Relationship between the development of Simulium maculatum (Diptera: Simuliidae) and the thermal regime

Rasa Bernotienė,Galina Bartkevičienė

doi:10.14411/eje.2011.050

Abstract

Warmer temperatures in the past 30 years have significantly influenced the seasonal development of insects throughout Europe. As a result of the outbreaks of black flies that have occurred in southeastern Lithuania since the 1970s it is hypothesized that this increase in black fly activity is due to the change in climate. To test this hypothesis the development of Simulium maculatum Meigen under different conditions was determined. This revealed that the time of hatching of S. maculatum eggs in Lithuania was influenced by winter air temperatures, especially those in March. Pupation in S. maculatum is associated with the increase in air and water temperatures that occur at the end of April and in May. The emergence of S. maculatum black flies occurs most often in May. At a water temperature of 13.2°C (1999), S. maculatum took 42 days to develop and half this time (21 days) when the water tem- perature was 18.8°C (2005). The number of black flies that emerged each year was determined by air temperature but unaffected by rainfall in June (either per month or per ten-day period).

Highlights

The black fly Simulium (Byssodon) maculatum Meigen was described from Germany in 1804
In 1997–2002 and in 2007–2009 the mean winter air temperature exceeded the long term average and the beginning of S. maculatum development was close to the mean of 121 days from 1st January or earlier
As there has been an increase in the numbers of outbreaks of black flies in south eastern Lithuania since the 1970s it is hypothesized that this increased black fly activity is associated with changes in the climate

Summary

Introduction

The black fly Simulium (Byssodon) maculatum Meigen was described from Germany in 1804. Once widespread S. maculatum is extinct in many of the large river systems in central Europe (Zwick & Crosskey, 1980). S. maculatum has been an abundant inhabitant of the Nemunas River in Lithuania since the 1970s. It is the main pest species in southern Lithuania (Žygutienơ & Pakalniškis, 1997; Žygutienơ & Sprangauskaitơ, 1998) and the subject of biological control since 1998 (Pakalniškis et al, 2006). The time of eclosion and development of the larvae in the Nemunas River varies between years. The schedule of black fly control measures in the Nemunas River, which depend on larval eclosion and development, varies between years

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