INTERVIEW ABOUT THE PINE PROCESSIONARY ON “elclickverde.com”
ECONEX NEWS
INTERVIEW ABOUT THE PINE PROCESSIONARY ON “elclickverde.com”
25th of January, 2016
The biologist and journalist, Mónica Rubio, interviewed Diego Gallego, doctor of biology and director of the R+D+I department at SANIDAD AGRÍCOLA ECONEX LTD, about the pine processionary (Thaumetopoea pityocampa).
A large number of forests of the Region are harshly damaged by pine processionary (Thaumetopoea pityocampa) nests. These nests are full of caterpillars. It seems that high winter temperatures accelerate the start of their biological cycle. Population was alarmed because of the early beginning of this pest. However, most of the people who go hiking in the forest know that these caterpillars have urticant hairs which produce severe allergic outbreaks in people and animals. Also, it is known that this pest causes huge defoliations which end up in death of extended pine areas. But it is not completely true…
«Processionary causes trees to die and it is not a forest pest in the Mediterranean ecosystems» clarified Diego Gallego, doctor of biology. He differentiated 2 possible situations in which this lepidoptera can appear: Natural and urbanised environment.
In a natural environment, processionary has an essential role which is unknown for a lot of people. Gallego explained that in the same way as it occurs with the Mediterranean pine engraver beetle – another known insect that attacks pine-, processionary is an endemic pine forest species. And what makes this species be fundamental is that «Processionary is the largest consumer of Carrasco pine needles (Pinus halepensis). Therefore, it is the main second-producer of pine forests because there are very few species that are capable of eating that large quantity of pine needles». Dr. Diego mentioned that this fact gains relevance because of the way that pine needles rot in the field. Processionary solves this problem because it eats the pine needles and «it is generated a big amount of excrement which not only holds nitrogen but also, turns the humidity up. For these reasons, it is an important element of the matter and energy cycle». Moreover, he highlighted that processionary never kills pine trees because they always produce new shots although processionary can leave them without pine needles. It can happen that pine trees die but it is because of other reasons unconnected to processionary.
However, pine tree weakness caused by droughts is not one of these reasons. Gallego, who works with pest problems and their management, pointed out that «processionary is not related to the pine tree weakness as it happens with the Mediterranean pine engraver beetle».
The damage caused by processionary is more visible in sparse and small size pine forests than in mature ones. Also, he emphasised that «It only eats pines». For this reason, in natural environment it makes more difficult eradicate this pest. Dr Diego explained that «It is not a forest problem; it is a public health problem. In this second case (urbanised environment), this pest could be eradicated if it is chosen not to plant this pine species in gardens. For example: Avoid planting pines trees in schools».
In addition, he mentioned that the natural enemies of pests – especially parasites- can be used as pest control agents. «In order to make the most of them, it is important not to exterminate forest insects or do it but only when it is inevitable». They are not the unique natural enemy: «Vertebrates, in particular birds, are also one of them, although they are not the main ones. But it is also relevant to protect them with bird nest. Unfortunately, the only specialised birds which eat this caterpillar are cuckoos and great spotted cuckoo. These two kinds of birds depend on magpies. The problem is that magpies are not common in almost all the Region ».
For these reasons, in forest and limited public use areas, «it is given priority to natural enemies as pest control agents in contrast with exterminating forest insects ».
On the contrary, in high public use areas, like parks, private gardens, schools and similar, «it is an imperative problem and the processionary levels have to be zero. For this reason, it has to be eradicated by using all possible technical tools based on the level of presence of processionary. It would be necessary to use pheromones and traps to capture adults when there are only a few, remove nests or even authorized pyrethroids. These solutions put an end to all arthropod wildlife but it is given priority to public health over environment. So, the effort has to be gathered there» explained Dr Diego.
In conclusion, Gallego is not too worry about it because «processionary is controlled by its natural enemies and other chemical solutions». But the key point is that people who visit pine forests, are concerned about it. «As far as I know, the phase of burial has started this year between two and three months before the usual moment. In general, it is in March when the caterpillars travel in a line, coming down from the nests via the tree trunks, travelling around ten metres on the ground until finding an appropriate place to bury themselves. They are quite synchronic ». It means that this process is simultaneous in most of the nests and takes between 15 and 20 days. Diego declared that this year the phase of burial has started at the end of December but he did not know how long it would take. The expert highlighted that «the most important points are to touch neither nests nor caterpillars and control and keep pets away. It can be dangerous to dogs and people who have allergies. The best solution is to avoid areas with high presence of nests».
“Processionary caterpillars, which travel in a line, coming down from the nests via the tree trunks, develop urticant hairs. It can come off easily and produce severe allergic reactions.”
He detailed that the intensity of processionary attacks is cyclic and local. It is known that there are not wide attacks in any part of the Region. Gallego explained « Normally, these attacks are intense in some areas and quite few in others. And it changes in a cyclic way each seven or eight years». He did not know how things are this year but he believes that it will be like always. He clarified «The problem is that these areas with intense attacks are close to cities or are busy areas. It is because social alarm can be generated among population and things can seem to be worse than they really are». On 8 January, The Ministry of Water, Agriculture and Environment, for its part, issued a letter explaining that «caterpillars have been detected in the fifth larval stage, something usual in the spring months. This situation is observed in the central part of the Region and the forests surrounded the Guadalentín valley».
In any case, processionary is a rejected and unknown animal because how many of you know that who guides the trip in a line, coming down from the nests via the tree trunks is always a female? Maybe some of you know it, but do you recognise the pine processionary in the moth/butterfly stage?
www.elclickverde.com is a website about nature in the Region of Murcia and Southeast of Spain. It offers journalist reports and an entertainment guide in order to promote the diversity of the natural heritage of the Region and the potential of the Southeast ecosystems. In this way, promoting knowledge, dissemination and communication of nature in these areas.
