Sess08 5 boukhris bouhachem s., sellami h.,souissi r. & el fahem m. – can mineral oil protect...
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Transcript of Sess08 5 boukhris bouhachem s., sellami h.,souissi r. & el fahem m. – can mineral oil protect...
9Th Triennial Conference of APA, Kenya, June30 - July 4, 2013
Can mineral oil protect seeds against aphid transmission of Potato virus Y?
Boukhris-Bouhachem S., Sellami H., Souissi R. & El Fahem M.
GIL
Potato Seed Problem
• PVY is the most important virus on potato
• 12% of refused production
• Decrease of the yield (40%)
• PVY is transmitted by more than 70 aphidspecies with non-persistent manner
• Emergence of virus strain decreasing thequality of potato seeds PVYNTN , PVYNW
POTATO VIRUS Y (PVY)
• Famille : Potyviridae• Genre : Potyvirus• More than 30 plant hosts
• Variability of PVY
Potato isolates
PVYO PVYC PVYN
PVYNTN
PVYNW
95% PVYNTN
PVYO
PVYNTNrec + PVYO
PVYNTNrec
PVYNTN
PVY diversity in seed potato production in Tunisia
95% PVYNTN
in the laboratory
Efficiency of transmission of 14 Vectors of PVY in Tunisia
To evaluate the efficiency of the mineral oil with insecticides as preventive treatment to control Aphids and PVY infection of potato
OBJECTIVES
High quality of seeds
STEPS OF STUDY
1.Trapping of aphids
2.Treatments of potato (field)
3. Aphid acquisition and transmission of PVY with
oil coat plants (in laboratory)
1. Aphid sampling
• Aerial sampling:– Suction trap
• Foliage sampling :– 30 leaves every
week during the growing season
Suction trap
Cap Bon
KorbaINRATSoliman
Aerial sampling by suction trap, daily catches
- Population dynamic
- Frequency
- Risk of contamination
- Treatment decision
FOLLOWED APPROACHES
Aphid flight data
0
100
200
300
400
500
600
1/3 8/3 15/3
22/3
29/3 5/4 12/4
19/4
26/4 3/5 10/5
17/5
24/5
31/5
Dates
Aph
ids/
day
ThiamethoxamImidacloprid
Pymethrozine
Haulm destruction
2. EXPERIMENT1
treatment 1: insecticides only
treatment 2: insecticides + oil
• Experimental design: 4 repetitions, 3 treatments (T,I, P)
• Elementary plots: 625 m2 (5mx1000m) separated by1m to avoid interactions
Experimental station (Korba)
Detection of PVY on 200 tubers (may)
CT
TC
Evaluation of the weight of 100 tubers
Control of phytotoxicity
Treatment results on aphid populations and PVY infection
Mean numbers of aphid coloniesPVY infections/
200tubersInsecticides Thiamethoxam Imidacloprid Pymetrozine
Dates 7/4 14/4 21/4 12/5 28/4 5/5 12/10
Treatment 1a 9 6 25 27 13 31 9,5%
Control 1 b 35 43 215 50 102 103 12%
Treatment 2 a 21 9 12 26 15 34 2.5%
Control 2 b 66 52 193 79 89 158 4%
Treatments with different letter are significantly different (p=0.05, ANOVA)(+): positive samples by DAS-ELISA
Treatment reduction of aphids
0%
20%
40%
60%
80%
100%
Treatment 1 Treatment 2
Means followed by common letters are not significantly different at 5% level
Aphids
aa
Comparison of potato yield in the two treatments 1,2
33,2529,75 30,13
26
0
5
10
15
20
25
30
35
Control Treatment1 Control Treatment 2
Potato yield (kg)
a
a aa
to explore the possibility of acquisition and transmission of PVY by the most efficient vector Myzus persicae after the oil application on potato plants.
EXPERIMENT 2
1- Aphids : • Myzus persicae populations
2 - PVY isolates : PVYNTN on tobacco
3 – Potatoes :• TransmissionN. tabacum Xanthi -> Potatoes
Aphid transmission in the laboratory
Method of transmission
2 hours to starve 3 mn acquisition of PVYNTN
Inoculation on potato Plants tests 3 hours
Treatment DAS-ELISA après 15 jours
15 days
ELISA
Aphid feeding on infected potato and then moved on healthy plants
coated with oil
No acquisition,no transmission
Acquisition,transmission
Acquisition, notransmission
coated with oil
PVY infection
ELISA results after 15 days inoculation of healthy potato by M. persicae
Aphids that feed on infected potato treated with oil then sucking on healthy plants
Infected aphids
feeding on healthy plants treated with mineral oil
infected aphids
feeding on potato
healthy plants without oil treatment
Infected potato plants
0 (+)/40 0(+)/40 38 (+)/40
Conclusion
• Mineral oil is efficient to reduce PVY transmission when well coated
• No phytotoxicity observed on plqnt sprqyed with oil
• Application of oil have no negative effect on the yield
Future Investigations
• use of crop border
• further evaluation of the use ofbiopesticides in combination with oils
• selection of resistant plant to aphids and PVY
Thank you