Diocalandra Frumenti - a serious threat to Palm Trees.
Diocalandra frumenti is a small caterpillar (about 5 mm) that was discovered for the first time in the Canaries in 1998. It then proliferated to Fuerteventura, Lanzarote and more recently in Tenerife. This caterpillar is a serious threat to some palm trees. In order to avoid its proliferation the la Consejería de Agricultura, Ganadería, Pesca y Alimentación has published an Order on 29/10/2007 which includes rules to control its development.
This animal has been detected primarily in Cocos nucifera, Phoenix dactylifera, Phoenix canariensis y Elaeis guineensis. Guest Plants.
There is little known about the biology of Diocalandra but the climatic conditions of the Canaries allow the animal to breed without interruption during the entire year. The full cycle (egg-adult) takes 2-3 months during which it passes 4 phases: egg, larvae, pupa and adult.
The egg has an oval form and a bright semi-transparent colour and is not easy to detect as it only measures 1mm. They are deposited separately.
The larvae have a yellowish colour, without legs, segmented and with a hard head. At the end of this phase, after 8-10 weeks, the larvae can measure 6-8mm. The larvae feed themselves with the vegetal interior of the palm tree, forming galleries and cause by this the severe damage to the tree.
After that the pupa is formed in these galleries and it takes about 10-12 days to transform.
The adults measure 6-8mm, are dark and do have 4 lighter spots on the back. Damage Symptoms caused by the Diocalandra Frumenti
The larvae of Diocalandra Frumenti eat their way through roots, flowers, fruits and leaves, creating galleries. Normally one can discover a gummy-like excretion at the entrance of the galleries. The action of the larvae is the major cause of the yellowing and dropping of the palm leaves. A very typical symptom of their presence is called "Clorosis" and is the yellowing and even whitening of young leaves. Also D. Frumenti can cause secondary damages like fungal growth (Gliocladium vermoesenii y Thielaviopsis paradoxa) Behaviour of Diocalandra Frumenti Fabricius
When cutting green palm leaves these emit a volatile substance (Kairomonas) that some insects can detect and allow them to localise the future guest. Due to the severe damages the Red Caterpillar and the Diocalandra can cause, the cutting of green leaves is only authorized when unavoidable and by previous permission through the competent administration. The application of oil-based paint or applying mastic on the cuts and immediately after the cutting significantly reduces the emission of these Kairomonas and thus the attraction of the insects to the cut. It is immediately after the cutting that the insects drop their eggs into the wound and therefore it is the best moment to treat the palm trees with protective chemicals to kill the adults. Control of Diocalandra Frumenti THE CUTTING OF GREEN LEAVES IS ONLY ADMITTED IN STRICTLY SPECIFIED OCCASIONS! BEFORE CUTTING: REQUEST OFFICIAL PERMISSION AT THE RELEVANT OFFICE IMMEDIATELY AFTER CUTTING:
- painting of the cutting with oil-based products as recommended