Evaluation of Spirotetramat (Insecticide) on scale insects on citrus in Algeria

Abstract: Insecticidal tests containing Spirotetramat were carried out in a citrus orchard(variety Washington navel) with an aim of fighting against the scale insects. The evaluationof the biological activity of this product compared to a natural control and to two otherreference products (Ultracide 40 and Dursban 4), was made continuously until harvest on thepopulation of Lepidosaphes beckii as a species dominant and representative of the mediumof experimentation. Under the effect of Spirotetramat applied in June 2008 to the pulps of1.2l/ha, 3000l/ha and 4000l/ha, the levels of population regress in a spectacular way by oftenposting zero values any confused stage (adult and larvae). The analysis of the percentages ofcorrected mortalities reveals a strong mortality in the larvae exceeding the 50% compared to36% in the adults. This double action, supported by the reduction ratios of fruitfulness whichborder the 100%, mark well particular mode of action of Movento which appears on theprocess of ovogenesis by disturbing the biosynthesis of the lipids indeed. This activityappeared as of the application of the product and was spread out in time with the same widthuntil the maturation of the fruits, that is to say one duration estimated at more than 140 days,equivalent to the remanence of this active matter. It is this continuous pressure exerted on thepopulation of the cochineals which determined a quasi-total protection of the involving fruitto the harvest of the ratios de reduction of about 70% compared to the natural witness andDursban and of 99.42% compared to Ultracide. On the environmental level, Spirotetramatseems to develop a very satisfactory selectivity with respect to auxiliary fauna (parasitoïdesand other species). The results in this field attest that this one practically does not carry ofdamage to the parasitoïdes particularly Aphytis lepidosaphes; quite to the contrary, it allowsa development quasi indifferent nearer to the natural conditions compared to the referenceproducts to the authorized amounts.