Citizen science data reveal regional heterogeneity in phenological response to climate in the large milkweed bug, Oncopeltus fasciatus.

Regional populations of geographically widespread species may respond to different environmental factors across the species' range, generating divergent effects of climate change on life-history phenology. Using thousands of citizen science observations extracted from iNaturalist and associated with corresponding temperature, precipitation, elevation, and daylength information, we examined the drivers of adult mating and of nymphal phenology, development, and group size for populations of the large milkweed bug, Oncopeltus fasciatus, in different ecoregions. Research-grade iNaturalist images were correctly identified 98.3% of the time and yielded more than 3000 observations of nymphal groups and 1000 observations of mating adults spanning 18 years. Mating phenology showed distinct regional patterns, ranging from year-round mating in California to temporally restricted mating in the Great Lakes Northeastern Coast ecoregion. Relative temperature increases of 1°C for a given daylength expanded the mating season by more than a week in western ecoregions. While increases in relative temperature delayed mating phenology in all ecoregions, greater winter precipitation advanced mating in the California ecoregion. In the eastern ecoregions, nymphal phenology was delayed by increases in summer rainfall but was advanced by relative temperature increases, whereas in western regions, relative temperature increases delayed nymphal phenology. Furthermore, accumulated growing degree days (AGDD) was a poor predictor of developmental progression, as we found a positive but weak correlation between AGDD and age structure only for the Appalachian Southeast North America and the Great Lakes Northern Coast ecoregions. These complex phenological responses of O. fasciatus are just one example of how populations may be differentially susceptible to a diversity of climatic effects; using data across a species' whole distribution is critical for exposing regional variations, especially for species with large, continental-scale ranges. This study demonstrates the potential of photodocumented biodiversity data to aid in the monitoring of life history, host plant-insect interactions, and climate responsiveness.

Insect chemical ecology: chemically mediated interactions and novel applications in agriculture.

Insect chemical ecology (ICE) evolved as a discipline concerned with plant-insect interactions, and also with a strong focus on intraspecific pheromone-mediated communication. Progress in this field has rendered a more complete picture of how insects exploit chemical information in their surroundings in order to survive and navigate their world successfully. Simultaneously, this progress has prompted new research questions about the evolution of insect chemosensation and related ecological adaptations, molecular mechanisms that mediate commonly observed behaviors, and the consequences of chemically mediated interactions in different ecosystems. Themed meetings, workshops, and summer schools are ideal platforms for discussing scientific advancements as well as identifying gaps and challenges within the discipline. From the 11th to the 22nd of June 2018, the 11th annual PhD course in ICE was held at the Swedish University of Agricultural Sciences (SLU) Alnarp, Sweden. The course was made up of 35 student participants from 22 nationalities (Fig. 1a) as well as 32 lecturers. Lectures and laboratory demonstrations were supported by literature seminars, and four broad research areas were covered: (1) multitrophic interactions and plant defenses, (2) chemical communication focusing on odor sensing, processing, and behavior, (3) disease vectors, and (4) applied aspects of basic ICE research in agriculture. This particular article contains a summary and brief synthesis of these main emergent themes and discussions from the ICE 2018 course. In addition, we also provide suggestions on teaching the next generation of ICE scientists, especially during unprecedented global situations.

Volatile and Contact Chemical Cues Associated with Host and Mate Recognition Behavior of Sphenophorus venatus and Sphenophorus parvulus (Coleoptera: Dryophthoridae).

Beetles in the genus Sphenophorus Schönherr, or billbugs, potentially utilize both volatile and non-volatile behavior-modifying chemical signals. These insects are widely distributed across North America, often occurring in multi-species assemblages in grasses. However, details about their host- and mate-finding behavior are poorly understood. This study tested the hypothesis that volatile organic compounds from host-plants and conspecifics direct the dispersal behavior of hunting billbug S. venatus Say. Further, we characterized the cuticular hydrocarbon profiles of two widespread pest species, S. venatus and bluegrass billbug S. parvulus Gyllenhaal, to assess the potential role of contact pheromones in mate-recognition. In Y-tube olfactometer bioassays, S. venatus males were attracted to a combination of conspecifics and Cynodon dactylon host-plant material, as well as C. dactylon plant material alone. S. venatus females were attracted to a combination of male conspecifics and host-plants but were also attracted to male conspecifics alone. Field evaluation of a putative male-produced aggregation pheromone, 2-methyl-4-octanol, identified from two congeners, S. levis Vaurie and S. incurrens Gyllenhaal, did not support the hypothesis that S. venatus and S. parvulus were also attracted to this compound. Gas chromatography-mass spectrometry analysis of S. venatus and S. parvulus whole-body cuticular extracts indicated a series of hydrocarbons with qualitative and quantitative interspecific variation in addition to intraspecific quantitative variation between males and females. This study provides the first evidence that S. venatus orients toward host- and insect-derived volatile organic compounds and substantiates the presence of species-specific cuticular hydrocarbons that could serve as contact pheromones for sympatric Sphenophorus species.

Billbug (Coleoptera: Dryophthoridae: Sphenophorus spp.) Seasonal Biology and DNA-Based Life Stage Association in Indiana Turfgrass.

Eleven species of billbugs (Coleoptera: Dryophthoridae: Sphenophorus spp. Schönherr) infest managed turfgrass in North America. However, the regional variation in species composition remains unresolved and the seasonal phenology of several species has not been well documented. The latter gap is largely due to the inability to identify the larval stage to species-a confounding problem with several sympatric insect species. We used field trapping (adults) and soil sampling (larvae and pupae) surveys along with a DNA-based life-stage association to characterize the biology of billbugs associated with turfgrass in the Midwestern United States. Pitfall trapping at four locations in Indiana revealed four billbug species: S. venatus Say, S. parvulus Gyllenhaal, S. minimus Hart, and S. inaequalis Say. Sphenophorus venatus was the most abundant species on warm-season turfgrass while S. parvulus was most abundant on cool-season turfgrass. Investigation of S. venatus seasonal biology revealed two overwintered life stages-larva and adult-which resulted in two overlapping cohorts and two larval generations. Degree-day models describing S. venatus activity were more accurate for first-generation adults and larvae than for overwintering life stages. Maximum-likelihood analyses provided the first molecular species identification of billbug larvae and direct evidence that S. venatus larvae are capable of overwintering above 40°N latitude. Findings clarify the utility of molecular markers (CO1, 18S, and ITS2) for describing billbug larval population dynamics and seasonal phenology in regions where several sympatric billbug species occur. These results support the development of sustainable management strategies based on billbug seasonal phenology in different regions of North America.