Estudo de três lepidópteros pragas e suas interações em cana-de-açúcar

Abstract

The Telchin licus licus (Drury, 1773) (Lepdoptera: Castniidae) and the Hyponeuma taltula (Schaus, 1904) (Lepidoptera: Noctuidae, Herminiinae) have become important sugarcane puts due to the rapid growth of their populations and the difficulties in controlling both of them. Due to the small amount of information available in literature and to study the interaction between them and other Lepidoptera and natural enemies, a research of a diet for rearing the T.licus licus insect adults was conducted to be able to understand better these two species. Some biological aspects were also observed and the influence of plants attacked by the T. licus licus, the H. taltula and the Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) with the preference of D. saccharalis oviposition and attraction of Cotesia flavipes (Cameron, 1891) (Hymenoptera: Braconidae). The investigation of the pathogenicity of Baculovirus Spodoptera isolates was studied in D. flavipennella. The effect of five diets (D1, D2, D3, D4 and D5) on the development of T. licus licus was evaluated, and the characterization of the chemicals substances released by virgin females with 24 and 48 hours old after the emergence. The D1 and D5 diets were disregarded because they promoted high mortality in the larval stage. After the statistical analysis at 5% probability, it was observed that the D3 and D4 diets were well accepted. The larvae fed with these diets showed greater weight gain and shorter duration in days (p <0.05). When the D2 diet was compared to the D4 and D3 diets, it showed higher mortality in the larvae stage. The D3 and D4 diets favored the production of a greater number of pupae and adults (p <0.05). The adults from the D2, D3 and D4 diets fed with 5% sucrose solution showed an average increase of three days in their life. The D3 and D4 diets were considered appropriate for production of adult T. licus licus. The volatile compounds present in the last three segments of the abdomen of virgin females from D3 and D4 diets were similar to those coming from the field virgin females (p <0.05). While evaluating the oviposition preference for D. saccharalis and the attraction of C. flavipes for canes in relation to sugarcane plants infested by different lepidopteran pests, it was possible to observe that D. saccharalis females have oviposition preference for the non-infested sugarcane (p <0.05), while C. flavipes females are attracted by volatile compounds emitted by sugarcane plants infested by D. saccharalis and in a smaller scale by H. taltula (p <0.05). Moreover, it was found that the use of volatile compounds emitted directly by the plants is more efficient than the extracts obtained from the plants (p <0.05). The effectiveness of three isolates (I-6, I-18 and I-19) of the Baculovirus spodoptera in D. flavipennella neonate larvae was verified because there is no information about the use of baculovirus isolated from the biological control of D. flavipennella. Fifty-six D. flavipennela neonate larvae were used per treatment, which were grouped in four repetitions with 14 larvae. The percentage of efficiency of the I-18 and I-6 isolates were the best differing from the I-19 (p <0.05). The I-18 and I-6 isolates can be used as bio-insecticide for D. flavipennella (p <0.05). With the results obtained in this thesis, it can be concluded that the giant borer can be raised in a laboratory to extract the pheromone glands from the adults. There is interaction between healthy plants and oviposition preference by D. saccharalis in relation to plants infested by lepidopterans. There is attraction of the natural enemy C. flavipes by plants attacked by D. saccharalis and in a smaller scale by H. taltula. There is B. spodoptera isolates with potential for being used in the biological control of D. flavipennella.