Distribution of \u3cem\u3eCotesia rubecula\u3c/em\u3e (Hymenoptera: Braconidae) and Its Displacement of \u3cem\u3eCotesia glomerata\u3c/em\u3e in Eastern North America

A survey was conducted from May to Oct of 2011 of the parasitoid community of the imported cabbageworm, Pieris rapae (Lepidoptera: Pieridae), in cole crops in part of the eastern United States and southeastern Canada. The findings of our survey indicate that Cotesia rubecula (Hymenoptera: Braconidae) now occurs as far west as North Dakota and has become the dominant parasitoid of P. rapae in the northeastern and north central United States and adjacent parts of southeastern Canada, where it has displaced the previously common parasitoid Cotesia glomerata (Hymenoptera: Braconidae). Cotesia glomerata remains the dominant parasitoid in the mid-Atlantic states, from Virginia to North Carolina and westward to southern Illinois, below latitude N 38° 48′. This pattern suggests that the released populations of C. rubecula presently have a lower latitudinal limit south of which they are not adapted

Crop pests and predators exhibit inconsistent responses to surrounding landscape composition

The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies

Solution-processed semiconductors for next-generation photodetectors

Efficient light detection is central to modern science and technology.Current photodetectors mainly use photodiodes based on crystalline inorganic elementalsemiconductors, such as silicon, or compounds such as III–V semiconductors. Photodetectorsmade of solution-processed semiconductors — which include organic materials, metal-halideperovskites and quantum dots — have recently emerged as candidates for next-generation lightsensing. They combine ease of processing, tailorable optoelectronic properties, facile integrationwith complementary metal–oxide–semiconductors, compatibility with flexible substrates andgood performance. Here, we review the recent advances and the open challenges in the field ofsolution-processed photodetectors, examining the topic from both the materials and the deviceperspective and highlighting the potential of the synergistic combination of materials and deviceengineering. We explore hybrid phototransistorsand their potential to overcome trade-offsin noise, gain and speed, as well as the rapid advances in metal-halide perovskite photodiodesand their recent application in narrowband filterless photodetection