Toward a Comprehensive Approach to the Biological Control of Wireworms

Transcription

1 Toward a Comprehensive Approach to the Biological Control of Wireworms Todd Kabaluk, Research Biologist Integrated Pest Management Agassiz Research and Development Centre British Columbia

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3 Microbial pesticides come from insect diseases Fungi Metarhizium spp., Beauveria spp., Paecilomyces spp., Lecanicillium spp. Bacteria Bacillus thuringiensis Viruses viruses from source insects (e.g. Cydia pomenella (codling moth), Spodoptera exigua (beet army worm), Anticarsi gemmatalis (velvet bean caterpillar)) Microsporidia / Protozoa Nosema locustae Nematodes Steinernema spp., Heterohabditis spp.

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5 Why Biopesticides? a component of IPM minimized risk to environment, applicators, food and consumers no MRL! good for agriculture near urban areas pesticide-resistance management organic production products can be persistent

6 Biological Control of Wireworms and Click Beetles Using Metarhizium, an insect fungal disease

7 Terminology Metarhizium LRC112 -discovered by AAFC -experimental, not registered -kills a wide range of wireworm species Metarhizium Met52 -commercial, registered in Canada for other pests -NA distribution rights: Novozymes Biologicals Inc. -it is still experimental for wireworms Different effects depending on wireworm vs. click beetle AND SPECIES

8 We make Metarhizium in our lab Inoculate nutrient broth with fungal conidia (=spores) Incubate inoculated broth for 72 hours to make blastospores Prepare grain substrate (weighing, placing in breathable bags, sterilizing) Let the fungus grow on grain for 10 days Dry sporulated grain for 7 days Inoculating grain with blastospore suspension Sporulated grain ( Metarhizium granules ) or spore powder for field application

9 Field research on A. obscurus and A. lineatus in BC - proxy for A. sputator in maritime provinces A. lineatus A. obscurus A. sputator A. lineatus A. obscurus

10 AAFC Agassiz blessed with with a wireworm infestation

11 A Comprehensive Approach to the Biological Control of Wireworms includes: -Reducing the input of new larvae from adults -Reducing existing larvae to sub-threshold levels -Preventing wireworm build-up once a subthreshold level is achieved -Periodic inundative control interventions -Achieving management with a minimal environmental impact

12 Wireworm Biocontrol includes taking advantage of life cycle and behaviours Intense feeding Relaxed feeding Image courtesy of Top Crop Manager

13 Generalizing a production system for potato Biocontrol of beetles during this time would reduce egg laying and input of new larvae X Example crop rotation X X Biocontrol of larvae remaining in the soil Year 1 Grain undersown with clover Year 2 Clover Year 3 Potato Prime egg-laying sites for beetles, building up the wireworm population Sustains wireworms already in the soil Potatoes damaged by existing wireworms in the soil, including those arising from previous two years rotation crops

14 Rotation Years: Can amending the soil with Metarhizium reduce input of new larvae? Beetles released into containers (ratio of 1 : 1.4 ) Recovering neonates/ early instars beginning after 4 months 0(!) Field soil with 10 4 natural Met spores/g Sterilized field soil Met spores/g ADDED Sterilized field soil This suggests: -good opportunity for reducing input of new larvae during rotation years by amending soil with Metarhizium > seed treatments, broadcast, sprays

15 Rotation Years Attract and Kill with bands of Metarhizium and pheromone granules (attracts )

16 Pheromone granules improve the efficacy of Metarhizium when targeting click beetles using a banded application Field trails 2014 and Percent mortality of click beetles in the field (the majority of beetles pick up fatal infections in as little as 3 hours) High rate Metarhizium Low rate Metarhizium No pheromone granules in Metarhizium band With pheromone granules in Metarhizium band

17 Click Beetle Pheromones - A *NEW * formulation From liquid... to granular We make pheromone granules in our lab

18 Rotation Years: Granules might also be used for mating disruption????

19 Rotation years: What about Metarhizium field sprays? Spraying should work New oil-emulsion formulations expected to kill up to 100%, and be persistent Will also kill female beetles > Trials using oil-emulsion in 2016

20 Application of Metarhizium spores -field trials from 2010 and Spore granules % beetle mortality Spore dust Aqueous spore spray Matador (λ cyhalothrin) -spray positive control Number of days after treatment

21 Temperature ( C) 3 click beetle species (Ao, AL, As) x 2 Metarhizium strains (LRC112, Met52) + controls The effect of seasonal temperatures on click beetle mortality -assessing mortality at more realistic temperatures when biocontrols would be applied 25 Min/Max temperatures programmed using 30 year averages June 1-31 May April Time (days) dd

22 Heat unit crash course -a unit used to determine the heating requirements of plants, insects, microbes, to reach certain life stages Mean daily temperature selected base temperature = heat units for that day -then, add up the heat units for each day Example: 12C (mean daily temperature) 5C (base temperature) = 7 heat units for that day 16C (mean daily temperature) 5C (base temperature) = 11 heat units for that day TOTAL SO FAR: 18 heat units Heat units accumulate over time, and precisely predict biological events The number of heat units required for a potato to reach flowering is fixed. If temperatures are cool, it just takes longer for heat units to accumulate to reach that fixed number. We related click beetle mortality to seasonal temperatures and heat units (degree days)

23 % beetle mortality % beetle mortality Mortality of Agriotes lineatus retained at three spring/early summer temperature profiles April May June Met52 Over time (days) Strain X % mortality 90% mortality HUs Over heat units (= degree days) HUs

24 Lethal heat units (LHU) for two Metarhizium strains to kill 50% and 90% of the big three Beetle Met species strain LHU 50 LHU 90 A. lineatus Met StrainX A. obscurus Met StrainX A. sputator Met StrainX - -

25 Cumulative heat units (HU) How will Met52 perform as a biocontrol for Agriotes sputator on Prince Edward Island? Harrington, Prince Edward Island (2015 weather data) Predicted Agriotes sputator Click Beetle Mortality Dates Based on Metarhizium Met52 Application Dates May 21 May 14 May 7 Metarhizium application date HU to kill 90% of beetle population HU to kill 50% of beetle population June 7 June 11 June Number of days after applying Metarhizium June 29 June 26 June 24

26 Harrington, Prince Edward Island (2015 weather data) Predicted Agriotes sputator Click Beetle Mortality Dates Based on Metarhizium Met52 Application Dates Met52 application date Date on which 50% of affected population are killed Date on which 90% of affected population are killed May 7 June 4 June 24 May 14 June 7 June 26 May 21 June 11 June 29 It takes a while -but is the infection affecting beetle reproduction before they die? > Research 2016

27 What about the wireworms remaining in the soil at planting time?

28 Wireworm feeding holes in tubers Biological Control of Wireworm Larvae using Metarhizium LRC112 (targeting larvae in soil using a broadcast preplant incorporated application) Treated Control -33% Trial Miel02 1 Trial Miel01 2 Bodnar02 Trial 3 Trial Pop02 4 VanPer00 Trial 5 VanPer00 Trial 6 Seed New New Index Seed New tubers tubers tubers tubers tubers tubers

29 A new method for targeting wireworm larvae -attract and kill with CO 2 generating capsules impregnated with Metarhizium. ATRACAP

30 % damaged tubers + s.e. ATRACAP (sometimes) improves the efficacy of Metarhizium when targeting larvae in the soil (to be formulated with LRC112 for Canada) 5 Economic threshold 0 Untreated control Metarhizium alone Metarhizium impregnated CO 2 capsules CO 2 capsules alone

31 Virulence of Metarhizium strains toward pest Elaterids Met 52* (Commercial) StrainX (Experimental) Agriotes obscurus Adults high high Larvae low high Agriotes lineatus Adults moderate high Larvae low high/moderate Agriotes sputator Adults high moderate Larvae unknown moderate *Novozymes Biologicals Inc.

32 Comprehensive Wireworm Biocontrol - Review Seed treatment, broadcast or spray applications Attract and kill or autodissemination Oil-emulsion spray Attract and kill (and its refinement) BCPPI

33 Important things that we don t know: -effect of Metarhizium infection on click beetle reproduction -how targeting the beetles will be reflected in the larval (wireworm) population in soil > first data in October subjects of current research

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