biological control

Common gorse (Ulex europaeus) is one of the most invasive species worldwide. Biological control of gorse by two pre-dispersal seed predators (the weevil Exapion ulicis and the moth Cydia succedana) is used in New Zealand. Gorse shrubs are distributed along wide natural gradients, and this could influence seed predation. The aim of this study was to identify factors that influence seed predation along two natural gradients, of light availability and gorse density. Seed predation was studied in the native range of the species, in south-west France.

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One of the strongest patterns in the historical record of biological control is that programmes targeted against lepidopteran pests have been far less successful than those targeted against homopteran pests. Despite fueling considerable interest in the theory of host–parasitoid interactions, biological control has few unifying principles and no theoretical basis for understanding the differential pattern of success against these two pest groups.

Withdrawal of the use of cheap, persistent organochlorine insecticides in New Zealand pastures has shifted the emphasis of insect pest control to non-chemical methods during the last 10-15 years.

Invasive weeds have been shown to alter ecosystem processes such as decomposition and nutrient cycling. However, little is known about the effects of introduced biocontrol agents on these processes. This study examined the effects of alligator weed (Alternanthera philoxeroides) and its biocontrol agent, the alligator weed flea beetle (Agasicles hygrophila), on nutrient cycling in a northern New Zealand lake.

We studied the genus- and species-specialist monophagous herbivorous insects of Senecio (Asteraceae) in Auckland, New Zealand. With the exception of the widespread S. hispidulus, the eight native Senecio species in mainland Auckland (two endemic) are typically uncommon and restricted to less modified conservation land. However, 11 naturalised Senecio have established and are often widespread in urban and rural habitats.