New data on Agrilus auroguttatus
Agrilus auroguttatus (Coleoptera: Buprestidae – EPPO Alert List) is a wood borer which has recently been introduced into California (US), probably from Arizona (US). In California, A. auroguttatus is causing extensive tree mortality on native oak species (see EPPO RS 2013/058). Recent studies have been conducted in the USA and provide new information about this pest.
Determination of its area of origin in Arizona
In California, the development of a classical biological control program against A. auroguttatus is a high priority due the continuing ecological and economic damage caused by this insect since its introduction. In order to determine its area of origin, an analysis of the genetic relationships existing between and within populations of A. auroguttatus from Arizona and California has been conducted. Although the area of origin for the invasive population in California could not be firmly determined, results suggest that the Dragoon Mountains (Cochise county in Arizona) could be a possible area of origin. Future surveys for natural enemies which might be used in the biological control of A. auroguttatus will be focussed on the Dragoon Mountains area (Lopez et al., 2014b).
The flight performance of adults of A. auroguttatus under different age (old/young), mating (virgin/mated) and nutritional (fed/starved) status was assessed under controlled conditions using computerized flight mills. Adults were attached to flight mills for a 24 h period, and the total distance flown, flight times and velocities, number and duration of flight periods, body size and weight were measured. It was observed that nutrition, body size, and interactions between nutrition and age were important factors (gender and mating status had no influence), and that A. auroguttatus was only capable of flying relatively short distances during a 24 h period. The general results of these experiments indicate that A. auroguttatus is unable to fly long distances across habitats that lack suitable host plants. The authors concluded that their work supports the hypothesis that human-aided transportation (probably via infested oak firewood) from Southern Arizona across the Sonora desert has led to the introduction and subsequent spread of A. aurogutattus within the native oak woodlands of Southern California (Lopez et al., 2014a).
Lopez VM, McClanahan MN, Graham L, Hoddle MS (2014a) Assessing the flight capabilities of the goldspotted oak borer (Coleoptera: Buprestidae) with computerized flight mills. Journal of Economic Entomology 107(3), 1127-1135.
Lopez VM, Rugman-Jones PF, Coleman TW, Hoddle MS, Stouthamer R (2014b) Population genetics of goldspotted oak borer, Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae): investigating the origin of an invasive pest of native oaks in California. Biological Invasions 16(11), 2393-2402.