Applying polarization-based traps to insect control

Following the new findings described in Chap. 21 regarding the use of polarization cues by chironomids to detect water bodies suitable for oviposition, an effort was initiated to apply reflection-polarization traps to divert chironomid females from laying their eggs in the natural reservoir and by this to control the chironomid population. In this chapter we first review this effort and its outcome and suggest insights into the future development of chironomid reflectionpolarization oviposition traps and population control. Then we present three different types of polarization-based tabanid trap: a liquid trap, a sticky horseflypaper and a photovoltaic trap. All three trap types share the common feature that they lure positively polarotactic tabanid flies with strongly and linearly polarized light reflected from special shiny black visual targets. Due to their horizontally polarizing bait surface, the liquid and the photovoltaic traps as well as the horizontally aligned horseflypaper capture water-seeking male and female tabanids attracted to the horizontal polarization of bait-reflected light. If the surface of the horseflypaper is vertical, it catches host-seeking female tabanids lured to the strongly polarized trap-reflected light. The tabanid-capturing efficacy of all three trap types has been proven in field experiments. The scientific basis of these traps is the two kinds of positive polarotaxis in tabanid flies. The advantages and disadvantages of these different tabanid traps are also discussed here; furthermore, it is described how these traps could be improved in the future, and how they can be combined with the traditional canopy trap, for instance. These studies demonstrate well how basic scientific knowledge, i.e. the positive polarotaxis in chironomids and tabanids, can be applied in the design of new insect traps.