Étude des populations d'Oulema melanopus L. et Oulema lichenis Weiss. (Coleoptères Chrysomelidae) sur blé dans la région parisienne

Abstract

Des informations sont données sur la présence généralisée des Oulema en céréaliculture et la biologie des insectes est brièvement rappelée. Après avoir mentionné les phénomènes importants pour la compréhension de la dynamique des populations : concentration en été des adultes hors des cultures, diapause imaginale, colonisation des céréales au printemps par les adultes en vol, vie larvaire sédentaire et solitaire, développement larvaire très rapide pour chaque stade, nymphose de O. melanopus dans le sol, rôle des entomophages quasiment nul dans la régulation des populations, le dispositif et les méthodes d'échantillonnage pour les études de dynamique de population sur blé sont exposés. Tandis que la population est caractérisée par son niveau très bas et une fécondité médiocre des femelles, il apparait que les facteurs climatiques du printemps, défavorables aux Oulema, seraient la principale cause de cet état des populations dans la région parisienne où le seuil de nuisibilité n'est jamais atteint. Mots clés additionnels : Dynamique de population, adultes, ceufs, larves, échantillonnage. SUMMARY Populations of Oulema melanopus L. and Oulema lichenis Weiss. (Coleoptera Chrysomelidae, on wheat in the Paris region. Oulema spp. arc generally present on ccrcal crops. The biology of these insects in briefly reviewed. The important factors for their population dynamics wcrc : concentration of the adults away from the crop in summer, diapausc as adults, colonization of ccrcal crops by flying adults in spring, solitary sedentary and very rapid larval dcvclopment, pupation in soil, low activity of cntomophagous insects in regulating the population. Methods arc given for sampling populations on wheat. Numbers were generally low and females produced few eggs. This appeared to be mainly due to climatic factors in spring, which are unfavorable in the Paris region. so that the economic damage additional threshold is never reached.

Evaluation of infestation by cereal leaf beetles (Oulema spp.) on six varieties of durum wheat (Triticum dirum, Desf.) seedlings in arid conditions of Setif, Algeria

“…The monitoring of cereal leaf beetles population dynamic was done through counting adult beetles individuals by adopting the method of hunting for, followed by the collection of some specimens which are preserved for later identification. The larvae are placed in boxes and fed with pieces of wheat leaves under ambient temperature, according to Chambon et al (1983).…”

The emerging problem in cereal crops in North-Eastern Tunisia: The cereal leaf beetles Oulema spp. (Coleoptera; Chrysomelidae; Criocerinae) dynamic populations and infestation rate

“…The genus Oulema Gozis (1886) (Coleoptera; Chrysomelidae; Criocerinae) contains four harmful species for cereals. Oulema melanopus Linneaus (1758) is considered as pest with real economic damages although it is a very abandoned species by researchers [1] . It is the most dreadful Oulema species in the Mediterranean region and North Africa [2] and the most worldwide dispersed [3] .…”

“…Tetrastichus julis Walker (1839) (Hymenoptera; Eulophidae) is a parasitoid that reduces and maintains successfully cereal leaf beetles' populations under the economic threshold [5] . Lacewings are effective for capturing leaf beetles' larvae [1] . On the other side, larvae of O. melanopus can be easily controlled in the chemical way by pyrethroid application [7] .…”