Effects of temperatures on the development and reproduction of the armyworm, Mythimna roseilinea: Analysis using an age-stage, two-sex life table

The armyworm Mythimna roseilinea（Walker） is a major pest of grain crops in South China. So far little is known about its basic biology and ecology, making prediction of population dynamics difficult. This study examined the relationships of individual development and population growth with temperature based on an age-stage, two-sex life table of M. roseilinea reared on maize in the laboratory at 18, 21, 24, 27 and 30℃. The highest values of net reproductive rate（R_0） and fecundity were observed at 21 and 24℃, respectively. Both the intrinsic rate of increase（r） and finite rate of increase（λ） increased significantly and mean generation time（T） decreased significantly with increasing temperature. M. roseilinea was able to develop, survive and lay eggs at all temperature regimes tested. Development rates of the egg, larval, pupal, as well as the whole pre-oviposition stages had a positive linear relationship with temperature. The calculated development threshold temperatures of egg, larval, pupal, pre-oviposition and total pre-oviposition stages were 13.29, 8.39, 14.35, 7.42, and 12.24℃, respectively, and their effective accumulated temperatures were 63.59, 445.00, 211.11, 89.02, and 698.95 degree-days, respectively. These results provide insight into temperature-based phenology and population ecology of this insect pest and will allow population prediction and management available in the field.

THE POSSIBILITY ANALYSIS OF NATURAL POPLAR-BIRCH FOREST RECOVERY TO BROAD-LEAF KOREAN PINE FOREST THROUGH THE METHOD OF LIFE TABLE IN THE XIOAXING'AN MOUNTAINS

The basic principle of life table method is deseribed, and the method of tree height instead of tree age in static life table is suggested, and it is also discussed that the possibility of natural poplar -birch forest recover to broad-leaf Korean pine forest on low pitches in the Xiaoxing'an Mountains by this method. If there is no particular situation, Korean pines after high than 5m under natural Poplar-birch forest will basically survive and make their way into dominant callopy accompanied by climax broad-leaf species.

Life Table of Natural Population of Gastrolina depressa

[Objective]The paper was to understand the population development regularity of Gastrolina depressa in natural environment in Guizhou Province.[Method]The population dynamics of G.depressa was studied by establishing life table of natural population of G.depressa via field observation and calculating dynamic trend index of population.[Result]The mortality rates in egg stage,pupal stage and adult stage accounted for 26.42%,10.96%and 8.22%of the total mortality rate,respectively.The mortality rate in larval stage was the highest,accounting for 54.40%of the total mortality rate,higher than the total mortality rate in the other three stages.The population dynamic trend index I=9.25,I>1 indicated that the population showed an upward trend.[Conclusion]Under the natural conditions,the population of G.depressa shows upward trend,and human intervention is needed to control the population.The larval stage is the weak stage of the insect,which is the best time to control the insect.

Effects of Aschersonia aleyrodis on the life table and demographic parameters of Bemisia tabaci

The present study reports the sublethal effects of the entomopathogenic fungus, Aschersonia aleyrodis（Webber） on Bemisia tabaci（Gennadius）（Homoptera： Aleyrodidae）. A fungal suspension of A. aleyrodis isolate Aa005 containing 1×107 conidia mL^-1 was sprayed against B. tabaci on eggplant leaves under greenhouse conditions. The effects of fungal application on survival as well as life table parameters of the whitefly were observed at different post inoculation periods. The results indicated that A. aleyrodis can significantly affect the survival of 1st, 2nd, and 3rd nymphal instars of B. tabaci. Developmental periods of different instar nymphs were not affected by fungal application. A. aleyrodis spores persisted well and significantly affected the survivorship of young instar nymphs of B. tabaci at different post incubation periods. Life table results suggested that A. aleyrodis has no impact on general fecundity and longevity of B. tabaci. When the pathogen was exposed to the open environment and maintained for a relatively longer period, a reduction in the reproductive rate and intrinsic rate of increase was caused by the fungal spores, though the sublethal effects were not as good as the control treatment. The results suggest that the ability of spores to suppress an increase in whitefly population persists well after incubation of spores to the external environment（up to 9 days）.

Family identification of China’s mortality patterns and deviation analysis with model life tables

This study identifies China’s mortality pattern families by using data from national and provincial censuses and one-percent sample surveys of China,and then compares them with families in the Coale-Demeny and United Nations model life tables.Based on available data,the findings show there are seven families of mortality patterns in China.Their characteristics differ primarily during adolescence,and young and middle adulthood while resembling during infancy,toddlerhood,childhood and late adulthood or old age.Abnormally higher mortality is seen in females than males during infancy and childhood in three of the seven families of mortality patterns.As for the difference in male and female mortality in old age in the seven families of mortality patterns,it can be ignored.The comparison with the Coale-Demeny and UN model life tables shows the deviations of China’s families of mortality patterns from the families in the two model life tables vary at different mortality levels,with some similarities existing in the deviations at high and low mortality levels,whereas the difference in the deviations at the medium mortality level primarily appears during non-elderly years.The widely used Coale-Demeny West Pattern and the United Nations General Pattern,however,are not applicable to the studies of China’s mortality.Miscalculations commonly happen in the mortality patterns for adolescents,young and middle adults,and elderly people.

Age-stage, two-sex life tables of Bactrocera cucurbitae （Coquillett） （Diptera： Tephritidae） with a discussion on the problem of applying female age-specific life tables to insect populations

Age-stage, two-sex life tables of the melon fly, Bactrocera cucurbitae （Coquil- let-t） （Diptera： Tephritidae）, reared on cucumber （Cucumis sativus L.）, sponge gourd （Luffa cylindrica Roem） and a carrot medium （mashed Daucus carota L. mixed with sucrose and yeast hydrolysate） were constructed under laboratory conditions at 25 4- loc, 65% 4- 0.5% relative humidity, and a photoperiod 12 ： 12h （L ： D）. The intrinsic rates of increase of B. cucurbitae were 0.144 6, 0.141 2 and 0.068 8 days on cucumber, sponge gourd, and carrot medium, respectively. The highest net reproduction rate was 172 offspring per fly reared on sponge gourd. The mean generation times ofB. cucurbitae ranged from 34 days reared on cucumber to 56 days reared on carrot medium. The life history raw data was analyzed using the traditional female age-specific life table and compared to results obtained using the age-stage, two-sex life table. When the age-specific female life table is applied to an age-stage-structured two-sex population, survival and fecundity curves will be improperly manipulated due to an inability to include variation in preadult development time. We discussed different interpretations of the relationship between the net reproductive rate and the intrinsic rate of increase to clarify possible misunderstanding in the literature.

Comparative life table analysis of Tetranychus urticae （Acari Tetranychidae） on 14 soybean genotypes

The life table parameters of two-spotted spider mite （TSSM）, Tetranychus urticae Koch, on 14 soybean genotypes （Sari, Sahar, Tellar, Zane, Ks3494, LI7, Dpx, 032, 033, Clark, Hill, 127, Tms and Williams） were evaluated at 28 ±1℃, 65% ± 5% RH and a photoperiod of 16 ： 8 h L ： D. The survivorship data （lx） of adult females were fitted to the Weibull frequency distribution model in all genotypes tested. Based on the Weibull parameters, the survival curve was type I on all genotypes, which indicated that the mortality mostly occurred in old individuals. Furthermore, two mathematical models （Analytis and Enkegaard） were fitted to age-specific fecundity data （mx）. The highest intrinsic rate of increase （rm） was recorded on L17 （0.392） and the lowest values of this parameter were obtained on Tms （0.233）, Hill （0.236）, 032 （0.236）, 127 （0.237） and Clark （0.240）. In addition, net reproductive rate （R0） and finite rate of increase （λ） of the TSSM had the highest value on L17 as 45.521 and 1.475, respectively. The lowest values of these parameters were recorded on Tms as 12.149 and 1.258, respectively. Doubling time （DT） varied significantly on different genotypes and the shortest and longest values of this period were obtained on L17 and 032, respectively. Our findings revealed that Tms, Hill, 032, 127 and Clark were less suitable genotypes, suggesting that they are more resistant to the TSSM than the other genotypes.

Biology and life table studies of the oriental tobacco budworm, Helicoverpa assulta （Lepidoptera： Noctuidae）, influenced by different larval diets

Development, survivorship, pupal weight, oviposition, and life table parameters of the oriental tobacco budworm, Helicoverpa assulta Guenée, were evaluated in the laboratory on an artificial diet, pepper （Capsicumfrutescens L.）, and tobacco （Nicotiana tobacum L.）. We found that the average developmental time of immature stages was longest on tobacco （36.2 d）, intermediate on pepper （34.4 d）, and shortest on artificial diet （33.5 d）. Immature survival from egg to pupa varied from 31% on tobacco, 43% on pepper, and 74% on artificial diet. Pupal weight ranged from 197.4 mg/pupa on tobacco, 233.1 mg/pupa on pepper and 253.4 mg/pupa on artificial diet. The average numbers of eggs laid by adults reared as larvae on the artificial diet, pepper, or tobacco were 614, 421 and 334 eggs/female, respectively. Numbers of remaining eggs in ovaries of the adult females reared as larvae on the artificial diet, pepper, or tobacco were 16, 26, and 42 eggs/female, respectively. The longevity of adult females developed from larvae reared on the three diets was not significantly different, whereas the longevity of male adults from the larvae reared on artificial diet was longer （16.8 d） than that for males reared on tobacco （13.8 d） and pepper （13.3 d）. The intrinsic, finite, gross, and net rates of increase were highest for females reared as larvae on artificial diet, lowest for females emerging from larvae reared on tobacco, and intermediate for females emerging from larvae reared on pepper. Generation times and doubling time of H. assulta were shortest for larvae fed artificial diet, intermediate from larvae reared on pepper, and longest from larvae reared on tobacco. We concluded that the artificial diet was the most suitable larval diet ofH. assulta followed by pepper, and tobacco.

Effect of Verticillium lecanfi on biological characteristics and life table of Serangium japonicum （Coleoptera： Coccinellidae）, a predator of whiteflies under laboratory conditions

Effects of entomopathogenic fungus Verticillium lecanii on biological characteristics and life table of Serangiumjaponicum, a predator of whiteflies against five different conidial concentrations （1 × 10^4, 1 × 10^5, 1 × 10^6, 1 × 10^7, and 1 × 10^8 conidia/mL） were studied under laboratory conditions. The developmental periods for all immature stages （from eggs, 1 st, 2nd, 3rd, 4th instar nymph and pupae up to emergence） among the treatments were significantly different when compared to that of control, and the longest development period was observed as treated with 1 × 10^8 spore/mL. However, no significant difference on the percent survival of all immature stages was observed among the treatments and control. Also, there were no significantly different effects of V. lecanii on mean generation time, intrinsic rate, the finite rate of increase and longevity of S. japonicum among the treatments and control.

Survival, development and life tables of two congeneric ladybirds in aphidophagous guilds

Two congeneric aphidophagous ladybirds, Coccinella septempunctata and Coccinella transversalis, were reared on three aphid species, Lipaphis erysimi, Myzus persicae and Aphis nerii, to estimate the effect of prey quality and intra- and interspecific interactions on their survival and development of life stages. Mortality of first instar ladybirds of both species was highest feeding on A. nerii. Preimaginal mortafity was lowest when feeding on L. erysimi （C. septempunctata, 1.6% and C. transversalis, 3.2%）, and highest when feeding on A. nerii （ C. septempunctata, 6.2% and C. transversalis, 8.2%）. Comparatively higher weight and larger size of C. septempunctata along with the lower levels of mortality recorded suggested that it is more likely to have acted as an intraguild predator than C. transversalis. High recorded mortality of C. transversalis is attributed to probable intraguild predation on account of its smaller size. The major sources of mortality were probably cannibalism, intraguild predation and other unknown factors. Lower prey quality increased the incidence of cannibalism and intraguild predation, especially in C. transversalis. The investigation suggests an intrinsic competitive advantage for C. septempunctata over C. transversalis in guilds of three aphid species.

Estimating index of population trend by re-sampling techniques （jackknife and bootstrap） and its application to the life table study of rice leaf roller, Cnaphalocrocis medinalis （Lepidoptera： Pyralidae）

Taking a published natural population life table of rice leaf roller, Cnaphalocrocis medinalis （Lepidoptera： Pyralidae）, as an example, we estimated the population trend index, I, via re-sampling methods （jackknife and bootstrap）, determined its statistical properties and illustrated the application of these methods in determining the control effectiveness of bio- agents and chemical insecticides. Depending on the simulation outputs, the smoothed distribution pattern of the estimates of I by delete-1 jackknife is visually distinguishable from the normal density, but the smoothed pattern produced by delete-d jackknife, and logarithm- transformed smoothed patterns produced by both empirical and parametric bootstraps, matched well the corresponding normal density. Thus, the estimates of I produced by delete-1 jackknife were not used to determine the suppressive effect of wasps and insecticides. The 95% percent confidence intervals or the narrowest 95 percentiles and Z-test criterion were employed to compare the effectiveness of Trichogrammajaponicum Ashmead and insecticides （powder, 1.5% mevinphos ＋ 3% alpha-hexachloro cyclohexane） against the rice leaf roller based on the estimates of I produced by delete-d jackknife and bootstrap techniques. At a = 0.05 level, there were statistical differences between wasp treatment and control, and between wasp and insecticide treatments, if the normality is ensured, or by the narrowest 95 percentiles. However, there is still no difference between insecticide treatment and control. By Z-test criterion, wasp treatment is better than control and insecticide treatment with P-value 〈 0.01. Insecticide treatment is similar to control with P-value 〉 0.2 indicating that 95% confidence intervals procedure is more conservative. Although similar conclusions may be drawn by re-sampling techniques, such as the delta method, about the suppressive effect of trichogramma and insecticides, the normality of the estimates can be checked and guaranteed, and the correlation among sequential life stages of rice leaf roller is also considered in the estimation. Judged by the P-values from Z-test, the delta method is more conservative.

Fitness of fall armyworm,Spodoptera frugiperda to three solanaceous vegetables

The fall armyworm(FAW),Spodoptera frugiperda Smith(Lepidoptera:Noctuidae)is an important agricultural pest that invaded China in the middle of December 2018.As a polyphagous pest,FAW is identified as a serious threat to agricultural production and food security in China.Pepper(Capsicum annuum L.),tomato(Solanum lycopersicum Mill.)and eggplant(Solanum melongena L.)are three of dominant solanaceous vegetables of this country.To our knowledge,the effects of these plants on the performances of FAW have not been well studied.In this study we assessed the fitness of this pest to these three plants.Results showed that FAW can complete its life cycle when fed with tomato and pepper,but not on eggplant.The population parameters of FAW fed with maize(Zea mays L.)and the three solanaceous vegetables were compared using the age-stage,two-sex life table method.Developmental duration was significantly different in the larval stage,but not in the pupae stage.FAW fed with pepper had the longest pre-adult period(41.73 d)and the lightest pupal weight(0.1134 g);the survival rate was lower than FAW fed with tomato.Significant differences were observed in the mean fecundity of female,with the highest(943.95 eggs)laid by FAW fed with tomato.FAW had the shortest mean generation time(T),the highest intrinsic rate of increase(r)and finite rate of increase(λ)on maize,and the highest net reproductive rate(R_(0))on tomato.Overall,FAW fitness on the three solanaceous vegetables was:tomato>pepper>eggplant.This study provides the foundation for further assessment of FAW risk to solanaceous vegetables and for establishing corresponding control strategies in China.

New Characteristics of Active Life Expectancy of the Elderly in China

Life expectancy of the elderly is a significant problem in China, and it changes not only the health care, but also the pension. This study used tracking data from the Chinese Urban and Rural Elderly Population Survey to calculate the age-specific Active Life Expectancy (ALE) of the Chinese elderly population aged 60 years and over. For analysis, this population was divided into different sub-populations according to gender, census register and region. The main conclusions of our study are as follows: 1) The quality of life for elderly males may be greater than that for elderly females;2) There were significant differences in Active Life Expectancy (ALE) and Inactive Life Expectancy (ILE) between urban and rural elderly;3) The differences in ALE between the eastern, central and western regions of China were not significant;and 4) The increased remaining life expectancy of the elderly was mainly attributed to the extended ALE in the lower age group and the expanded ILE in the higher age group. This study expands the knowledge of Chinese elderly’s life expectancy in different health status.

Analyses of Numerical Responses and Main Life Parameters for Determining the Suppression of Amblyseius cucumeris on Panonychus citri

In this paper, the numeral response and main parameters of experimental population life table were analyzed for determining the suppressing ability of Amblyseius cucumeris on Panonychus citri. The result showed that: (1) Under 21-31°C and 1 - 9 prey densities/leaf fragment condition, the prey consumptions of A. cucumeris increased with the temperature or prey density; (2) In 1:3 predator-prey ratio treatment, the suppression of P. citri (Ro=34.0053; T=19.4369; t=3.8204) was rather weak, it was enhanced as the ratio over 5:30, and the populations of P. citri in these treatments can be fully controlled within 4-5 days; (3) Under 25±1°C, 80-85% RH and 15L: 9D illumination conditions, the net reproductive rate, mean generation duration and the time for population double increase of P. citri (Ro=34.0053; T=19.4369; t=3.8204) were higher than those of A. cucumeris (Ro=21.8750; T=16.8943; t=3.7954). While the intrinsic rate of increase and finite rate of increase of the former (rm=0.1814; λ=1.1989) were lower than those of the latter (rm=0.1826; λ=1.2004). These results indicated that A. cucumeris is a desirable bio-control agent to suppress P. citri at lower population stage in citrus orchard.

Thelytokous Diglyphus wani:A more promising biological control agent against agromyzid leafminers than its arrhenotokous counterpart

Diglyphus wani(Hymenoptera:Eulophidae)is a dominant parasitoid that attacks agromyzid leafminers.Two reproductive types occur in D.wani:arrhenotoky(in which virgin females produce only male offspring;and virgin females mate with males to produce bisexual offspring)and thelytoky(in which virgin females produce female offspring).As a potential biological control agent,exploring the differences in the relevant biological parameters of both strains is necessary.In this study,comparisons between the two strains of D.wani were performed by evaluating the life table and host-killing rate.The thelytokous strain exhibited significantly better life table parameters than its arrhenotokous counterpart.Higher values for the intrinsic rate of increase,finite rate of increase,net reproductive rate,and fecundity were found in the thelytokous strain.The thelytokous strain also performed better than the arrhenotokous strain in terms of net parasitism,host-feeding,host-stinging,and total host-killing rates.Thus,populations of the thelytokous strain could grow fast and kill more hosts.In conclusion,the thelytokous strain of D.wani may be the more promising biological agent against agromyzid leafminers compared to its arrhenotokous counterpart.Also,since the thelytokous strain of D.wani is only known to produce females,it should be given priority in future biocontrol applications owing to the cost savings of breeding only females.

Effect of Artificial and Corn Leaves Diets on Development, Survival and Reproduction of Spodoptera frugiperda (Lepidoptera: Noctuidae) in Sierra Leone

The use of artificial diets to mass reared insect stock under laboratory conditions, promotes knowledge about the biology, behavior, and nutritional requirements of insects;with such information being fundamental for the formulation of efficient integrated pest management programs (IPM) strategies. However, the artificial diets used for rearing Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in the laboratory in this study, do not contain wheat germ, used for routine laboratory rearing. The aim of this study was to compare food preference and consumption by S. frugiperda larvae, as well as evaluate insect developmental parameters in the standard diet and the bean-based diets under laboratory conditions. Four artificial diets were used: a standard diet based on broad beans (Phaseolus vulgaris L.) used to rear S. frugiperda (D1), a diet with the substitution of two types of beans, cowpea (Vigna unguiculata L.) (D2) and pigeon pea (Cajanus cajan L) (D3);and a diet of fresh corn leaves (D4), the host plant of the pest species. Using a multiple-choice test, we observed that the larvae preferred diets D4 followed by D1. The relative consumption rate (RCR), relative growth rate (RGR), relative metabolic rate (RMR), approximate digestibility (AD), efficiency of conversion of ingested food (ECI), efficiency of conversion of digested food (ECD), and the metabolic cost (CM) for S. frugiperda fifth instar larvae varied among diets. The diet D4 resulted in better ingestion, digestion, assimilation, and conversion of food, but with a metabolic cost to assimilate the food. The different bean varieties present in the diet influenced larval length, larval periods, larval survival, pupal periods, sex ratio, pupal weight, and pupal survival;but fecundity and longevity of adults were not affected. The different bean-based diets did positively influence population growth, with the most outstanding being D4. From the results of this study, the most adequate diet for rearing S. frugiperda in the laboratory is D4.

Effects of constant and stage-specific-alternating temperature on the survival, development and reproduction of the oriental armyworm, Mythimna separata(Walker)(Lepidoptera: Noctuidae)

Migratory insects make diverse adaptive strategies in response to changes in external environment. Temperature has an impact on the survival, development, reproduction, and migration initiation of insects. Previous research has primarily been focused on the effects of constant temperature on populations, but changing temperature has received less attention. Three constant temperature treatments（20, 25 and 30℃） and three pupal-alternating temperature treatments（20–25, 25–20 and 25–30℃） were set up to study the relationship between temperature and population development by age-stage, two-sex life table analysis in the oriental armyworm, Mythimna separata Walker, a notorious migratory pest in grain crops. The 25℃ treatment was considered optimal with 20 and 30℃ as low suitable temperature and high temperatures, respectively. The survival rate was relatively low before third instar larvae at 20℃（63.0%） and 20–25℃（70.1%）, and extreme low after pupal stage at 30℃（20.6%）. Developmental duration of each stage was negatively correlated with temperature. The adult preoviposition period, when most migratory insects initiate migration, was the shortest at 25℃（2.69d） but was lengthened at both low suitable（7.48d for 20℃, 6.91d for 25–20℃ and 4.57d for 20–25℃） and high temperatures（3.74d for 25–30℃ and 5.00d for 30℃）. Both low suitable and high temperature decreased lifetime fecundity, net reproductive rate and the intrinsic rate of increase, with variability observed across developmental duration and stage during non-optimal temperature. The results expand knowledge of the relationship between changing temperature and armyworm population development, and adaptive strategies in complex ambient environment.

Sublethal Effects of Metaflumizone on Plutella xylostella (Lepidoptera: Plutellidae)

Metaflumizone is a novel sodium channel blocker insecticide, which has been registered for controling the diamondback moth （DBM）, Plutella xylostella （Lepidoptera： Plutellidae） in China. It is unavoidable for DBMs to be exposed to sublethal dose of metaflumizone in brassicaceous vegetable field. Sublethal effects of metaflumizone at LC15 （1.06 mg L-1） and LCz5 （2.03 mg L-1） on the biological characteristics were investigated. Pupation rate, pupal period and pupal weight were significantly declined comparing with the control （P=0.05） when third instar larvae were exposed to LC15 and LC25 of metaflumizone. Comparing the control group to LC15 and LC25 treatment groups, there were significant differences in the development periods of eggs, first instar larvae, pupae and total preoviposition period. The peak of age-specific fecundity in LC15 and LC25 treatment groups was lagged behind control group. Mean values of intrinsic rate of increase （rm）, net reproductive rate （R0） and finite rate of increase （λ） observed from the LCl5 and LC25 treatment groups were lower than those from the control group. But mean values of gross reproduction rate （GRR） was not different. The mean generation time （T） of the treatment groups was prolonged. Whether sublethal doses of metaflumizone could stimulate reproduction in the long term needs further investigation on continuous generations.

Health Inequalities during 20 Years of Rapid Economic Development in China (1980-2000):A Mortality Analysis

Objective To examine the influence of China＇s economic reforms on population health and regional mortality rates.Methods Longitudinal study measuring the mortality trends and their regional variations.Using data from the three most recent national censuses,we used the model life table to adjust the mortality levels within the population for each census,and to calculate life expectancy.We then examined the variation in patterns of mortality and population health by economic status,region and gender from 1980-2000.Results Life expectancy varied with economic status,province,and gender.Results showed that,although life expectancy in China had increased overall since the early 1980s,regional differences became more pronounced.Life expectancy for populations who live in the eastern coastal provinces are greater than those in the western regions.Conclusion Differences in life expectancy are primarily related to differences in regional economic development,which in turn exacerbate regional health inequalities.Therefore,it is necessary to improve economic development in less developed regions and to improve health policies and the public health system that address the needs of everyone.