The effect of kaolin and the microbial biopesticides Prestop-Mix and - PowerPoint PPT Presentation

The effect of kaolin and the microbial biopesticides Prestop-Mix and BotaniGard on respiratory physiology and longevity of bumblebees ( Bombus terrestris L.) Riin Muljar a Marika Mänd a , Reet Karise a , Guy Smagghe b a Department of Plant Protection, Estonian University of Life Sciences b Department of Crop Protection, Ghent University

Entomovector technology • New method • Bees (foragers) as vectors to distibute plant protection agents to flowers • Precise application, smaller amounts of preparations needed • Uses powdery biopreparations • Must be safe • Plant products (strawberries etc) • Honey • Vectoring insect

Effect on respiratory physiology • Insect respiration • vulnerable system, easily affected by stressors • reflects the metabolic rate of the organism https://sciencemodalities.wordpress.com/tag/respiratory-system-in-animals/ • different respiratory patterns: • Continuous (Cont.) http://www.biog1445.org/demo/05/tracheasystems.15.html • Cyclic (CGE) • Discontinuous (DGE) DGE CGE Cont. 7.95 0.60 O -1 ) 6.95 0.45 VCO 2 (ml h 5.95 0.30 F 4.95 0.15 3.95 0 30 60 90 120 150 0 3000 6000 9000 12000 15000 C Time (min)

• Flow through respirometry : LI-7000 CO 2 /H 2 O analyzer combined with IR-actography o Metabolic rate, respiratory rhythms o Water loss rate o Muscle contractions CO 2 (mlh -1 ) H 2 O (mlh -1 ) lihasaktiivsus (voldid) 5 5 http://www.licor.com/env/products/gas_analysis/LI-7000/ 4 4 V CO 2 mlh -1 V H 2 O µlh -1 3 3 2 2 1 1 0 0 30 60 90 120 150 180 Aeg (min)

Our experiment • Are powdery formulations affecting bumble bee physiology? • Causing respiratory failure? • Changing cuticule properties? • Bumble bees ( B. terrestris L. ) : Koppert Biological Systems • Treatments: • Prestop Mix - fungus Gliocladium catenulatum , • Kaolin powder - formulation additive (carrier /diluent) • BotaniGard - fungus Beauveria bassiana • Wheat flour • Blank control http://www.natupol.com%2Ffileadmin%2F_processed_%2Fcsm_Natupol_4e72229ee1.png

Single topical treatment: • Immediate effect (N=6 each treatment; 18 ° C) • metabolic rate (MR) • water loss rate (WLR) – respiratory and cuticular WLR • measured 3 h before and 3 h after treatment • Long term effect (N=20 each treatment; 18 ° C and 28 ° C) • longevity

Results Metabolic rate (VCO 2 ml h -1 ) Metablic rate: Kaolin • No significant differences before Prestop Mix BotaniGard and after treatment Wheat flour decrease • MR normally decreases during long increase Control observation -100% -75% -50% -25% 0% 25% 50% 75% 100% • Kaolin and Prestop Mix increase MR Individuals (%) - irritation? Water loss rate (VH 2 O μ l h -1 ) Kaolin decrease Prestop Mix increase Water loss rate: BotaniGard • Kaolin and Prestop Mix caused Wheat flour significant increase in WLR Control -100% -75% -50% -25% 0% 25% 50% 75% 100% Individuals (%)

Respiratory and Cuticular WL • Can be measured during the periods of DGE • We calculated the mean respiratory and cuticular WLR of 3 consecutive cycles of DGE ( µl h -1 ) Respiratory WL Total WL Cuticular WL Respiratory WL = Total WL – Cuticular WL

• No difference in mean Respiratory WL • Significant differences in Cuticular WL: Kaolin and Prestop Mix Cuticular water loss Respiratory Water loss Mean; Whisker: Mean±SE Mean; Whisker: Mean±SE 0,8 * Before 0,12 n.s. n.s. 0,7 Before After treatment n.s. After treatment 0,10 0,6 V H2O μl h -1 V H2O μl h -1 n.s. n.s. 0,5 0,08 n.s. 0,4 0,06 * 0,3 n.s. 0,04 n.s. 0,2 0,02 0,1 0,00 0,0 Kaolin BotaniGard Control Kaolin BotaniGard Control Prestop Mix Wheat flour Prestop Mix Wheat flour

Longevity [Temperatuure võrreldes:] • Median longevity shorter at 18 ° C *** BotaniGard • Maximum longevity shorter at 28 ° C [Temperatuure eraldi vaadates:] • At 18 ° C only BotaniGard differed significantly • At 28 ° C BotaniGard and kaolin differed significantly

Conclusions • Our results indicate that powdery formulations of microbial pest control agents may pose some risk to vectoring bees, still the risk is much lower than with synthetic pesticides. • The standard risk assessment should include physiological methods, for instance respirometry, and include analyses of the effects of inert materials of microbial pesticides.

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