Insect Predation on Native Legumes. Arvid Boe and Paul Johnson South Dakota State University

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1 Insect Predation on Native Legumes Arvid Boe and Paul Johnson South Dakota State University

2 Objectives Develop baseline inventory of phytophagous and parasitoid insects affecting seed crop of native legumes Determine impact of seed predators on viable seed production of native legumes

3 Study Areas Primary: Oak Lake Field Station near Astoria, SD Numerous other sites in N. Gt. Plains

4 Materials and Methods Collected inflorescences during and at end of growing seasons Placed in rearing chambers (e.g., milk cartons, whirl packs) Collect larvae and adults as they emerge in chambers in laboratory Determine frequency of pod/seed predation

5 Legumes Canada milk-vetch (Astragalus canadensis) Groundplum milk-vetch (A. crassicarpus) Pliant milk-vetch (A. flexuosus) Standing milk-vetch (A. adsurgens) Purple prairieclover (Dalea purpurea) False indigo (Amorpha fruticosa) Wild licorice (Glycyrrhiza lepidota)

6 Bruchid Beetles (Acanthoscelides) Wild licorice C. milk-vetch False indigo Acanthoscelides aureolus, perforatus, submuticus Amblycerus robiniae emerging from seed of honey locust (Gleditsia triacanthos)

7 Phytophagous Wasps (Hymenoptera:Chalcidoidea) Female Male Bruchophagus grisselli McDaniel and Boe (Eurytomidae); new species from wild licorice

8 Parasitic Hymenoptera (Parasitoids) From Canada milkvetch Mesopolobus sp. Eurytoma tylodermatis Eupelmus vesicularis Dinarmus acutus (male and female)

9 Canada Milk-vetch Mature Seed Crop Infested Pods/Exit Holes

10 Canada Milk-vetch Seed predators: Acanthoscelides perforatus (Chrysomelidae:Bruchinae) and Tychius liljebladi (Curculionidae) Parasitoids Dinarmus acutus (Pteromalidae) (introduced) Eupelmus vesicularis (Eupelmidae) (introduced) Eurytoma tylodermatis (Eurytomidae) Pteromalidae

11 Canada Milk-vetch Pod predation at Brookings and Oak Lake 25% for T. liljebladi 18% for A. perforatus Parasitization 6% for T. liljebladi larvae primarily E. tylodermatis 22% for A. perforatus larvae E. vesicularis and D. acutus

12 Canada Milk-vetch A. perforatus T. liljebladi Parasitoids

13 Canada Milk-vetch Adult beetles active on flowers (late June) T. liljebladi larvae exit pods late July-Aug. and pupate in soil A. perforatus larvae overwinter in cocoons in pods cocoons early as late Aug., pupation in May A. perforatus larvae attacked mostly in cocoon

14 Canada Milk-vetch Other parasitoid unidentified chalcid (Pteromalidae) Predator of A. perforatus larvae Isohydnocera tabida (Coleoptera:Cleridae)

15 Groundplum Milk-vetch Acanthoscelides fraterculus

16 Groundplum Milk-vetch Flowers in late April Plants produced pods Up to 80% pod predation by A. fraterculus Up to 60% of seeds in single locule damaged Unfertilized ovules a bigger factor in seed production

17 Pliant Milk-vetch Tychius sp. larvae exit pods mid-late July as for Canada milk-vetch Viable seed production very low shriveled seeds

18 Pliant Milk-vetch Tychius sp. Eupelmus sp. Pteromalidae Braconidae

19 Pliant Milk-vetch Up to 50% pod predation by Tychius sp? Parasitism exceeded 50% E. tylodermatis, Eupelmus vesicularis 2 unidentified chalcids (Pteromalidae, Eupelmidae) 2 unidentified braconid wasps (Ichneumonoidea:Braconidae)

20 Standing Milk-vetch NO POD PREDATION Sympatric with pliant milk-vetch

21 Purple Prairieclover Seed Beetles (top); Parasitoids (bottom)

22 Purple Prairieclover Seed predators Apion tenuirostrum (Curculionidae) Acanthoscelides seminulum (Bruchinae) Midges (Diptera:Cecidomyiidae) Parasitoids Tetrastichus venustus (Eulophidae) Unidentified chalcids (Pteromalidae, Eulophidae)

23 Purple Prairieclover Practically no viable seed produced A. tenuirostrum and midges much more prevalent than A. seminulum A. teniurostrum and midge larvae exit pods in summer A. seminulum larvae overwinter in pods

24 False Indigo A.submuticus Lyrcus incertus Parasitoids Dinarmus acutus Exit Holes

25 False Indigo Seed predator: Acanthoscelides submuticus (Bruchinae) Parasitoids (Chalcidoidea) Lyrcus incertus (Pteromalidae) Dinarmus acutus (Pteromalidae) Horismenus sp. (Eulophidae) Eupelmus sp. (Eupelmidae)

26 False Indigo Pod predation at Oak Lake 35% in % in % in % in 2002 Location, year, and plant effects sig. (P<0.05) Other locations 56% at Lake Goldsmith in % at Oakwood Lake in % at Bismarck, ND in 1999 and 2000

27 False Indigo Observations Adult beetles active on inflorescences at flowering Most of the adult beetles emerge in the field during Sep.-Oct. However, some adults over-winter inside the pods

28 Wild Licorice Exit Holes (2)

29 Wild Licorice Collected seed from about 50 populations (MT, ND, SD) Seed predation ranged from 7 to 70 % Mean=42% Seed predators are Acanthoscelides aureolus and Bruchophagus grisselli Parasitoids: Dinarmus acutus, Eupelmus vesicularis, Eupelmus sp., Uscana semifumipennis (egg parasite), Eurytoma tylodermatis, Liodontomerus perplexus, L. longfellowi, Mesopolobus sp.

30 Conclusions Increased understanding of the diverse insect fauna assoc. native legumes Predation varied among legume species [0% (standing milk-vetch) to nearly 100% (purple prairieclover)] Within legume species, considerable spatial and temporal variation in pod/seed predation Intriguing plant-insect, insect-insect interactions beg more research Insect resistance in standing milk-vetch?

31 Conclusions In conjunction with systematic collections, seed increases, experimental evaluations, and commercial seed production of native legumes, we need to: Identify seed predators and their parasitoids, including describe new species Quantify seed losses due to various predators Describe/understand life histories of seed predators and their parasitoids

32 Acknowledgements Financial support provided by grant from Oak Lake Field Station Research Incentive Program Appreciation to Dr. Nels Troelstrup, Jr., Director of Oak Lake Field Station, for his support and assistance throughout the study