Közvetlen és közvetett polarotaxis vizsgálata tegzeseknél és kétszárnyúaknál = Direct and indirect polarotaxis in caddis flies

A kutatás eredményei: 1. BÖGÖLYÖK ÉS ÁRVASZÚNYOGOK POZITÍV POLAROTAXISA Kutatásaink során a bögölyök és az árvaszúnyogok számos faja esetében sikerült bebizonyítanunk mindkét nem esetében a pozitív polarotaxis meglétét, miáltal ezek a rovarok az összetett szemük ventrális részével képesek érzékelni a vízszintesen poláros fényt. A bögölyök vizsgálata kapcsán elsőként tártuk fel a közvetett polarotaxis alapját, amelynek a célja nem a vízbe való petézés, vagy a vízbe való érkezés. A bögölyök pozitív polarotaxisának felismerése lehetőséget adott számunkra olyan új optikai alapon működő bögölycsapda prototípusok kifejlesztésére, amelyek hatékonyabban csapdázzák a rovarokat, mint a jelenleg forgalomban lévők. 2. POLÁROS FÉNYSZENNYEZÉS ÉS ÖKOLÓGIAI CSAPDÁK Kutatásaink összegzéseként bevezettük a nemzetközi szakirodalomba a poláros fényszennyezés fogalmát, amely a hagyományos fényszennyezés egy új fajtája, amit a fényt erősen polarizáló mesterséges tükröző felületek keltenek. Polarotaktikus vízirovarokkal folytatott terepkísérletekben és képalkotó polarimetriai mérésekkel meghatároztuk a poláros fényszennyezés legfőbb forrásait, amelyek minden polarotaktikus vízirovarra poláros ökológiai csapdaként hatnak. A poláros fényszennyzés hozzájárulhat egyes rovarpopulációk kipusztulásához, és megbolygathatja a rájuk épülő táplálkozási hálózatokat is. Kutatásaink során több lehetőséget is találtunk a poláros fényszennyezés csökkentésére vagy megszüntetésére. | The results of the research: 1. POSITIVE POLAROTAXIS OF TABANIDS AND CHIRONOMIDS We presented evidence for positive polarotaxis, i.e., attraction to horizontally polarized light stimulating the ventral eye region, in both males and females of tabanid and chironomid species. The novelty of our findings is that positive polarotaxis has been described earlier only in connection with the water detection of some aquatic insects ovipositing directly into water. A further particularity of our discovery is that in the order Diptera and among blood-sucking insects the studied tabanids are the first known species possessing ventral polarization vision and definite polarization- sensitive behavior with known functions. The polarotaxis in tabanids makes it possible to develop new optically luring traps being more efficient than the existing ones. 2. POLARIZED LIGHT POLLUTION AND POLARIZATION ECOLOGICAL TRAPS We introduced a new term, the polarized light pollution (PLP), meaning all adverse effects on polarotactic aquatic insects attracted by horizontally polarized light reflected from artificial surfaces. In numerous choice experiments with polarotactic insects and using imaging polarimetry we gave experimental evidence of PLP. We suggested several remedies of PLP, which is a byproduct of the human architectural, building, industrial and agricultural technology, and it may allow to function feeding webs composed of polarotactic insects and their predators

How did amber get its aquatic insects? Water-seeking polarotactic insects trapped by tree resin

Abstract Amber contains numerous well-preserved adult aquatic insects (e.g., aquatic beetles — Coleoptera, water bugs — Heteroptera, dragonflies — Odonata, caddisflies — Trichoptera, mayflies — Ephemeroptera, stone flies — Plecoptera). Since amber is fossilised resin of terrestrial conifer trees, it is an enigma how aquatic insects have ended up in the resin. Based on field studies in a Hungarian forest along a freshwater creek we suggest that tree resin traps water-seeking flying polarotactic aquatic insects because of its property to polarise reflected light. The sticky tree resin was modelled by a water-proof, transparent, colourless insect-monitoring glue laid on vertical and horizontal fallen tree trunks next to the creek. Adults of various polarotactic aquatic insect species were trapped only by the horizontal sticky trunk. In earlier field experiments we showed that these insects find water by means of the horizontal polarisation of water-reflected light, and therefore are attracted to and land on all surfaces which reflect horizontally polarised light. Using imaging polarimetry, we revealed the criterion of polarisation-based trapping by resiny tree trunks. According to our observations, flying aquatic insects can be trapped by sticky (resiny) regions of fallen tree trunks that reflect horizontally polarised light and thus attract polarotactic species. The resin continues to flow out of the trees even when fallen over or fractured in a storm. Our findings support and complement an earlier hypothesis, according to which amber-preserved adult aquatic insects have been trapped by resiny bark when they dispersed over land

Spectral Sensitivity Transition in the Compound Eyes of a Twilight-Swarming Mayfly and Its Visual Ecological Implications

Aquatic insect species that leave the water after larval development, such as mayflies, have to deal with extremely different visual environments in their different life stages. Measuring the spectral sensitivity of the compound eyes of the virgin mayfly (Ephoron virgo) resulted in differences between the sensitivity of adults and larvae. Larvae were primarily green-, while adults were mostly UV-sensitive. The sensitivity of adults and larvae were the same in the UV, but in the green spectral range, adults were 3.3 times less sensitive than larvae. Transmittance spectrum measurements of larval skins covering the eye showed that the removal of exuvium during emergence cannot explain the spectral sensitivity change of the eyes. Taking numerous sky spectra from the literature, the ratio of UV and green photons in the skylight was shown to be maximal for θ ≈ − 13° solar elevation, which is in the θmax = -14.7° and θmin = -7.1° typical range of swarming that was established from webcam images of real swarmings. We suggest that spectral sensitivity of both the larval and adult eyes are adapted to the optical environment of the corresponding life stages.Funding provided by: National Research, Development and Innovation Fund of Hungary*Crossref Funder Registry ID: Award Number: 131738/PD_19Funding provided by: Ministry for Innovation and TechnologyCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100015498Award Number: ÚNKP-21-3Funding provided by: Jan Gershoj*Crossref Funder Registry ID: Award Number