1. 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

2. 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 aphid
species with non-persistent manner
• Emergence of virus strain decreasing the
quality of potato seeds PVYNTN , PVYNW

3. 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

4. PVYO
PVYNTNrec +
PVYO
PVYNTNrec
PVYNTN
PVY diversity in seed potato production
in Tunisia
95% PVYNTN

5. in the laboratory
Efficiency of transmission of 14 Vectors of PVY in Tunisia

6. 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

7. 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)

8. 1. Aphid sampling
• Aerial sampling:
– Suction trap
• Foliage sampling :
– 30 leaves every
week during the
growing season
Suction trap

9. Cap Bon
KorbaINRAT
Soliman
Aerial sampling by suction
trap, daily catches
- Population dynamic
- Frequency
- Risk of contamination
- Treatment decision
FOLLOWED APPROACHES

10. 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
Aphids/day
Thiamethoxam
Imidacloprid
Pymethrozine
Haulm
destruction

11. 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 by
1m to avoid interactions

12. Experimental station (Korba)
Detection of PVY on
200 tubers (may)
CT
TC
Evaluation of the
weight of 100 tubers
Control of
phytotoxicity

13. Treatment results on aphid
populations and PVY infection
Mean numbers of aphid colonies
PVY infections/
200tubers
Insecticides 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

14. 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

15. Comparison of potato yield in the two
treatments 1,2
33,25
29,75 30,13
26
0
5
10
15
20
25
30
35
Control Treatment1 Control Treatment 2
Potato yield (kg)
a
a
a
a

16. 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

17. 1- Aphids :
• Myzus persicae populations
2 - PVY isolates : PVYNTN on tobacco
3 – Potatoes :
• Transmission
N. tabacum Xanthi -> Potatoes
Aphid transmission in the laboratory

18. Method of transmission
2 hours
to starve 3 mn acquisition of PVYNTN
Inoculation on potato
Plants tests 3 hours
TreatmentDAS-ELISA après 15 jours
15 days
ELISA

19. Aphid feeding on infected potato and then moved
on healthy plants
coated with oil
No acquisition,
no transmission
Acquisition,
transmission
Acquisition, no
transmission
coated with oil

20. 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

21. 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

22. Future Investigations
• use of crop border
• further evaluation of the use of
biopesticides in combination with oils
• selection of resistant plant to aphids
and PVY

23. Thank you