Using an ecological model to identify Arthropod species for risk assessment of GM Bt soybean in South Africa. Nadine Schutte & Johnnie Van den Berg IPM - Program Unit for Environmental Sciences and Management North-West University Potchefstroom 2520 South Africa Biosafety symposium, March 2019 Pretoria, South Africa Introduction Arthropods are important to human lives and the functioning of natural ecosystems. Ecological services: • Pollination • Pest control • Nutrient flow • Maintenance of soil structure • Recycling of matter • Fungus control Photo: AS Botha Soybean pest species include: • African bollworm (Helicoverpa armigera) • Painted lady (Vanessa cardui) • Semi-looper (Thysanoplusia orichalcea) • Green stink bug (Nezara viridula) Photos: PD Janse van Rensburg Photos: AS Botha Bt soybeans > environmentally friendly • GM crops have been planted in SA since 1998 • Ecological risk assessment (ERA) • Bt soybean: in the assessment phase Photos: PD Janse van Rensburg • Risk assessment – risks are identified – seriousness are characterized – informed decisions • Major ecological concern of Bt crops: Potential impact on non-target arthropods Natural enemies Beneficial organisms Pollinators Non-target organisms: Non-target pests Secondary pests Non-pests New pests For the organism to be affected – must be exposed to the Bt toxin 2 exposure pathways Directly Indirectly Through consumption Through consumption of an of Bt crop organism that consumed Bt crop Herbivore: bollworm Predator: spider Direct effects Indirect effects Neuroptera Diptera parasitoids Lepidoptera: target pest Dermaptera Hymenoptera Gut-microbes • Risk assessment process takes time • Delays the registration process of the crops • Need to be done efficiently & effectively • Scientific inputs are needed to assist in the regulatory process Ecotoxicology model Ecological model Problem statement • Bt soybean could affect non-target species directly or indirectly • Assessments are hampered by the lack of a species checklist Aims: • To assess the diversity of Arthropods • To identify non-target species • To place these species in functional groups • To prioritize these species Photos: PD Janse van Rensburg Materials and Methods • Field surveys conducted at 5 sites in 4 major soybean production provinces • Feb – Apr 2018 • Adapted D-vac method for sampling arthropods • Sampled 3 times at each site during the growing season • Pre-, post- and during bloom Sorted Identify: family level Morphological species Counted numbers of individuals 1. Establish functional groups Herbivores Lepidoptera 2. Classify the non-target larvae species 3. Prioritized species Detritivores Predators Flies Spiders 4. Select high priority species to test Pollinators Parasitoids 5. Determine experimental end Honey Wasps points – to be done in future bees Results and Discussion • Bollworm = target species 2.48% of total • Lepidopterans 4.9% of total Blattodea • Others (97.51%) - non-target species Herbivores Morpho- Number of Order Priority species species individuals Coleoptera 57 Chrysomelidae MS 1 579 Chrysomelidae MS 14 23 Lepidoptera 11 Nymphalidae MS 1 112 Noctuidae MS 1 39 Orthoptera 8 None 0 Hemiptera 36 Aphididae MS 2 324 Cicadellidae MS 1 286 Cicadellidae MS 2 190 Miridae MS 1 (Nph) 153 Pentatomidae MS 2 (Nezara) 239 100 9 1945 Predators Morpho- Number of Order Priority species species individuals Araneae 37 Theridiidae MS 4 72 Thomisidae MS 2 129 Thomisidae MS 4 60 Coleoptera 26 Anthicidae MS1 141 Anthicidae MS2 22 Coccinellidae MS5 129 Diptera 2 Dolichopodidae MS1 59 Thysanoptra 1 None 0 Hemiptera 16 Miridae MS4 72 Anthocoridae MS1 95 Geocoridae MS1 101 76 10 1155 Parasitoids Morpho- Number of Order Priority species species individuals Diptera 3 Tachinidae MS1 52 Tachinidae MS2 72 Tachinidae MS3 375 Hymenoptera 62 Braconidae MS26 234 Calcidoidea MS10 174 Calcidoidea MS27 84 Calcidoidea MS28 70 65 7 1061 Pollinators Morpho- Number of Order Priority species species individuals Hymenoptera 14 None 0 Coleoptera 6 None 0 2 20 0 0 Detritivores Morpho- Number of Order Priority species species individuals Collembola 1 Entomobryoidea MS1 89 Orthoptera 7 None 0 Diptera 15 Muscidae MS4 150 3 23 2 239 12 023 Individuals 284 Morpho-species 28 Priority species 5 Functional groups Selection matrix to rank priority species Maximum potential exposure Possible adverse effect Species Occurrence Abundance Presence Linkage Significance Damage **Rank Chrysomelidae MS1 Certain High Anytime Sometimes – strong Aphididae MS2 Certain High Anytime Sometimes – strong Anthicidae MS1 Certain Medium Anytime Always – not strong Coccinellidae MS 5 Occasional Medium Mostly pre- Sometimes flowering – strong Tachinidae MS3 Certain High Post- Sometimes flowering – strong Braconidae MS26 Certain High Anytime Sometimes – strong Conclusion • Surprisingly high diversity of non-target arthropods • 28 priority species were identified in 5 functional groups and 6 were assigned high priority • Endpoints will be set in future • This study provides a framework for selecting priority species for monitoring possible effects of Bt soybean on NTOs in South Africa Acknowledgements Method Orders Families Total Total Morpho- individuals species Beating 13 53 110 5 286 D-vac 15 103 284 12 023 Sticky traps 7 NA 18 77 575 94 884 Categ. Box & Whisker Plot: Shannon(H'(loge)) Categ. Box & Whisker Plot: Shannon(H'(loge)) 1.6 1.4 Diversity indices 1.2 1.4 1.0 1.2 0.8 1.0 P=0.0005 P=0.93 0.6 Beating sheet 0.8 Shannon(H'(loge)) Shannon(H'(loge)) 0.4 0.6 0.2 0.4 0.0 0.2 Mean Mean Bethal Fouriesburg Bothaville Nigel Non-Bt Bt Mean±SE Mean±SE Treatments Mean±1.96*SE Treatment Mean±1.96*SE Categ. Box & Whisker Plot: Shannon(H'(loge)) Categ. Box & Whisker Plot: Shannon(H'(loge)) 1.6 1.50 1.45 1.4 1.40 1.2 1.35 P=0.187 D-vac 1.30 1.0 P=0.937 1.25 Shannon(H'(loge)) Shannon(H'(loge)) 0.8 1.20 1.15 0.6 1.10 0.4 1.05 Mean Mean Bethal Fouriesburg Bothaville Nigel Non-Bt Bt Mean±SE Mean±SE Localities Mean±1.96*SE Treatment Mean±1.96*SE Fig. 4,5. Shannon diversity values for localities. Fig. 6,7. Shannon diversity values for non-Bt and Bt Sticky traps P=0.0005 P=0.896 Fig. 8. Abundance results for the sticky trap data Fig. 9. Abundance results for the sticky trap data between the different localities. between the non-Bt and Bt..