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Testing Dose-Dependent Effects of the Nectar Alkaloid Anabasine on Trypanosome Parasite Loads in Adult Bumble Bees.

Anthony WE, Palmer-Young EC, Leonard AS, Irwin RE, Adler LS - PLoS ONE (2015)

Bottom Line: In addition, recent studies have found that consuming nectar secondary compounds may decrease parasite loads in pollinators.Our results support a medicinal role for anabasine at the highest concentration; moreover, we found no evidence for a survival-related cost of anabasine consumption across the concentration range found in nectar.Our results suggest that consuming anabasine at the higher levels of the natural range could reduce or clear pathogen loads without incurring costs for healthy bees.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Massachusetts Amherst, Amherst, Massachusetts, United States of America.

ABSTRACT
The impact of consuming biologically active compounds is often dose-dependent, where small quantities can be medicinal while larger doses are toxic. The consumption of plant secondary compounds can be toxic to herbivores in large doses, but can also improve survival in parasitized herbivores. In addition, recent studies have found that consuming nectar secondary compounds may decrease parasite loads in pollinators. However, the effect of compound dose on bee survival and parasite loads has not been assessed. To determine how secondary compound consumption affects survival and pathogen load in Bombus impatiens, we manipulated the presence of a common gut parasite, Crithidia bombi, and dietary concentration of anabasine, a nectar alkaloid produced by Nicotiana spp. using four concentrations naturally observed in floral nectar. We hypothesized that increased consumption of secondary compounds at concentrations found in nature would decrease survival of uninfected bees, but improve survival and ameliorate parasite loads in infected bees. We found medicinal effects of anabasine in infected bees; the high-anabasine diet decreased parasite loads and increased the probability of clearing the infection entirely. However, survival time was not affected by any level of anabasine concentration, or by interactive effects of anabasine concentration and infection. Crithidia infection reduced survival time by more than two days, but this effect was not significant. Our results support a medicinal role for anabasine at the highest concentration; moreover, we found no evidence for a survival-related cost of anabasine consumption across the concentration range found in nectar. Our results suggest that consuming anabasine at the higher levels of the natural range could reduce or clear pathogen loads without incurring costs for healthy bees.

No MeSH data available.


Related in: MedlinePlus

Effects of anabasine treatment on probability of infection at time of death.Anabasine treatment significantly affected the mean probability of bees having detectable C. bombi at time of death (P = 0.0256).
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pone.0142496.g001: Effects of anabasine treatment on probability of infection at time of death.Anabasine treatment significantly affected the mean probability of bees having detectable C. bombi at time of death (P = 0.0256).

Mentions: There was a significant effect of the anabasine treatment on the probability that bees had detectable C. bombi at death (df = 3, Wald Chi-Square = 9.2925, P = 0.0256). Post-hoc tests found near-significant differences between the medium and high-anabasine treatment (z = 1.96; P = 0.0503) but not other comparisons of individual treatments (/z/ < 1.3, P > 0.2). However, the high-anabasine treatment was significantly different from all other treatments combined (z = -2.93; P = 0.0034); final infection rate in the high-anabasine group was less than half of that in any other treatment group (Fig 1). Anabasine treatment also affected mean parasite load (F3,56 = 3.79, P = 0.015), again with the lowest C. bombi cell counts in the high anabasine treatment. Pairwise comparisons with a Tukey’s test showed a significant reduction in parasite loads in the high anabasine treatment compared to the medium treatment (P = 0.0126, Fig 2) and marginally different between the high and the low treatment (P = 0.051). None of the other pairwise comparisons were significantly different (P > 0.1 for all).


Testing Dose-Dependent Effects of the Nectar Alkaloid Anabasine on Trypanosome Parasite Loads in Adult Bumble Bees.

Anthony WE, Palmer-Young EC, Leonard AS, Irwin RE, Adler LS - PLoS ONE (2015)

Effects of anabasine treatment on probability of infection at time of death.Anabasine treatment significantly affected the mean probability of bees having detectable C. bombi at time of death (P = 0.0256).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4636389&req=5

pone.0142496.g001: Effects of anabasine treatment on probability of infection at time of death.Anabasine treatment significantly affected the mean probability of bees having detectable C. bombi at time of death (P = 0.0256).
Mentions: There was a significant effect of the anabasine treatment on the probability that bees had detectable C. bombi at death (df = 3, Wald Chi-Square = 9.2925, P = 0.0256). Post-hoc tests found near-significant differences between the medium and high-anabasine treatment (z = 1.96; P = 0.0503) but not other comparisons of individual treatments (/z/ < 1.3, P > 0.2). However, the high-anabasine treatment was significantly different from all other treatments combined (z = -2.93; P = 0.0034); final infection rate in the high-anabasine group was less than half of that in any other treatment group (Fig 1). Anabasine treatment also affected mean parasite load (F3,56 = 3.79, P = 0.015), again with the lowest C. bombi cell counts in the high anabasine treatment. Pairwise comparisons with a Tukey’s test showed a significant reduction in parasite loads in the high anabasine treatment compared to the medium treatment (P = 0.0126, Fig 2) and marginally different between the high and the low treatment (P = 0.051). None of the other pairwise comparisons were significantly different (P > 0.1 for all).

Bottom Line: In addition, recent studies have found that consuming nectar secondary compounds may decrease parasite loads in pollinators.Our results support a medicinal role for anabasine at the highest concentration; moreover, we found no evidence for a survival-related cost of anabasine consumption across the concentration range found in nectar.Our results suggest that consuming anabasine at the higher levels of the natural range could reduce or clear pathogen loads without incurring costs for healthy bees.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Massachusetts Amherst, Amherst, Massachusetts, United States of America.

ABSTRACT
The impact of consuming biologically active compounds is often dose-dependent, where small quantities can be medicinal while larger doses are toxic. The consumption of plant secondary compounds can be toxic to herbivores in large doses, but can also improve survival in parasitized herbivores. In addition, recent studies have found that consuming nectar secondary compounds may decrease parasite loads in pollinators. However, the effect of compound dose on bee survival and parasite loads has not been assessed. To determine how secondary compound consumption affects survival and pathogen load in Bombus impatiens, we manipulated the presence of a common gut parasite, Crithidia bombi, and dietary concentration of anabasine, a nectar alkaloid produced by Nicotiana spp. using four concentrations naturally observed in floral nectar. We hypothesized that increased consumption of secondary compounds at concentrations found in nature would decrease survival of uninfected bees, but improve survival and ameliorate parasite loads in infected bees. We found medicinal effects of anabasine in infected bees; the high-anabasine diet decreased parasite loads and increased the probability of clearing the infection entirely. However, survival time was not affected by any level of anabasine concentration, or by interactive effects of anabasine concentration and infection. Crithidia infection reduced survival time by more than two days, but this effect was not significant. Our results support a medicinal role for anabasine at the highest concentration; moreover, we found no evidence for a survival-related cost of anabasine consumption across the concentration range found in nectar. Our results suggest that consuming anabasine at the higher levels of the natural range could reduce or clear pathogen loads without incurring costs for healthy bees.

No MeSH data available.


Related in: MedlinePlus