Search

The article discusses the study on the attraction and antennal reaction of Vespula vulgaris, a common wasp, to chosen synthetic chemicals in New Zealand beech forests. Vespid wasps are a major problem for it affects the biodiversity of native birds and invertebrates. Seven recognized wasp attractants including acetic acid, isobutanol, and heptyl butyrate were field tested but only heptyl butyrate and octyl butyrate pulled in higher number of wasps than a trap which is non-baited.

1. Intraspecific competition can be an important factor influencing the individual fitness of organisms. This study reports density-dependent effects on the fecundity of the beech scale insect ( Ultracoelostoma assimile, Hemiptera: Margarodidae) on naturally occurring, canopy-dominant red beech ( Nothofagus fusca, Fagaceae) trees in New Zealand. For the first time an increasing intensity of intraspecific competition at increasing spatial scales within individual host trees is demonstrated. 2. Beech scale insect ‘tests’ containing adult female scale insects and eggs were collected from the trunks of 10 red beech trees [17.7–48.5 cm in diameter at breast height (1.4 m), d.b.h.] with varying densities of scale insect infestation. The relationship between individual female fecundity and scale insect density at three spatial scales: local (within 5 cm), lower trunk (below 2 m above ground level), and whole tree, was tested. 3. Beech scale insect fecundity was density dependent, with total female egg load decreasing with increasing scale insect density. The strength of the density-dependent effect increased with increasing spatial scale, suggesting that scale insects are creating a tree-wide drain on the quality of phloem sap, rather than depleting nutrients from localised, high-density areas within trees. These results indicate that at high densities, the New Zealand beech scale insect can have a negative effect on the nutritional quality of the phloem of red beech, thus negatively affecting conspecifics elsewhere on individual host trees. The increasing intensity of the effect with increasing spatial scale within individual trees emphasises the importance of measuring density-dependent effects at the appropriate spatial scale. [ABSTRACT FROM AUTHOR]