1993 Vol. 14, No. 4

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Scymnus is the largest genus of the family Coccinellidae,and about 600 species have been known to the world.The Scymnus fauna is rich in China.Up to the present,82 species were recorded from China.However,there are still many species remained unknown.The following are the descriptions of three new species from Yunnan and Hainan,China.The type specimens are deposited in the Insect Collection of South China Agricultural University,Guangzhou.
The family Lernaeidae forms into a monophyletic group of the order Cyclopoida by the following synapomorphies:The lst antenna short,lst maxilla uniramous or disappeared.The family Lernaeidae consists of 12 genera.Among them the genus Areotrancheilus was created by Wilson according to a single discovery.Henceforth no further descriptions have been made and most structures shch as antenna,oral appendage,thorax-pods and egg sac have been left unknown.Therefore it is diffcult to be compared with other genera and is not included in the present consideration of phylogenetic reconstruction.The family Cyclopidae is considered here as the outgroup of Lernaeidae.Polarities of characters recognized from all genera of Lernaeidae are determined by comparing to the outgroup Cyclopidae in order to distinguish apomorphic states from plesiomorphic states.Through comparative analysis,21 characters have been recognized and the states of these characters have shown mosaic distributions among 11 genera of Lernaeidae.Based on the mosaic distributions and of character states and the parsimonious principle,the intergeneric phylogenetic cladogram of Lernaeidae has been reconstructed.Clade Ⅰ and Ⅱ comprise the first sister group by 3 characters which show mosaic distributions.Clade Ⅰ consists of 5 genera and clade Ⅱ of 6 genera.Among 12 genera of Lernaeidae,7 genera occur in Africa,7 genera in Asia,3 genera in America,2 genera in Europe.The individuals of Lernaeidae are parasitized mainly on the fishes of Osteichthyes,particularly on fishes of Cypriniformes.Tropical Asia and Africa are the diversifying and originating centre of Cypriniformes.The distribution centre of Lernaeidae is situated also in tropical Asia and Africa,and is well agreed to the distribution centre of their hosts.This agreement demonstrates from one aspect the coevolution between parasites and their hosts.The water currents in Qinghai-Tibet plateau usually flow swiftly with a frigid water temperature.So far no individuals of Lernaeidae have been reported to parasitize on the fishes of the plateau.It is supposed here that the frigid water temperature be the main barrier to restrict the dispersion of Lernaeidae parasites.
The morphological differentiation of Discogobio is expressed in macro-structures and micro-structures.In the macro-structures,the differentiation showes the changes of sucking disc size that can be divided into two types.One type is the large sucking disc,whose posterior edge extend to or beyond anterior margin of eye vertically and width of central pad is equal to or larger than the diameter of eye;another is the small sucking disc,whose posterior edge does not extend to anterior margin of eye vertically and width of central pad is smaller than the diameter of eye.Although the macro-morphology differentiation of sucking disc of Discogobio seems related to environment where every species lives,actually it is only a superficial phenomenon.Because D.yunnanensis with large sucking disc and D.macrophysallidos with small sucking disc can be found simultaneously in rivers as well as lakes or pools.So the authors consider that types of sucking disc may be a clue of recording the differentiating history of Discogobio rather than a clue of recording their adaptation for varied niches.The two groups with different types of sucking disc are two natural groups who were derived from an ancestor.In the micro-structures,the differentiation is expressed in changes of papillae distribution and tentacle numbers at the top of papillae.Based on the results observed by scanning electron microscopy and ecological information of Discogobio,it is inferred that the distribution of papillae on disc and the tentacles at top of papillae are more connected with habitats of the fishes.When they evolved continually for adapting various environment,the two groups shown different ways in their micro-morphology.The development of large sucking disc group evolved mainly towards expanding distributive area of papillae on the central pad and increasing tentacle numbers at the top of papillae;in this group D.elongatus developed perfectly and more adapted swift current niches.The development of small sucking disc group evolved in two aspects respectively.One was of expanding distributive area of papillae on the central pad and increasing tentacle numbers at the top of papillae,so the adhensive ability of the sucking disc can be strengthened,such as rivers populations of D.macrophysallidos;another was not of strengthening the adhensive ability of the sucking disc,so the papillae on the sucking disc was scattered and with less tentacles and the ability of the fishes movement were developed by enlarging the diameter of eye and expanding the length of barbel,and D.longibarbatus is a representative.Therefore,the sucking disc morphological differentiation of Discogobio is a complex phenomena,which records the evolutionary history of Discogobio and adaptation of every species in the genus.
The analysis method of spatial pattern was applied to study the aggregation and dispersion tendencies of green bobacco aphid [Myzus persicae (Sulzer)] among whole and vertical strata of tobacco plant.From transplanting to ripe,which are the periods of tobacco plant growth,the aggregation and dispersion tendencies of green tobacco aphid among upper,middle and lower leaves were traited by using Mont Lloyds method and combining the model of Iwao (m-m) and improved Iwaos model.The results show that green tobacco aphid has two aggregative peaks which are in the late June and mid-July,respectively.The aggregation and dispersion tendencies of green tobacco aphid are some different among different parts of tobacco plant,as the result of natural selection and adaptation.The green tobacco aphid appears aggregative pattern among whole tobacco plant and upper,middle and lower leaves.The analysis can help the rational control of green tobacco aphid.
There were many articles which revealed the regulation of animal populations,but there was not the article that in same condition researched into effects of many factors on density of population at same time.Our work was carried out in Minqin Experimental Station of Adminstering Desert from April to mid-June in 1989.In order to study that action administered desert by human,vegetation,potential available food resources,densities of competitive species and physical and chemical characters of soil affect population density of Phrynocephalus przewalskii.The results showed that it was in significant that the action administered desert by human affects population density of Phrynocephalus przewalskii.The potential available food resources,vegetation,the moisture of soil,the densities of competitive species are determinate factors which affect population density of Phrynocephalus przewalskii.Because the changes of population density of Phrynocephalus przewalskii along with any changes of these factors,these factors all have the effects on regulating population.
The effects of acute progressive hypoxia on the respiration rate of the Chinese freshwater crab,Eriocheir sinensis,acclimated at three temperatures were investigated with a closed respirometer.E.sinensis can maintain its respiration rate down to the critical point (Pc) and from this point its respiration rate declines rapidly,reaching zero at a lower ambient oxygen concentration called the zero respiration oxygen concentration.Because of this,a new hyperbolic equation is introduced to express the relationship between respiration rate and ambient oxygen concentration.A new method for calculating the Pc value is also developed.The Pc values for E.sinensis at 20-35℃ range from 1.92-3.47 mg/l.
Population Spike (PS) elicited by perforant path stimulation in the dentate gyrus (DG) of freely moving rats was recorded.Rats were trained on discrimination learning.The results were as follows:(1)High-frequency stimulation (HFS) of the medial septal nucleus (MS) temporarily caused a suppression of PS in DG;(2) HFS of MS following daily training session caused a significant suppression of the development of learning-dependent long-term potentiation (LDLTP),and correspondingly,a prevention of the acquisition of discriminative responding;(3)HFS of MS resulted in a significant decrease (P<0.01) of the maximal level of the potentiation of PS amplitude.These results suggest that MS exerts an inhibitory modulated effects on LDLTP in DG,which mainly affects the development of LDLTP.
The resting metabolic rate was measured with Kalabakhov-Skortsov respirometer at different temperatures on the Yellow-bellied Tragopan (Tragopan caboti) chickens in development and their adults at different seasons.In a few days after hatching,the body temperature of the Yellow-bellied Tragopan varied with ambient temperature.Their chemical thermoregulation ability was established basically at about 9 days.The relationships between RMR and temperatures in the Yellow-bellied Tragopan adults were linear regression.The slope of regression equations for spring,summer and autumn were insignificantly different.It is supposed that the chemical thermoregulation ability of the Yellow-bellied Tragopan was insignificantly different among the three seasons.The metabolic levels are insignificantly different among seasons too.
This paper reported:1.The [60]Co-γ radiation induced pyrethroid-resistance of predatory mite,Amblyseius nicholsi,an important natural enemy of citrus red mite Panonychus citri.2.Some other biological effects of [60]Co-γ radiation on A.nicholsi.The LC[50]s of S-5439 (a pyrethroid insecticide) to the two strains,FR2 and PFR which were radiated three times with 2000 rad (dosage rate=140 rad/min) of γ-ray and selected with S-5439 for 12 months,were 1.3347×10[-3] and 1.4307×10[-3] ppm respectively,and were about 23-fold compared with that of the sensitive strain.And the selecting periods of FR2 and PFR were shorter than half that of FR1 and PDFR which were selected only with S-5439 for 27 months.FR1,FR2 and PDFR were all performed some extent cross-resistance to other pyrethroid insecticides.The LC50s of the tested pyrethroids to FR1,FR2 and PFR were higher than their application concentrations in fields.It will be desirable for the practical utilization of these resistant strains in biological control of pest mites.The results of radiation genetics suggested that A.nicholsi might be a parahaploid species.The increase of [60]Co-γ dosage resulted in the decrease of sexual ration (♀:♂).The RLD[50]s (Medium Radiation Lethal Dosage) of F1 eggs estimated from the obtained data were different in the two cases of radiating only male father or both male and female parents.
Phenotypic differences of fin isozymes (EST,LDH,SOD,IDHP,MDH) and fin proteins in four different gynogenetic clones of silver crucian carp,red common carp and multiple tetraploid allogynogenetic crucian carp were comparatively analysed through polyacrylamide gradient gel electrophoresis.The results suggested that major part of phenotypic differences among the individuals of multiple tetraploid allogynogenetic crucian carp came from intraspecific genetic differences of silver crucian carp (different gynogenetic clones).The multiple tetraploid allogynogenetic crucian carp whose female parents were clone D silver crucian carp showed individual differences in EST isozymes,and these differences were related to the polymorphism of EST isozymes in red common carp.Therefore,these heterogeneity among the individuals that included genetic effect come from male parents.Moreover,it was found that the fin proteins and fin EST isozymes manifested obvious individual differences,which could be used as genetic marker to distinguish different multiple tetraploid allogynogenetic crucian carp.
The report which follows studies on the embryonic development of Misgurnus anguillicaudatus.The haploids had the obvious haploid syndrome.The development rate of gynogenesis haploids,compared with that of diploids was the same before Melanoid eye stage.But it was hardly to identify the developmental stages of gynogenesis haploids after Melanoid eye stage.The gynogenesis haploids couldnt survival for more than 15 days in 22℃ to 25℃.We had also made comparative studies on the morphogenesis of the internal orgens of the diploids at the exhaustion of york stage and those of the haploids at the same development ages as the diploids.The rusults showed that most internal organs of the haploids were imperfect and the nuclei were small,but the nucleo-cytoplasmic ratio of the cells was normal.
The cell strain ZC-7901 of Grass Carp snout tissue was adopted for the research of packing from basic chromatin fibres to chromosomes.In studying of the subject,four methods were used:The induction of premature chromosome condensation in interphase nuclei by fusing with metaphase cell;the "elongation" of chromosomes; the moderate hypo-osmosis of culture cells and spreading chromatin.Scanning and transmission electron microscopes were used to investigate the prepared specimens.The observations showed that the basic structure of fish chromatin was the same as that of mammalians,which was the nucleofilament of 10 nm in diameter.There were two patterns from the chromatin packing into the chromosome:One was the multiple spiralization from the basic fibre into the chromatid of about 300 nm in diameter,and then to the sister chromatids which twisted into the chromosome;the other one was the directly fold coupling from 30 nm or 60 nm solenoids into the chromosome in which the partial helical irregular fibres coexisted.It was suggested that the spiralization was the normal packing pattern of the chromosomes of Grass Carp,and the fold coupling was the rapid and premature condensation.
Integrated Pest Management involves the complicated ecosystems,Computer has become the effective decision-making tools used in manipulating such ecosystems.Statistic analysis,constructions of models and simulation of ecological processes are the preliminary applications of computer-aided decision-making in IPM.In recent years,DBMS (Database Management System),DSS (Decision Support System) and EXS (Expert System) of IPM have been developed on the basis of the above work.This implies that the period of scientific decision in IPM comes.In some senes,the progresses in the techniques of computer hardwares and softwares have changed the past of IPM,are influencing the present of IPM and will make the future of IPM.