Understanding how host-crop genotypes affect the life history of insect pests is important for developing and using varietal resistance as a pest control measure. Here we determined how wild and cultivated sugarcane genotypes affect key life-history traits and the demographic performance of the root spittlebug, Mahanarva fimbriolata (Stål; Hemiptera: Cercopidae), a major pest of sugarcane, which produces most of the world's sugar and bioethanol. In the greenhouse, plants of four sugarcane genotypes (two wild and two cultivated) were infested with newly-ecloded spittlebug nymphs. A longitudinal life-table experiment was conducted recording developmental time, survival, reproductive output, and longevity of the released spittlebug nymphs. One of the promising sugarcane genotypes was the accession IM76-229 (Saccharum robustum Brandes & Jesw. ex Grassl), which allowed only 20% of nymph survival to adulthood and reduced the spittlebug longevity by 10 d. Such effects on these life-history traits led to a negative intrinsic rate of population growth (rm = -0.002) of the insects, indicating that the test population would eventually go extinct on this sugarcane genotype. An opposite trend (i.e., population growth) was obtained for the insects raised on Saccharum spp. (SP81-3250 and SP80-1816 cultivars) and Erianthus arundinaceus (Retz) Jeswiet (Kawandang genotype). These results show that S. robustum IM76-229 genotype has resistance traits that drastically reduce spittlebug population growth and indicate that it can be used in breeding programs aiming to develop sugarcane cultivars with resistance to spittlebugs.
Keywords: Erianthus arundinaceus; Saccharum sp; breeding for plant resistance to insects; life history; population fitness.
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