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Intro to High Tunnel Insect Pests and Natural Enemies, 2015

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by Christopher Philips, Assistant Professor, Dept. of Entomology, University of Minnesota.

Presented at the 2015 Minnesota Statewide High Tunnel Growers Conference, Beginning Grower Workshop

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Intro to High Tunnel Insect Pests and Natural Enemies, 2015

  1. 1. Introduction to High Tunnel Insect Pests and Natural Enemies Christopher Philips Assistant Professor Fruit and Vegetable Entomologist University of Minnesota Department of Entomology North Central Research & Outreach Center (NCROC)
  2. 2. High Tunnel IPM To reduce pests below damaging levels while maintaining economic profits, environmental quality and safety.
  3. 3. IPM Implementation • Step 1 – Identify the pest. • Step 2 – Evaluate the pest infestation level • (sampling, monitoring, amount of injury). • Step 3 – Assess the tolerance level of the commodity to injury. • Step 4 – Take an action (or no action!).
  4. 4. Insect identification • Why do I need to identify it anyway? • Determines your management strategy • Different problems require different solutions • NOT ALL INSECTS ARE BAD
  5. 5. Aphids Whiteflies Spider mites Thrips Common Pests
  6. 6. Spotted wing Drosophila (SWD) • Drosophila suzukii • native to Asia • lays eggs into healthy, ripening soft fruits, using a saw-like ovipositor SWD non-SWD Photo credits: N. Gompel (top); M. Hauser (bottom)
  7. 7. What are my management options? 1) Biological 2) Genetic 3) Cultural 4) Mechanical 5)…Chemical… (last option, only when necessary)
  8. 8. 94 75 49 27 2 55 17 27 0 10 20 30 40 50 60 70 80 90 100 TSSM GPA Melon GH WF BW-WF Silverleaf onion thrips WFT Resistance to Insecticides
  9. 9. Thrips (A) Flower thrips, Frankliniella tritici (B) Western flower thrips, Frankliniella occidentalis (C) Tobacco thrips, Frankliniella fusca (D) Soybean thrips, Neohydatothrips variabilis Scale bars represent 0.5 mm. Onion thrips, Thrips tabaci
  10. 10. Thrips >7,000 species described worldwide most are not pests Biology migrate into MN Frequency A recent survey of Midwest greenhouse operators identified WFT as the most difficult greenhouse pest to manage 20°C, ~ 19 days. 25°C, ~ 13 days.
  11. 11. Damage have piercing-sucking, multi-purpose mouthparts. The mouthparts are used to pierce leaves, flowers, seeds, pollen grains, and fruit, as well as to drink open liquids such as nectar, water, or insect secretions; transmit pathogens Thrips Hosts and Damage Extremely wide host range
  12. 12. Thrips feeding damage on cucumber fruit. Thrips feeding damage on cucumber leaves Thrips Damage Oviposition scars and feeding damage on sweet pepper. Thrips egg-laying scars on tomato Thrips feeding damage on pepper leaves. A very important aspect of thrips is the transmission of virus diseases. Tomato spotted wilt virus, transmitted by the • western flower thrips, • tobacco thrips, and • onion thrips.
  13. 13. Sanitation • Remove weeds that act as a thrips (virus) refuge. • Remove and destroy crop residues and affected plants after harvest. • Pasteurize soil to kill immature thrips. • Pruning Thrips Cultural and Mechanical
  14. 14. Thrips Biological Control Amblyseius cucumeris • Amblyseius cucumeris prefers a diet of thrips but is considered a generalist because it can survive on pollen and spider mites in the absence of thrips. A. cucumeris will work best at a temperature of 70˚F or above and RH > 65%. Orius insidiosus • Minute pirate bug is a common generalist predator found naturally in many field-grown crops. • It preys on thrips, whiteflies, spider mites, aphids and many other pests. It can survive on pollen in the absence of prey.
  15. 15. Intrinsic capacity of Orius insidiosus to reduce flower thrips populations Predator-Prey Ratios 1 : 217 = population suppression 1 : 51 = rapid local extinction From: Sabelis & Van Rijn (1997) Thrips as Crop Pests. (Lewis, ed.) CAB International, UK Thrips Predation Photo Joe Funderburk
  16. 16. Whiteflies Silverleaf and sweetpotato whiteflies (Bemisia argentifolii and B. tabaci) Greenhouse whitefly (Trialeurodes vaporariorum) Bandedwinged whitefly (Trialeurodes abutilonea)
  17. 17. Biology Do not overwinter in MN continue from year to year in greenhouses Frequency Common pest in MN Control There is really no easy way to control whiteflies Whiteflies
  18. 18. Aphids Melon/cotton aphid, Aphis gossypii Green peach aphid, Myzus persicae Biology Overwinter and migrate into MN Frequency Common pest in MN Control Usually not necessary; biological control
  19. 19. Aphids and Whiteflies Hosts and Damage Numerous Host Damage • Piercing/sucking mouthparts, • plant distortion and discoloration, • leaf chlorosis, • leaf withering and premature leaf drop plant • death; • Excrete honeydew, promotes the growth of sooty mold
  20. 20. Aphids and Whiteflies Damage Tomato yellow leaf curl virus Vector taxa Vector group Total plant viruses Hemiptera Aphids 197 Whiteflies 128 Melon aphids are known to transmit 44 plant viruses, while green peach aphids are known to transmit more than 100 plant viruses
  21. 21. Aphid and Whitefly Management • Prevent outbreaks of aphids by scouting weekly and releasing natural enemies at the first sign of damage. • Inspect the upper and lower surfaces of plant leaves • If you disturb the plant foliage, whitefly adults will fly up and be easier to spot. • Use a hand lens • Also check for evidence of natural enemies such as lady beetles, lacewings, syrphid fly larvae and the mummified skins of parasitized aphids. Look for disease-killed aphids as well: • They may appear off-color, bloated or flattened.
  22. 22. Sanitation • Remove weeds in and around high tunnels Limit the use of quick-release fertilizer Aphid and Whitefly Cultural and Mechanical Photo credit: Galen Weston,
  23. 23. Biological control of Aphids: Parastitoids Aphidius colemani Works best at a temperature of 50 to 76˚F and tolerates cool temperatures. Aphidius ervi This small, black wasp parasitizes all types of large aphids. It prefers an air temperature of 86˚F.
  24. 24. Biological Control of Whiteflies: Parasitoids Encarsia formosa (Hymenoptera: Aphelinidae) 8-10 eggs per day Primary Prey: whiteflies and aphids Key Characters: parasitized hosts turn black Vegetable crops: release needed Eretmocerus eremicus E. formosa prefers an average temperature above 64˚F, and RH >70%
  25. 25. Parasitoids Insect which lives in or on another insect during its immature stages. Differs from parasitism in that: 1. only larval stages are parasitic, adults are typically free flying 2. larvae eventually kill their host
  26. 26. Two-spotted Spider Mite Biology Overwinters in MN Frequency Common pest in MN
  27. 27. Feed on over 180 host plants, including over 100 cultivated species Damage • Spider mites injure leaves by piercing cells and sucking out cell contents. • This injury produces white or yellow spots or "stippling" that is heaviest on the underside of the leaves • As mite numbers increase, these white speckles will increase in number, the leaf will take on a bleached appearance and die. Two-spotted Spider Mite Host and Damage
  28. 28. • Chemical control of spider mites generally involves pesticides that are specifically developed for spider mite control • Few insecticides are effective for spider mites and many even aggravate problems. • Furthermore, strains of spider mites resistant to pesticides frequently develop, making control difficult. 0 20 40 60 80 100 TSSM 94 Two-spotted Spider Mite Management
  29. 29. Two-spotted Spider Mite Cultural and Mechanical Sanitation • remove alternative hosts could reduce infestation of plants nearby • disposing of old or infested plant material Inspections Avoid over-fertilization • promotes succulent new growth which is more susceptible to two-spotted mites. Use of high-pressure water spray or overhead irrigation to dislodge spider mites
  30. 30. Predators are very important in regulating spider mite populations and should be protected whenever possible. Important predators include: the predatory mites, • Phytoseiulus persimilis, • Mesoseiulus longipes, • Neoseiulus californicus, • Neoseiulus fallicus • Galendromus occidentalis The lady beetle, Stethorus; The minute pirate bugs, Orius; Two-spotted Spider Mite Biological control
  31. 31. Predatory Mites Acari: Phytoseiidae 67 genera, 2,000 species Primary Prey: spider mites, thrips; fungus gnats Predatory Stage: nymphs and adults Key Characters: teardrop shape; fast moving Vegetable crops: most greenhouse crops Amblyseius fallacis Galendromus occidentalisMesoseiulus longipes Phytoseiulus persimilis Neoseiulus californicus
  32. 32. Anatomy Body structure, mouthparts Reproduction Parthenogenic, haplodiploidy, polyembryony Ontogeny Growth rate, metamorphosis, pest stage Insect Ecology Environmental interactions Why Do Insect Pest Problems Occur?
  33. 33. Insect Growth and Development Affected by two major factors, time and temperature The amount of heat required by an organism to complete its development is known as physiological time. • Minimum or lower developmental threshold is the temperature below which insect development is negligible. • Maximum or upper developmental threshold is the temperature at which insect growth stops.
  34. 34. Why Do Insect Pest Problems Occur? • Almost unlimited food and improved environmental conditions • Multiple generations - up to 12-15 / year • Limited natural enemies to reduce populations • Some life stages are not susceptible to treatment • Major insecticide and miticide resistance
  35. 35. Biological control • “the enemy of my enemy is my friend” • e.g., predators, parasitoids, pathogens • Biological control is a method of controlling pests using other living organisms. Types of Biological Control Classical Augmentation inundative releases and inoculative releases Conservation
  36. 36. Arthropod Predators True Bugs Beetles Flies Others • lacewings • Spiders • Mites
  37. 37. Getting Started • Start small and start early • Pesticide Residues and when needed use soft pesticides • Good Sanitation • Weed management is critical • Clean Transplants +
  38. 38. Questions?
  39. 39. What are my management options? 1) Biological 2) Genetic 3) Cultural 4) Mechanical 5)…Chemical… (last option, only when necessary)
  40. 40. Types of Natural Enemies Generalists and Specialists Predators and Parasitoids Pathogens
  41. 41. Nymphs and adult stage Primary Prey: whiteflies, thrips, aphids Predatory Stage: nymphs and adults Key Characters: very small, black and white coloration Vegetable crops: most Minute Pirate Bugs Hemiptera: Anthocoridae
  42. 42. Intrinsic capacity of Orius insidiosus to reduce flower thrips populations Predator-Prey Ratios 1 : 217 = population suppression 1 : 51 = rapid local extinction From: Sabelis & Van Rijn (1997) Thrips as Crop Pests. (Lewis, ed.) CAB International, UK Thrips Predation Photo Joe Funderburk
  43. 43. Big-eyed bugs Hemiptera: Goecoridae Geocoris punctipes Big-eyed bug Primary Prey: insect eggs, small insects and larvae Predatory Stage: nymphs and adults Key Characters: small black, gray or tan with large eyes Vegetable crops: most
  44. 44. Damsel bugs Hemiptera: Nabidae Nabis spp. Primary Prey: insect eggs, small insects and larvae Predatory Stage: nymphs and adults Key Characters: slender yellowish-brown with narrow head, prominent eyes and long antennae Vegetable crops: most
  45. 45. Primary Prey: aphids and whiteflies Predatory Stage: larvae Key Characters: Mosquito-like adults; small orange maggots Vegetable crops: most attacked by aphids Predatory Midge Diptera: Cecidomyiidae Predatory Midge: Feltiella acarisuga
  46. 46. Hover Flies Diptera: Syrphidae Primary Prey: aphids and small caterpillars Predatory Stage: larvae Key Characters: adults resemble bees, maggots are tapered near head, green or pinkish, near aphids Vegetable crops: most attacked by aphids
  47. 47. Primary Prey: aphids, mites, small insects, eggs Predatory Stage: larvae and adults Key Characters: alligator-like larvae; red or orange adults with black markings Vegetable crops: most Lady Beetles Coleoptera: Coccinellidae Coleomegilla maculata Larva C. septempunctata Delphastus pusillusDelphastus catalinae Stethorus punctum Harmonia axyridis 450 species of lady bugs in NA
  48. 48. Rove Beetles Coleoptera: Staphylinidae Primary Prey: root maggot eggs, other soft bodied insects Predatory Stage: larvae and adults Key Characters: slender, short forwings Vegetable crops: cole crops, onions, corn, and others
  49. 49. Ground Beetles Coleoptera: Carabidae Many, many species - usually ground-dwelling generalist predators Larva Elaphrus Clivina Notiophilus Lebia Primary Prey: soil-dwelling eggs larvae and pupae Predatory Stage: larvae and adults Key Characters: dark, sometime metallic color; fast moving, ground dwelling, thread-like antennae Vegetable crops: most
  50. 50. The True Bugs Key Characteristics Piercing-sucking mouthparts Generalist feeding Omnivorous Stink bugs Minute Pirate Bugs Big-Eyed Bugs Damsel Bugs Assassin Bugs
  51. 51. Predatory Flies Hover Flies Predatory Midge
  52. 52. Predators – Beetles Lady Beetles Rove Beetles Soldier Beetles Ground Beetles
  53. 53. Other Predators Spiders Praying Mantids Mites Lacewings
  54. 54. Lacewings Neuroptera: Chrysopidae/Hemerobiidae Primary Prey: aphids and other pests Predatory Stage: larvae Key Characters: green or brown adults; net-veined wings; alligator-like larvae with sickel-shaped jaws Vegetable crops: most

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