Читать книгу Honey Bee Medicine for the Veterinary Practitioner - Группа авторов - Страница 32

Fries and Camazine (2001) outline three distinct things that a pathogen must do to reproduce and disperse to a new honey bee colony. A pathogen must: (i) infect a single honey bee; (ii) infect multiple honey bees; and (iii) infect another colony. Of these, it is the spread to another colony that should most concern beekeepers and bee doctors:

In terms of fitness, the successful transfer of a pathogen's offspring to a new colony is a critical step in its life history. If a parasite or pathogen fails to achieve a foothold in another host colony, the parasite will not increase its reproductive fitness, regardless of how prolific it has been within the original host colony. Thus, hurdles #1 and #2 (intra‐individual and intra‐colony transmission) are important aspects of pathogen fitness only to the extent that they contribute to more efficient inter‐colony transmission

(Fries and Camazine 2001).

The transfer of pathogens or parasites from one colony to another horizontally can occur by four main routes: drifting, robbing, contact while foraging, and shared use of a contaminated environment. Drifting occurs when a forager enters another colony by accident, something that is largely a byproduct of modern apiary management since the wide spacing of wild colonies largely precludes drifting (Seeley 2017b; Seeley and Smith 2015). Robbing occurs primarily during periods of a nectar dearth, when strong colonies attempt rob honey from weak ones. In this case, pathogen transfer is most likely to occur from the weak colony to the strong colony, though the opposite is also possible. The transfer of pathogens during contact while foraging has been described in both natural and experimental models, including video documentation of a Varroa mite jumping onto a foraging honey bee the instant the bee lands on a flower (Peck et al. 2016). Finally, diseases can be spread from one colony to another through sharing of contaminated water, as has been observed with infections of the microsporidium Nosema apis (L'Arrivée 1965).