Screening for Resistance to Adult Spittlebugs (Hemiptera: Cercopidae) in <I>Brachiaria</I> spp.: Methods and Categories of Resistance

Abstract

Both nymphal and adult stages of several species of spittlebugs (Hemiptera: Cercopidae) are key economic pests of brachiariagrasses (Brachiaria spp.) in tropical America. Progress has been made in the characterization and development of antibiosis resistance to nymphs in brachiariagrasses. Essentially no attention has been given to screening germplasm for resistance to adults. To support current breeding programs, a series of experiments was conducted to develop a methodology to screen for adult damage and to study categories of resistance to adult feeding damage. Six host brachiariagrass genotypes were used: two susceptible checks (CIAT 0606 and CIAT 0654) and four nymph-resistant genotypes (CIAT 6294, CIAT 36062, CIAT 36087, and SX01NO/0102). Test insects were Aeneolamia varia (F.) and Zulia carbonaria (Lallemand). None of the nymph-resistant genotypes was antibiotic to adults. All four nymph-resistant genotypes showed tolerance to A. varia and Z. carbonaria feeding damage. The levels of tolerance to adults of Z. carbonaria, a larger, more aggressive species, were lower. Of the four nymph-resistant genotypes, only CIAT 6294 and CIAT 36087 showed some tolerance to Z. carbonaria expressed as lower leaf damage scores, less chlorophyll loss, and lower functional plant loss indices. The fact that a genotype like SX01NO/0102, which is highly antibiotic to nymphs, is susceptible to adult damage suggests that mechanisms of resistance to the two spittlebug life stages may be independent. Results of these studies suggest a need to incorporate routine screening for tolerance to adult feeding damage as an additional selection criterion in the breeding scheme.

Resistance mechanisms of sugarcane cultivars to spittlebug Mahanarva fimbriolata

“…Different antibiosis levels for spittlebugs have been observed by researchers in many cultivated plant species (e.g., Auad et al, 2007;Cardona et al, 2004;Lapointe et al, 1992;López et al, 2009;Miles et al, 2006;Pabón et al, 2007 andHeinrichs, 1983), although little information was available for sugarcane genotypes prior to this study. One of the few studies involving sugarcane did report significant effects for six sugarcane cultivars on M. fimbriolata nymph survival (Garcia et al, 2011) and reported nymph survival values were similar to those in this study (78 % for SP81-3250).…”

Characterizing Herbivore Resistance Mechanisms: Spittlebugs on <em>Brachiaria</em> spp. as an Example

“…A few key parameters we have considered to design our test include the age of the host plants, the species and developmental stage of the spittlebugs, the infestation level, and the duration of plant-insect contact 8,9,12 . Several rounds of experimentation and protocol refinement may be needed to reach to a rapid, cost-effective, reliable, assay that adequately predicts herbivore resistance in the field.…”

Evaluation of forage grass resistance to Mahanarva fimbriolata (Stål)

“…López et al (2009) developed a methodology to evaluate the resistance of grasses to adult stages based on the observation of the visible leaf damage and the loss of chlorophyll, but they did not address the parameters adopted in the present study.…”

“…Combined with the lower adult longevity, the low number of eggs can drastically reduce the population of this insect. López et al (2009) suggested that grasses with high levels of antibiosis to nymphs can be highly damaged by adults of the same species and recommended the inclusion of adult assessments as additional selection criteria in the development programs of new cultivars.…”

“…Another option is the use of resistant plants, which stands out because it is the most appropriate tool for these situations from an economic and environmental perspective and can be used with biological and cultural controls, thereby contributing to the integrated management of this pest (Nilakhe 1987;Vendramim 1990;Lapointe and Sonoda, 2001;Valério 2005). Several studies are being developed toward the goal of selecting a grass that is resistant to both the nymphs and adults of spittlebugs (Ferrufino and Lapointe 1989;Valério et al 1997;Cardona et al 2004;López et al 2009;Cardona et al 2010).…”