Drosophila suzukii

Abstract N°:
Insect-proof nets to protect cherry trees from
Drosophila suzukii and Rhagoletis cerasi
C. Weydert, G. Charlot & J-F. Mandrin
Centre Technique Interprofessionnel des Fruits et Légumes (Ctifl), 751 Chemin de Balandran – 30127 BELLEGARDE, France.
[email protected]
Drosophila suzukii M. is officially detected in France since 2010 and is now widespread in the country. It causes big damages mainly on cherry and soft fruits
(strawberry, raspberry, blackberry etc.). Its characteristics – polyphagous, capacity of quick reproduction, mobility – makes Drosophila suzukii a formidable pest.
The cheery fly (R. cerasi) and Drosophila suzukii are currently managed in France by chemical treatments, that are often not sufficient to control the pest and not
compatible with the long-term environmental and social requirements. In the framework of a national project, we have been working on sustainable methods of
protection against these two pests: alternative products (clay, push or pull products…), mass trapping, biological control (parasitoids and predators) and insectproof nets.
The insect proof net protection is currently the only one that allows producing high quality fruits and ensures a regular production.
Methods:
A new design of cherry orchards?
Which mesh of net ?
Laboratory trial (2012)
 Testing the ability of a greater range of meshes to prevent passage of D. suzukii.
 Six D. suzukii (males and females, regardless) in a clear
plastic tube covered by the tested nets.
 The tubes were placed in a clear square plastic box (10
x 10cm), in which we had a little apple cider vinegar
and water in a plastic cap.
Fig 1: Laboratory trial
 After half a day, the number of D. suzukii was observed inside and outside the tubes. At least 4 replications /net.
Row by row protection (2013/ 2014)
 Two cherry rows protected and one row without any protection as a control.
 11 different varieties under the nets and 7 different varieties without protection.
 Mesh size of the net: 6 x 8 (1.40 mm x 0.95 mm).
 Covers to protect from rain. Put on before (2012) or after flowering (2013-2014).
 Trees trained by central leader, 2.70 metres high by 2 metres wide.
At harvest, all the cherries are picked and a sample of 100 fruits per modality is taken to observe the
cherries regarding cracking and worm infestation.
Fig 3: Row by row protection
Fully-protected orchard (2012/ 2014)
The trial began in 2010, 1 year after planting (and just before the arrival of D. suzukii in France!).
Two rows, one with the variety Bellise®Bedel* and one with the variety Folfer*. In the same plot, two
rows without protection as a control.
 Mesh size of the nets : 1.38 x 1.71 mm (6 x 5) for the walls and 1.38 x 1.38 mm (6 x 6) for the top.
 Nets on the top folded from mid-December to the beginning of March to avoid damages in case of
snowfall. Bumblebees are released for the pollination.
 The trees are grafted on Gisela 6 and trained by fruiting wall.
 Hover flies (from Koppert Company) are released at the beginning of flowering to control aphids.
 All year long, record of climatic conditions, survey of D. suzukii, R. cerasi, symptoms of monilia on
flowers and fruits, aphids.
 At harvest, all the cherries are picked and three samples of 100 fruits per variety are taken to observe cherries regarding worm infestation.

Trials in orchards (2009/2013)
 Different types of net tested in an orchard
(with company Filpack).
 Varieties Fertard cov in 2011, Fertard cov and
Summit in 2012 and 2013.
 Each tree was wrapped with the net. Four replications.
 100 fruits per tree were evaluated regarding
worm infestation.
Fig 2: Trees wrapped with
different mesh size of net
Row by row protection
Results:
Number of D. suzukii through the nets
7,0
6,0
5,0
4,0
4,0
Fig 4: Fully-protected orchard
Laboratory trial
4,3
3,0
Only the mesh “6 x 9”, 1,1 mm2 completely prevents the passage of D. suzukii.
2,4
2,0
1,0
0,3
0,0
0,0
1,38 x 1,71
1,38 x 1,38
1,38 x 1,14
1,40 x 0,95
1,37 x 0,81
6x5
6x6
6x7
6x8
6x9
Fig 5: Results of the laboratory trial
Trials in orchards
The mesh of “6 x 7” was the
most efficient with no damage of D.suzukii and R. cerasi
and the meshes “6 x 5” and
“6 x 6” were quite good, with
only 2% of damage in conditions of high D. suzukii populations .
Nets
Meshes Weight Shading
(mm) (g/m2)
(%)
Control
2011
2012
2
82
21
16
0
78
0
16
/
/
/
/
6x5
1,38 x
1,71
79
6x6
1,38 x
1,38
85
18
0
1
0
0
0
2
6x7
1,38 x
1,14
93
20
/
/
0
0
0
0
Fully protected orchard
% wormy cherries (D. suzukii)
Bellise
12
17
/
/
0
0
0
2
11
10
Folfer
10
Fig 6: Results of the trial in orchards
(tree by tree protection)
8
6
6
4
2
2
2
1
0
0
0
2011
2012
2013
2014
Fig 8: Results of the fully protected orchard
The nets were very efficient against R. cerasi (only 2% damage
in 2011 because of holes in the nets) but not efficient against D.
suzukii.
Conclusions:
Protecting the trees with insect-proof nets is an expensive solution: 25 000 to
35 000€/ha for a “row by row” protection without covers and 50 000 to 60 000€/
ha if covers are added. The estimated duration of life of the nets is 8 years.
We still have a lack of knowledge on the possible side-effects of the protection by
nets, be they positive (efficacy against monilia and other pests like Cossus cossus,
Capnodis tenebrionis…) or negative (effect on the climate…). Nevertheless, it is
currently the only one that allows producing high quality fruits without a large
number of insecticides. While waiting for other sustainable – and perhaps less expensive- control methods, this type of protection could be interesting to ensure a
profitable cherry production.
Wormy
Variety Modality
cherries* (%)
Protected
Mid
6/27/2013
season Control
7/5/2013
Late Protected
season Control
0
0
36
1
2
0
74
4
* Only Drosophila suzukii
Fig 7: Wormy cherries and cracking Row by row protection—2013
Treatment frequency 2012 2013 2014
index
Fully protected orchard
1
1
2
Control
/
8
4.7
Fig 9: TFI of the fully protected orchard and the control plot
Without any treatment against R. cerasi, D. suzukii and monilia,
no treatment or few treatments against aphids, the Treatment
Frequency Index could be limited to 1 or 2 treatments per year.
Factors controlled with the current equipment
 Rhagoletis cerasi
 Craking
 Monilia (with covers put on before flowering)
 Goat moth (Cossus cossus)
 Capnodis tenebrionis
Factors currently not under control
 Drosophila suzukii
Mesh size too large!
Project 2014-2015: replacement with “6 x 8” nets (mesh size: 1,4
mm x 0,95 mm).
 Aphids (depending the year)
Hover flies releases must be improved to precise the number of hover flies needed per ha and when is the best period for release.
 Cherry doubling
In 2012, during the hottest hours of the day: +1 to +1,5°C inside the
protection compared to outside.
Project: 2014/2015: Top nets gray instead of transparent to improve
shading and lower temperature inside the protection.
Since 2013, this work has been carried out in the framework of a national project on D. suzukii ,
MINISTERE DE l’AGRICULTURE,
DE L’AGROALIMENTAIRE ET DE LA FORET
avec la contribution financière du compte
d’affectation spéciale
«Développement agricole et rural »
Cracking
(%)
Fully protected orchard
R. cerasi D. suzukii R. cerasi D. suzukii R. cerasi D. suzukii
2,21 x
3,42
10
Dates
2013
5x4
72
The Row by row protection with a mesh size of “6 x 8” (1.40 mm x
0.95 mm) was very efficient against D. suzukii in 2013 and 2014. Even
on the control plot, there was no damage of R. cerasi, but we can suppose that the efficiency would have been very good too on this pest.
In 2013 there was a low percentage of cracking on the control plot
and no cracking under the covers.
The covers could be put on before the flowering to avoid monilia on
flowers (tested in 2012) but the efficacy on this disease still have to be
confirmed and in this case bumblebees are required for pollination.
starting in 2013 for 3 years and involving 13 partners (research and experimentation).
This programm is founded by the French Ministry of Agriculture, Food and Forest.
ADIDA