Controle biológico e alternativo do percevejo de renda (Vatiga manihotae) (Drake) (Hemiptera: Tingidae) na cultura da mandioca (Manihot esculenta Crantz)

Abstract

Cassava (Manihot esculenta) is an important tropical crop, constituting the main source of energy for more than 500 million people in Africa and South America is a culture that traditionally had a low incidence of insect pests, however, in recent seasons some species have shown a high population, especially among those Vatiga manihotae (Drake) (Hemiptera: Tingidae), which causes early defoliation and significant reduction in photosynthetic rate. To contribute to knowledge about the control of this insect, it was evaluated in laboratory conditions, the activity of alternative pesticides and entomopathogenic fungi for the control of V. manihotae. Therefore, we tested commercial products Natualho®, Compostonat®, Pironat®, Plant Clean®, Pyronin®, Lime Sulfur and Mattan Plus® on the insecticidal activity and beyond these Vertinat®, Metanat® and Bovenat® in oviposition deterrence. The work was conducted on plants of cassava fecula branca variety. The application of the products was carried out on the underside of leaves with the aid of an airbrush device coupled to a compressor flow of air. For the experiment of inhibition of oviposition, four cassava leaves were infested with 20 adult of lacebug for oviposition. The leaves were wrapped in plastic cages, allowing oviposition for 48 h after the adults were removed and the eggs quantified. To check the mortality of insect nymphs (3rd instar) and adults were transferred to four upper leaves of cassava, and where the application of products. During 10 days there were daily observations on the number of dead insects. In the trial with the entomopathogenic fungi, we used 13 isolates of Beauveria bassiana, an isolate of B. brongniartii, four of Metarhizium anisopliae and two isolates of Sporothrix insectorum, in addition to commercial products based on fungi, Metanat®, Bovenat® and Vertinat®. The isolates were grown in medium and appropriate conditions and suspensions concentration standardized at 1  109 conídios mL and applied to 3rd instar nymphs and adults. Evaluations were made every other day for 10 days. The products had low efficiency in controlling the lacebug, with a mortality of 54.4% in nymphs with Lime Sulfur and 12.6% for adults with Pyronin®. Natualho® showed 92% of the oviposition deterrence of V. manihotae. The entomopathogenic fungi were pathogenic, and the isolated IBCB34 B. bassiana was the most effective in nymphs and adults, causing, respectively 100% and 85% mortality