that their biocontrol potential is realized.

Anthropogenic noise decreases signal active space, or the area over which male bird song can be detected in the environment. For territorial males, noise may make it more difficult to detect and assess territorial challenges, which in turn may increase defense costs and influence whether males maintain territory ownership. We tested the hypothesis that noise affects the ability of male house wrens (Troglodytes aedon) near active nests to detect intruders and alters responses to them. We broadcast pre-recorded male song and pink noise on territories to simulate intrusions with and without noise, as well as to noise alone. We measured detection by how long males took to sing or approach the speaker after the start of a playback. To measure whether playbacks changed male behavior, we compared their vocal responses before and during treatments, as well as compared mean vocal responses and the number of flyovers and attacks on the speaker during treatments. Noise did not affect a male’s ability to detect an intruder on his territory. Males altered their responses to simulated intruders with and without noise compared to the noise-only treatment by singing longer songs at faster rates. Males increased peak frequency of songs during intrusions without noise compared to noise-only treatments, but frequency during intruder plus noise treatments did not differ from either. When confronting simulated intruders in noise, males increased the number of attacks on the speaker compared to intruders without noise, possibly because they were less able to assess intruders via songs and relied on close encounters for information. Although noise did not affect intruder detection, noise affected some aspects of singing and aggressive responses, which may be related to the challenge of discriminating and assessing territorial threats under elevated noise.

Anthropogenic noise changes the acoustic environment in which avian signals have evolved, possibly decreasing active space or the area over which signals may be detected and discriminated by receivers. Linking signal transmission patterns to signal function and species’ spatial ecology is important for understanding behavioural changes of receivers in noise. We tested whether varying levels of ambient noise affectstransmission of two structurally distinct sections of male house wren (Troglodytes aedon) song used for short- and long-distance communication. We placed our experiment in an ecological context by measuring signal degradation and attenuation in relation to species-typical spacing patterns to investigate whether song structure is maintained within (short-distance within-pair communication) and between territories (long-distance male-male and extra-pair communication) depending on noise levels. Songs experienced more masking and fell below thresholds for detection and discrimination at shorter distances under noisier conditions. Decay of signal-to-noise ratios and cross-correlation factors in noise were so pronounced that song components used for both short- and long-distance communication did not transmit beyond average territory boundaries. Noise masking could affect species ecology: if signals are not detected by intended receivers in noisier habitats, settlement, space use and social interactions may be fundamentally altered compared to those in quieter environments.

Biodiversity is an essential attribute of sustainable agroecosystems. Diverse arthropod communities deliver multiple ecosystem services, such as biological control, which are the core of integrated pest management programs. The molecular analysis of arthropod diets has emerged as a new tool to monitor and help predict the outcomes of management on the functioning of arthropod communities. Here, we briefly review the recent molecular analysis of predators and parasitoids in agricultural environments. We focus on the developments of molecular gut content analysis (MGCA) implemented to unravel the function of community members, and their roles in biological control. We examine the agricultural systems in which this tool has been applied, and at what ecological scales. Additionally, we review the use of MGCA to uncover vertebrate roles in pest management, which commonly receives less attention. Applying MGCA to understand agricultural food webs is likely to provide an indicator of how management strategies either improve food web properties (i.e., enhanced biological control), or adversely impact them.

Stink bugs (Hemiptera: Pentatomidae) are polyphagous pests that cause significant economic losses to a variety of crops. Although many species have been documented to aggregate within agricultural fields, much less is known regarding the timing and distribution of adults and nymphs within and between surrounding non-crop habitat. Therefore, we explored the spatiotemporal distribution of Euschistus servus (Say), Euschistus tristigmus (Say), and Chinavia hilaris (Say), three species of North American origin, and examined whether distribution patterns varied between species according to habitat. Stink bugs were monitored weekly for three years within an 18 km² grid of pheromone-baited traps. We tested whether habitat affected distribution patterns, used spatial analysis by distance indices (SADIE) to identify aggregations, and visualized distributions with interpolated maps. Overall, E. servus adults were captured in crops, whereas E. tristigmus adults and nymphs were mainly captured in forests. Accordingly, distribution patterns of E. tristigmus were relatively stable over time, whereas aggregations of adult E. servus varied over space, and the timing of aggregations reflected the phenology of major crops. Chinavia hilaris was most often captured in forest, followed by crop habitat. Pest management strategies for stink bugs may require an area-based management approach that accounts for movement in agricultural fields and surrounding habitat.

The reproductive success of animals breeding in cities is often lower compared to counterparts that inhabit rural, suburban, and peri-urban areas. Urban dwelling may be especially costly for offspring development and survival. Diet composition and diversity may underlie factors that lead to lower fitness, particularly if prey abundance and quality decline in modified environments. Moreover, breeding success may change over the course of a season, an effect that may be augmented in urban areas. In this study, we tested the hypothesis that habitat and date affected nestling house wren (Troglodytes aedon) body condition and survival, and examined whether diet explained differences in nestling success. We monitored urban and rural populations of house wrens breeding in nest boxes, and tested whether clutch size, nestling survivorship, and nestling body condition varied by habitat or by date, and then characterized the diet of a subset of nestlings with DNA metabarcoding of fecal samples. Urbanization had clear impacts on house wren nestling fitness: urban broods contained fewer, smaller nestlings. Early nestling survival decreased as the breeding season progressed, and this effect was more pronounced in the urban population. However, the diets of urban and rural nestlings were similar and did not explain differences in body condition. Instead, across populations, diet changed with date, becoming less diverse, with fewer Lepidoptera and more Orthoptera. Regardless of habitat, adult house wrens provide nestlings with similar types of foods, but other factors, such as quantity or quality of prey delivered, may lead to fitness disparities between urban and rural nestlings.