The olive fly: how to defend yourself

The olive fly ( Bactrocera Dacus oleae ) This is one of main phytophagous that attack the olive grove and it is the insect that causes the most damage and therefore represents the main obstacle to the income of those who produce oil or table olives.

We found this fly present throughout the Mediterranean basin is a parasite extremely polyphagous also attacks several plants of the genus Olea, whose presence in several Asian and African regions has allowed its spread also in non-European regions.

In the next article, we learn how to recognize the fly Yes identify the damage it causes to olives explaining how to fight it with biological methods . To avoid pesticides, the use of traps and prevention is particularly interesting.

Contents [Ocultar]

  • How to recognize the olive fly

  • The life cycle of the fly

    • Oil fly damage

  • Fight this fly

    • Prevent the insect

    • Deterrent treatments

    • Insecticides and traps

  • More information and bibliography on dacus oleae


How to recognize the olive fly

The olive fly belongs to the Diptera family. , as are the fruit fly and the cherry fly. It differs from the latter by a few morphological characteristics: the adult olive fly is one of the least visible insects of the family. Although the insect looks a bit like the other diptera, it is not difficult to distinguish the fly from other enemies of the olive grove such as the mealy bug and the olive moth.

Have a wingspan of about 12 mm with a small dull spot barely visible at the wingtip. The body of the insect is distinguished by its extremely colorful reflections.

the food which develops inside the pulp of the drupes of the olive tree, reaches a length of 7 to 9 mm at maturity.

fly life cycle

The population dynamics of the olive fly is strongly influenced by certain climatic factors, Dacus oleae is present in all Italian olive-growing regions .

The adults of the oil fly are very low temperature resistant and rather long term in the northern olive-growing regions, despite the harsh climate, they manage to survive the winter. (thixag_12) In the north (thixag_12) the fly in general (thixag_12) makes three generations a year (thixag_12), when the spring rains and humidity cause the drupes to swell, combined with the high fertility of adult females, the dynamics of population increases dramatically.

In the olive-growing regions of the south , where the winter temperatures are quite mild, the pupae manage to survive the season, and the olive fly can prolong the breeding period. In southern Italy it is very common to leave unpicked olives on the tree, there is also a massive presence of wild olive trees, also a host plant for the insect. These two factors favor, although more slowly, the continuation of reproduction, also reaching six generations in the year. .

The olives are beaten when they reach the size a chickpea Infestations that are not sufficiently controlled continue to worsen during the autumn period, when the percentage of infested olives can reach just under 100%.

Oil fly damage

spawn Diptera usually take place after a few test bites, as the adult females proceed to check the olive’s suitability to receive their eggs. Normally only one egg is laid per drupe . Newly hatched larvae they dig tunnels inside the olive tree then escape to pupate in the ground. The damage caused to the olives is enormous. They usually dry out and fall off before reaching maturity, thus compromising the olive harvest.

If the attack takes place during the growth period of the fruit, this it rots and therefore becomes non-marketable in the case of table olives. In the case of oil olives poor quality oil is obtained due to its high acidity, due to oil fly damage.

Compare this dipteran

When it comes to control, you can choose to intervene at different levels. Prevention is carried out by avoiding the creation of favorable conditions for the fly, then deterrent treatments such as kaolin and Bordeaux mixture can be carried out, or the capture can be directed.

Prevent the insect

In organic farming, oil fly control aims to reduce damage, reduce losses in terms of productivity and income below an acceptable threshold. Even without pesticide treatments in an agroecosystem under balanced conditions, natural enemies, associated with high temperatures and low humidity, contribute to limiting the proliferation of this pest. In this case, no intervention is therefore necessary to kill the insects, but the focus is on prevention .

balanced size It is very effective in preventive defense, with the aim of aerating the foliage. In the case of irrigated olive groves, preference should be given to methods that avoid wetting the leaves always because the humidity is favorable to the fly.

Deterrent treatments

If prevention is not enough, kaolin, copper salts and Bordeaux puree can be effective methods to deter the oil fly. These substances are also often used to combat various diseases of the olive tree and also have an effect on the presence of the fly. In this case, the effect is to deter egg-laying by the female, caused by the presence of substance in the drupes which acts as a physical barrier .

Regarding copper treatments, due to the impact of the metal on the environment, the doses of 4 kg of copper active ingredient per year and per hectare must not be exceeded (limit updated in the legislation in January 2019) ; it is obvious that kaolin is not subject to this limitation.

Insecticides and traps

In an organic crop, synthetic chemical insecticides are not allowed, to save the bees it is good to be very careful to also intervene with treatments of natural origin aimed at poisoning the fly and not very selective (such as pyrethrum or spinosad). In any case, it is always advisable Attention to the population and only use these techniques when the damage threshold is high and involves a considerable loss of income.

For this reason, the technique of mass capture or attraction and death is widely used in organic farming , which is carried out through devices that attract individuals. attraction can be reached with pheromones That is food substances (proteins, ammonium salts, sugary substances), the common goal is to attract adults, who remain trapped.

Pheromone traps use sex bait, while food traps with sugar or protein baits are usually simpler and cheaper , affordable even for inexperienced olive growers and also suitable for small olive groves or trees kept in the garden for ornamental purposes. Are included in this category Tap Trap and Glass Trap to be filled with food bait based on ammonia and raw fish, very easy to prepare at home.

More information and bibliography on dacus oleae

For those who want to learn more about the olive fly, we recommend the book » agricultural entomology by Zangheri-Masutti, a reference manual on crop pests. As for the capture, a bulletin from the Edmund Mach Foundation is very interesting, in which the periods of greatest insect capture are represented in the form of graphs.

Those who want to continue reading about the Orto Da Coltivare can find more information about the Tap Trap in the dedicated article, where you can also find prescriptions with doses of bait. Also in OdC you will find an overview of the different insect enemies of the olive tree and a general guide on how to manage the cultivation of this tree organically.

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