Pollen chemical and mechanical defences restrict host-plant use by bees.

Plants produce an array of chemical and mechanical defences that provide protection against many herbivores and pathogens. Putatively defensive compounds and structures can even occur in floral rewards: for example, the pollen of some plant taxa contains toxic compounds or possesses conspicuous spines. Yet little is known about whether pollen defences restrict host-plant use by bees. In other words, do bees, like other insect herbivores, tolerate the defences of their specific host plants while being harmed by non-host defences? To answer this question, we compared the effects of a chemical defence from Lupinus (Fabaceae) pollen and a putative mechanical defence (pollen spines) from Asteraceae pollen on larval survival of nine bee species in the tribe Osmiini (Megachilidae) varying in their pollen-host use. We found that both types of pollen defences reduce larval survival rate in some bee species. These detrimental effects were, however, mediated by host-plant associations, with bees being more tolerant of the pollen defences of their hosts, relative to the defences of plant taxa exploited by other species. This pattern strongly suggests that bees are adapted to the pollen defences of their hosts, and that host-plant use by bees is constrained by their ability to tolerate such defences.

Spatio-temporal patterns in the history of colonial botanical exploration in India.

A study of Indian botany during the colonial period provides us with an interdisciplinary sphere covering science, politics, sociology, economics, and other associated domains. The presentation of this rich legacy to general readers often restricts itself to the descriptive accounts of explorers with little analysis of the intermingling of socio-political dynamics, landscape, and geography. We attempt to revisit the colonial plant exploration history through spatio-temporal analyses to understand how explorers with divergent interests traversed the country in different periods and directions. Our findings show that the Himalayas drove most of the explorations followed by the Deccan peninsula, the Western Ghats, and the Gangetic plain. In general, company/crown administered areas were better surveyed and documented than native states. Furthermore, through a prioritization exercise, we identify the centers of prominence, highlighting their political, economic, and social importance in contemporary India. In sum, this article shows the potential of applying Historical Geographic Information System (HGIS) mapping for spearheading future research and creating space for possible dialogs among historians, political scientists, and ecologists.