Reply to Negri et al.: Air pollution and health impacts on bees: Signs of causation.

In their Letter, Negri et al. (1) point out four concerns with our recent publication (2). The first is that the study is correlative, and the next two that we did not measure the toxicity of air pollution directly, nor how the particulate matter (PM) measured on the surface of the cuticle and internal organs could be impacting health. Finally, the authors are concerned with the identity of the elements we found using scanning electron microscopy coupled with X-ray spectroscopy (SEM-EDX). First, some specific responses. The assertion that we did not investigate the contact between PM and the internal organs is erroneous and is already shown in figure 2 (crop and midgut … [↵][1]1To whom correspondence may be addressed. Email: shannon{at}nice.ncbs.res.in or geetha{at}nice.ncbs.res.in. [1]: #xref-corresp-1-1