Biologie du prédateur aphidiphageEumicromus angulatus [Neur.: Hemerobiidae]: Études au laboratoire et observations dans le sud-ouest de la France

Abstract

L'élevage de l'HémérobeEumicromus angulatus (Stephens) effectué au laboratoire à 20°C avec une nourriture aphidienne (Myzus persicae) permet de préciser la durée du développement et les conditions nécessaires à l'obtention d'un taux de survie élevé. Le choix d'un site artificiel de ponte conditionne la fécondité des femelles accouplées. La ponte des femelles vierges est faible ou nulle et leur longévité est très écourtée. L'étude du développement larvaire d'E. angulatus dans les conditions hivernales naturelles ainsi que l'expérimentation au laboratoire sous diverses photopériodes. indiquent l'existence d'une diapause imaginale induite par les courtes photopériodes. Ceci se manifeste par un allongement de la durée de préoviposition, une activité et une consommation alimentaire réduites. Une comparaison avec les conditions de la diapause deChrysopa carnea Stephens est établie. The brown lacewingEumicromus angulatus (Stephens) is a larval and imaginal aphidophagous predator. We found it around Toulouse in undergrowth, essentially in meadows and in alfalfa, but always in few number. It feeds on various aphids. The laboratory rearing gives the duration of the stages of development at 20°C and states the modalities of spinning the cocoon. The sexual maturation of imagines occurs after a period of 5 or 6 days during which the normal development requires aphid food. A single mating permits in most cases a regular laying throughout the female's life. But some can sometimes copulate a second time. The longevity is important and reaches 3 to 5 months. The species is greatly fecund (1,500 to 2,300 eggs) and most fertile (90 to 98% of eggs with embryo). A suitable artificial substratum for egglaying presents a fibrous structure or a thin hairy surface, the selection of which is a determining element for oviposition and consequently a main condition for high fecundity (table 1). The laid eggs are scattered and in preference pasted on the vertical walls, then on the floor in the rearing cage (table 2). The fecundity of the virgin female is extremely reduced (fig. 1).) They lay sterile eggs. The consumption of their own eggs is often observed (auto-oophagy). Out-of-doors rearing combined with laboratory rearings under various photoperiodic conditions define modalities of the autumnal development and overwintering. The larval and nymphal development may last up to the beginning of winter. Then we only found imagines of which activity is reduced. Adults undergo a diapause induced by short days (table 3). This diapause is expressed by an extension of the sexual maturation period. Its intensity is low. The early action of short day photoperiods (larval and nymphal stages) does not allow the development of the ovary upon emergence; its later action (young imago) first reduces, then stops the egglaying. The diapause is spontaneously eliminated without a return in long day photoperiods being necessary. It is followed in nature by a thermal quiescence. A comparison with the conditions of the diapause ofChrysopa carnea Stephens is made. The mating and the initiation of the oviposition are possible under natural conditions starting from April. Then they only depend on availability of food. Afterwards there follow five broods the adults of which overlap because of their great longevity.

DOI: 10.1007/BF02371658

Cite this paper

@article{Miermont2006BiologieDP, title={Biologie du pr{\'e}dateur aphidiphageEumicromus angulatus [Neur.: Hemerobiidae]: {\'E}tudes au laboratoire et observations dans le sud-ouest de la France}, author={Y. Miermont and Michel Canard}, journal={Entomophaga}, year={2006}, volume={20}, pages={179-191} }