We describe flight variability in the woodwasp Sirex noctilio Fabricius, 1793 (Hymenoptera: Siricidae) by studying tethered females in a flight mill device and analyzing output data by a time series methodology. Twenty-eight wasps were flown during 24 h-long periods, under controlled temperature and lighting conditions. The maximum distance recorded was 49 km, and mean velocity was 0.37 m s–1. All wasps lost weight during flight (mean weight loss of 10.0% of initial body mass). By using a wavelets analysis on the flight mill time series output, we identified three distinct flight patterns: regular (long acceleration–deceleration spells), periodic (alternation of acceleration–deceleration spells without resting) and pulsating (resting spells interrupted by bursts of flight activity). The first two flight patterns are indistinguishable using traditional flight mill data analysis. Flight patterns for each individual were significantly dependent on wasp body mass, suggesting a relationship with the resources used in flight and their availability. Large females flew sequentially through a regular-periodic-pulsating sequence but medium sized wasps flew mostly with periodic and pulsating patterns. The smallest wasps flew only in a pulsating pattern, being incapable of long, sustained flight. Variability in size and behavior can have significant consequences on population dynamics by determining local and regional dispersal. An important outcome of our work is the introduction of wavelet analysis to study tethered flight data series for the first time. This methodology allowed us to uncover and statistically test individual variability in insect flight characteristics.
1 November 2007 in Entomologia Experimentalis et Applicata
The invasive woodwasp Sirex noctilio has become one of the most significant pests of pine forests throughout the northern and southern hemispheres. In Patagonia (southern Argentina), S. noctilio was first detected in the early 1990s. However, in less than two decades, and despite intensive control efforts, populations have spread, and outbreaks have been observed. In this paper, we outline and define several key ecological and behavioral features of S. noctilio (namely, spatiotemporal population dynamics, phenology and dispersal) and briefly discuss their implications for the design, implementation and evaluation of local and regional management strategies. We argue that limited information on pest ecology and the extrapolation of control measures without local adaptation may together have affected management success. We conclude that efforts directed to understanding of pest ecology and life-history traits as expressed in specific invaded habitats may help us improve our competence in controlling invasive forest insects.