If the demographic parameters in a matrix model for the dynamics of a structured population are dependent on a parameter u, then the population growth rate r = r(u) and the net reproductive number R0 = R0(u) are functions of u. For a general matrix model, we show that r and R0 share critical values and extrema at values u = u∗ for which r(u∗) = R0(u∗) = 1. This allows us to re-interpret, in ter...

spodoptera littoralis (boisd.) (lepidoptera: noctuidae) is an important injurious pest of such crop plants as cotton, clover, alfalfa, sugar beet and vegetables as well. larvae of this pest feed on about 40 plant families many of which are of high economic importance. demography of s. littoralis was studied on an artificial diet at 25±2 ?c, 65±5 % rh and 16l:8d in the laboratory. data analysis ...

Temperature effects on organisms are of multiple scientific interests, such as for their life history performance and for the study of evolutionary strategies. We have cultured two sympatric branchiopod species from an ephemeral pond in northern Taiwan, Branchinella kugenumaensis and Eulimnadia braueriana, and compared their hatching rate, maturation time, sex ratio, growth of body length, surv...

life table gives the most comprehensive explanation of the survivorship, development, and reproduction of a population. the life table parameters of an aphidophagous midge, aphidoletes aphidimyza were studied on different densities (5, 10, 20, 40, 60, 80) of third instar nymphs of aphis gossypii as prey in a growth chamber (25 ± 1 °c, 70 ± 5% rh and a photoperiod of 16l: 8d h). the pre-oviposit...

the impairment of the reproductive performance of pesticide resistant individuals in pesticide-free environment is the result of fitness costs associated with pesticide resistance, which is often determined by resource allocation from a basic physiological process to the protection against pesticides, favoring survival at the expense of reproduction. in this study, the fecundity life table para...

demographic parameters of the pink stem borer, sesamia creticalederer (lepidoptera: noctuidae) were estimatedon its two main host plants, maize and sugarcane. the present studywas conducted under laboratory conditions at 27±1˚c, 50±10% relative humidity (rh %), and a photoperiod of 0:24 (l:d) hour for the larval stage and 16:8 (l:d) hour for the other life stages. the raw data were analyzed bas...

the life table parameters of schizaphis graminum (rondani) (hemiptera: aphididae) on four commercial cultivars of wheat (kohdasht, pastor, tajan and zagros) were determined in laboratory conditions. fertility life table were constructed using age-specific survivorship (lx) and age-specific fecundity (mx) and subsequently analyzed using jackknife method and anova. there were significant differen...

the effect of temperature on demographic parameters of the greater wax moth, galleria mellonella (l.) was studied at 23, 25, 27, and 30 °c, 50 ± 10% rh and a photoperiod of 16:8 (l: d) h. the life table parameters were estimated according to the age-stage, two-sex life table procedure. in addition, the bootstrap technique was employed for estimating the means, variances, and standard errors of ...

ooencyrtus fecundus ferriere & voegele (hymenoptera: encyrtidae) is one of the gregarious egg parasitoids of sunn pest that can superparasitize the host. superparasitism has inverse effects on fitness, reproductive potential, competition ability and adult size of gregarious parasitoids. in this study, the effects of superparasitism and its intensity (four levels including singleton, twin, tripl...