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.

Effective accumulated temperature and developmental threshold temperature for Semanotus bifasciatus(Motschulsky) in Beijing

In order to understand the occurrence and development of Semanotus bifasciatus （Motschulsky）, a borer insect of Platycladus orientalis in parts of northern and eastern China and to improve its prediction, the developmental threshold temperature （C1） and effective accumulated temperature （K） of S. bifasciatus were determined under conditions of constant and variable temperatures. The results show that under constant temperatures the value of C1 has a range of 8.90±1.77℃and the value of K lies between 95.19±13.14 degree-day for eggs; the values for larvae are C1= 13.26±3.06℃ and the number of degree-day is K 2,885.07±187.87 degree-day; for pupae the ranges are C1 = 8.93±2.49℃ and K= 131.20±25.63 degree-day. Under the condition of ambient temperatures, the values for eggs are C1= 17.33±1.24℃ and K= 70.79±8.99 degree-day. It is suggested that S. bifasciatus adults over-winter in a state of dormancy, not at a diapause. Warm winter may accelerate the life cycle ofS. bifasciatus. Equations can be used to predict an early occurrence ofS. bifasciatus.

Developmental Threshold Temperature and Effective Accumulated Temperature of Potosia brevitarsis Lewis

[ Objective] The paper was to study the relationship between temperature and development of Potosia brevitarsis Lewis. [ Methods] Six constant tem- peratures （21, 24, 27, 30, 33 and 36 ℃ ） were set in the laboratory to study developmental threshold temperature and effective accumulated temperature of P. brevitarsis. [ Result] The developmental durations of various states of P. brevitarsis were shortened with the increasing temperature ranged from 21 ℃ to 36 ℃ ; the developmental rates were accelerated with the increasing temperature. The developmental threshold temperatures of egg, larva, pupa and pre-ovipesition of adult were estimated to be 12.79, 9.15, 14.86 and 13.80 ℃, respectively; the effective accumulated temperature were 136.25, 3 031.31,308.92 and 98.35 d · ℃, respectively. The developmental threshold temperature and effective amcumulated temperature for one complete generation were 9.96 ℃ and 3 628.73 d · ℃, re- spectively. Combined with meteorological data, the theoretical generation number of P. brevitarsis occurred in Shihezi was presumed to be one per year, which was basically coincided with actual occurrence generations in fields. [ Conclusion] The paper provided theoretical basis for effective control against P. brevitarsis.

Changes of Essential Substance Contents in Exorista civilis Rondani during Diapause Stage

[ Objective ] The paper was to study the occurrence regularity of Lysiphlebus testaceipes Cresson. [ Method ] With Aphis craccivora Koch as the breeding host, developmental duration, development threshold temperature and effective accumulative temperatme of L. testaceipes Cresson were studied at six constant tem- peratures of 12, 16, 20, 24, 28 and 32℃ in the laboratory, respectively. [ Result] The developmental durations of each growth stage of L. testaceipes Cresson were shortened with the increasing temperature ranged from 12 to 32℃, and the growth rate was significantly accelerated with the increasing temperature. However, when the temperature was up to 32℃, the growth and development from mummy to adult was suppressed, and the developmental duration was extended for 0.45 d than that at 28℃. The developmental durations from egg to adult at 12, 16, 20, 24, 28 and 32℃ were 38.50, 21.25, 14.11, 12.17, 10.28 and 9.01 d, respectively. The developmental threshold temperatures of egg-mummy, mummy-adult and egg-adult were estimated to be 6.5, 6.25 and 5.36℃, respectively; and the effective accumulated temperatures were 136.28, 75.74 and 227.23 d·℃, respectively. [ Conclusion] Forecast formula of developmental duration and Logistic models were established according to effective accumulated temperature and developmental threshold temperature.

A PRELIMINARY SIMULATION OF EFFECTS OF CLIMATE CHANGE ON RICE IN THE MIDDLE AND LOWER REACHES OF CI-IANGJIANG RIVER AND WINTER WHEAT PRODUCTION ON THE HUANG-HUAI-HAI PLAIN

In this paper,based on the analysis of the variation of effective accumulated temperature and precipita- tion in the last 100 years,together with the potential impacts of greenhouse effects on the climate in China simulated with the current major climatic models(GFDL,GISS,NCAR,OSU and UKMO),the impacts of climate change on rice in the middle and lower reaches of Changjiang River and winter wheat production on the Huang-Huai-Hai Plain~* are simulated with the available weather-yield statistic models on the assumption that te- mperature variation ranges 1—4℃ and precipitation variation ranges ±10—20%.The result is that under the current planting systems and agrotechniques,the impact of climate change on wheat production is more signifi- cant than that on rice;the climatic conditions of agricultural production in the north of China will become more favourable while those in the south of the middle and lower reaches of Changjiang River remain the same;but those in the southern part of North China and the basins between Changjiang River and Haihe River are rather unstable.In general,it is difficult to reach the conclusion that advantages or disadvantages dominate in such climate changes because of uncertainties.