Empoasca fabae

Empoasca fabae belongs to family Cicadellidae and genus Empoasca within order Hemiptera.[1] They are more commonly referred to as the potato leafhopper.[1] In North America they are a serious agricultural pest.[2] Every year millions of dollars are lost from reduced crop yields and on pest management.[3] Crops that are impacted the most are potatoes, clover, beans, apples and alfalfa .[4]

Empoasca fabae
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hemiptera
Family: Cicadellidae
Genus: Empoasca
Species: E. fabae
Binomial name
Empoasca fabae

Appearance

Adults have pale to iridescent green bodies with 6 or 8 white spots on their pronotum.[4] They have a distinctive white H shape mark between their head and wing base.[5] Their bodies are approximately 3 mm long and have on their front wings near its tip a crossvein.[4] Adults and nymphs move by hopping among host plants.[5] However, only adults can fly.[6]

Appearance of a closely related species from family Cicadellidae genusEmpoasca.

Diet

They are able to feed and reproduce on at least 200 different plant species across twenty-six families.[1] In total herb genera represents 64% of their hosts .[7] Adults prefer to feed on the leaves and stems, while the nymphs prefer the leaves .[8] Their specialized mouth parts are able to pierce into the plant tissue and remove its sap.[9] The ability to inhabit a wide range of hosts, is due to the variation in their feeding behaviors .[10]

Migration

Empoasca fabae is a seasonal migration species.[11] If they are flying at night, it takes two or three days to reach their summer destinations.[12] Research suggests that they are using winds as a passive means to help migrate.[11] The direction of the winds influence their distribution within their summer range.[11] Typically, the winds blow in a north-northeast direction towards Northern and Midwest United States.[11] Factors such as warm temperatures and lack of Precipitation increases their range .[12] Cold temperatures, major precipitation, and unsuitable environmental conditions are factors that will stop migration to continue more north .[12] In late summer, cold fronts start to appear sending cues for them to leave.[11] As they leave they get caught up in these fronts which carry them south to southwest to their overwintering range.[11]

Habitat and Range

Winter

Due to their inability to tolerate the cold winter temperatures they must migrate south.[11] Adults overwinter on hosts in the pine and mixed hardwood forests along the Gulf of Mexico and in the Southern United States.[13] Eastern Texas and Oklahoma, Virginia, Louisiana, Florida, Georgia, South and North Carolina, Alabama, Tennessee, Arkansas, and Mississippi, have documented populations. .[13] Before migrating back to their summer range they change their hosts to herbaceous legumes then to new spring foliage of deciduous trees .[13]

Summer

Their summer range extends across the Midwest and eastern parts of Canada and the United States.[14] In Canada, they are found only in the Great Lakes region .[11] They are able to inhabit a wide range of habitats.[10] Only about 32% of individuals actually occupies croplands.[10] The remaining individuals will reside in fields, woodlands, scrublands, waste places, and parks.[10] Precipitation will deposit individuals upon plant hosts where they will quickly re-establish themselves .[15]

Development and Reproduction

Dispause

Before migrating they mate and enter reproductive diapause.[13] Empoasca fabae begin to enter into reproductive dispause at the end of July.[16] The entire population remains in this state for its migration and overwintering period .[13] This diapause period ends from mid-January through February, and they begin to sexually mature .[13]

Egg laying

During the spring migration north the majority of the individuals are females.[17] When they return if temperatures are above 10 °C they can start oviposition and populations grow and re-establish themselves.[18] Empoasca fabae arrives back to their summer ranges during April or early May depending on the location.[19]

During the summer months they can, on average, lay eggs over a span of 96 days.[20] Peak population densities occur during late May to late June.[9] Many overlapping generations appear.[9] After this their population densities begin to decline slowly.[19] Individuals have a tendency to aggregate as their populations increase.[19] At the end of the summer, individuals either die or migrate south.[21]

Eggs and hatchlings

Eggs are laid on their hosts, they are transparent and small in size.[5] Every day females will lay 2 or 3 eggs a day on the plant’s stem and leaf veins .[22] The egg’s incubation period ranges from 4 through 23 days, the hatchings are called nymphs.[20] New hatchlings are white in colour and develop their green colouring as they age.[20] The nymphs undergo five instars before becoming adults.[17] As they develop, they lose their skin and develop their wings.[5] Empoasca fabae develops into adults in 8 through 37 days. [20] Their entire lifecycle is a month long.[22]

As a Pest

Hopperburn

Hopperburn in plants is caused by E. fabae's feeding on its hosts .[17] As they feed their saliva mechanically injures the phloem and parenchyma cells .[2] The plant also suffers damage to its vascular cambium, and to its vascular bundles .[17] Within 24 hours of being infested, rates of photosynthesis,and transpiration are reduced, leaves accumulate starch, and transport of photoassimilates are reduced .[7]

The first symptoms of hopperburn is that a leaflet's margins start to curl up.[7] As a plant's infestation increases, its leaves cup downward, and they start to turn from green to yellow.[23] In severe infestations this leads to leaf necrosis in which the leaf margins and intervein areas turn brown.[23] Older plants completely lose their leaves.[24] Young plants display tip-wilting and will be stunted in height.[24] Plants that were damaged by stem feeding suffered more damage to their physiologies than those which were damaged by leaf eating .[8]

Research has shown that water stressed plants increase nymph's development time.[6] This causes severe hopperburn due to the increase plant stress response.[22]

Economic Impacts

Hopperburn leads to reduced plant growth and reproduction .[25] In some heavily infested fields up to 75% of the yield is lost, it depends on what stage of development the plants are in .[14] Obviously, this leads to reductions in crop yields and large economic losses.[25] For example in 1988 the losses of alfalfa crops in Northeast United states ranged from $32-$66 per hectare.[26] The amount of crop damage is directly proportional to the population density.[14] Most crop damage comes from the future generations of the initial arrivals back to the summer range.[12]

Climate Change

Research has indicated that over the last 62 years they have been arriving back to their summer range earlier by ten days.[27] Warmer temperatures increases the time and speed of egg hatching and nymph development.[18] There is increasing concern that climate change will shift the overwintering and summer ranges more northward.[27] This will exacerbate the problem of pest management and increase economic losses. .[27]

Pest Management

Usually, crop detection of E. fabae is too late as hopperburn is the first visual symptom of a major infestation.[22] Regular crop inspections with a sweep net are essential to help reduce massive economic losses.[22] Another visual cue is the death of leaves with small pits holes throughout them resulting from their eggs.[5] Host expansion is likely caused from the loss of natural resistance through extensive plant breeding.[1]

Currently, the only effective method that exists for controlling E. fabae's infestations is the heavy application of insecticides.[14] Short-lived insecticides such as carbaryl are commonly used; however they require costly reapplications.[15]

Research is indicating the possibility of being able to control populations by increasing E. fabae's natural enemies as part of pest management plan.[28] Percent mortality has been shown to be highest in individuals in younger instars.[16] Research has shown that natural resistance and pesticide use are just as effective, but neither is capable to fully contain populations.[29] To create more effective management programs and reduce pesticide use it’s essential to understand their dispersion, temporal and spatial patterns.[19]

References

  1. 1 2 3 4 ”Lamp, W., D., Miranda, L., Culler & Alexander, L. (2011) “Host Suitability and Gas Exchange Response of Grapevines to Potato Leafhopper (Hemiptera: Cicadellidae)”. Journal of Economic Entomology 104 (4): 1316-1322.
  2. 1 2 ”Delay, B., P, Mamidala, A, Wijeratne., S, Wijerante, O, Mittapalli, J, Wang., and Lamp, W. (2012). “Transcriptome analysis of the salivary glands of potato leafhopper, Empoasca fabae”. Journal of Insect Physiology 58 (12): 1626-1634.
  3. ↑ ”., M, Serrano., & Ranger, C. (2005). “Mechanisms of Hopperburn: An Overview of Insect Taxonomy, Behavior, and Physiology.” Annual Review of Entomology 50(1): 125-151..
  4. 1 2 3 "Bland R.G., Jaques H.E. (2010). How to Know the Insects 3rd Edition. Waveland Press Inc. p.163.
  5. 1 2 3 4 5 ”Dudley, J. (1921). “The Potato Leafhopper and its control”. United States Department of Agriculture: Farmers Bulletin 1225, 1-16..
  6. 1 2 ” Hoffman, G., D, Hogg, & Boush, M. (1991). “Potato Leafhopper (Homoptera: Cicadellidae) Life History Traits on Water-Stressed Alfalfa in the Early Regrowth and Bud Stage”. Environmental Entomology 20(4): 10581066 .
  7. 1 2 3 ” Lamp, W., Nielsen, G., Fuentes, C., & Quebedeaux, B. (2004) “Feeding Site Preference of Potato Leafhopper (Homoptera: Cicadellidae) on Alfalfa and its Effect on Photosynthesis”. Journal of Agricultural and Urban Entomology 21 (1): 25-38
  8. 1 2 ”Lamp, W., Nielsen, G., Fuentes, C., & Quebedeaux, B. (2004) “Feeding Site Preference of Potato Leafhopper (Homoptera: Cicadellidae) on Alfalfa and its Effect on Photosynthesis”. Journal of Agricultural and Urban Entomology 21 (1): 25-38
  9. 1 2 3 ”Potter, D., & Spicer, P. (1993). “Seasonal Phenology, Management, and Host Preferences of Potato Leafhopper on Nursery-Grown Maples” Journal of Environmental Horticulture 11(3): 101-106..
  10. 1 2 3 4 ” Lamp, W., G, Nielson., & Danielson, S. (1994). “Patterns among Host Plants of Potato Leafhopper, Empoasca fabae (Homoptera: Cicadellidae.” Journal of the Kansas Entomological Society 67(4): 354-368.
  11. 1 2 3 4 5 6 7 8 "Taylor, R., & Reling, D. (1986). Preferred Wind Direction of Long-Distance Leafhopper (Empoasca fabae) Migrants and its Relevance to the Return Migration of Small Insects. Journal of Animal Ecology 55(3): 1103-1114.
  12. 1 2 3 4 ”Carlson, J., M, Whalon., D, Landis., & Gage, S. ( 1992). “Springtime weather patterns coincident with long-distance migration of potato leafhopper into Michigan.” Agricultural and Forest Meteorology 59(3-4): 183-206
  13. 1 2 3 4 5 6 ”Taylor, P., & Sheilds, E. (1995). “Phenology of Empoasca fabae (Harris) (Homoptera: Cicadellidae) in its Overwintering Area and Proposed Seasonal Phenology”. Environmental Entomology 24 (5): 1096-1108.
  14. 1 2 3 4 ”Medeiros, A., W, Tingey., & De Jong, W. (2004). “Mechanisms of Resistance to Potato Leafhopper, Empoasca fabae (Harris), in Potato”. American Journal of Potato Research 81(6): 431-441..
  15. 1 2 ”Van Timmeren, S., J, Wise, C, Vandervoort., & Isaacs, R. (2011). “Comparison of foliar and soil formulations of neonicotinoid insecticides for control of potato leafhopper, Empoasca fabae (Homoptera: Cicadellidae), in wine grapes.” Pest Management Science 67(5): 560-567.
  16. 1 2 ” Erlandson, W., & Obrycki, J. (2015). “Population Dynamics of Empoasca fabae (Hemiptera: Cicadellidae) in Central Iowa Alfalfa Fields.” Journal of Insect Science 15(1): 1-6.
  17. 1 2 3 4 ”Maletta, M., M, Henninger, & Holmstrom, K. (2006). “Potato Leafhopper Control and Plastic Mulch Culture in Organic Potato Production”. HortTechnology 16 (2): 199-204.
  18. 1 2 ”Sidumo, A., E, Sheilds., & Lembo, A. (2005). “Estimating the Potato Leafhopper Empoasca fabae (Homoptera: Cicadellidae) Overwintering Range and Spring Premigrant Development by Using Geographic Information System.” Journal of Economic Entomology 98 (3): 757-764.
  19. 1 2 3 4 ”Bentz, J., & Townsend, A. (2004). “Spatial and temporal patterns of abundance of the potato leafhopper among red maples.” Annals of Applied Biology 145(2): 157-164. .
  20. 1 2 3 4 ”Poos, F. (1932). “Biology of the Potato Leafhopper, Empoasca Fabae (Harris), and Some Closely Related Species of Empoasca.” Journal of Economic Entomology 25(3): 639-646.
  21. ↑ ”Taylor, P., E, Sheilds., M, Tauber., & Tauber, C. (1995). “Induction of Reproductive Diapause in Empoasca fabae (Homoptera: Cicadellidae) and Its Implications Regarding Southward Migration”. Environment Entomology 24 (5): 1086-1095.
  22. 1 2 3 4 5 ”Townsend, L. (2012). “Potato Leafhoppers.” University of Kentucky. Version 2012.2. ENT facts http://www2.ca.uky.edu/entomology/entfacts/ef115.asp Retrieved 28 November 2015
  23. 1 2 "Murray, J., M, Paul., & Schaafma, A. (2001) “Determination of traits associated with leafhopper (Empoasca fabae and Empoasca kraemeri) resistance and dissection of leafhopper damage symptoms in the common bean (Phaseolus vulgaris)”. Annals of Applied Biology. 139(3): 319-327.
  24. 1 2 ” Backus, E., M, Serrano., & Ranger, C. (2005). “Mechanisms of Hopperburn: An Overview of Insect Taxonomy, Behavior, and Physiology.” Annual Review of Entomology 50(1): 125-151.
  25. 1 2 " Backus, E., M, Serrano., & Ranger, C. (2005). “Mechanisms of Hopperburn: An Overview of Insect Taxonomy, Behavior, and Physiology.” Annual Review of Entomology 50(1): 125-151.
  26. ↑ Lamp,W., Nielsen, G., & Dively, G. (1991)“Insect Pest-Induced Losses in Alfalfa: Patterns in Maryland and Implications for Management.” Journal of Economic Entomology 84(2): 610-618..
  27. 1 2 3 ” Baker, M., P, Venugopal., & Lamp, W. (2015). “Climate Change and Phenology: Empoasca fabae (Hemiptera: Cicadellidae) Migration and Severity of Impact”. Plos One 10 (5): 1-12
  28. ↑ ”Erlandson, W., & Obrycki, J. (2010). “Predation of Immature and Adult Empoasca fabae (Harris) (Hemiptera: Cicadellidae) by Three Species of Predatory Insects.” Journal of the Kansas Entomological Society 83(1): 1-6.
  29. ↑ Ghidiu, G., D, Douches., K, Flecher., & Coombs, J. (2011). “Comparing Host Plant Resistance, Engineered Resistance, and Insecticide Treatment for Control of Colorado Potato Beetle and Potato Leafhopper in Potatoes.” International Journal of Agronomy 11(6): 516-523
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