The impact of host starvation on parasite development and population dynamics in an intestinal trypanosome parasite of bumble bees

Abstract

S U M M A R YHost nutrition plays an important role in determining the development and success of parasitic infections. While studies of vertebrate hosts are accumulating, little is known about how host nutrition affects parasites of invertebrate hosts. Crithidia bombi is a gut trypanosome parasite of the bumble bee, Bombus terrestris and here we use it as a model system to determine the impact of host nutrition on the population dynamics and development of micro-parasites in invertebrates. Pollenstarved bees supported significantly smaller populations of the parasite. In pollen-fed bees the parasite showed a temporal pattern in development, with promastigote transmission stages appearing at the start of the infection and gradually being replaced by choanomastigote and amastigote forms. In pollen-starved bees this developmental process was disrupted, and there was no pattern in the appearance of these three forms. We discuss the implications of these results for parasite transmission, and speculate about the mechanisms behind these changes.

Pharmacophagy and pharmacophory: mechanisms of self-medication and disease prevention in the honeybee colony (Apis mellifera)

“…Pollen and honey were shown to have the highest variability in their pharmacophagic activity for several Apis (Tables III and IV) and nonApis bee species (Boorn et al 2010;Chanchao 2009b;Chan-Rodríguez et al 2012;da Cruz et al 2014;Kimoto-Nira and Amano 2008;Logan et al 2005;Temaru et al 2007;Vandenberg 1994). An outstanding nonpharmacophagic but defensive usage of stored honey was observed for the stingless bee Hypotrigona braunsi .…”

Consumption of a nectar alkaloid reduces pathogen load in bumble bees

“…Each bee was initially fed a 2 l drop containing 10 4 C. bombi in 30% sucrose solution and we monitored individuals until the entire drop was consumed. This dose falls within the range of C. bombi cells shed in the feces of infected bees in previous studies (Logan et al 2005;Schmid-Hempel and Schmid-Hempel 1993), and therefore simulates cells available for transmission to naïve individuals. Bees were reared in individual 15-ml vials and received either a 0.5-ml solution of 250 ng/ l gelsemine in 30% sucrose (Alkaloid bees, n = 35) or 0.5 ml of 30% sucrose only (Control bees, n = 35) along with a pollen lump daily for 10 days.…”

“…Alternatively, the consumption of alkaloids might alter the host's gut environment, making it less hospitable for pathogen cells. Logan et al (2005) proposed this mechanism after pollen consumption altered the rate at which C. bombi populations increased within hosts, perhaps by aVecting their adherence to the gut wall. Consumption of alkaloids may also increase gut pH, which could be deleterious to pathogen cells (Stiles and Paschke 1980).…”

“…Since C. bombi is known to occur in the nectar of wild Xowers (Durrer and Schmid-Hempel 1994), nectar secondary metabolites may inXuence the survival and infectivity, and consequently the transmission, of this pathogen. Furthermore, for gut pathogens such as C. bombi, host diet can signiWcantly aVect the severity of infection by altering immunocompetence, metabolic processes, or by limiting nutrient availability for the parasite (Cory and Hoover 2006;Logan et al 2005;Wink and Theile 2002). Hence, in Xowers or in the guts of Xower visitors, nectar secondary metabolites may beneWt pollinators via antimicrobial action.…”

Capacity of mosquitoes to transmit malaria depends on larval environment

“…We did not measure EIP in our study as we dissected salivary glands at a single time point during infection. However, differences in parasite replication rate due to the influence of temperature, for example, are known to affect length of the EIP, with important consequences for vectorial capacity [4,10] We are not aware of any studies exploring the effects of mosquito condition (larval through to adult) on malaria parasite development but nutritionally-dependent parasite replication has been observed in other invertebrate-parasite systems [30,[80][81][82]. If EIP is affected by mosquito condition, this could add to the influence of larval habitat on malaria transmission.…”