Abstract Detail

Recent Topics Posters

Hernández Villanueva, Miguel Ángel [1], Díaz Castelazo, Cecilia [2].

Extrafloral nectaries of Cedrela odorata (Meliaceaea) mediating ant activity and its potential in shoot borer control in forests and plantations in Veracruz, Mexico.

Extrafloral nectaries (EFNs) are nectar glands on diverse plant organs that often attract insect predators of herbivores, promoting plant-insect mutualism. EFNs, visited by ants, occur at developing leaves of the red cedar (Cedrela odorata, Meliaceae) on coastal Veracruz, Mexico. However, the potential of EFnectar of C. odorata on ant attraction has never been studied. This is essential to explore biological control potential by ants on the shoot borer Hypsipyla grandella (Lepidoptera), the main pest on plantations of C. odorata in the neotropics. At 40 randomly selected C. odorata trees per site (2 tropical semideciduous forests, 3 plantations) on central Veracruz, we estimated the day-night frequency and richness of ants visiting EFNs, the proportion of active EFNs and its influence on ant visitation. Twenty ant species were found, forest sites showing higher richness (7-12 spp.) than plantations (0-7). Ant frequency on EFNs was lower for two managed plantations (fumigation practices) compared to sites with no management (i.e. forests) (H=65.86, P < 0.0001). Proportion of active EFNs on each site was generally lower on plantations compared to forests (H=57.17, P < 0.0001). In plantation 3 we found a significant positive correlation between total amount of EFNs and ant visitation frequency (rho=0.34, P < 0.05); also at this plantation -the site with higher damage levels by H. grandella-, we found a significant positive correlation between percentage of active EFNs and shoot borer damage (rho=0.36, P < 0.05), suggesting an herbivory-induced nectar secretion, presumably to reclute ants as natural enemies. Only at one forest site, a significant negative correlation was found between the proportion of active EFNs and ant visitation frequency (rho=-0.35, P < 0.05); this is a seasonal environment and factors other than EFN activity may influence ant activity, such as abiotic factors or abundance of other EFN-bearing plants. Ants may have different potentials for controlling H. grandella in plantations and forests, thus we should consider these jointly with abiotic and management-derived variables.

Broader Impacts:
Extrafloral nectaries occur at developing leaves of the red cedar (Cedrela odorata, Meliaceae) on coastal Veracruz, Mexico. However, the potential of EFnectar of C. odorata on ant attraction has never been studied. This is essential to explore biological control potential by ants on the shoot borer Hypsipyla grandella (Lepidoptera), the main pest on plantations of C. odorata in the neotropics. Twenty ant species were found, forest sites showing higher richness than plantations. Ant frequency on EFNs and proportion of active EFNs was lower in plantations compared to sites with no management (forests). We did found correlation between total amount of EFNs and ant visitation frequency and presumably an herbivory-induced nectar secretion, suggesting an important defensive activity of ants against shoot borer. This is the first research that consider the effect of EFN and ant activity occuring on Cedrela odorata both in natural and managed systems, and provides foundation to integrated natural control of H. grandella pest.

1 - Instituto de Ecología, A.C. (INECOL), Red de Interacciones Multitróficas, Carretera antigua a Coatepec no. 351, El Haya, Xalapa, Veracruz, 91070, MEXICO
2 - Instituto de Ecología, A.C. (INECOL), Red de Interacciones Multitróficas, Carretera antigua a Coatepec no. 351, El Haya, Xalapa, Veracruz, 91070, MEXICO

Keywords:
Cedrela odorata
extrafloral nectaries
ant activity
shoot borer
semideciduous forest
red cedar plantations
Mexico.

Presentation Type: Recent Topics Poster
Session: P
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM
Number: PRT011
Abstract ID:1111