Transgenerational effects of multiple mating in Spodoptera litura Fabricius (Lepidoptera: Noctuidae).

Polyandrous mating can result in sexual conflict and/or promote the evolution of mating patterns. Does multiple mating by females support the genetic benefits hypothesis and can it be validated as an evolutionary strategy? If we are to decipher the consequences of sexual interactions and understand the interplay of sexual conflict and multiple generational benefits, the transgenerational effects need to be followed over multiple generations. We investigated the effects of three mating patterns, single mating, repeated mating, and multiple mating, on parental Spodoptera litura copulation behavior, and then identified the impact on the development, survival, and fecundity of the F1 and F2 generations. Fecundity was not significantly affected in the F1 generation but was substantially enhanced in the F2 generation. There was a reversal of offspring fitness across the F2 generations from the F1 generations in progeny produced by multiple mating. In addition, the intrinsic rate of increase, finite rate of increase and net reproductive rate in the F1 generation the multiple mating treatment was significantly lower than in the single mating treatment, but there was no apparent effect on the F2 generation. Repeated mating had no significant effects on progeny fitness. We postulate that multiple mating imposes cross-transgenerational effects and may ultimately influence multigenerational fitness in S. litura.

Effects of temperature on the adults and progeny of the predaceous mite Lasioseius japonicus (Acari: Blattisociidae) fed on the cereal mite Tyrophagus putrescentiae (Acari: Acaridae).

The predatory mite Lasioseius japonicus Ehara is a newly recorded species in China that has been shown to have great potential as a biological control agent. The species is a soil-dwelling mite that is known to prey on various pests including economically important mites, fungus gnats and other terricolous arthropods. Considering that temperature is one of the most important factors affecting the population dynamics of arthropods, the development, survival and reproduction of L. japonicus were evaluated under indoor conditions at seven temperatures: 19, 22, 25, 28, 31, 34 and 37 °C, at 75% relative humidity and L0:D24 h photoperiod. The mites were fed on the cereal mite Tyrophagus putrescentiae (Schrank) and the data were analyzed using the two-sex life table. The results demonstrated that L. japonicus could complete their development and reproduce at temperatures between 19 and 34 °C, but were unsuccessful at 37 °C. Increasing temperature shortened the development time of the pre-adult stage and the average generation time (T). The life table parameters indicated that at temperatures from 22 to 31 °C the development rate and reproduction of L. japonicus were highest: at 22, 25, 28 and 31 °C the net reproduction rate (R0) was 55.5, 61.6, 61.2 and 59.0, respectively, and the average fecundity rate (F) was 81.7, 88.0, 102.0 and 86.8, respectively. The maximum values of intrinsic population growth rate (r) (0.341) and finite rate of increase (λ) (1.407) occurred at 31 °C.

Demography and Mass-Rearing Harmonia dimidiata (Coleoptera: Coccinellidae) Using Aphis gossypii (Hemiptera: Aphididae) and Eggs of Bactrocera dorsalis (Diptera: Tephritidae).

We compared rearing Harmonia dimidiata (F.) (Coleoptera: Coccinellidae) on four combinations of Aphis gossypii Glover (Hemiptera: Aphididae), and eggs of Bactrocera dorsalis Hendel (Diptera: Tephritidae), using the age-stage, two-sex life table. The four combinations were: both larvae and adults were reared on aphids; larvae were reared on aphids and adults were reared on fresh fruit fly eggs; larvae were reared on lyophilized fruit fly eggs and adults were reared on aphids; and larvae were reared on lyophilized eggs and adults were reared on fresh eggs. The highest intrinsic rate of increase (r = 0.1125 d-1) and net reproductive rate (R0 = 260.7 offspring) were observed when both larval and adult stages of H. dimidiata were reared on A. gossypii. When B. dorsalis eggs were used as rearing media for larvae, adults, or both, the values of r and R0 were significantly decreased. The lowest values (r = 0.0615 d-1 and R0 = 38.6 offspring) were observed when both larvae and adults were reared entirely on B. dorsalis eggs. Despite the lower r and R0 values, our results showed that B. dorsalis eggs could be considered as an adequate, less expensive alternative diet for rearing H. dimidiata because of the time and labor savings resulting from the ease of preparation and the ability to store the eggs for timely usage. The mass-rearing analysis showed that the most economical rearing system was to rear larvae on A. gossypii and adults on B. dorsalis eggs.

Linking Demography and Consumption of Henosepilachna vigintioctopunctata (Coleoptera: Coccinellidae) Fed on Solanum photeinocarpum (Solanales: Solanaceae): With a New Method to Project the Uncertainty of Population Growth and Consumption.

Because life tables are capable of providing the most comprehensive description on the survival, stage differentiation, and the reproduction of animal populations, they can be considered as the bases of population ecology and pest management. Researchers concerned with studies involving life tables inevitably face the problem of describing the variabilities that occur in the survival, stage differentiation, and fecundity data. Finding a means to include these variabilities in population projections concerning pest management may be problematic. Henosepilachna vigintioctopunctata (F.) (Coleoptera: Coccinellidae) is a pest of many plant species in Asia, including cultivated crops, ornamentals, and wild plants. The raw life history data (survival, stage differentiation, and fecundity) and consumption rate of both sexes of H. vigintioctopunctata reared on Solanum photeinocarpum Nakamura et Odashima (Solanales: Solanaceae) were collected in the laboratory and analyzed based on the age-stage, two-sex life table theory. The intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R0), mean generation time (T), and net consumption rate (C0) of H. vigintioctopunctata were 0.1312 d-1, 1.1402 d-1, 603.5 offspring, 48.8 d, and 77.8 cm2, respectively. By using the bootstrap technique with 100,000 samples, we demonstrated that the life tables constructed based on the 2.5th and 97.5th percentiles of R0 and λ can be used to describe the variabilities found in the survival and fecundity curves and to project the uncertainty of population growth.

Demography and Population Projection of Aphis fabae (Hemiptera: Aphididae): with Additional Comments on Life Table Research Criteria.

We collected developmental, survival, and reproduction data for Aphis fabae Scopoli (Hemiptera: Aphididae) reared on faba bean, Vicia faba L. 'Sevilla' at four constant temperatures (15, 20, 25, and 30°C), 70% relative humidity, and a photoperiod of 16:8 (L:D) h. The highest intrinsic rate of increase (r = 0.4347 d(-1)) and finite rate (λ = 1.5445 d(-1)) were observed at 25°C. The population projection based on the age-stage, two-sex life table quantitatively revealed the growth potential and stage structure of the aphid. We have included the following suggestions to aid researchers in life table studies: 1) The bootstrap method should be used to estimate the variance and SEs of developmental time, survival rate, fecundity, and population parameters. 2) The required number of bootstraps is dependent on the life table data--the higher the variation among individuals, the higher the number of bootstraps should be. In most cases, we suggest that 100,000 bootstraps should be used to obtain a stable estimate of variance and SEs. 3) Computer projection based on the age-stage, two-sex life table should be used to reveal the stage structure during population growth. 4) We used a simple equation based on the total fecundity, survival rate to adult stage, and first reproductive age to detect possible errors in life table parameters. 5) To assist readers in comprehending results, life table studies should include the cohort size, preadult survival rate, number of emerged female adults, mean fecundity, survival and fecundity curves, and population parameters.