The influence of cucumber offered as a host plant either alone or with Aphis gossypii Glover (Hemiptera: Aphididae) was studied on the various life table and biological characteristics of the predatory bug Macrolophus pygmaeus Rambur (Hemiptera: Miridae). The nymphal development was studied at 15, 20, 25, 30 and 35°C while adult performance was assessed at 15, 20, 25 and 30°C, using a 16L : 8D photoperiod and 65 ± 5% r.h. Nymphs completed their development at all temperatures except at 35°C. Nymphal development took significantly longer time in the absence than in the presence of prey at 20 and 25°C, but the reverse was true at 15°C. Nymphal mortality was highest at 15°C in the presence of prey and it was mainly recorded at the first and second stages. Females oviposited a small number of eggs at all temperatures but not at 30°C in the absence of prey. The average number of eggs per female was almost similar with or without prey, being highest at 20°C, and adult longevity was highest at 15°C. The results concerning population parameters clearly showed that cucumber with or without prey can not support a population increase of M. pygmaeus. However, it seems that A. gossypii on cucumber inhibits development of M. pygmaeus more than when this aphid species is not present. This adverse effect on this host plant-prey system possibly results from the particular aphid genotype on cucumber, leading to high nymphal mortality, reduced fecundity and short adult life-span of M. pygmaeus.
The growth parameters of the green lacewing, Chrysoperla nipponensis-B (Okamoto), were studied under laboratory conditions. The highest mortality was recorded in the immature stages (instars 1st, 2nd, 3rd and pupae) of C. nipponensis fed on the eggs of Corcyra cephalonica (37.26%). The sex ratios (proportion of female to male) when reared on the eggs of C. cephalonica and an artificial diet with ginger were 0.93 : 1.00 and 0.87 : 1.00, respectively. The maximum life spans of females reared on the eggs of C. cephalonica and an artificial diet with ginger were 63 and 64 days, respectively. The females reared on the eggs of C. cephalonica produced the highest number of eggs (10.4) on the fifth day of oviposition, whereas on the artificial diet with ginger it was 9.26 on the eighth day of oviposition. The net reproductive rate (Ro) and maximum gross reproductive rate (GRR) of C. nipponensis fed on the eggs of C. cephalonica were 69.50 and 223.10 females per female per generation, respectively, whereas for the artificial diet with ginger they were 117.24 and 236.89 females per female per generation, respectively. Mean generation time (T) was 37.06 and 48.16 for the eggs of C. cephalonica and artificial diet with ginger, respectively. The intrinsic rate of natural increase (r) was 0.11 and 0.09 females per female per day for the eggs of C. cephalonica and artificial diet with ginger, respectively. The finite rate of increase (λ) was 1.12 and 1.11 females per female per day for the eggs of C. cephalonica and artificial diet with ginger, respectively. The population doubling time (DT) was 6.05 days on the diet of eggs of C. cephalonica and 7.00 on the artificial diet with ginger., Shafique A. Memon, Dzolkhifli Omar, Rita Muhamad, Ahamd S. Sajap, Norhayu Asib, Arfan A. Gibal., and Obsahuje bibliografii
Laboratory experiments were used to investigate the influences of 25 combinations of temperature and barley plant growth stage (5 × 5 factorial combination of temperature and barley plant growth stage) on the development, survival and reproduction of the Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko). For each of the 25 treatments, the developmental time and nymphal production of 72 RWA individuals were recorded (1800 RWA in total) throughout their entire lifetimes. The collected data were used for analyzing demography, modelling phenology, and simulating population growth of RWA. In this paper, the results of demographic analyses are reported. Specifically, for each treatment, cohort life tables, reproductive heterogeneity tables (parity and birth intervals), and reproductive schedule tables were constructed, and demographic parameters such as intrinsic rate of increase, life-span, fecundity, life table entropy, etc. calculated. Based on these analyses, the most important summary demographic statistics are reported. Using the intrinsic rate of increase (rm) as an example, a procedure is demonstrated that builds a dynamic rm model by applying the Best Subset Regression approach. A more comprehensive (considering reproductive heterogeneity and schedule tables) yet concise (comprising dynamic rm models) demographic model than that based on standard life table analysis alone is presented.
Qualitative and quantitative differences in prey are known to affect the life histories of predators. A laboratory study was used to evaluate the suitability of three aphid prey, Aphis gossypii, Aphis craccivora and Lipaphis erysimi, for the ladybird beetle, Anegleis cardoni (Weise). Development was fastest on A. gossypii followed by A. craccivora and L. erysimi. Percentage pupation, immature survival, adult weight and the growth index were all highest when reared on A. gossypii and lowest on L. erysimi. Similarly, oviposition period, lifetime fecundity and egg viability were all highest on a diet of A. gossypii, lowest on L. erysimi and intermediate on A. craccivora. Age-specific fecundity functions were parabolic. Adult longevity, reproductive rate and intrinsic rate of increase were all highest on A. gossypii and lowest on L. erysimi. Life table parameters reflected the good performance on A. gossypii and poor performance on L. erysimi. Estimates of individual fitness values for the adults reared on A. gossypii and A. craccivora were similar and higher than that of adults reared on L. erysimi. Thus, the three species of aphid can all be considered essential prey for A. cardoni.
The common pistachio psyllid (CPP) is thought to respond to nutrient availability in pistachio trees. We determined the effect of a deficiency of leaf iron (Fe) has on the abundance of the pistachio psyllid at a regional scale. First, we monitored the abundance pistachio psyllid in four pistachio orchards (24 trees as 24 repetitions) located in Maybod County, Yazd province in the centre of Iran and then measured leaf nutrient levels. Orchards were located up to 2.6 km apart. Multivariate regressions were used to determine the relationship between leaf nutrients and CPP population growth. The results indicate that the number of psyllid eggs and population growth rate of the nymphs was negatively correlated with Fe levels in the leaves, while peak numbers of psyllid eggs were positively correlated with the levels of Cu in the leaves. In a manipulative field experiment, we conducted two experiments: (1) pistachio trees treated with iron compared with control trees, and (2) pistachio trees previously treated with iron were treated with ammonium sulphate and compared with trees treated with ammonium sulphate. In the first experiment, psyllids in leaf disc-cages had a significantly greater intrinsic rate of population increase and net reproductive rate on Fe-treated trees than the control trees (Stage 1). In the second experiment, psyllids in leaf disc-cages had similar intrinsic rates of population increase and net reproduction both on the ammonium sulphate treated trees (control) and those previously treated with iron. This indicates that iron may have reacted negatively with nitrogen content of the leaves. In general, these findings indicate that when there is a deficiency of iron in the leaves, the application of nitrogen fertilizer had little effect on the performance of CPP and may have played a minor role in the population dynamics of CPP, but the application of a Fe fertilizer without considering the nitrogen content of the leaves may lead to a population outbreak.