Behavior of Tetranychus evansi on tomato and interaction with its predator Phytoseiulus longipes . Application for an Integrated Pest Management Strategy in Tropical Conditions

Abstract

Tetranychus evansi is an invasive pest observed in East Africa and West to the 2000s, which causes damage to strong economic impact on Solanaceae. Its outbreaks generally lead to intensive chemical control with products that are not always effective. The mite Phytoseiulus longipes proved to be the best predator to control T. evansi but the intensive use of chemical pesticides can make it difficult its effectiveness in the field. The efficacy of Metarhyzium anisopliae ICIPE-78 has been demonstrated recently. But the quality of the spores recommended in foliar spraying is affected by the effect of temperature and hygrometry. These are just some of the parameters, Effectiveness of control methods recommended to control T. evansi. A better understanding of the behavior of T. evansi and its interactions with P. longipes should allow us to optimize control of this new pest. The main objective of my thesis was to study the dispersal behavior of T. evansi on tomato and its interactions with P. longipes in order to implement a method of integrated control in tropical conditions. I studied the dispersal behavior of T. evansi on a leaf and a tomato plant compared to that of T. urtica e. My studies showed a herd behavior of low density T. evansi and a high density dispersion. I also highlighted its circadian migration with a large influx of migrants at the beginning of the year, Afternoon and another weaker at night. In addition, the number of ascending individuals was similar to the number of descending individuals. My studies of interactions between T. evansi and P. longipes showed a leaching behavior of T. evansi in the presence of P. longipes through visual, vibratory and olfactory signals and an attractive behavior of P. longipes for T. evansi Through vibratory and olfactory signals. Volatile compounds emitted by T. evansi and attractants of P. longipes were linalool and methyl salycilate (MeSA). To improve the efficiency of entomopathogenic fungi against T. evansi, I investigated the effectiveness of a foam impregnated with M. anisopliae. I have shown that this impregnated foam placed around the stem, A tomato plant significantly reduced a population of T. evansi with a remanence of 36 days provided that the foam was placed above the infestation. This technique can be supplemented by a release of P. longipes which seem insensitive to M. anisopliae. Finally, through a case study, I confirmed the invasiveness of T. evansi in Benin with 65% loss of production loss on the tomato, 56% for African gboma (or eggplant) and 25 % For amaranth. Producers have all used chemical pesticides based on pyrethroids and organophosphates but none of them seems to have been effective. Hence their use of frequent sprays of the order of 3, 6 and 12 treatments per month on average on the amaranth, Gboma and tomato respectively. A control method adapted to the herd behavior of T. evansi could be the use of netting impregnated with acaricide or M. anisopliae deposited on the spot of infested plants or combined with predators on a larger scale. Another strategy would be to combine linalool and / or MeSA-producing plants as attractants for predatory mites. Under shelter, plants intensively grown, could be protected by foams impregnated with M. anisopilae and predators. All of these environmentally-friendly methods should enable effective control of this new Solanaceae pest in sub-Saharan Africa. (Author's abstract) A control method adapted to the herd behavior of T. evansi could be the use of netting impregnated with acaricide or M. anisopliae deposited on the spot of infested plants or combined with predators on a larger scale. Another strategy would be to combine linalool and / or MeSA-producing plants as attractants for predatory mites. Under shelter, plants intensively grown, could be protected by foams impregnated with M. anisopilae and predators. All of these environmentally-friendly methods should enable effective control of this new Solanaceae pest in sub-Saharan Africa. (Author's abstract) A control method adapted to the herd behavior of T. evansi could be the use of netting impregnated with acaricide or M. anisopliae deposited on the spot of infested plants or combined with predators on a larger scale. Another strategy would be to combine linalool and / or MeSA-producing plants as attractants for predatory mites. Under shelter, plants intensively grown, could be protected by foams impregnated with M. anisopilae and predators. All of these environmentally-friendly methods should enable effective control of this new Solanaceae pest in sub-Saharan Africa. (Author's abstract) Anisopliae deposited on the spot of infested plants or combined with predators on a larger scale. Another strategy would be to combine linalool and / or MeSA-producing plants as attractants for predatory mites. Under shelter, plants intensively grown, could be protected by foams impregnated with M. anisopilae and predators. All of these environmentally-friendly methods should enable effective control of this new Solanaceae pest in sub-Saharan Africa. (Author's abstract) Anisopliae deposited on the spot of infested plants or combined with predators on a larger scale. Another strategy would be to combine linalool and / or MeSA-producing plants as attractants for predatory mites. Under shelter, plants intensively grown, could be protected by foams impregnated with M. anisopilae and predators. All of these environmentally-friendly methods should enable effective control of this new Solanaceae pest in sub-Saharan Africa. (Author's abstract) Plants intensively grown, could be protected by foams impregnated with M. anisopilae and predators. All of these environmentally-friendly methods should enable effective control of this new Solanaceae pest in sub-Saharan Africa. (Author's abstract) Plants intensively grown, could be protected by foams impregnated with M. anisopilae and predators. All of these environmentally-friendly methods should enable effective control of this new Solanaceae pest in sub-Saharan Africa. (Author's abstract)