The effect of light of different spectra on invertebrates active at dusk and in broad daylight.

Nie tylko intensywność nasłonecznienia i temperatura, ale również długość fali i temperatura barwy światła ma wpływ na różne funkcje organizmu. Poznano już wpływ światła o różnym spektrum na życie roślin i człowieka, jednak mało jest informacji na ten temat dotyczących bezkręgowców. Nie wiemy, czy tak jak w przypadku ssaków, żródła światła typu LED wpływają na poprawne funkcjonowanie organizmu, czy wpływają na aktywność ruchową bądź nie zaburzają cyklu okołodobowego. Celem eksperymentów było zbadanie oddziaływania światła o różnej długości fal pochodzącego z diod LED na aktywność ruchową bezkręgowców dnia pełnego i zmierzchu. W wyniku przeprowadzonych badań stwierdzono wpływ zarówno długości fali światła, jak i temperatury barwowej światła na aktywność ruchową badanych bezkręgowców. Wykazano, że nie ma jednolitego schematu wpływu danego oświetlenia na bezkręgowce o różnych preferencjach świetlnych. Na podstawie przeprowadzonego doświadczenia można wnioskować, że zmiana oświetlenia na LED o określonej barwie, w środowisku człowieka, może znacząco wpływać na funkcjonowanie organizmów bezkręgowych.Not only sunlight intensity and temperature, but also the light wavelength and colour temperature affect various body functions. The importance of the spectrum of light in the life of plants and humans has already been demonstrated. However, similar information on the effect of the light spectra on invertebrates is scarce. We do not know, whether, similarly to mammals, LEDs affect their correct body functions, influence their motor activity or disturb their circadian rhythm. The aim of the study was to verify the effect of the LED light of various wavelengths on motor activity of invertebrates having different preferences for the light intensity in their natural environment. The obtained results show that the light wavelength and colour temperature influence the motor activity of the studied insects. It was demonstrated that a scheme in which a given light affects insects of different light preferences is not uninform. On the basis of the conducted study it can be concluded that a change in exposure to LED light of specified colour in the human environment may significantly affect functioning of invertebrates

Heat box.

<p>Heat box used to measure the latency to escape from noxious temperature (50°C) in cockroaches.</p

Levels of oxidative stress marker (MDA) and catalase activity in cockroaches after five-trial and single-trial heat box tests.

<p>Levels of oxidative stress marker (MDA) and catalase activity in cockroaches after five-trial and single-trial heat box tests.</p

Results of statistical analysis of five-trial heat box test data.

<p>Results of statistical analysis of five-trial heat box test data.</p

Five-trial heat box test.

<p>Latency to escape from noxious heat—50°C (s; mean ± SEM) after administration of water (Con), vehicle (V), capsaicin 0.0001mM (C 0.1) and 0.1mM (C100), menthol 2mM (M), thymol 1mM (T), camphor 15mM (CMF), allyl isothiocyanate 3mM (AITC) and capsazepine 0.0001mM (CPZ) in American cockroaches. Insects were exposed to the test compound and placed at 50°C once a day for five days–each dose administration and exposure to heat was repeated every 24 hours—five trial heat box test. Letters indicate results statistically significant vs. control (A) or solvent (B) group in each tested day (Mann-Whitney U test with Holm adjustment).</p

Altered heat nociception in cockroach <i>Periplaneta americana</i> L. exposed to capsaicin

<div><p>Some natural alkaloids, e.g. capsaicin and camphor, are known to induce a desensitization state, causing insensitivity to pain or noxious temperatures in mammals by acting on TRP receptors. Our research, for the first time, demonstrated that a phenomenon of pharmacological blockade of heat sensitivity may operate in American cockroach, <i>Periplaneta americana</i> (L.). We studied the escape reaction time from 50°C for American cockroaches exposed to multiple doses of different drugs affecting thermo-TRP. Capsaicin, capsazepine, and camphor induced significant changes in time spent at noxious ambient temperatures. Moreover, we showed that behavioral thermoregulation in normal temperature ranges (10–40°C) is altered in treated cockroaches, which displayed a preference for warmer regions compared to non-treated insects. We also measured the levels of malondialdehyde (MDA) and catalase activity to exclude the secondary effects of the drugs on these processes. Our results demonstrated that increase in time spent at 50°C (five versus one trial at a heat plate) induced oxidative stress, but only in control and vehicle-treated groups. In capsaicin, capsazepine, menthol, camphor and AITC-treated cockroaches the number of exposures to heat had no effect on the levels of MDA. Additionally, none of the tested compounds affected catalase activity. Our results demonstrate suppression of the heat sensitivity by repeated capsazepine, camphor and capsaicin administration in the American cockroach.</p></div

Results of Wilcoxon-signed rank test for five-trial heat box test.

<p>Results of Wilcoxon-signed rank test for five-trial heat box test.</p

Behavioral thermoregulation in cockroaches after repeated compound administration.

<p>Ambient temperature preferred (°C; mean±SEM) by American cockroaches exposed to vehicle, capsaicin 0.0001mM (C 0.1) and 0.1mM (C100), capsazepine 0.0001mM (CPZ), menthol 2mM (M), thymol 1mM (T), camphor 15mM (CMF) and allyl isothiocyanate 3mM (AITC). Cockroaches were exposed to the test compounds for five days–each dose was repeated every 24 hours and then the insect was placed in the thermal gradient for 24 hours (n = 12 for each substance). * indicates values statistically significant from vehicle group (Mann-Whitney U test with Holm adjustment, * p<0.05; **p<0.01; *** p<0.001).</p

Experimental design.

<p>The scheme of the experimental design.</p