Towards a solution to protect endangered mangoes productions in Réunion ?

ALPHATEX, in collaboration with the company HORTIBEL, is currently working to find a solution in the fight against the fruit fly on mango trees, which is currently taking place in Reunion Island.

Alphatex is specialized in arboriculture and horticulture nettings. We offer high quality insect nets to protect crops.
Hortibel is a Reunionese company which supplies agricultural producers from this region.

ALPHATEX

The fruit fly causes losses for mango producers in Reunion Island

Following various observations, we can conclude that :

The presence of the fruit fly has a strong impact on the harvest of fruits suitable for consumption, it even divides by 5 the quantity of mangoes that can be sent to the sales network.

1. More precisely, these fruit flies are : BACTROCERA ZONATA, CERATITIS CAPITATA and BACTROCERA DORSALIS.

Mango producers manage their crops :

• Without any biological treatments against fruit flies.
• With biocontrols such as pheromones, augmentarium (a tool that was put at the disposal of Reunionese producers to fight against fruit flies), talc…
• With little to no tree pruning

Producers don’t use chemical solutions and most importly, they are not willing to. ALPHATEX and HORTIBEL have decided to study a mechanical method in order to support existing tools. Therefore, we tried to use nettings to protect mango trees.

Under certains conditions, the Biotex 800 insect screen can prevent fruit flies from deteriorating mangoes.

The Biotex 800 net against fruit fly, an example with a Reunionese producer

The Biotex netting has great characteristics which can solve mangoes producers’ problems. This net is :

• Narrow enough to prevent fruit flies from going through.
• Ventilated enough to lower climatic effects on trees.
• Very light and easy to set, so it does nor crush trees.
• Available in large dimensions, to provide a large area of coverage.

Test carried out in December 2020

The nets were placed on mango trees. The Heidi variety was chosen because its mangoes are very sensitive to the fruit fly. This variety, unlike the JOSE variety, doesn’t have dried flower stems from the previous year that present a risk and could tear the net.

These trees height does not exceed 3.5 metres. The netting was put on trees when its fruits were still green.

The producer did this test with three replicates :

1st replicate

The net was put in place December 8th, 2020 and mangoes were harvested January, 10th 2021.

Results :

• The producer was able to harvest every Heidi mangoes.
• There were no mangoes bitten by the fly.

2nd replicate

This one was a control row, without any net.

Results :

• Not a lot of mangoes were harvested (around 30%).
• Most of mangoes were bitten by fruits flies.

3rd replicate

The net was put in place on December 8th, 2020 and mangoes were harvested around the 10th of January.

Results :

• Every Heidi mangoes were harvested.
• There were no mangoes bitten by flies.

Fighting against fruit flies in Reunion Island thanks to the Biotex net : results of the experiment

Nets characteristics

As you can see on the pictures of this study, nets are wide and not very stretched between the trees :

• For a better wind and rain resistance
• To make the installation easier

The producer’s working method

The producer had to adapt his working method to be able to use Biotex nets in his orchards :

• The land was cleared before putting the net, in order to prevent it from tearing apart. The land will be cleared again when the net is removed.
• The handle of the fruit picker has been shortened for an easy handling under the net.
• The fruit transport crates were all placed under the net just before harvesting to avoid repeated lifting of the net.

Optimization

There are still some elements that need optimizations for the use of nets on this type of production.

• Plans for the installation and the removal of the BIOTEX net.
• Nets dimensions to best meet the needs of the market.
• Define the optimal tree size in order to put and remove Biotex net easily.
• Nets management in cases of strong winds.

It should be noted that this net could also be used against longicorn. However, this use remains to be tested.

BIOTEX 800 STOP flea

Material: PEHD
Weight: 50g / m²
Construction: Knitted Mono filament
Ultra-violet resistance: 320 Kly (3 to 4 seasons)
Shading: 10%
Windbreak effect: 44%
Permeability to water (sprinkling): flat 95% – on hoops 85%

More info

If you supply producers who have issues with fruit flies in their mango crops, you can contact us. We’ll gladly help you to find a way to solve this problem. To contact us :

• Mail : alphatex@alphatex.eu
• Phone : +33 (0)2 35 56 33 56

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