A Mantel test (correlation between matrices) was used to compare similarity in galling
species and host plant family among sites (with PASt 1.86).
observ.), allowing quantification of past galling
history of plants.
1996,1997) selected for low root galling
and egg mass production and of the cultivar Kenstar were germinated on wet filter paper at room temperature.
The results from the Mantel-Haenszel test [ILLUSTRATION FOR FIGURE 2 OMITTED] show that there was no difference in galling
rate here between wild plants and those transplanted back to their original site, after the effects of site had been removed (Mantel-Haenszel [[Chi].sup.2] = 0.824; P = 0.364).
Each generation of the midge yielded an estimate of genetic and environmental variation for resistance to galling
. At high midge densities at the beginning of the outbreak in 1989, substantial genetic variance, both discontinuous and continuous, in resistance to galling
was revealed in the willows; heritability for this trait ranged upwards to about 0.5.
insects have the ability to manipulate the development of plant tissue and promote its growth (Stone and Schonrogge, 2003) and the development of these structures has been an adaptive strategy of many insects for their food and even protection against predators (Mani, 1964; Stone and Schonrogge, 2003).
Variations on climatic conditions and water availability affect the host plant phenology, and could therefore alter the life cycle and the distribution of galling
insects as demonstrated by Oliveira et al.
Under this scenario, reduction in competition favored mutants exploiting plant parts other than leaves (leaf galling
being considered ancestral; Yang and Mitter, 1994).
- The plant was the experimental unit for galling
(n = 10 ungalled, 10 galled).
However, all these features would be responsible for the evolutionary success of galling
insects in such plants, since the action of predators, parasites and pathogens on galling
insects could be less effective in the scleromorphic vegetation types (Goncalves-Alvim & Fernandes 2001, Fernandes et al.
In order to completely test the PVH it is necessary to evaluate the relative rate of growth of the plant module, nutrients, and even secondary compounds at the time of gall induction, because galling
insect larvae may alter the nutritional content of the attacked organ.
Our paper reports an independent test of the relationship between galling
and soil fertility in a different biogeographical province, that of New South Wales, Australia.