Transcript Public PLH Ecology

‫تأثير نقص المغذيات في النباتات على سلوكيات التغذية‬
‫في قافزات األوراق‬
‫‪Effects of Nutrient Deficiency in Plants on Probing Behavior of Potato Leafhopper‬‬
‫عبدالرحمن بن سعد الداود‬
Background - Insect

Potato leafhopper, Empoasca fabae (Harris)
Background - Insect
Potato leafhopper, Empoasca fabae (Harris)
 Host plant includes 220 species in 100
genera from 26 families, including plants of
varied chemistry and morphological types
 Serious pest in two important crops in
Minnesota, alfalfa and potato
 Probing severely limits yields of both plants

Background - Alfalfa
Probing of potato leafhopper on alfalfa
causes a hypertrophy in the vascular
cambial regions that leads to crushing of
phloem sieve elements,
 Photosynthate translocation is interrupted
leading to a physiological injury termed
hopperburn

Background - Potato
On potato, symptoms of PLH probing injury
include
Paling of veins,
Curling of leaflets, and
Finally causing necrosis of tissues on edges
of leaflet.
 Necrosis is associated with accumulation of
photosynthate due to damage of phloem
tissues, this damage is termed hopperburn.

Background- Boron

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

Deficiency causes
Disintegration of cell walls and collapse of
affected tissues
Background- Nitrogen
Enhances cell elongation,
Increases foliage growth, and
Increases yield by increasing tuber numbers
 May alter
Physiology, morphology, and microclimate
of plants and subsequently affect survival of
insect herbivores

Background - Monitoring
One way to manage pests is to modify
favorable habitat in a way that provide less
adequate environments, by providing
unsuitable sources of food
 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
Duration and number of events of probing
waveforms, especially Ia, could be used as
an indication of the degree of probinginduced injury that occurs on host plants
 Therefore, probing behavior of female
potato leafhopper adults on alfalfa and
potato plants maintained at different
nutrient levels were quantified

Material & Methods
Female potato leafhopper adults (3-7 d old)
 Alfalfa, cv. 'Arrow'
 Potato, cv. 'Russet Burbank’
 The Missouri AC electronic monitoring
system
 Chart recorder
 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
Table 1.1 Number of probes by potato leafhopper on alfalfa maintained at 3
different nutrient levels
Parameter
Mean per insect
Complete
No. probes per 2 h
Boron
Calcium
21.4  2.8 A
29.1  4.5 A
18.6  2.8 A
(n = 30)
(n = 30)
(n = 30)
Results - Boron and Calcium Deficit
Table 1.3 Mean duration of probing, waveforms (summed within probes), and
waveform events, by potato leafhopper on alfalfa maintained at 3 different nutrient
levels
Parameter
Mean duration (min) per 2 h
Complete
Boron
Calcium
Probing duration per insect
77.5  4.2 A
74.9  5.9 A
74.5  5.5 A
(n = 30)
(n = 30)
(n = 30)
Waveform duration per insect, per type
Ia
44.3  3.7 A
50.9  5.8 A
37.9  4.9 A
(n = 30)
(n = 30)
(n = 29)
Ic
31.9  2.4 A
20.8  3.0 B
38.1  4.7 A
(n = 30)
(n = 30)
(n = 30)
Conclusion- Boron and Calcium Deficit

In our study, nutrient deficit appeared to
induce a probing behavior shift from
multiple cell laceration (Ia) on borondeficient plants to the presumably less
injurious behavior of Fluid probing (Ic)
predominant on calcium-deficient plants
Probing Behavior of Potato Leafhopper on
Potato Influenced by Plant Nitrogen Content
Results - Plant Nitrogen Content
Table 2.1 Number of probes by potato leafhopper on potato maintained at 4
nitrogen levels
Parameter
100% N
Mean per insect
30.2  4.7A
(n = 37)
No. probes per 2 h
20% N
10% N
28.2  5.7A
(n = 26)
30.3  6.2A
(n = 29)
0% N
22.1  4.1A
(n = 24)
Results - Plant Nitrogen Content
Table 2.2 Mean duration of probing, waveforms (summed within probes), and
waveform events, by potato leafhopper on potato maintained at 4 nitrogen levels
Parameter
100% N
Mean duration (min) per 2 h
20% N
10% N
0% N
Probing duration per insect
52.3  4.5A
(n = 37)
55.7  6.3A
(n = 26)
72.5  5.5AB
(n = 29)
83.1  6.6B
(n = 24)
Waveform duration per insect per type
Ia
19.9  3.4A
(n = 37)
18.9  3.3A
(n = 25)
25.7  5.8A
(n = 29)
20.2  4.8A
(n = 24)
Ic
17.6  2.6A
(n = 36)
20.3  4.6A
(n = 25)
20.6  3.5A
(n = 26)
41.4  6.2B
(n = 24)
Results - Plant Nitrogen Content
Table 2.3 Shoot height of potato plants maintained at 4 nitrogen levels
Parameter
Shoot
100% N
Dimensions (cm)
20% N
10% N
5.8  0.4A
(n = 37)
4.9  0.4AB
(n = 26)
4.7  0.3B
(n = 29)
0% N
1.9  0.2C
(n = 24)
Conclusion - Plant Nitrogen Content


0% N treatment results in a shift in probing
behavior from a multiple cell laceration (Ia) to an
increased direct or indirect phloem ingestion (Ic),
the latter being a behavior that is less injurious to
the plant
Phloem ingestion (Ic) 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
Table 3.1 Number of probes by potato leafhopper on top, middle, and bottom
leaves of potato plant
Parameter
Mean per insect
Top
No. probes per 2 h
Middle
Bottom
7.5  1.6A
13.4  2.9A
24.4  4.7B
(n = 20)
(n = 20)
(n = 20)
Results - Leaf Locations on Potato
Table 3.3 Mean duration of probing, waveforms, and waveform events, by
potato leafhopper on top, middle, and bottom leaves of potato plant
Parameter a
Top
Mean duration (min) per 2 h
Middle
Bottom
Probing duration per insect
42.6  6.9A
36.3  4.9A
57.9  7.6B
(n = 20)
(n = 20)
(n = 20)
Waveform duration per insect per type b
Ia
6.4  1.8A
11.1  2.6A
20.3  4.8B
(n = 20)
(n = 20)
(n = 20)
Ib
12.3  3.7A
14.2  3.01A
16.8  8.2A
(n = 9)
(n = 14)
(n = 12)
Ic
23.9  5.3A
12.5  2.1A
19.8  2.8A
(n = 19)
(n = 19)
(n = 20)
Conclusion - Leaf Locations on Potato


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
Probing behavior of potato leafhoppers was
altered on potato due to leaf position
Finally!



In These experiments, it was shown that varying
the levels of nutrients had some significant effects
on probing behavior of potato leafhopper
Future research may show that nutrient
management can be used to reduce the injury
causing potential of potato leafhopper
Increased consumption of the lower protein diets
was achieved by eating the same size meals more
frequent
Finally! (cont.)


Duration and occurrence of Ia and Ic can be
indictors of probing preference of potato
leafhoppers
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