Arthropod Community On A Cu Hyperaccumulator, Elsholtzia Splendens Nakai Ex F. Maekawa (Lamiales: Lamiaceae), And Cu Concentration In Two Insect Herbivores

Heavy metals in soil can be transferred to arthropods through food chains and accumulated in these animals. The thesis describes major factors affecting their transfer to and accumulation in arthropods, and their impacts on different trophic guilds including herbivores, predators, parasitoids and detritivores at population and community levels. Potential ecological risks on arthropod community are to be clarified when using Elsholtzia splendens Nakai ex F. Maekawa, a Cu hyperaccumulator, to remedy Cu contaminated soilObjectives of this study are to determine arthropod taxa and abundance on E. splendens and Cu concentrations in major species, and subsequently to found a basis for future studies involving interactions between E. splendens and arthropods and risk assessment of this plant for soil-remediation purpose.Arthropod taxa and abundance were surveyed on the canopy of E. splendens in Fuyang, Zhejiang, China from late August to mid November, 2005. A total of over 15600 individuals were collected on seven dates, which belonged to two classes (Insecta and Arachnida), 10 orders, and at least 43 families. Insects accounted for 93.6% of the arthropods. Thysanoptera, Coleoptera and Diptera were the dominant taxa, and Homoptera, Orthoptera, Lepidoptera, Hymenoptera and Araneida were common taxa.In the collected arthropods, herbivores, predators, parasitoids and detritivores accounted for 74.1, 6.3, 1.1 and 17.8%, respectively. The rest 0.7% of individuals were uncertain of their trophic positions. Thrips and Chrysomelids were the most abundant herbivores, followed by pyrgomorphids and cicadellids. Most of predators were spiders, and all of parasitoids were hymenopteran wasps. In the detritivores, Chironomids were the most abundant, followed by cyclorrhaphan flies.Cu concentrations were determined in Atractomorpha sinensis nymphs and adults collected in late August and late September, and in larvae of a noctuid species collected in late August, early September and early October on the canopy of E. splendens. The Cu in A sinensis and the noctuid was 71.5-106.2 and 12.5-84.0 mg kg~-1, respectively, with an average of 87.9 and 48.3 mg kg~-1, respectively.Cu concentrations of both insects were related significantly with collection time, but not significantly with their body size. For A. sinensis, big individuals had higher Cu concentrations in early September and early October than in late August, but the concentrations of small and moderately sized individuals varied little with time. For the noctuid larvae, big and moderately sized individuals had higher Cu concentrations in late September than in late August, but small ones had similar concentrations between the two times.In a climatically controlled chamber (28±1 ℃, L16:D8), E. splendens was planted in pots containing mixed vermiculite and perlite without Cu. At about 220 d after seeding, plants (around 65 cm in height) were used to collect their volatile using SPME. Eleven chemicals were identified using GC-MS, p-pinene, D-limonene, elsholtzia ketone, dehydro elsholtzia ketone, γ-elemene, humulene, caryophyllene, a-caryophyllene, and three sesquiterpenes. The most abundant volatiles were caryophyllene and y-elemene, followed by humulene and a-caryophyllene.