Diversity of galling insects in Styrax pohlii (Styracaceae): edge effect and use as bioindicators

Abstract

Impacts of forest fragmentation and edge effect on plant-herbivores interactions are relatively unknown, and the relationships between galling insects and their host plants are very susceptible to environmental variations. The goal of our study was to test the edge effect hypothesis for galling insects associated with Styrax pohlii (Styracaceae) host plant. Samplings were conducted at a fragment of semi-deciduous forest in Goiânia, Goiás, Brazil. Thirty host plant individuals (15 at fragment edge and 15 in its interior) were sampled in July of 2007; in each plant, 10 apical branches were collected at the top, middle and bottom crown levels. Our results supported the prediction of greater richness of gall morphotypes in the edge habitat compared with remnant interior. In a similar way, gall abundance and frequency of attacked leaves were also greater in the fragment edge. These findings consequently suggest a positive response of galling insect diversity to edge effect; in the Saint-Hilaire forest, this effect probably operates through the changes in microclimatic conditions of edge habitats, which results in an increased hygrothermal stress, a determinant factor to distribution patterns of galling insects. We also concluded that these organisms could be employed as biological indicators (i) because of their host-specificity, (ii) they are sensitive to changes in plant quality, and (iii) present dissimilar and specific responses to local variation in habitat conditions. Rev. Biol. Trop. 59 (4): 1589-1597. Epub 2011 December 01.

Ommatissus Lybicus Infestation in Relation to Spatial Characteristics of Date Palm Plantations in Oman

“…They attributed this to a high number of natural enemies' movement from the wild plant to main crop. However, other studies disagree with the current results, such as those concerning the infestation of galling insects on Styrax pohlii Fritsch [39] and the infestation of Fagus orientalis Lipsky [53]. The authors explain the preference of insects to attack stressed plants at the edge were due to climate stress.…”

“…The infestations of the woodwasp S. noctilio on Pinus ponderosa Douglas ex C. Lawson were found to be correlated negatively with the nearest infested field [38]. Also, it was found that a large area field may influence the richness/diversity of beneficial arthropods [39]. In contrast, a strong relationship between infestation and small area plantations was found [40].…”