Resistência de cultivares de bananeira Musa spp. (Zingiberales: Musaceae) ao ácaro Raoiella indica Hirst (Acari: Tenuipalpidae)

Abstract

The mite Raoiella indica Hirst, 1924 (Acari: Tenuipalpidae) causes negative impacts on several plant species, which the most important in the families Arecaceae and Musaceae. In Brazil, there is scarcity of studies investigating banana varieties resistant to the mite R. indica. Thus, the objective was to test six banana cultivars (Musa spp.) to determine the survival of R. indica and to verify the possible resistance of the cultivars to this mite. The work was carried out at the Laboratory of Entomology and Acarology /LEA at UFAL, Campus of Arapiraca. The desing was completely randomized with seven treatments (six banana cultivars - 'Grand Naine', 'Maçã', 'Prata Anã', 'Prata Catarina' 'Prata Gorutuba' and 'Thap Maeo' plus the control treatment – coconut palm Cocos nucifera L.) and 10 repetitions. Leaf disks of banana and coconut cultivars were infestad with five couples of R. indica and maintained in B.O.D., at 25 ± 2 oC, 57% ± 5 RH and 12h photophase. The number of live mites and their offspring as well as oviposition were evaluated daily. With the data obtained, it was possible to calculate the average survival of adults and of females and males separately, in addition to egg viability and survival of immature forms. The results were subjected to analysis of variance and their means compared usind the Scott-Knott test. The maximum longevity of R. indica was observed in the coconut palm at 44 days and at 42 days in the banana cultivar 'Prata Catarina'. The lowest numbers of longevity were observed in 'Grand Naine' (27 days) and in 'Prata Anã' (34 days). Regarding the sex of the mite, regardless of the cultivar, the females had greater longevity and survived until the 44th day of evaluation. Total oviposition was higher in the control (13.16 eggs) and among cultivars it was higher in 'Thap Maeo' (1.86 eggs). The lowest oviposition averages occurred in 'Prata Anã' (0.43 ovos) and 'Grand Naine' (0.05 ovos). The oviposition period ranged from 21.9 days in the coconut palm to 2.1 days in the 'Grand Naine' cultivar. Considering the viability of the entire development period (egg-larvae-nymph-adult) of R. indica, the survival of the mite was higher in 'Prata Catarina' and in 'Thap Maeo' where there was the longest oviposition period and the highest average number of eggs. In the 'Grand 'Naine' and 'Maçã', the immature forms did not reach the adult stage. The 'Grand Naine' and 'Maçã' cultivars were considered resistant to R. indica attack under the given conditions.

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