Biology and ecology of Elatophilus nigricornis Zetterstedt (Hemiptera Anthocoridae) predator of Matsucoccus feytaudi Ducasse (Homoptera Matsucoccidae) in the South-East of France

The pine scale Matsucoccus feytaudi was accidentally introduced into the ma ritime pine stands of the Maure and Esterel Forests. It is the primary caus e of the dieback of 120000 ha stands and its specialist predator Elatophilu s migricornis has been studied. It is possible to maintain and raise it in laboratory conditions but its output is not prolific enough to envisage pro pagation which would allow it to be released in natural conditions. When ra ised in laboratory conditions the time required for its development (table II) and fecundity have been determined. In natural conditions, nymphs devel op in trunk bark cracks, adults mate, but females insert eggs in needles. T he population of the eggs is distributed according to two gradients: a decr easing gradient from the bottom to the top of the trees and a decreasing gr adient from the trunk to the extremities of the branches (figures 3 and 4). The distribution of its nymph populations on the trunk and branches is dif ferent before (figure 5) and after (figures 6 and 7) the invasion of M. fey taudi. In reality, the distribution of the predator nymph populations alway s coincides with that of its host even when that of the latter changes. E. nigricornis-produces produces at least three generations a year tone for M. feytaudi) and overwinters at the fertilized female stage (figures 1 and 2) . Two sampling methods have allowed us to estimate the population levels wh ich have developed during (figure 8; table III; and after the pine scale in vasion (figures 9 and 10, table V). Even when there was widespread destruct ion of the trees attacked due to the action of the xylophagous, there is a link between the size of the E. nigricornis populations on the trees and th e capacity of the tree to survive. In stands where more than half the trees survived it was found that in 6 years the level of weekly captures was mul tiplied by 26 (figure 9). Finally, on regeneration trees which replaced the old stands that had been destroyed or felled, the population levels are 3 times greater (figure 10).