Relationship between the Population Dynamics of the Gypsy Moth (Lymantria dispar L., Lymantriidae: Lepidoptera) and the Genetic Polymorphism of the Nuclear Polyhedrosis Virus

The population dynamics of the gypsy moth and the genomic DNA of the nuclear polyhedrosis virus (NPV) pathogenic for this insect were simultaneously studied using nucleic acid molecular hybridization (NAMH). It was demonstrated that population outbreaks of the gypsy moth were accompanied by an increase in its sensitivity to NPV and in the genetic polymorphism of NPV strains circulating in the insect populations. The hybridization activity of the virus strains isolated at the phase of gypsy moth population growth was significantly higher (p < 0.001) than the activity of the strains isolated at the phase of population decrease.     

Ecology of Nuclear Polyhedrosis Virus in Western Siberian Populations of the Gypsy Moth (<Emphasis Type="Italic">Lymantria dispar</Emphasis> L.)

The impact of the nuclear polyhedrosis virus on the population dynamics of the gypsy moth Lymantria dispar L. has been studied. The results have shown that polyhedrosis morbidity in the western Siberian population of the insect is relatively low, compared to that reported for North American and European populations. A possible cause of this situation is found in the high migration activity of moths in the Asian L. dispar populations, which allows the virus load on the biotope to remain relatively stable and insufficient for the initiation of mass viral diseases during population outbreaks.__________Translated from Ekologiya, No. 3, 2005, pp. 222–226.Original Russian Text Copyright © 2005 by Ilinykh.     

Physiological Age of Host Plant Foliage and Survival of Gypsy Moth Larvae

The pH of leaf homogenates of common birch (Betula verrucosa L.), a food plant of gypsy moth (Lymantria dispar L.) larvae, was measured at different times of day in the course of leaf organogenesis, and midgut pH was measured in gypsy moth larvae phenotypically differing in the color of the hypodermis at the fifth instar. A possible relation between these parameters is discussed.     

The role of rapid induced resistance of host plant in trophic interactions between <Emphasis Type="Italic">Betula pendula</Emphasis>, <Emphasis Type="Italic">Lymantria dispar</Emphasis>, and <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis>

Life history traits of gypsy moth larvae markedly decrease under the effect of host plant insect resistance, but no significant changes occur in immunity parameters such as hemolymph phagocytic activity and lysozyme-like activity of hemolymph plasma and midgut tissue; moreover, alkaline protease activity in the midgut contents becomes higher. The actual sensitivity of the larvae to Bacillus thuringiensis remains unchanged.     

Remote effect of nuclear polyhedrosis virus on the gypsy moth (<Emphasis Type="Italic">Lymantria dispar</Emphasis> L.) in its natural environment

The remote effect of the nuclear polyhedrosis virus on the gypsy moth was studied for the first time under natural conditions. In the generation that developed from infected eggs, the weight of pupae was reduced, sex ratio was altered, and female fecundity and egg fertility were lower than in control individuals. The F₁ progeny of these moths were characterized by an increased rate of latent virus carriage and high mortality caused by the combined effect of polyhedrosis and insect parasites.     

Influence of experimental conditions on manifestation of the group effect in the gypsy moth, <Emphasis Type="Italic">Lymantria dispar</Emphasis> L.

The effect of rearing conditions for gypsy moth larvae on parameters of their development (its duration and mortality) was studied in experiments with early instar larvae reared singly or in groups. The manifestation of the group effect was analyzed depending on the choice of experimental unit (the larva or the rearing container) and the amount of volume per larva. The observed effects were evaluated quantitatively.     

The response of gypsy moth (<Emphasis Type="Italic">Lymantria dispar</Emphasis> L.) larvae infected with nuclear polyhedrosis virus to induced resistance in birch (<Emphasis Type="Italic">Betula pendula</Emphasis> Roth.)

The effects of birch resistance induced by its artificial defoliation on the development of gypsy moth larvae and their sensitivity to viral infection and on the state of the antioxidant and detoxification systems of the insect midgut were studied. The dynamics of larval body weight; larval mortality and its etiology; glutathione-S-transferase (GT), nonspecific esterase (NE), and catalase (CAT) activities; and the ratio between the concentrations of oxidized and reduced thiol-containing compounds (RSSR/RSH) were estimated. In larvae feeding on the leaves of a previously defoliated plant, body weight was decreased, NE was inhibited, and the RSSR/RSH ratio was increased.     

Analysis of Trophic Indices in Gypsy Moth (Lymantria dispar L.) Larvae from Two Geographic Populations

Specific features of larval feeding in two geographic populations of the gypsy moth are considered. It is shown that in larvae reared on an artificial diet, trophic indices depend on several factors, including the age and sex of larvae and the food plant on which the parental generation developed in nature. It is shown that larval micropopulations belonging to the same geographic population but feeding in nature on different plant species differ from each other to a greater extent than those of different geographic populations feeding on the same species.     

Effect of heat stress on morphophysiological characteristics and biochemical parameters of stress response in gypsy moth (Lymantria dispar L.) larvae

Experiments on daily exposure of gypsy moth larvae to heat stress have shown that it leads to an increase in the survival rate of larvae with reduced adaptation to artificial diet (AD) and a decrease in the survival rate of larvae well adapted to AD. It has been found that acetylcholine esterase and tyrosinase activities and the concentration of tyrosine derivatives are reduced significantly in stress-exposed larvae. The conclusion is drawn about a possible relationship between change in the level of larval adaptation to food and a switch in metabolism of tyrosine derivatives from hormone synthesis to melanin synthesis pathway.     

Insularization and polymorphism in marginal island populations of <Emphasis Type="Italic">Pinus sylvestris</Emphasis> L.

Comparative allozyme analysis of 26 marginal island populations of Pinus sylvestris L. and 20 populations from the center of the species range has confirmed, at the species level, the Wright-Dubinin “island model” of automatic genetic processes and Mayr’s hypothesis about homozygotization of small isolated populations at range boundaries. It has been shown that the polymorphism of isolated populations sharply decreases when their area is reduced below 15–20 km² and increases to the level observed in the center of the range when the population area exceeds 50–100 km². A chorogenetic classification of marginal P. sylvestris populations is proposed.     

The possibility of sustainable pest management by introducing bio-diversity: simulations of pest mite outbreak and regulation

Since the late 1980s, spider mite pests have caused serious damage to many moso bamboo (Phyllostachys pubescens) forests in China’s Fujian province. The culms of this plant are an essential component of the building and handicraft industries, and the shoots are a prized food item in many Asian countries. Furthermore, bamboo forests play an important soil conservation role in mountainous areas. We examined pest mite outbreaks in several moso bamboo plantations in Fujian, and could show that a change in cultivation style from polyculture (a kind of mixed forest) to monoculture (all plants other than bamboo were removed) was primarily responsible for the local extinction of an important predaceous mite species. This phenomenon is due to the periodic shedding of leaves by the bamboo, which forces the predator mites occurring on bamboo to switch to prey mite species that occur on other plants. We then tried to elucidate the factors that resulted from such a cultivation change. Adopting a computer simulation approach, we could successfully show that at least two plants, moso bamboo and Chinese silvergrass, are necessary to maintain stable predator–prey interactions in moso forests. That is, systems consisting of one common predator and two host-specific pest mites on different host plant species frequently became stable when the pest mites were at low density. This finding indicates clearly that bio-diversity, even when it consists of only two plants and three mite species as in this study, is necessary for the sustainable regulation of large-scale forests, such as moso bamboo plantations.     

Effect of biotic factors on growth and survival of the Oriental river prawn <Emphasis Type="Italic">Macrobrachium nipponense</Emphasis> (De Haan) in warm-water aquaculture

Biotic factors such as intraspecific competition, stocking density, and parameters of feeding have been compared with respect to their effect on the growth and survival of monosex and mixed populations of the Oriental river prawn Macrobrachium nipponense (De Haan) in warm-water aquaculture. The results suggest that biotic factors—in the present case, social interactions and, to some extent, the efficiency of food assimilation—may be more effective than genetic factors in controlling differences in the size composition of the population.     

MANAGING POLLUTION FROM SSI<Emphasis Type="SmallCaps">s</Emphasis> – DESIGNING FOR A SUSTAINABLE INSTITUTION

The common effluent treatment plants (CETPs) are being propagated as the policy response to circumvent the pollution problem from the small-scale industries (SSIs), which abound in developing countries. The formation of the CETPs has been hailed as a collective action or co-operative solution to a common problem involving all the agents responsible for pollution. This paper investigated the desired criteria for designing an institution aimed at solving a common resource problem and factors ensuring the smooth functioning or sustainability of the institution. The design criteria and factors are then tested on a CETP set up in the Indian state of Haryana. The CETP, which was commissioned in 1997 had to be converted to a sewage treatment plant (STP) as the collective arrangement collapsed. The criteria used in the present analysis are that of Ostrom’s [Governing the Commons. Cambridge, UK, Cambridge University Press, 1990] design principles, whereas the factors considered for sustainability are the one suggested by Rawls [A Theory of Justice. USA, Harvard University Press, 1971]. The analysis indicates that the Kundli CETP failed in both counts as neither all the design principles were met nor did the institution fulfil different sustainability criteria. The paper concludes with the lessons that can be learnt from Kundli’s failure. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Irregularity in frequency of mast seed years in <Emphasis Type="Italic">Quercus floribunda</Emphasis> a late successional species of Central Himalaya

The mid altitudinal oak, Quercus floribunda forms predominantly evergreen forest in Central Himalaya between 2000–2400 m. It is late successional, mature phase species that has limited regeneration on disturbance prone sites. This oak produces mast seed crops at an interval of 2–3 years. During masting in Q. floribunda the seed fall and germination is upto ten times greater than in normal years, emphasizing the importance of mast year crop in forest maintenance. However, no mast year in this species since the last nine years (1997–2005) is a matter of serious concern. The rise in the summer and winter temperature over a period of 15 years appear to have affected the frequency of masting in this oak. The importance of masting can be adjudged from the fact that 97% of the surviving seedlings m⁻² are of the mast year crop.     

基于Landsat影像巢湖蓝藻水华暴发时空变化特征及其驱动因素分析

为研究巢湖蓝藻水华暴发的规律,该文以Landsat影像作为数据源,采用AFAI指数对藻华进行提取,分析1983～2017年巢湖蓝藻暴发的时空动态变化特征,并探讨巢湖藻华暴发的驱动因素。结果表明：1983～2017年巢湖藻华暴发频次、持续时间都在增加,历年最早暴发时间逐渐提前,藻华覆盖面积总体呈增加趋势。巢湖藻华主要分布在西北入湖口,西北部是巢湖藻华暴发的核心区。从其驱动力分析发现,风速、气温和大气压力是导致巢湖暴发重要影响因子,人口增长、GDP快速发展、施肥增加以及生活污水排放量增加是导致巢湖藻华现象日益严重的重要人为因素。     

Variations in breeding success and daily nest survival of Whiskered Tern (<Emphasis Type="Italic">Chlidonias hybrida</Emphasis>) at two Iranian colonies

Variations in breeding success of the Whiskered Terns (Chlidonias hybrida) were studied in two wetlands; Anzali (2005 and 2008) and Zarivar (2007–2008) in north and west Iran. Nesting success was modeled and compared using information-theoretic approach implemented in program Mark in order to assess effects of colony locations, years and nest initiation dates on the probability of daily nest survival. Clutch size did not vary between colonies and years. Breeding success varied between colonies (Zarivar > Anzali), and years only in Anzali (2005 > 2008). Overall daily nest survival was 0.977. (95% LCI 0.973, UCI 0.981), equivalent to a Mayfield nest survival of 0.317. (95% LCI 0.255, UCI 0.387). Egg-laying periods and colony site were important covariates affecting the daily survival rates (Σω _i = 0.86 and Σω _i = 0.83, respectively), while, the support for the effect of year was less (Σω _i = 0.41). We concluded that Lake Zarivar provides a more favorable nesting location for Whiskered Terns probably because of little changes in rainfall and water depth during the breeding seasons which influence breeding performance.     

Mating systems in the steppe lemming (<Emphasis Type="Italic">Lagurus lagurus)</Emphasis> and narrow-skulled vole (<Emphasis Type="Italic">Microtus gregalis</Emphasis>) from the Northern Kulunda Steppe

A comparative analysis of reproductive behavior has been performed in the steppe lemming (Lagurus lagurus) and narrow-skulled vole (Microtus gregalis). The results show that the species are similar in certain behavioral features indicative of the stability of mating pairs. However, in the narrow-skulled vole, unlike in the steppe lemming, mature males in olfactory tests show preference for receptive sibling females versus non-kin females. Probably, it is the absence of the incest taboo that allows the involvement of young of the year in reproduction within growing family groups and accounts for “coloniality” of the species.     

Salinity tolerance polygon of <Emphasis Type="Italic">Hydrobia ulvae</Emphasis> (Pennant, 1777) (Mollusca: Hydrobiidae)

To estimate the capacity of the White Sea littoral mollusk Hydrobia ulvae (Pennant, 1777) for adaptation to changes in ambient salinity, the range of its tolerance to increased and decreased salinity was determined experimentally. The results were used to plot the salinity tolerance polygon. On this basis, it was estimated that H. ulvae can live in a salinity range of 6–85‰.     

Cyclicity of the European water vole population as a factor of biodiversity in ecosystems of Western Siberia

Population outbreaks of the European water vole (Arvicola amphibius = Arvicola terrestris) in the northern forest-steppe of Western Siberia have been analyzed over more than 100 years. The results show that the period of the A. amphibius population cycle averages 8 years and its amplitude reaches a factor of 10³–10⁴, with population outbreaks leading to large-scale rearrangements in the ecosystem. In particular, the abundance of other species in the murine rodent community decreases with a 1-year lag, while the abundance of myophagous predators increases in the last year of the outbreak or in the next year.