ABSTRACT
Gypsy moth Lymantria dispar (GM) is a polyphagous insect and one of the most significant pests in the forests of Eurasia and North America (U.S. and Canada). Accurate information on GM cold-hardiness is needed to improve methods for the prediction of population outbreaks, as well as for forecasting possible GM range displacements due to climate change. As a result of laboratory and field studies, we found that the lower lethal temperature (at which all eggs die) range from -29.0 °C to -29.9 °C for three studied populations of L. dispar asiatica, and no egg survived cooling to -29.9 °C. These limits agree, to within one degree, with the previously established cold-hardiness limits of the European subspecies L. dispar, which is also found in North America. This coincidence indicates that the lower lethal temperature of L. dispar is conservative. Thus, we found that the Siberian populations of GM inhabit an area where winter temperatures go beyond the limits of egg physiological tolerance, because temperatures often fall below -30 °C. Apparently, it is due to the flexibility of ovipositional behavior that L. dispar asiatica survives in Siberia: the lack of physiological tolerance of eggs is compensated by choosing warm biotopes for oviposition. One of the most important factors contributing to the survival of GM eggs in Siberia is the stability of the snow cover.
Subject(s)
Cold Temperature , Moths/physiology , Ovum/physiology , Animals , Female , Oviposition , SiberiaABSTRACT
INTRODUCTION: One of the most urgent problem of modern medicine is the fight against the disease caused by the Human Immunodeficiency Virus (HIV) - HIV infection. The chemical compounds have improved the situation for infected people, but they are toxic, disrupt the metabolism and cannot eliminate the integrated virus from the body. The emergence of resistant HIV strains makes these treatments ineffective. Often, the death of HIV-infected people occurs as a result of the development of opportunistic infections caused by viruses of the Herpesviridae family. Therefore, the search for new therapeutic and preventive drugs that are less toxic and active against several viruses at the same time is relevant. Basidiomycetes, higher fungi, are a source of medicinal compounds that have antimicrobial properties, as well as antiviral ones. Humic compounds (HS) of various nature also have antiviral activity.The aim of the study was to obtain nontoxic compounds from the basidiomycete Inonotus obliquus and humic compounds from brown coals and to test their activity against viruses that are pathogenic to humans: HIV and Herpes Simplex Virus (HSV). MATERIAL AND METHODS: The antiviral activity of melanin extracts obtained from the culture of the chaga fungus Inonotus obliquus and HS from the brown coal of the Kansko-Achinsk Deposit was studied using a model of MT-4 lymphoblastoid cells infected with HIV type 1 (HIV-1) strains and a monolayer culture of Vero cells infected with HSV type 1 (HSV-1) using virological and statistical research methods. RESULTS AND DISCUSSION: It was found that all the studied compounds did not have a cytotoxic effect on cells at a concentration of 100 mcg/ml. It was shown that extracts of basidiomycetes and HS have antiviral activity against HIV-1 and HSV-1. EC 50 (50%-effective concentration) for HIV-1 was 3.7-5.0 mcg/ml, selectivity index 28-35. Antiherpetic activity was detected at a dose of 50-100 mcg/ml. The antiviral effectiveness of melanin compounds was established both in the «preventive¼ (2 hours before cell infection) and in the «therapeutic¼ regimen of drug administration, both for HIV-1 and HSV-1. The presence of antiviral activity of melanin and HS in relation to the RNA-containing HIV-1 virus and DNA-containing HSV-1 virus in our study coincides with the results of a number of authors in relation to influenza viruses, herpes virus, HIV, hepatitis B virus, Coxsackievirus, smallpox vaccine virus, which suggests that the type of nucleic acid in the virus does not play a fundamental role in the antiviral action of these drugs. It is also clear that HS is effective against both enveloped and non-enveloped viruses. CONCLUSION: In general, it can be concluded that melanin and humic compounds are characterized by low toxicity in the presence of both virucidal and antiviral activity. This allows us to consider the studied compounds as the basis for creating safe medicines that are effective against pathogens of various viral infections.
