Kaolin as inert material in bio- pesticide formulations supplements - PowerPoint PPT Presentation

Kaolin as inert material in bio- pesticide formulations supplements the hazard to useful insects Reet Karise Riin Muljar Marika Mänd

Pesticide studies • Field exp • Semi-field exp • Mortality tests • Behavioural exp • Learning • Choice • PER • ... • Physiological exp – Dissection – In-vivo?

Respiration • Reflects the metabolic rate of the organism • Easily vulnerable system

MR and respiratory patterns Continuous (Cont.) Cyclic (CGE) Discontinuous (DGE) Cont.

• Flow through respirometry: LI-7000 CO 2 /H 2 O analyzer combined with IR-actography – Metabolic rate – Respiratory rhythms – Water loss rate - 1 - 1 C O ( m l h ) H O ( m l h ) l i h a s a k t i i v s u s ( v o l d i d ) 2 2 5 5 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)

LD50 = 0.059 mg/bee Neurotoxic effect Contact action: alpha-cypermethrin Dipping in water solution of 4 0.004% Fastac 50EC for 10 sec DGE => Continuous 3 VCO 2 (ml h -1 ) 0.004%: obtained 0.099 μg /bee 2 0.002%: obtained 0.087 μg /bee 1 0 0 1 2 3 4 5 6 Time (hours) 28 Median Longevity of bumble bees (days) 4 24 25%-75% Non-Outlier Range 20 Extremes DGE => CGE 0.002% 3 16 VCO 2 (ml h -1 ) b b 12 2 8 4 1 a 0 0 0.004% 0.002% Dist. water 0 1 2 3 4 5 6 The treatment Time (hours)

Entomovector technology • New method • Uses powdery biopreparations • Decreases the amounts of preparations needed • Must be safe – Plant products – Vectoring insect – Insect products (honey)

Kaolin • Kaolin powder – Used against stored product pests – Causing respiratory failure? – Changing cuticule properties? • Kaolin particle film – Physical barrier/deterrent – visually or tactilely unrecognizable as a host • Kaolin is frequently used as inert materials in bio-preparations

Our experiment Are kaolin and powdery formulations affecting bumble bee physiology? • Bumble bees: Koppert Biological Systems • Treatments: – Kaolin – Prestop Mix ( Gliocladium catenulatum ) – BotaniGard ( Beauveria bassiana ) – Wheat flour – Blank treatment for control

Single treatment, immediate effect (N = 6; 18 ° C) – Immediate effect on metabolic rate and water loss rate (measured 3 h before and 3 h after the treatment) – Effect on cuticular and respiratory WL Single treatment, long term effect – Effect on mortality (N = 20; 18 ° C and 28 ° C)

Results • MR normally Metabolic rate (VCO2 ml h-1) decreases during Kaolin Prestop Mix long observation BotaniGard • Powders have Wheat flour decrease increase Control capacity to prevent -100% -75% -50% -25% 0% 25% 50% 75% 100% calming process Individuals (%) • Normally water loss Water loss rate (VH 2 O μ l h -1 ) is not changing or Kaolin decrease Prestop Mix changing a few increase BotaniGard • Kaolin and Prestop Wheat flour Mix caused Control significant increase -100% -75% -50% -25% 0% 25% 50% 75% 100% in WL rate Individuals (%)

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

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

The longevity • Median longevity shorter at 18 ° C *** BotaniGard • Maximum longevity shorter at 28 ° C • At 18 ° C only BotaniGard differed significantly • At 28 ° C BotaniGard and kaolin differed significantly

Conclusions • Kaolin increases permeability of insect cuticle to water vapour • This may affect the survival of individuals • The testing inert materials is not obligatory • Yet these might pose risks to pollinators or vectoring insects • Physiological methods, for instance respirometry, can be one way to discover sub- lethal effects of pesticides or other stressors