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Understanding spider mites and other high tunnel insects, 2015


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by Christopher Philips, Assistant Professor | Department of Entomology, University of Minnesota

Presented at the 2015 Minnesota Statewide High Tunnel Conference.

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Understanding spider mites and other high tunnel insects, 2015

  1. 1. Understanding Spider Mites and Other High Tunnel Insects Christopher Philips Assistant Professor Fruit and Vegetable Entomologist University of Minnesota Department of Entomology North Central Research & Outreach Center (NCROC)
  2. 2. Aphids Whiteflies Spider mites Thrips Insects in High Tunnels
  3. 3. High Tunnel IPM IPM programs use current, comprehensive information on the life cycles of pests and their interaction with the environment. This information, in combination with a variety of techniques to reduce the risk of pest damage by the most economical means, and with the least possible hazard to people, property, and the environment.
  4. 4. 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!).
  5. 5. Insect identification • Why do I need to identify it anyway? • Determines your management strategy • Different problems require different solutions • NOT ALL INSECTS ARE BAD
  6. 6. Why Do Insect Pest Problems Occur? • Why are pest insects free from the control of natural enemies and diseases? • How do modern agriculture and forestry practices contribute to problems? • What effects have the movement of plants and insects had on pest problems?
  7. 7. Abiotic factors Physical (environmental) Climate Space Insecticides Mortality Density Independent Mortality % mortality is not related to host density Density dependent mortality As host population increases, % mortality increases -related relationship Biotic Factors Intraspecific competition (crowding) Dispersal/migration Dormancy/diapause Genetic diversity Interspecific Natural enemies Competitors Food organisms Insect Life Cycles Number of generations per year - Voltinism Why Do Insect Pest Problems Occur?
  8. 8. 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.
  9. 9. Insects in High Tunnels • Multiple generations - up to 12-15 / year • Limited natural enemies to reduce populations • Almost unlimited food • Improved environmental conditions • Some life stages are not susceptible to treatment • Major insecticide and miticide resistance
  10. 10. 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 Pesticides
  11. 11. Aphids Whiteflies Spider mites Thrips Common Pests
  12. 12. Two-spotted Spider Mite Biology Overwinters in MN Frequency Common pest in MN E. Erbe, USDA-ARS
  13. 13. Favored by hot dry conditions 4-14 days development increases with temeratureF 7-10 generations a year Adult females – 30 days ~100 eggs avg (up to 300) Two-spotted Spider Mite Life Cycle
  14. 14. 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
  15. 15. • Prevent spider mite outbreaks by scouting weekly and releasing natural enemies as needed. • Look for the characteristic spotting on plant leaves. • The two-spotted spider mite has two prominent spots on the upper surface of its body. • Look for mites on the undersides of leaves. Also look for their silken webbing D. Cappaert, Michigan State University, #5371009 Two-spotted Spider Mite Management
  16. 16. Control • 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
  17. 17. Two-spotted Spider Mite Cultural and Mechanical Sanitation • 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
  18. 18. Two-spotted Spider Mite 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.
  19. 19. Predators of Mites 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;
  20. 20. Predatory Mites Acari: Phytoseiidae 67 genera, 2,000 species Neoseiulus fallacis Galendromus occidentalisMesoseiulus longipes Phytoseiulus persimilis Neoseiulus californicus Can consume 20 eggs or five adults daily. Phytoseiulus persimilis highly specialized - preys only on the two-spotted spider mite Neoseiulus (Amblyseius) californicus. where high temperatures and/or relative humidity variations
  21. 21. Predatory Midge: Feltiella acarisuga Should be used in conjunction with a predatory mite. The gall midge larva feeds on spider mite eggs. Each female lays an average of 30 shiny yellow eggs near mite colonies They can consume over 300 mite eggs as they complete their development in about a week They then spin fluffy white cocoons on the underside of leaves, usually along a leaf vein,
  22. 22. Native to North America and is found throughout the mid-Atlantic region and also in the Midwest Stethorus punctum is strictly a predator of plant-feeding mites, particularly the spider mites such as the European red mite and the twospotted spider mite, and especially the eggs. S. punctum consume up to 100 mites per day Lady Beetles Coleoptera: Coccinellidae Stethorus punctum Photo: D.Asquith
  23. 23. Application • Start early to control spider mite populations since spider mites reproduce quickly at high temperatures and low humidity. • If used on a curative basis, introduce multiple mite species to clean up hot spots. • Always use the predatory midge in conjunction with a predatory mites. • Concentrate predator introductions at spider mite hot spots.. • Monitor predator activity by checking spider mite colonies weekly. Additional biological controls should be added as needed.
  24. 24. Management Challenges • New Pests • Resistance • Timing • Biology and ecology of natural enemies • Unintended consequences of other management 0 20 40 60 80 100 TSSM 94
  25. 25. 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)
  26. 26. Timing Biological control agents must be released before two-spotted spider mite populations reach damaging levels. • The population growth of predatory mites depends on the density and distribution of two- spotted spider mite populations as well as temperature and RH.
  27. 27. Biology and ecology of natural enemies • Most of the natural enemies require specific temperature and RH • found that in high tunnels the temperature and humidity fluctuated too widely to support this species except for several weeks in spring and summer
  28. 28. Weeds Soil Diseases Insects • Organophosphates (malathion), • Pyrethroids (bifenthrin, cyfluthrin, and permethrin) • Neonicotinoids (Acetamiprid, Clothianidin, Dinotefuran, Imidacloprid, Thiamethoxam) Unintended consequences
  29. 29. 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
  30. 30. 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 Thrips like dry conditions, so keep plants well watered and relative humidity high.
  31. 31. 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
  32. 32. 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.
  33. 33. Whiteflies Silverleaf and sweetpotato whiteflies (Bemisia argentifolii and B. tabaci) Greenhouse whitefly (Trialeurodes vaporariorum) Bandedwinged whitefly (Trialeurodes abutilonea)
  34. 34. 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
  35. 35. Aphids Melon/cotton aphid, Aphis gossypii Green peach aphid, Myzus persicae Biology Cabbage aphid overwinters as eggs in MN Green Peach aphid migrates into MN Frequency Common pest in MN Control Usually not necessary; biological control
  36. 36. 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
  37. 37. 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
  38. 38. Management Challenges • All of these pests thrive under tunnel conditions. • The dry foliage, stems, and fruit grown under intense irrigation and fertigation are ideal environments for these pests to flourish. • Unintended consequences of other management • Organophosphates (malathion), • Pyrethroids (bifenthrin, cyfluthrin, and permethrin) • Neonicotinoids (Acetamiprid, Clothianidin, Dinotefuran, Imidacloprid, Thiamethoxam)
  39. 39. Smith and Clement, Annu. Rev. Entomol. 2012. 57:309–28 Unintended consequences
  40. 40. • Suppress expression of important plant defense genes, • Alter levels of phytohormones involved in plant defense, • Decrease plant resistance to unsusceptible herbivores, spider mites Tetranychus urticae (Acari: Tetranychidae), in multiple, distantly related crop plants. Unintended consequences
  41. 41. Mites reared on treated foliage were extremely toxic to predators, eliciting sharp reductions in feeding, locomotion, and longevity Stethorus punctum Unintended consequences
  42. 42. Sanitation • Remove weeds in and around high tunnels Limit the use of quick-release fertilizer Aphid, Whitefly, and Thrips Cultural and Mechanical Photo credit: Galen Weston,
  43. 43. 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
  44. 44. Getting Started • Start small and start early • Pesticide Residues and when needed use soft pesticides • Good Sanitation • Weed management is critical • Clean Transplants +
  45. 45. Questions? Christopher Philips Assistant Professor Fruit and Vegetable Entomologist University of Minnesota North Central Research & Outreach Center (NCROC)
  46. 46. Questions?
  47. 47. Biology, ecology, and management of invasive species
  48. 48. Questions?
  49. 49. 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 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. The minute pirate bug will work best at a temperature of 70 to 90 degrees F and a day length of 11 hours or more.
  50. 50. 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.
  51. 51. 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%
  52. 52. 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