Résumé:
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.
