Boda et al. (2014) Naturwissenschaften

Pál Boda, Gábor Horváth, György Kriska, Miklós Blahó, Zoltán Csabai (2014): Phototaxis and polarotaxis hand in hand: night dispersal flight of aquatic insects distracted synergistically by light intensity and reflection polarization. Naturwissenschaften, online early, doi: 10.1007/s00114-014-1166-2

 

Abstract
Based on an earlier observation in the field, we hypothesized that light intensity and horizontally polarized reflected light may strongly influence the flight behaviour of night-active aquatic insects. We assumed that phototaxis and polarotaxis together have a more harmful effect on the dispersal flight of these insects than they would have separately. We tested this hypothesis in a multiple-choice field experiment using horizontal test surfaces laid on the ground. We offered simultaneously the following visual stimuli for aerial aquatic insects: (1) lamplit matte black canvas inducing phototaxis alone, (2) unlit shiny black plastic sheet eliciting polarotaxis alone, (3) lamplit shiny black plastic sheet inducing simultaneously phototaxis and polarotaxis, and (4) unlit matte black canvas as a visually unattractive control. The unlit matte black canvas trapped only a negligible number (13) of water insects. The sum (16,432) of the total numbers of water beetles and bugs captured on the lamplit matte black canvas (7,922) and the unlit shiny black plastic sheet (8,510) was much smaller than the total catch (29,682) caught on the lamplit shiny black plastic sheet. This provides experimental evidence for the synergistic interaction of phototaxis (elicited by the unpolarized direct lamplight) and polarotaxis (induced by the strongly and horizontally polarized plastic-reflected light) in the investigated aquatic insects. Thus, horizontally polarizing artificial lamplit surfaces can function as an effective ecological trap due to this synergism of optical cues, especially in the urban environment.


Keywords
Ecological trap, Visual ecology, Photopollution, Polarized light pollution, Phototaxis, Polarotaxis, Cue synergism

Boda & Csabai (2012) Hydrobiologia

P. Boda, Z. Csabai (2012): When do beetles and bugs fly? A unified scheme for describing seasonal flight behaviour of highly dispersing primary aquatic insects. Hydrobiologia, online open

DOI: 10.1007/s10750-012-1350-3

Abstract

Changes of seasonal dispersal flight were investigated based on a wide spectrum of aquatic Heteroptera and Coleoptera species. We hypothesized that species or groups of species can be characterized by various seasonal patterns of dispersal flight. Dispersal activity was studied in a lowland marsh located in NE Hungary during a 30-week long monitoring period. Insects were attracted to highly polarising horizontal shiny black plastic sheets laid onto the ground. There are no periods of the year (from April till October) when insects are not rising into the air, but species have various seasonal flight activity. Dispersal flight activity of 45 species could be described. These activities assessed based on a seasonal approach and proportional classification. Based on these results, three seasonal patterns and twelve sub-patterns were defined. Comparing the observed patterns with previously reported dispersal activity data, we argue that observations found in the literature fit well with patterns defined here, therefore, to assess the dispersal behaviour, a unified scheme can be established. Owing to this unified scheme, the seasonal dispersal activity of primary aquatic insects observed in different studies becomes highly comparable. This scheme can be a useful tool for assessing dispersal behaviour of insects across other geographic regions.

Keywords

Flight behaviour, Seasonal patterns, Year-long dispersal, Polarotaxis, Coleoptera, Heteroptera