Miniature-dispenser-based bioassay to evaluate the compatibility of powder formulations used in an entomovectoring approach.
BACKGROUND
Entomovectoring as a plant protection strategy demands the design of an appropriate bioassay to assess the risks of potential side effects of the powder formulations in the dispenser towards the vectoring insect. This study reports on the development of a laboratory miniature-dispenser-based bioassay. This bioassay system was used to investigate the compatibility of five model products, Prestop-Mix, Signum, kaolin, wheat flour and cellulose, with the bumblebee, Bombus terrestris L.


RESULTS
The laboratory one-way miniature-dispenser bioassay showed that the fungicides and the carrier/diluent kaolin caused a worker mortality of > 70% after 5 weeks of exposure, while worker loss with wheat flour and cellulose was no higher than in the blank control (i.e. empty miniature dispenser) (<25%). The laboratory two-way miniature-dispenser bioassay comprised separated passageways and demonstrated that only kaolin was toxic (89 ± 11%). These results were also confirmed in a flight-cage experiment. In addition, a negative effect was observed against reproduction/colony development when nests were exposed to kaolin (P < 0.05) in the two-way miniature-dispenser and flight-cage bioassays.


CONCLUSIONS
In the context of entomovectoring technology, the developed laboratory two-way miniature-dispenser bioassay gives a reliable prediction of the hazards associated with powder products. Additionally, the present data indicate the possibility of using cellulose and kaolin as respective negative and positive control carriers/diluents in future risk assessment experiments. Overall, the results show that, apart from kaolin, the tested fungicides and carriers/diluents are safe to be used with B. terrestris.
Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
Veerle
V
Mommaerts
Kurt
K
Put
Jessica
J
Vandeven
Guy
G
Smagghe
D000818:Animals; D001516:Bees / Q000187:drug effects* / Q000502:physiology; D001681:Biological Assay / Q000379:methods*; D002626:Chemistry, Pharmaceutical; D005426:Flight, Animal; D005659:Fungicides, Industrial / Q000737:chemistry* / Q000633:toxicity; D007753:Laboratories; D008422:Materials Testing / Q000379:methods*; D008904:Miniaturization / Q000379:methods*; D054817:Pollination; D011208:Powders / Q000633:toxicity
D005659:Fungicides, Industrial; D011208:Powders