Selection of signal grass genotypes for resistance to collaria oleosa (distant, 1883) (hemiptera: miridae)

Abstract

The bug Collaria oleosa (Distant, 1863) has frequently been found attacking forage crops, where it causes leaf damage in the form of whitish striae, leading to a reduction in photosynthesis. The aim of this study was to select signal grass, Brachiaria ruziziensis, genotypes that show resistance to C. oleosa. Adult insects were collected from a greenhouse at Embrapa Dairy Cattle Research Center, Brazil. Insects were sexed and held in acrylic cages in a laboratory; eggs produced were placed in Petri dishes and housed in a climatic chamber until the nymphs hatching, that were isolated in plastic containers (2.5 cm × 2.5 cm) until the fourth instar, and then transferred to Petri dishes (5.0 cm × 2.5cm). One adult pairs were placed in mating cages and fed on the same diet as the developing nymphs. Our study incorporated a fully randomized design with seven replicates, using 26 genotypes of B. ruziziensis and a marandu cultivar (Brachiaria brizantha). We evaluated the duration and viability of each instar and the nymphal stage, adult longevity, and the number of eggs/female. Significant differences were found for each instar duration, nymphal stage, adult longevity, and fecundity of C. oleosa on different plant genotypes. The genotypes CNPGL BR 07, CNPGL BR 14, CNPGL BR 43, CNPGL BR 76, CNPGL BR 91, CNPGL BR 100, and B. brizantha were selected as having influenced C. oleosa biology cycle, and are recommended as the most appropriate lines to follow in the breeding programs of B. ruziziensis.