Resistência de cultivares de café arábica (Coffea arabica) ao bicho-mineiro Leucoptera coffeella (Lepidoptera: Lyonetiidae)

Abstract

The leaf miner Leucoptera coffeella (Lepidoptera: Lyonetiidae) is considered the main coffee crop pest due to its widespread occurrence and economic losses caused to producers. The use of resistant cultivars is one of the most promising alternatives for leaf miner control. The Procafé Foundation launched the Siriema AS1 cultivar, which is resistant to both leaf miner and rust. Thus, this study aimed to assess the leaf miner resistance of commercial arabica coffee cultivars, correlating the infestation with climatic factors, as well as evaluating and characterizing the types of resistance (antixenosis and/or antibiosis) of cv. Siriema and its progenies. The experiments were conducted under field conditions in the southern region of Minas Gerais, Brazil. The first experiment consisted of using 28 commercial cultivars and 2 clones from the panel of cultivars of the INCT-Café, in the municipality of Lavras, and the second one, with cv. Siriema and its progenies, was performed using seedlings from the Procafé Experimental Farm. Leaf miner sampling was carried out monthly in the field, randomly assessing three leaves, per plot, of the third/fourth pair of leaves from branches of the upper third of the plants, proceeding in the same way for the middle third. The following parameters were assessed: percentage of intact mined leaves, number of mines per leaf, and intensity of injury, according to a quantitative scale of the percentage of leaf area attacked by the leaf miner. In the laboratory, the categories of leaf miner resistance (antixenosis and/or antibiosis) of cv. Siriema and its progenies were characterized, comparing them with the commercial cultivar Arara through tests of preference for oviposition and biological development. Differences in leaf miner infestation were found between the cultivars in the field experiment. In addition, accumulated precipitation was an important factor in regulating the level of pest infestation in the field. Injury intensity also varied significantly between genotypes, with high and low infestation rates, and was significantly correlated with the number of mines per leaf. The ‘Siriema’ progeny genotypes tested in the laboratory did not interfere with the oviposition of L. coffeella and, therefore, have no antixenosis resistance. The greatest negative effects of antibiosis resistance on ‘Siriema’ progenies were observed in the larval stage. Pupal stage and adult longevity were not negatively affected by resistant genotypes. Studies on the influence of climatic factors on the population fluctuation of L. coffeella are important to guide pest monitoring, as these data allow us to predict when and at what intensity the pest may appear in the crop. Moreover, the characterization of resistance categories and levels in cv. Siriema and its progenies may contribute to the advancement of arabica coffee genetic improvement programs for the development of productive commercial cultivars resistant to leaf miner.