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Interest from the US commercial aviation industry and commitments established by the US Navy and Air Force to use renewable fuels has spurred interest in identifying and developing crops for renewable aviation fuel. Concern regarding greenhouse gas emissions associated with land-use change and shifting land grown for food to feedstock production for fuel has encouraged the concept of intensifying current prominent cropping systems through various double cropping strategies. Camelina (Camelina sativa L.) and field pennycress (Thlaspi arvense L.) are two winter oilseed crops that could potentially be integrated into the corn (Zea mays L.)-soybean [(Glycine max (L.) Merr.] cropping system, which is the prominent cropping system in the US Corn Belt. In addition to providing a feedstock for renewable aviation fuel production, integrating these crops into corn-soybean cropping systems could also potentially provide a range of ecosystem services. Some of these include soil protection from wind and water erosion, soil organic C (SOC) sequestration, water quality improvement through nitrate reduction, and a food source for pollinators. However, integration of these crops into corn-soybean cropping systems also carries possible limitations, such as potential yield reductions of the subsequent soybean crop. This review identifies and discusses some of the key benefits and constraints of integrating camelina or field pennycress into corn-soybean cropping systems and identifies generalized areas for potential adoption in the US Corn Belt.

Butterflies such as the atala hairstreak, Eumaeus atala Poey, and the frosted elfin, Callophrys irus Godart, are restricted to frequently disturbed habitats where their larval host plants occur. Pupae of these butterflies are noted to reside at the base of host plants or in the leaf litter and soil, which may allow them to escape direct mortality by fire, a prominent disturbance in many areas they inhabit. The capacity of these species to cope with fire is a critical consideration for land management and conservation strategies in the locations where they are found. Survival of E. atala pupae in relation to temperature and duration of heat pulse was tested using controlled water bath experiments and a series of prescribed fire field experiments. Survival of E. atala pupae was correlated to peak temperature and heat exposure in both laboratory and field trials. In addition, E. atala survival following field trials was correlated to depth of burial; complete mortality was observed for pupae at the soil surface. Fifty percent of E. atala survived the heat generated by prescribed fire when experimentally placed at depths ≥ 1.75cm, suggesting that pupation of butterflies in the soil at depth can protect from fatal temperatures caused by fire. For a species such as E. atala that pupates above ground, a population reduction from a burn event is a significant loss, and so decreasing the impact of prescribed fire on populations is critical.

Pollinating insects are in decline throughout the world, driven by a combination of factors including the loss of forage resources. The maize (Zea mays L.)– and soybean [Glycine max (L.) Merr.]–dominated agriculture of the Central and Midwestern United States produces a landscape relatively devoid of nectar and pollen resources. Introducing specialty oilseeds into current crop rotations could provide abundant floral resources for pollinating insects as well as a high‐value crop for growers. We investigated the nectar sugar resources and insect visitation throughout flower anthesis of nine specialty oilseed crops in west‐central Minnesota and eastern South Dakota during the 2013 and 2014 growing seasons. Total sugar produced over anthesis (TS) was highest for echium (Echium plantagineum L.) at 472 kg ha−1. Canola (Brassica napus L.), crambe (Crambe abyssinica Hochst.), echium, borage (Borago officinalis L.), and cuphea (Cuphea viscosissima Jacq. × Cuphea lanceolata W. T. Aiton) produced enough sugar in one hectare to supply the annual sugar needs of a least one managed honey bee (Apis mellifera L.) colony. Pollinators visited flowers of all crops, with as many as 90 insects min−1 observed. Our study is unique as we measured nectar sugar production, flower density, and insect visitation throughout anthesis for multiple specialty oilseed crops, providing a seasonwide perspective of the flux of nectar resources for pollinators. Adding specialty oilseed crops into current crop rotations could aid in reversing pollinator decline by providing forage resources that are lacking in the current agricultural landscape.

The continuing pollinator crisis is due, in part, to the lack of year-round floral resources. In intensive farming regions, such as the Upper Midwest (UMW) of the USA, natural and pastoral vegetation largely has been replaced by annual crops such as maize (Zea mays L.), soyabean (Glycine max L.) and wheat (Triticum spp.). Neither the energy (nectar) nor protein (pollen) needs of pollinating and other beneficial insects are being met sufficiently by the new, high-intensity, agricultural landscape. Several potentially useful oilseed crops can be grown in the UMW, and many of these oilseeds are highly attractive to beneficial insects. Prior research showed that some of these oilseeds produced abundant nectar, but their corresponding values for pollen production are unknown. Accordingly, the aim of our research was to document pollen (and protein) production per unit area of twelve oilseed crops grown in Minnesota and associate these values with levels of beneficial insect visitation during anthesis. Our results show that oilseed crops such as camelina (Camelina sativa L.), flax (Linum usitatissimum L.) and pennycress (Thlaspi arvense L.) produce relatively little pollen (≤40 kg/ha); borage (Borago officinalis L.), calendula (Calendula officinalis L.), canola (Brassica napus L.), crambe (Crambe abyssianica Hochst) and cuphea (Cuphea viscosissima Jacq. × Cuphea lanceolata W. T. Aiton) produce bountiful pollen resources (50-150 kg/ha); and oilseed echium (Echium plantagineum L.) generates massive amounts of pollen (>400 kg/ha), about 50% of which is protein. Our study is unique in presenting a season-long perspective of pollen production in alternative oilseed crops, a resource valuable to pollen-feeding insects such as managed and wild bees.Diversification of UMW landscapes that includes alternative oilseed crops such as oilseed echium and cuphea can potentially provide a ready source of pollen and protein to help combat pollinator decline. K E Y W O R D SAgroecology, Apis mellifera L., cover crops, hymenoptera, natural enemies, nutrition | INTRODUCTIONThe world is experiencing an unprecedented decline in pollinating insects, including managed species like the honey bee, Apis mellifera L., as well as wild bee species (Potts et al., 2010). Many factors are at play, including habitat loss, disease, parasites, stress and pesticide exposure (Anderson & East, 2008;Brown & Paxton, 2009;Ricketts et al., 2008;Szabo, Colla, Wagner, Gall, & Kerr, 2012;Watanabe, 2008). Loss of habitat due to agricultural intensification and a reduction in plant biodiversity is one of the main contributors to the decline observed in pollinators (Ellis, Evans, & Pettis, 2010;Potts et al., 2010). Diversifying agriculture to include mass-flowering crops which provide essential Published 2017. This article is a U.S. Government work and is in the public domain in the USA. ). The value of these crops as forage resources to pollinators is limited. Maize and wheat are both wind-pollinated grasses, and do not produce nectar. Although maize pollen...

Relay‐cropping of the novel oilseeds winter camelina (Camelina sativa L.) and pennycress (Thlaspi arvense L.) with short‐season crops such as soybean [Glycine max (L.) Merr.] can provide economic and environmental incentives for adopting winter cover crop practices in the U.S. Upper Midwest. However, their ability to reduce nutrient loss in surface runoff is unknown. Accordingly, surface runoff and quality were evaluated during three seasonal phases (cover, intercrop, and soybean) over 2 yr in four cover crop–soybean treatments (pennycress, winter camelina, forage radish [Raphanus sativus L.], and winter rye [Secale cereale L.]) compared with no‐till and chisel‐till fallow treatments. Runoff was collected with Gerlach troughs and assessed for concentrations and loads of NO3−–N, total mineral N, soluble reactive P (SRP), and total suspended solids (TSS). Cumulative runoff and nutrient loads were greater during the winter cover phase because of increased snow melt and freeze–thaw released nutrients from living vegetation. In contrast, cumulative TSS was greater during intercrop and soybean phases due to high‐intensity rainfall events with an open soybean canopy. Average TSS loads during the intercrop phase were reduced by 75% in pennycress compared with fallow and radish treatments. During the soybean phase, average TSS, total mineral N, and SRP loads were generally elevated in cover crop treatments compared with no‐till. Overwintering cover crops may contribute to mobility of nutrients solubilized from living or decomposing vegetation; however, this was balanced by their potential to reduce runoff and TSS during high‐intensity spring rains.

We experimentally assessed ant-related oviposition and larval performance in the Miami blue butterfly (Cyclargus thomasi bethunebakeri). Ant tending had sex-dependent effects on most measures of larval growth: female larvae generally benefitted from increased tending frequency whereas male larvae were usually unaffected. The larger size of female larvae tended by ants resulted in a substantial predicted increase in lifetime egg production. Oviposition by adult females that were tended byC. floridanusants as larvae was similar between host plants with or without ants. However, they laid relatively more eggs on plants with ants than did females raised without ants, which laid less than a third of their eggs on plants with ants present. In summary, we found conditional benefits for larvae tended by ants that were not accompanied by oviposition preference for plants with ants present, which is a reasonable result for a system in which ant presence at the time of oviposition is not a reliable indicator of future ant presence. More broadly, our results emphasize the importance of considering the consequences of variation in interspecific interactions, life history traits, and multiple measures of performance when evaluating the costs and benefits of mutualistic relationships.

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