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Damage assessment caused by defoliating caterpillars in sweet potato clones
Authors: Sônia Maria Forti Broglio, Roseane Cristina Prédes Trindade, Marcelo Cavalcante, Paulo Vanderlei Ferreira
Number of views: 493
Damage assessment of caterpillars in the crop of sweet potatoes was studied with the aim of identifying whether the attack of these pests affect the crop yield. It was used clones obtained from CECA / UFAL from botanical seeds of open pollinated populations: CL - 01, CL - 03, CL - 04, CL - 10, CL - 11 e CL - 12 (Co Copinha); CL - 09 (Paulistinha Branca); CL - 13 e CL - 14 (Roxa de Rama Fina); CL - 02 (Co Branca); CL - 06 (60 Dias); and CL - 08 (Pixaim I). It was used randomized blocks designs with 12 treatments and 3 replicates. For identification of caterpillars, different samples were collected manually and sent to the Entomology Laboratory of the CECA/ UFAL and were maintained until adult emergence, which were killed, mounted, photographed and sent for identification. The damage rating was conducted in two periods: before application of a chemical insecticide (deltamethrin) and the second 15 days after treatment. For classification of the notes was used a scale notes from 1 to 5 (1 = 1-20 %; 2= >20-40 %; 3= >40-60 %; 4 = >60-80 %; 5 = >80-100 %). The notes were given by four people, in the central two meters floor area of each plot. After taxonomic identification, the species proved to be involved: Spodoptera dolichos (Fabr., 1794), S. cosmioides (Walk., 1858) and S. albula (Walk., 1857) (Noctuidae); Pseudoplusia includens (Walk., 1857) (Noctuidae) and Agrius cingulatus (Fabr., 1775) (Sphingidae). The damage caused by caterpillars, when not applied insecticide was significant, and it was a clone with the highest average, the highest preference for feeding by the caterpillars. Clones 2, 3, 4 and 10 did not differ from one clone, noting also low yield. Clones 6, 9 and 13 showed the lowest average infestation of caterpillars, followed by higher yield. The insecticide deltamethrin was efficient in controlling the caterpillars because the occurrences of damage decreased after application, with no statistically significant difference between treatments. The averages ranged from 0.90 to 1.46. This is the first record of the occurrence of S. dolichos, S. cosmioides, S. albula, P. includens and A. cingulatus sweet potato in the State of Alagoas. The injuries caused by defoliating caterpillars affected productivity.