Migrating moths collected in tower-mounted light traps in northern New South Wales, Australia: influence of local and synoptic weather

Abstract

Catches of moths in tower-mounted light traps in northern New South Wales were analysed in relation to local and synoptic weather. Catches were correlated with windspeed, relative humidity and possibly rainfall. No correlations were obtained with temperature or moon phase. Catches were more likely to occur when winds were from the east, and were associated with wind shifts. There was a significant association with the passage of depressions or troughs, but not cold fronts. The traps were considered to be poor indicators of migration associated with fronts, because these were accompanied by high winds in which trap efficiency was reduced. Stepwise multiple regressions using temperature, relative humidity, rainfall and windspeed accounted for only about 25% of the variance, much lower than in comparable studies with ground level light traps. These results are thought to indicate that the trap catches were reflecting long-distance migration, which was usually associated with disturbed weather. Back tracking with upper wind data was used to define probable sources of moths. In the spring and early summer, these sources were predominantly to the north and west of the traps, in semi-arid pastoral and subhumid cropping zones. In the late summer and autumn they were predominantly to the south and east, in the humid pastoral and forest zone. These results are discussed in relation to the migratory strategies of several important agricultural pest species.

The effect of the tree species ratio of European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) on polyphagous and monophagous pest species – Lymantria monacha L. and Calliteara pudibunda L. (Lepidoptera: Lymantriidae) as an example

“…In every investigated forest stand, one trap was fixed on a 1.80-m-high metal gibbet. The operation of the light traps within the (Gregg et al, 1994;Steinbauer, 2003). As a consequence, the synchronous operation of light traps is necessary for a legitimate comparison of moth catches from different biotopes (Intachat et al, 1997).…”

Insects in Flight

“…Gregg et al (1994) found reduced catches of migratory moths when wind speed increased, as did Edwards et al (1987) for Culicoides midges. Gentle rain may not reduce catches but heavy rain and moderate or strong winds do so.…”

Effect of light colours and weather conditions on captures of Sogatella furcifera (Horváth) and Nilaparvata lugens (Stål)

“…The wind force was significantly negatively correlated with light trap catches of N. lugens. Wind generally affects catch size, that is, a significantly negative correlation exists between total moth catch and wind speed (Gregg et al 1994). In addition, catches of insect species may be increased by placing windshields on the windward side of the traps (Hollingswort et al 1961).…”