Effect of plant extracts on immature stages and adults females of Mononychellus tanajoa (Bondar) (Acari: Tetranychidae)

Estudou-se o efeito de extratos aquosos de nim (Azadirachta indica A. Juss), cravo-da-índia (Syzigium aromaticum L.) e cinamomo (Melia azedarach L.) na sobrevivência de ovos, larvas, ninfas e fêmeas adultas do ácaro verde da mandioca, Mononychellus tanajoa (Bondar) (Acari: Tetranychidae). Discos de folhas de mandioca com 30 ovos cada foram imersos nos extratos e deixados a secar por 30 minutos em condições ambientais. Na testemunha, os discos foram imersos em água destilada. Nos ensaios com larvas, ninfas e fêmeas adultas, foram utilizados 40 indivíduos para cada extrato e concentração testada. Os extratos de nim nas concentrações 0,5, 2,5 e 5% p/v causaram mortalidade de 16,8, 59,2 e 60% dos ovos, enquanto que o cravo-da-india a 5% causou 10,8% de mortalidade. Na testemunha, houve mortalidade de 4,2% dos ovos. A mortalidade de larvas, protoninfas e deutoninfas de M. tanajoa com extrato de nim nas concentrações 2,5 e 5% variou de 57,5 a 100% e de 85 a 100%, respectivamente, porém não se obteve mortalidade nesses estágios com o extrato de nim a 0,5%. Extrato de cravo-da-índia a 5% não causou mortalidade significativa de larvas e ninfas. Fêmeas tratadas com extratos de nim nas concentrações de 2,5 e 5% apresentaram mortalidade de 97,5 e 100%, enquanto que as fêmeas tratadas com extratos de cinamomo e cravo-da-índia nas mesmas concentrações tiveram mortalidade de apenas 5 e 7,5% e 5 e 12,5%, respectivamente. Os resultados sugerem que os extratos de nim nas concentrações a partir de 2,5% são promissores para o controle de M. tanajoa.The effect of aqueous extracts of neem (Azadirachta indica A. Juss), clove (Syzigium aromaticum L.) and chinaberry (Melia azedarach L.) on survival of eggs, larvae, nymphs and adults females of the cassava green mite, Mononychellus tanajoa (Bondar), was studied. Egg treatment consisted of dipping cassava leaf discs with 30 eggs into each plant extract concentration. Leaf discs dipped into destilled water were used as control. The treated and control leaf discs were dried for 30 minutes under environmental conditions. The effect of the several plant extracts on immature stages and females was studied by exposing 40 individuals to each plant extract concentration. Neem extract at concentrations 0.5, 2.5 and 5% w/v caused mortality of 16.8, 59.2 and 60% of the eggs, while the clove 5% w/v and the control treatment caused mortality of 10.8 and 4.2%, respectively. Larvae, protonymphs and deutonymphs treated with neem extracts at 2.5 and 5% had mortality ranging from 57.5 to 100% and from 85 to 100%, respectively, but they were not killed by neem extract at 0.5%. Clove extract at 5.0% did not cause any significant mortality of larvae and nymphs. Neem extracts at 2.5 and 5% caused 97.5 and 100% mortality of M. tanajoa females, while, at the same concentrations, chinaberry extracts caused only 5 and 7.5% mortality and clove extracts caused 5 and 12.5% mortality of females, respectively. These results suggest that neem extracts at concentrations higher than 2.5% are promising for M. tanajoa control