Contribution à l’étude de la bio écologie des populations de la mineuse de la tomate Tuta absoluta (Lepidoptera, Gelechiidae) en vue de l’optimisation de son contrôle dans la région de Mascara

Abstract

Tuta absoluta is a devastating pest of Solanaceae crops such as tomato or potato. Originated from North America, T. absoluta’s larveae can cause 100% yield reduction on crops production. In last years, this microlepidoptera has spread rapidly in Mediterranean countries such as Algeria, causing serious damages. The present study was carried out to investigate the bio-ecology and populations dynamics of T. absoluta. Laboratory and greenhouse observations, and field pheromone trapping were undertaken. Moreover, we assessed efficiency of the bacterium Btk against T. absoluta. In laboratory study of different biological parameters of T. absoluta, we compared development times, mortality rates and sex-ratio at different stages of the insect’s growth. Our results revealed some variations we could attribute to the environment conditions such as temperature or substrate. Furthermore, we demonstrated that T. absoluta was able to set up a parthogenetic mode of reproduction, qualified to be “optional”. Population dynamics study highlighted the succession of five generations from December to July. Our results revealed that the early damage occurred mostly in the northern and mainly in northwest directions. Moreover, when the trapping level was low, the damage was reduced and mainly located on the lower part of the plants. Then gradually as attack frequency increased, the damage became visible on the upper parts. A polynomial relationship was established between a mirid Macrolophus sp and that of T. absoluta. To fight T. absoluta we have assessed a basic formulation made of Bacilus thurungiensis kurtaski on larval populations of the pest. The Btk treatment at 0.5 mg/ml resulted in 36.04% and 53.61% of larvae mortality after two and four days, respectively. We suggest the conjugation of the efforts of the researchers to find reasonable solutions being able to get through it devastating mattering who threatens the agriculture; the later works will, undoubtedly, try to answer these concerns.