Longhorn boll stem borer

Apricot diseases

by admin
January 29, 2024

The scientific name : Cerambyx duxfald
the family : coleoptera
Symptoms of the disease :
Leg holes
Sawdust exit.
Splitting of branches and trees, especially small ones.
The presence of multiple tunnels deep in the wood and under the bark, with more than one larvae present inside these tunnels.
Resinous materials appear at the entrances to the tunnels.

Description of the insect:

A large insect, 50 mm long, brown in colour, with clear wrinkles on its chest, and antennae longer than the body.

Caterpillar: 70 mm long, legless worm, cream colour, its head and first thoracic ring are large, and the body gradually decreases in diameter until the end of the abdomen (males have long, dark chestnut antennae; diminished nape, while females, in contrast, have antennae Short, dark purple in color; extended nape.

The virgin is free and is found near the exit hole.

The causes of disease :
Females usually choose host plants based on: tree age, bark thickness, trunk diameter (selected hosts tend to have a bark diameter of less than 10 or 5-10 cm)
Its attacks are directed against weak but not dead trees
High relative humidity and temperatures around 25 are among the main factors contributing to the severity of the infection. The injury is mild if the relative humidity is 39% or less, moderate if it is 39-47%, and severe if it is 48% or more.
The soil is poor in nutrients and lack of fertilizer, and thus the trees are weak and have little ability to resist.
Lack and irregular irrigation during the egg-laying period.

Conditions suitable for the spread of the disease :
Egg survival depends on high humidity.
Lots of rain.

Disease development cycle :

The duration of the complete life cycle is three years, including a larval period of 26 to 28 months. The number of larval stages is estimated at six.
The first months of larval activity are limited to the superficial areas of the trunk and main branches of the host, and wood penetration occurs.
– The emerging adult takes advantage of existing burrows and eventually makes his way out.
The emergence period is short (8-10 days) and may be stimulated by rain. Adult life lasts about one month. The average number of eggs laid by one female is approximately 13 eggs.

Losses of disease spread

The infestation encourages increased susceptibility to the bark mite.
It causes trees to weaken and their lifespan is greatly crushed.
It leads to significant losses in productivity

Control strategy

Preventive measures to prevent the occurrence of the disease

Paying attention to the general condition of the trees, including good pruning and sterilizing the pruning shears before pruning.
Painting trees with white lime paint when the temperature rises above 32 degrees Celsius, to reduce the effect of sunlight, which causes burns to the tree and weakens it.
Spraying trees at the time the adult insects appear with modern pesticides to eliminate the adults and small larvae before they enter the wood.
This method is more effective if there is cooperation among the farmers of the region, combined with chemical control

Chemical and organic control recommendations
Organic control: The larvae can be removed by pushing a flexible wire into the larvae's entry hole and pulling it out.
The main predator of C. dux larvae is the Zeuzera pyrina (L.) larvae.
Collect adult insects early in the morning during the activity period by shaking the branches of fruit trees so that the insects fall, are collected and burned.
When the larvae are digging the stem, half a pill of Fostoxin is used and placed in the tunnel that the larva digs. Then the digging tunnel is closed, which leads to the larvae suffocating with the toxic gases rising from the pills of Fostoxin.
Chemical control: Spray dieldrin or chlordane on the lower parts of the trunk and the surrounding soil.
Sprays of malathion, dimethoate, diazinon, chlorthion, fenthion, or trichlorfon give good results.

References

Jolles, Philipp. “A Study of the Life-history and Control of Cerambyx dux, Fald., a Pest of certain Stone-fruit Trees in Palestine.” Bulletin of Entomological Research 23.2 (1932): 251-256.

TALHOUK, AS Contribution to the knowledge of almond pests in East Mediterranean countries: III. On biology of wood-boring Coleoptera 1. Zeitschrift für Angewandte Entomologie, 1976, 80.1-4: 162-169.

Saliba, L.J. “Observations on the biology of Cerambyx dux Faldermann in the Maltese Islands.” Bulletin of Entomological Research 67.1 (1977): 107-117.