Effectiveness of pheromone traps against Tuta absoluta

International audienceIn the Tunisian south, the heated greenhouses are an important axis of development of agriculture thanks to the big geothermal potential of this zone. Currently, this sector suffers from several phytosanitary problems. In the last years, a new insect, Tuta absoluta, threaten the cultures of cultivated tomatoes in heated greenhouses. To improve control of T. absoluta, the effectiveness of pheromone traps (associated or not with a source of light) and luminous traps (associated or not with water, with limed buckets for limed covers) were compared. The results show that the traps with pheromones significantly catch more adults of T. absoluta compared to all the other types of traps (average number of trapped adults of T. absoluta = 73.4 (± 142)). The luminous traps associated with water, with limed buckets as with limed covers show, as for them, an intermediate effectiveness. In spite of this slightly less effectiveness, the luminous traps have the advantage of low costs of production as well as the advantage of simultaneously capturing males and females of T. absoluta. ; Peer reviewe

Comparison of the effectiveness of the most used chemicals against Tuta absoluta in Tunisia

Control failures with several chemicals have prompted research into the resistance status of Tuta absoluta and the effectiveness of certain active ingredients against this pest. In this context, a comparison was made of the effectiveness of the most widely used chemicals against T. absoluta in Tunisia. The results show that the L1 larval stage of Tuta absoluta is very sensitive to all of the chemicals tested. Stage L2 is sensitive to Spinosad, indoxacarb and emactin, while Bacillus thuringiensis, martine do not cause 50% mortality. L3 stage mortality fluctuates between 20% and 80% mortality. The L4 stage is more affected by the treatment with Bacillus thuringiensis which can go to 100%. Based on these results, chemical treatments should be directed according to the dominant larval stage in the plants

Effect of soil management on biodiversity of nematode communities as a biological indicator of soil quality in oasis agro-ecosystem of Kebili

Nematode communities were monitored in 26 oases in Kebili under various agricultural systems. Differences between studied oases consisted in tillage frequency, soil amendment type (manure or manure+ mineral fertilizers), cover crops and field age. In addition, this study evaluated the importance of the C-P (Colonizer-Persistent) triangle and the faunal profile (representation of enrichment index vs. structure index) as a biological indicator and monitoring tools in support of soil quality assessment. The results showed that nematode communities were composed by 10 bacterial feeders (Ba), 3 fungal feeders (Fu), 12 plant parasites (PP), 4 omnivores (O), 1 predator (P) with the dominance of (Ba) and (PP) in all surveyed oases. The nematode communities differed slightly depending on oases age. Bacterial feeders and Discolaimium genus were found in both young and old ones. Plectus genus (Ba) was found only in young oases while Xiphinema, Criconema and Trichodorus genera (PP) were absent in these oases. Few nematode taxa were affected by soil amendment type and cover cropsincluding some bacterial and fungal feeders. The highest taxa richness was recorded in bare soils and in field with tillage frequency of 2 or 3 years. The lower MI (Maturity index) value was recorded in old oases. Most of studied oases were characterized either by a high soil disturbance level with a high abundance of cp-1 group (Bacterivore nematodes with c-p value =1)as an indicator of a disturbed food web or by a stressed soil with high abundance of cp-2 group (Bacterivore and fungivore nematodes with c-p value = 2) as an indicator of degraded food web. Only few sites showed a maturing and structured food webs with respectively low to moderate soil disturbance level and undisturbed soil. This study highlighted also that some nematode genera may potentially serve as differential bio-indicators of soil disturbance

Effectiveness of pheromone traps against Tuta absoluta

peer reviewedIn the Tunisian south, the heated greenhouses are an important axis of development of agriculture thanks to the big geothermal potential of this zone. Currently, this sector suffers from several phytosanitary problems. In the last years, a new insect, Tuta absoluta, threaten the cultures of cultivated tomatoes in heated greenhouses. To improve control of T. absoluta, the effectiveness of pheromone traps (associated or not with a source of light) and luminous traps (associated or not with water, with limed buckets for limed covers) were compared. The results show that the traps with pheromones significantly catch more adults of T. absoluta compared to all the other types of traps (average number of trapped adults of T. absoluta = 73.4 (± 142)). The luminous traps associated with water, with limed buckets as with limed covers show, as for them, an intermediate effectiveness. In spite of this slightly less effectiveness, the luminous traps have the advantage of low costs of production as well as the advantage of simultaneously capturing males and females of T. absoluta

Comparison of the effectiveness of the most used chemicals against Tuta absoluta in Tunisia

Control failures with several chemicals have prompted research into the resistance status of Tuta absoluta and the effectiveness of certain active ingredients against this pest. In this context, a comparison was made of the effectiveness of the most widely used chemicals against T. absoluta in Tunisia. The results show that the L1 larval stage of Tuta absoluta is very sensitive to all of the chemicals tested. Stage L2 is sensitive to Spinosad, indoxacarb and emactin, while Bacillus thuringiensis, martine do not cause 50% mortality. L3 stage mortality fluctuates between 20% and 80% mortality. The L4 stage is more affected by the treatment with Bacillus thuringiensis which can go to 100%. Based on these results, chemical treatments should be directed according to the dominant larval stage in the plants