Parasite-insecticide interactions: a case study of Nosema ceranae and fipronil synergy on honeybee

Abstract

In ecosystems, a variety of biological, chemical and physical stressors may act in combination to induce illness in populations of living organisms. While recent surveys reported that parasite-insecticide interactions can synergistically and negatively affect honeybee survival, the importance of sequence in exposure to stressors has hardly received any attention. In this work, Western honeybees (Apis mellifera) were sequentially or simultaneously infected by the microsporidian parasite Nosema ceranae and chronically exposed to a sublethal dose of the insecticide fipronil, respectively chosen as biological and chemical stressors. Interestingly, every combination tested led to a synergistic effect on honeybee survival, with the most significant impacts when stressors were applied at the emergence of honeybees. Our study presents significant outcomes on beekeeping management but also points out the potential risks incurred by any living organism frequently exposed to both pathogens and insecticides in their habitat.

Chronic neonicotinoid pesticide exposure and parasite stress differentially affects learning in honeybees and bumblebees

“…Thus, we would have expected that exposure to both these stressors, neonicotinoids and parasite N. ceranae, would be more harmful than one factor alone as previously reported as reduced survival or longevity in honeybees (e.g. [17]). However, we did not observe any interactive effects of these factors when it comes to learning and memory.…”

“…There is increasing evidence indicating that interactive effects particularly between insecticides and parasites/diseases may have detrimental impacts on bees (e.g. [17,18]). This is of major concern given that, due to anthropogenic influence, both wild and managed bees are increasingly exposed to sub-lethal concentrations of neonicotinoids [19], and emerging pathogens and parasites [20][21][22].…”

Honeybee health in Africa—a review

“…pathogens or parasites (Vidau et al 2011;Köhler et al 2012). Pettis et al (2012) reported a higher infection of Nosema species in honeybees exposed to neonicotinoids, while Aufauvre et al (2012) demonstrated the impact of multiple exposure to both parasites and pesticides. However, under field conditions, Retschnig et al (2015) found no interactions between N. ceranae and neonicotinoid pesticides, and therefore, more studies under natural situations are necessary before definitive conclusions can be made.…”

Distribution, epidemiological characteristics and control methods of the pathogen Nosema ceranae Fries in honey bees Apis mellifera L. (Hymenoptera, Apidae)

“…The interaction of parasites and insecticides added to other stress factors may have negative synergistic effect on bee survival, contributing to increased colony loss (Aufauvre et al 2012, Retschnig et al 2014. A synergetic effect has also been observed on the mortality of honey bees co-exposed to spores of Nosema spp.…”