Effect of a Fungicide and Spray Adjuvant on Queen-Rearing Success in Honey Bees (Hymenoptera: Apidae)

Abstract

Commercial producers of honey bee queens (Apis mellifera L.) have reported unexplained loss of immature queens during the larval or pupal stage. Many affected queen-rearing operations are situated among the almond orchards of California and report these losses in weeks after almond trees bloom. Almond flowers are a rich foraging resource for bees, but are often treated with fungicides, insecticides, and spray adjuvants during bloom. Anecdotal reports by queen producers associate problems in queen development with application of the fungicide Pristine (boscalid and pyraclostrobin) and spray adjuvants that are tank-mixed with it. To test the effect of these compounds on queen development, a new bioassay was developed in which queens are reared in closed swarm boxes for 4 d, until capping, with nurse bees fed exclusively on artificially contaminated pollen. Pollen was treated with four concentrations of formulated Pristine (0.4, 4, 40, and 400 ppm), a spray adjuvant (Break-Thru, 200 ppm), the combination of Pristine and spray adjuvant (400:200 ppm), the insect growth regulator insecticide diflubenzuron (100 ppm) as a positive control, or water as negative control. Chemical analysis revealed that low concentrations of pyraclostrobin (50 ppb), but no boscalid, were detectable in royal jelly secreted by nurse bees feeding on treated pollen. No significant difference in queen development or survival was observed between any of the experimental treatments and the negative control. Only diflubenzuron, the positive control, caused a substantial reduction in survival of immature queens.

Abiotic and biotic factors affecting the replication and pathogenicity of bee viruses

“…Colonies treated with chlorpyrifos and Pristine® had decreased queen emergence, but viral prevalence or abundance was not affected relative to chlorpyrifos alone [47]. In contrast, reduced queen emergence was not found when colonies in isolated swarm boxes were fed pollen treated with Pristine® or Pristine® with an adjuvant, whereas colonies treated with diflubenzuron, an insect growth regulator, had a significant reduction on queen survival [83]. …”

Fungicides affect Japanese beetle Popillia japonica (Coleoptera: Scarabaeidae) egg hatch, larval survival and detoxification enzymes

“…The findings of our study provide evidence that both propiconazole and chlorothalonil may have lethal or sublethal adverse effects on eggs and larvae of P. japonica . Previous studies have also reported sublethal effects of fungicides on larval and adult Coleoptera and Hymenoptera respectively. In our study, Daconil Weather Stik reduced survival of first‐instar larvae treated directly, and fewer first‐instar larvae hatched from treated eggs compared with the control.…”

“…It is possible that fungicides applied to turfgrass may inhibit detoxification enzymes in other turfgrass insects. Furthermore, suppression of these enzymes may leave individuals more susceptible to insecticide applications that are otherwise not directly toxic …”

“…Furthermore, suppression of these enzymes may leave individuals more susceptible to insecticide applications that are otherwise not directly toxic. 14 Japanese beetle grubs are facultative monophages 2 and likely rely on multiple detoxification enzymes for the metabolism of xenobiotics such as plant toxins and pesticides. 15 Ahmad 16 reported that there is significant P450 activity in the third-instar grubs of Japanese beetle.…”

Towards an integrated environmental risk assessment of multiple stressors on bees: review of research projects in Europe, knowledge gaps and recommendations

“…Specifically, as discussed in section 2, the default assumption for multiple chemicals is concentration addition. However, because of their specific toxicokinetic profile, there is an increasing evidence of synergistic effects of pesticides in bees (Gill et al, 2012;Hawthorne and Dively, 2011;Johnson and Percel, 2013).…”