Biology of bees.

This chapter discusses the bee fundamentals, including their taxonomy, diets, adaptations for plant foraging and biological development. It also compares solitary and social bees. Pollinator efficacy and effects of non-native bee species on native bees are also discussed.

Approach trajectory and solar position affect host plant attractiveness to the small white butterfly

While it is well documented that insects exploit polarized sky light for navigation, their use of reflected polarized light for object detection has been less well studied. Recently, we have shown that the small white butterfly, Pieris rapae, distinguishes between host and non-host plants based on the degree of linear polarization (DoLP) of light reflected from their leaves. To determine how polarized light cues affect host plant foraging by female P. rapae across their entire visual range including the ultraviolet (300-650 nm), we applied photo polarimetry demonstrating large differences in the DoLP of leaf-reflected light among plant species generally and between host and non-host plants specifically. As polarized light cues are directionally dependent, we also tested, and modelled, the effect of approach trajectory on the polarization of plant-reflected light and the resulting attractiveness to P. rapae. Using photo polarimetry measurements of plants under a range of light source and observer positions, we reveal several distinct effects when polarized reflections are examined on a whole-plant basis rather than at the scale of pixels or of entire plant canopies. Most notably from our modeling, certain approach trajectories are optimal for foraging butterflies, or insects generally, to discriminate between plant species on the basis of the DoLP of leaf-reflected light.

Anthropogenic Landscapes

It has been suggested that anthropogenic burning may have altered Southwest landscapes at a large scale. Southwestern biomes vary in their propensity for and their susceptibility to anthropogenic burning practices. Anthropogenic burning to enhance the productivity of wild plant foraging or agriculture was probably limited in scale; on the other hand, fire use in hunting, religious practice, and warfare may have impacted larger scales, though at lower intensity. Middle-elevation forests, woodlands, and grasslands were the biotic zones most likely to be impacted by anthropogenic burning, but sophisticated mimicry of natural fire regimes means that the evidence of such impact is ambiguous.