Ground beetle movement is deterred by habitat edges: a mark-release-recapture study on the effectiveness of border crops in an agricultural landscape.

Border crops can increase beneficial insect biodiversity within agricultural fields by supplementing insects with food and nesting resources. However, the effectiveness of border crops relies on insect movement between adjacent habitats and some insects might consider habitat boundaries as barriers. Therefore, understanding insect movement between habitats is needed to determine the effectiveness of border crops for ecosystem services such as pest control within agricultural habitats. Our objective was to compare ground beetle (Coleoptera: Carabidae) movement across soybean plots that were bordered by corn and grassland habitat to determine whether habitat boundaries were considered barriers of movement to predatory beetles. Using a grid of pitfall traps within these habitats, we conducted a mark, release, and recapture experiment to track and evaluate ground beetle movement patterns. We found that ground beetles stayed in the habitat of their release and that movement between habitats, despite the type of bordering habitat or type of edge, was uncommon. We also found that long-distance movement was rare as most beetles moved less than 5 m (regardless of release or recaptured habitat) and movement was perpendicular to habitat edges. These results suggest that any edge habitat, including agricultural-agricultural boundaries and natural-agricultural boundaries, are likely barriers to ground beetle movement. Therefore, in order for border crops to be effective in pest management by ground beetles, making habitat edges more permeable, especially using techniques such as edge softening, could promote cross-habitat movement and ultimately contribute to natural pest control in agricultural systems.

Flight capacity and behavior of Ephestia kuehniella (Lepidoptera: Pyralidae) in response to kairomonal and pheromonal stimuli.

Flight behavior is an important component to understand in the context of pest management. However, because of their small size, little is known about the flight capacity of most stored-product insects, and when a flight has been assessed, it usually consists of a propensity for initiating flight. Despite a priori expectations of the importance of flight for moths, there are no data about the flight capacity and little on the flight behavior of the Mediterranean flour moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). As a result, the objective of the current study was to (i) characterize the baseline flight capacity of E. kuehniella and (ii) determine how flight capacity is affected by the presence of kairomonal, pheromonal, or no stimuli. We found adult E. kuehniella flew a mean of 24-34 km in a 24-h period, and the distance flown per bout increased from 91 to 207 m in the presence of pheromones but decreased to 41 m when food was nearby compared to a negative control. The total number of flight bouts was 1.6-fold higher in the presence of pheromone compared to the negative control, but E. kuehniella flew significantly slower with pheromone and food cues present, suggesting they may be exhibiting an optimal foraging strategy. Our data on flight capacity results in qualitatively and quantitatively different conclusions about flight than those conclusions formed if only flight initiation is considered. Overall, this novel information is useful for understanding the spread within facilities and in the landscape (between facilities), as well as parameterizing ecological modeling.

Predicted range expansion of Prostephanus truncatus (Coleoptera: Bostrichidae) under projected climate change scenarios.

The larger grain borer (Prostephanus truncatus [Horn] [Coleoptera: Bostrichidae]) is a wood-boring insect native to Central America and adapted to stored maize and cassava. It was accidentally introduced to Tanzania and became a pest across central Africa. Unlike many grain pests, P. truncatus populations can establish and move within forests. Consequently, novel infestations can occur without human influence. The objectives of our study were to (i) develop an updated current suitability projection for P. truncatus, (ii) assess its potential future distribution under different climate change scenarios, and (iii) identify climate variables that best inform the model. We used WALLACE and MaxEnt to predict potential global distribution by incorporating bioclimatic variables and occurrence records. Future models were projected for 2050 and 2070 with Representative Concentration Pathways (RCPs) 2.6 (low change) and 8.5 (high change). Distribution was most limited by high precipitation and cold temperatures. Globally, highly suitable areas (> 75%) primarily occurred along coastal and equatorial regions with novel areas in northern South America, India, southeastern Asia, Indonesia, and the Philippines, totaling 7% under current conditions. Highly suitable areas at RCPs 2.6 and 8.5 are estimated to increase to 12% and 15%, respectively, by 2050 and increase to 19% in 2070 under RCP 8.5. Centroids of highly suitable areas show distribution centers moving more inshore and away from the equator. Notably, the result is a range expansion, not a shift. Results can be used to decrease biosecurity risks through more spatially explicit and timely surveillance programs for targeting the exclusion of this pest.

Differentiating spillover: an examination of cross-habitat movement in ecology spillover in ecology.

Organisms that immigrate into a recipient habitat generate a movement pattern that affects local population dynamics and the environment. Spillover is the pattern of unidirectional movement from a donor habitat to a different, adjacent recipient habitat. However, ecological definitions are often generalized to include any cross-habitat movement, which limits within- and cross-discipline collaboration. To assess spillover nomenclature, we reviewed 337 studies within the agriculture, disease, fisheries and habitat fragmentation disciplines. Each study's definition of spillover and the methods used were analysed. We identified four descriptors (movement, habitat type and arrangement, and effect) used that differentiate spillover from other cross-habitat movement patterns (dispersal, foray loops and edge movement). Studies often define spillover as movement (45%) but rarely measure it as such (4%), particularly in disease and habitat fragmentation disciplines. Consequently, 98% of studies could not distinguish linear from returning movement out of a donor habitat, which can overestimate movement distance. Overall, few studies (12%) included methods that matched their own definition, revealing a distinct mismatch. Because theory shows that long-term impacts of the different movement patterns can vary, differentiating spillover from other movement patterns is necessary for effective long-term and inter-disciplinary management of organisms that use heterogeneous landscapes.

Averaging and adding in children’s worth judgements

Under the normative Expected Value (EV) model, multiple outcomes are additive, but in everyday worth judgement intuitive averaging prevails. Young children also use averaging in EV judgements, leading to a disordinal, crossover violation of utility when children average the part worths of simple gambles involving independent events (Schlottmann, 2000). This study explored the origins of this averaging bias in children‘s worth judgements, assessing whether averaging also appears for riskless judgements and for other types of risky judgements. In Experiment 1, 8- year-olds judged the worth of having either one or two squares of chocolates in two formally equivalent tasks: Children made additive worth judgements when chocolates varied in size, but used averaging when they varied in winning probability. Performance on the EV task was slightly more advanced when risky followed riskless judgements, with some evidence of transfer. In Experiment 2, 5-year-olds gave additive worth judgements when judging variable fractions of chocolate pies, with displays closely parallel to the spinner discs used for the gambles in Experiment 1. In Experiment 3, 5-yearolds gave additive worth judgements of gambles in which to win either one or two prizes, with alternative rather than independent probabilities of winning. Thus the overgeneralisation of averaging processes to EV judgement, while persistent, neither reflects a general difficulty with additive value judgement, nor with displays showing positive and negative information, nor with risky judgement per se. It may come into play because children have difficulty appreciating the implications of independence, apparent also in other domains. Despite such difficulty, children realize that risky game outcomes go beyond what they can see, and so may apply averaging, as default strategy for population judgement, whereas addition might be the default for judging the sample itself(AU)