SignificanceDecades of research have fostered the now-prevalent assumption that noncrop habitat facilitates better pest suppression by providing shelter and food resources to the predators and parasitoids of crop pests. Based on our analysis of the largest pest-control database of its kind, noncrop habitat surrounding farm fields does affect multiple dimensions of pest control, but the actual responses of pests and enemies are highly variable across geographies and cropping systems. Because noncrop habitat often does not enhance biological control, more information about local farming contexts is needed before habitat conservation can be recommended as a viable pest-suppression strategy. Consequently, when pest control does not benefit from noncrop vegetation, farms will need to be carefully comanaged for competing conservation and production objectives.

Historically, agroecosystems have been designed to produce food. Modern societies now demand more from food systems-not only food, fuel, and fiber, but also a variety of ecosystem services. And although today's farming practices are producing unprecedented yields, they are also contributing to ecosystem problems such as soil erosion, greenhouse gas emissions, and water pollution. This review highlights the potential benefits of perennial grains and oilseeds and discusses recent progress in their development. Because of perennials' extended growing season and deep root systems, they may require less fertilizer, help prevent runoff, and be more drought tolerant than annuals. Their production is expected to reduce tillage, which could positively affect biodiversity. End-use possibilities involve food, feed, fuel, and nonfood bioproducts. Fostering multidisciplinary collaborations will be essential for the successful integration of perennials into commercial cropping and food-processing systems.

Genetically engineered (GE) insects have the potential to radically change pest management worldwide. With recent approvals of GE insect releases, there is a need for a synthesized framework to evaluate their potential ecological and evolutionary effects. The effects may occur in two phases: a transitory phase when the focal population changes in density, and a steady state phase when it reaches a new, constant density. We review potential effects of a rapid change in insect density related to population outbreaks, biological control, invasive species, and other GE organisms to identify a comprehensive list of potential ecological and evolutionary effects of GE insect releases. We apply this framework to the Anopheles gambiae mosquito – a malaria vector being engineered to suppress the wild mosquito population – to identify effects that may occur during the transitory and steady state phases after release. Our methodology reveals many potential effects in each phase, perhaps most notably those dealing with immunity in the transitory phase, and with pathogen and vector evolution in the steady state phase. Importantly, this framework identifies knowledge gaps in mosquito ecology. Identifying effects in the transitory and steady state phases allows more rigorous identification of the potential ecological effects of GE insect release.

As the rate of spread of invasive species increases, consumer-resource communities are often populated by a combination of exotic and native species at all trophic levels. In parasitoid-host communities, these novel associations may lead to disconnects between parasitoid preference and performance, and parasitoid oviposition may result in death of the parasitoid offspring, death of the host, or death of both. Despite their relevance for biological control risk and efficacy assessments, the direct and indirect population-level consequences of parasitoids attacking and killing their hosts without successfully reproducing (non-reproductive mortality) are poorly understood. Non-reproductive mortality induced by egg parasitoids (parasitoid-induced host egg abortion) may be particularly important for understanding the population dynamics of the invasive agricultural pest Halyomorpha halys (Hemiptera: Pentatomidae) and endemic stink bugs in North America, which are attacked by a suite of both native and introduced egg parasitoids. It is unclear, however, how various factors controlling parasitoid foraging and developmental success manifest at the population level. We constructed two related versions of a two-host-one-parasitoid model to evaluate the population-level consequences of non-reproductive host mortality. Egg abortion can result in strong negative or positive enemy-mediated indirect effects, taking the form of apparent competition, apparent parasitism, apparent amensalism, or apparent commensalism. For parasitoids limited in their reproductive output by the number of eggs they can produce, higher non-reproductive host mortality can reduce the strength of the positive indirect effect in cases of apparent parasitism, and it can reduce the negative indirect effect on the more suitable host in cases of apparent competition. For time-limited parasitoids, unsuitable hosts with high levels of non-reproductive parasitoid-induced mortality can be strongly suppressed in the presence of a suitable host, while the suitable host is only negligibly impacted (i.e., apparent amensalism). We evaluate these model-derived hypotheses within the context of H. halys and its native and nonnative parasitoids in North America, and discuss their application to risk assessment in biological control programs.

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