تأثير نقص المغذيات في النباتات على سلوكيات التغذية في قافزات الأوراق Effects of Nutrient Deficiency in Plants on Probing Behavior of Potato Leafhopper عبدالرحمن بن سعد الداود

Background - Insect n Potato leafhopper, Empoasca fabae (Harris)

Background - Insect n Potato leafhopper, Empoasca fabae (Harris) n Host plant includes 220 species in 100 genera from 26 families, including plants of varied chemistry and morphological types n Serious pest in two important crops in Minnesota, alfalfa and potato n Probing severely limits yields of both plants

Background - Alfalfa n Probing of potato leafhopper on alfalfa causes a hypertrophy in the vascular cambial regions that leads to crushing of phloem sieve elements, n Photosynthate translocation is interrupted leading to a physiological injury termed hopperburn

Background - Potato n On potato, symptoms of PLH probing injury include Paling of veins, Curling of leaflets, and Finally causing necrosis of tissues on edges of leaflet. n Necrosis is associated with accumulation of photosynthate due to damage of phloem tissues, this damage is termed hopperburn.

Background- Boron n Deficiency symptoms result in: Abnormalities in cell walls, Increase in cell wall thickening, Stunting of upper parts of plant, and Loss of yield

Background- Calcium n Deficiency causes Disintegration of cell walls and collapse of affected tissues

Background- Nitrogen n Enhances cell elongation, Increases foliage growth, and Increases yield by increasing tuber numbers n May alter Physiology, morphology, and microclimate of plants and subsequently affect survival of insect herbivores

Background - Monitoring n One way to manage pests is to modify favorable habitat in a way that provide less adequate environments, by providing unsuitable sources of food n Visual observation of PLH on plants does not reveal probing behavior occurring or suggest the extent of plant tissue injury. Electronic feeding monitor permits the distinguish of these probing behaviors

Objective n Duration and number of events of probing waveforms, especially I a, could be used as an indication of the degree of probing- induced injury that occurs on host plants n Therefore, probing behavior of female potato leafhopper adults on alfalfa and potato plants maintained at different nutrient levels were quantified

Material & Methods n Female potato leafhopper adults (3-7 d old) n Alfalfa, cv. 'Arrow' n Potato, cv. 'Russet Burbank’ n The Missouri AC electronic monitoring system n Chart recorder n Then, probing behavior of each insect was recorded for two hours

Material & Methods - Waveforms Waveform event: A period of time within a probe during which a single, uninterrupted waveform type is exhibited.

Probing Behavior of Potato Leafhopper on Alfalfa Influenced by Boron and Calcium Deficit

Results - Boron and Calcium Deficit

Conclusion- Boron and Calcium Deficit n In our study, nutrient deficit appeared to induce a probing behavior shift from multiple cell laceration (I a ) on boron- deficient plants to the presumably less injurious behavior of Fluid probing (I c ) predominant on calcium-deficient plants

Probing Behavior of Potato Leafhopper on Potato Influenced by Plant Nitrogen Content

Results - Plant Nitrogen Content

Conclusion - Plant Nitrogen Content n 0% N treatment results in a shift in probing behavior from a multiple cell laceration (I a ) to an increased direct or indirect phloem ingestion (I c ), the latter being a behavior that is less injurious to the plant n Phloem ingestion (I c ) involves less salivation, accordingly inducing fewer cell abnormalities and less hopperburn

Probing Behavior of Potato Leafhopper on Different Leaf Locations on Potato

Results - Leaf Locations on Potato

Conclusion - Leaf Locations on Potato n Potato leafhoppers on bottom leaves probed for significantly longer amount of time compared to middle and top leaves. This was due to the increase in duration of most waveform types n Probing behavior of potato leafhoppers was altered on potato due to leaf position

Finally! n In These experiments, it was shown that varying the levels of nutrients had some significant effects on probing behavior of potato leafhopper n Future research may show that nutrient management can be used to reduce the injury causing potential of potato leafhopper n Increased consumption of the lower protein diets was achieved by eating the same size meals more frequent

Finally! (cont.) n Duration and occurrence of I a and I c can be indictors of probing preference of potato leafhoppers n Moderate duration of both waveforms seem to indicate the preferred host. Our experiment support the previous finding that potato leafhopper prefer to probe on middle leaves of potato, hence a balance level of nitrogen content