This study determined the potential of the tortoise beetle (Coleoptera: Chrysomelidae) to control Canada thistle (Asteraceae) in Iran. Genetic analysis of the tortoise beetle, based on mitochondrial DNA, confirmed the presence of the species in Iran. A field experiment using five insect densities (0 to 20 larvae plant−1) showed a positive correlation between the number of larvae transferred and impact. Feeding by 20 larvae reduced total biomass of Canada thistle by 78% and the number of capitula by 94%. More important, when grown in competition with wheat, four and eight egg batches (corresponding to approximately 12 and 24 larvae) per Canada thistle plant increased wheat ear weight by 46 and 82%, respectively. Host range studies with 22 crop and 21 weed species using no-choice and multiple-choice tests under laboratory and field conditions and parallel data from a field survey showed that joint feeding and oviposition were restricted to Canada thistle and a few other weed species. Limited feeding, without oviposition, was recorded on an additional seven weed species but also on safflower (10 to 15% reduction in biomass), and common sunflower (< 10%); the latter only under no-choice conditions. The growing period of either crop species, however, does not coincide with the feeding period of the tortoise beetle in the field. Findings indicate that the tortoise beetle is a promising biological control agent for Canada thistle in arable crops and grasslands in Iran. Other complementary methods will likely be needed to prevent substantial yield losses.

Little is known about the change of species-rich tropical insect communities along habitat gradients. Diversity and species richness of geometrid moths were investigated at 15 anthropogenically disturbed sites in a montane area in the Andes of southern Ecuador representing a successional gradient. These plots were compared with six closed-forest understorey sites. We collected a total of 23,720 individuals representing 868 morphospecies. Local diversity increased with forest recovery and decreased with increasing distance to the natural forest. 18.6% of all species were found as unique singletons. The mean proportions of local singletons differed significantly between three succession classes. Forest understorey showed a higher proportion of singletons than early and late successional stages. Ordination of the moth samples showed a clear separation of geometrid ensembles at successional sites vs. the forest understorey sites. Patterns of species turnover were influenced by the degree of habitat openness, and to a lesser extent by elevation. However, faunal differences were not related to geographical distances between the sampling sites. In conclusion, geometrid moth ensembles of regenerating Andean montane forest remain diverse, but change significantly in composition relative to adjacent natural forest, whereas the diversity and composition of the geometrid fauna are far more strongly affected in non-forested habitats and abandoned pastures.

Geometrid moths were collected on Mt. Kinabalu (Sabah, Malaysia) along two habitat gradients, ranging from primary rain forest to cultivated areas. During 135 nights' trapping in 1997, 4585 individuals representing 500 species were attracted by light. Primary forest samples and those from old-grown regenerated forest exhibited high diversity (Fisher's α = 75–128), while agricultural areas as well as most secondary forests had a significantly lower diversity (α = 34–61). One 15-y-old secondary forest with a rich undergrowth vegetation also housed a diverse geometrid community (α = 89). In three paired samples, diversity of geometrid moths in the canopy was equal to or lower than in the understorey. Of six habitat variables tested, only undergrowth plant species diversity emerged as a significant predictor of geometrid diversity. The NESS index, in combination with multi-dimensional scaling, was used to investigate patterns of between-habitat diversity. Of two dimensions extracted, one represented the degree of habitat disturbance, while the other separated the two study areas. Geometrid samples of strongly disturbed habitats did not converge between sites, indicating that apart from the degree of human interference the regional species pool was also important in determining similarity among local communities.