Intraguild predation alters life histories in Neoseiulus barkeri and Scolothrips takahashii: asymmetric effects on development and reproduction.

The sublethal effects of pyriproxyfen (PYR, a juvenile hormone analogue) were investigated for two consecutive generations on life-history parameters, such as developmental time, pupal weight, fecundity, fertility and longevity of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae). After topical application bioassay of third instar larvae, the LC25 and LC50 values (as sublethal doses) were determined to be 1.49 and 2.01 μg/μl, respectively. The results showed that the egg incubation period, larval and pupal duration times and oviposition period were increased in treated groups compared with the control (treated with distilled water). Pupal weight, adult longevity, fecundity and fertility were significantly reduced in the treatment groups compared with the control. Using the age-stage, two-sex life table analysis, we found that the intrinsic rate of increase (r), finite rate of increase (λ), gross reproduction rate (GRR) and net reproductive rate (R 0) significantly decreased while the mean generation time (T) and doubling time (DT) increased in two treatment groups compared with the control. In addition, administration of PYR induced morphogenetic abnormalities including untanned pupae, larval–pupal intermediates and various defective adults. The LC50 value was more effective on all of the above biological characteristics than the LC25 for both generations, although parents were more affected than the offspring. In general, our results revealed that PYR was highly effective against P. xylostella in the laboratory both directly (causing mortality) and indirectly (disruption of normal growth and development). We conclude that PYR is an excellent candidate for suppressing populations of P. xylostella through its sublethal effects.

PDF HTML阅读 XML下载 导出引用 引用提醒 UV-B长期胁迫对麦长管蚜子代种群动态的影响 DOI: 10.5846/stxb201611172338 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（39970112，20470268）；高校博士点基金（20130204110004）；陕西省科技厅国际合作项目（2012） Effect on population dynamics of the offspring of Sitobion avenae Fabricius (Hemiptera: Aphididae) exposed to long term UV-B stress Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为了探明UV-B长期辐射亲代麦长管蚜Sitobion avenae Fabricius后对其子代种群动态的影响。采用特定年龄生命表方法，设置不同强度（0，0.50，0.70 mW/cm2）UV-B连续多代处理麦长管蚜成虫，统计麦长管蚜分别经历UV-B辐射一代，六代，十一代，十五代后其子代麦长管蚜存活率和繁殖力、繁殖参数、种群参数的变化。结果表明：（1）经UV-B处理亲代麦长管蚜后，其子代种群的内禀增长率r与周限增长率λ在低强度处理组各世代之间无显著差异，在高强度处理组各世代之间呈先上升后下降的趋势。（2）处理组麦长管蚜种群繁殖力F、净增殖率R0、平均世代周期T、产卵天数和成蚜寿命均在G7代达到最大值，且与对照组无显著差异。（3）亲代麦长管蚜经UV-B胁迫处理后对子代种群的存活率影响显著。研究结论：亲代麦长管蚜经过不同代数的UV-B胁迫，可显著影响子代的生长发育与繁殖，且对处于不同世代的子代生态学指标产生不同影响。研究的创新点在于探究亲代麦长管蚜经历紫外胁迫后对其子代生长、发育与繁殖的影响，为逆境胁迫下蚜虫的生态遗传与进化机理提供理论依据。 Abstract:Recently, ultraviolet-B radiation (UV-B) has been proven to have a strong selection pressure on the biosphere and ecological environment, significantly influencing living organisms. The rapid increase of solar UV-B reaching the surface of the earth is owing to stratospheric ozone depletion caused primarily by the Industrial Revolution. The responses of insect physioecology and growth to ultraviolet radiation enhancement have received increasing attention in the scientific community. Sitobion avenae Fabricius (Hemiptera:Aphididae) is a common wheat pest. It affects plants by ingesting sap from the ears, stems, leaves, and other tender plant parts. It also transmits viruses (e.g., barley yellow dwarf virus) during feeding, thereby reducing wheat yield and quality. It is a good subject for research because of its special characteristics of parthenogenesis and high fecundity. The increase of UV-B levels may fundamentally affect the population dynamics of S. avenae by altering its normal growth, development, and fecundity. The two-sex life table analysis is a common method to indicate biological growth, development, and fecundity, and includes the entire population (males, females, and those that die before the adult stages), so that the result is more realistic than analyses based only on the means of development time. To explore the effect on population dynamics of the offspring of S. avenae by exposing the mother generation to UV-B for a long time, the age-specific life table of S. avenae was established to evaluate life-table parameters of offspring of S. avenae. The mother generation was radiated to different intensities of UV-B (0, 0.5, 0.7 mW/cm2) for one, six, eleven, and fifteen generations. The results showed that:(1) There were no significant differences in the intrinsic rate of increase (r) and finite rate of increase (λ) among the treatment group of each generation under low intensity of UV-B, whereas the parameters of r and λ first increased and then fell with generations under high intensity of UV-B. (2) The effect of UV-B on the fecundity (F), net reproductive rate (R0), mean generation time (T), oviposition duration, and adult longevity peaked in the seventh generation. Moreover, no significant difference was found in the seventh generation between the control and treatment groups. (3) When S. avenae were under different intensity of UV-B radiation in the same generation, most parameters in the treatments groups were significantly lower than those in the control except the parameter T in the second and sixteenth generation. However, no significant difference was found in the seventh generation between the control groups and treatment groups, whereas F, R0, T, oviposition days, and adult longevity all had significant differences, but there were no significant differences between other parameters in the twelfth generation. (4) The survival rate of offspring of S. avenae exposed to UV-B stress was significantly influenced. Our research showed that the effect of long-term UV-B stress on S. avenae was accumulated in the progeny, had different impacts in different generations. Our research showed the population dynamics of the offspring of S. avenae after the mother generation was influenced by UV-B; thus, the results may provide a theoretical basis for ecological genetics and evolutionary mechanisms of aphid under adversity stress. 参考文献 相似文献 引证文献

Trichogramma achaeae Nagaraja and Nagarkatti (Hymenoptera: Trichogrammatidae) is currently used as biological control agent for several lepidopteran pests. Knowledge of thermal requirements is essential to optimize its rearing procedures and inundative releases. The biological characteristics and two-sex life table parameters of T. achaeae were determined at five constant temperatures (15, 20, 25, 30, and 35 °C) using Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs. T. achaeae was able to develop and survive from 15 °C to 30 °C, but not at 35 °C. Temperature significantly affected the preadult development time and adult longevity, decreasing when temperature increased from 15 °C to 30 °C. Temperature significantly altered the sex ratio, being female biased between 15 °C and 25 °C. Age-stage, two-sex life table analysis indicated that net reproductive rate (R0) was highest at 20 °C. Both the intrinsic rate of increase (r) and finite rate of increase (λ) increased with increasing temperature, while the mean generation time (T) decreased significantly. In addition, functional response of T. achaeae was studied, being significantly affected by temperature and host egg density, displaying a Holling type-I at 15 °C and a Holling type-II at 25 °C. The relevance of these results is discussed for the use of T. achaeae as biological control agent.

In agroecosystems, insects have to compete with chemical insecticides, which are frequently present at sublethal concentrations. The exposure of insects to these modest stresses is now well-established to generate hormesis effects, which has implications for controlling insect pests. In this study, we assessed the sublethal effects of thiamethoxam on the biological parameters of Aphis gossypii Glover (Hemiptera: Aphididae), adults (F0) and subsequent transgenerational impacts, i.e., on the progeny (F1 generation), using an age stage, two-sex life table analysis. Results showed that thiamethoxam exhibited high toxicity against adult A. gossypii with the LC50 of 0.313 mg L−1 after 48 h exposure. The LC5 and LC10 of thiamethoxam considerably reduced the adult cotton aphids (F0) longevity and fecundity, while the reproductive days were reduced only at LC10. The pre-adult stage was decreased, while the adult longevity, total longevity, and fecundity were significantly extended in F1 aphids after exposure of F0 aphids to the sublethal concentrations of thiamethoxam. Moreover, the key demographic parameters such as intrinsic rate of increase, finite rate of increase and reproductive days were significantly increased, while mean generation time and total prereproductive were significantly reduced in the progeny. No significant effects were observed on the net reproductive rate. Taken together, these results showed that the sublethal concentrations of thiamethoxam affect the directly exposed aphids (F0) while causing transgenerational hormetic effects on the F1 generation of A. gossypii. In conclusion, our research showed that thiamethoxam has both sublethal and transgenerational effects on cotton aphids; it could be effective in IPM programs targeting this key pest.

<b>Background and Objectives:</b> Black Soldier Fly (BSF), <i>Hermetia illucens</i> (Diptera: Stratiomyidae) has long been studied primarily in terms of their important role in organic waste management. This species has a special ability to digest a variety of organic matter, from vegetable waste, food waste, decaying animal tissues to livestock manure and then convert to nutritional biomass for animal feed. The different types of feed during the larval period will affect the life history of black soldier fly. This study was aimed to determine the development, survival, population parameters and reproductive potential of the BSF reared on tofu dreg by the age-stage, two-sex life table analysis. <b>Materials and Methods:</b> The treatments of immature stages were constructed under laboratory conditions and the adult stage were reared at a semi-outdoors screenhouse with full sunlight. <b>Results:</b> The intrinsic rates of increase (r), finite rate of increase (λ), net reproduction rate (R<sub>0</sub>) and mean generation time (T) were 0.0713 per day, 1.0739 per day, 23.95 offspring and 43.705 days, respectively. The result indicated that the maximum reproductive value of females occurred at 42 days. The overall development time from egg to adult stage of the BSF was 52.2±1.6 days. <b>Conclusion:</b> The BSF can perform optimal development, survival rate and reproductive potential when reared on tofu dreg.

Life table of Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae)

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

The aim of this work was to construct life table of Bemisia tabaci (Gen.) A and B (silverleaf whitefly B. argentifolii Bellows and Perring) biotype (Hem.: Aleyrodidae) on two host plants; cotton, (Gossypium hirsutum L.) and rapeseed, (Brassica napus L.). Experiments were conducted in a growth chamber under 24 ± 2ºC, 55±3% RH and 16:8 (L:D) h photoperiod on caged plants of cotton G. hirsutum L. (Varamin 76 variety) and rapeseed B. napus L. (global variety. The intrinsic rate of natural increase (r m), net reproductive rate (R0) and mean generation time (T) for B. tabaci A biotype was 0.1010 females per female per day, 18.4075 females per female and 30.079 day (d) on cotton; 0.1286, 30.6760 and 26.77 d on rapeseed; and for B biotype (B. argentifolii) those above respective parameters averaged 0.1033, 27.8426 and 32.74 d on cotton and 0.1750, 40.75 and 21.27 d on rapeseed. The total survival of A and B biotype from the egg to adult on cotton was 22.08 and 22.25, respectively. The results showed significant differences between the two biotype reared on either host plant for gross reproductive rate (GRR), net reproductive rate (R0 or NRR), intrinsic rates of increase (r m), finite rate of increase (λ), doubling time (DT) and mean generation times (Tc). To obtain a better understanding of the biology of these biotypes, Stable age distribution (Cx) and some other aspects of life history related to their hosts were also studied. Based upon the results, both biotypes showed a greater reproduction capacity on rapeseed than on cotton. Thus, rapeseed was more suitable host than cotton for two biotypes and this was an important factor in host plant selection for optimizing the control strategies of these major pests.

Lasioseius japonicus is a species of soil-dwelling predatory mite with great potential for controlling insect pests and has a broad application prospect in biological control. This study was conducted under indoor conditions to explore the development, survival and reproduction of L. japonicus on two diets. Through the construction of two-sex life table of L. japonicus, it was revealed that, when it preyed on eggs of Drosophila melanogaster, the intrinsic rate of increase (r) was 0.2614 d-1, the net reproductive rate (R0) was 57.76 offspring, the finite rate of increase (λ) was 1.2988 d-1, and the mean generation time (T) was 15.49 d. When preying on eggs of Sitotroga cerealella, the intrinsic rate of increase (r) of L. japonicus was 0.1560 d-1, the net reproductive rate (R0) was 20.96 offspring, the finite rate of increase (λ) was 1.1690d-1, and the mean generation time (T) was 19.41 d. In addition, the life expectancy and population growth trend of L. japonicus were simulated based on the above two alternative prey species. The results showed that feeding on the eggs of D. melanogaster is more beneficial to the growth and reproduction of L. japonicus.

BackgroundTelenomusremus Nixon is an important egg parasitoid of Spodoptera spp. pests and, as such, has potential as a biological control agent. Spodopteralitura (Fabricius) is a significant pest of many economically important crops worldwide. This study was conducted to evaluate the demographic parameters and functional response of T.remus on the S.litura eggs.ResultsT.remus can lay 186.90 eggs/female in the lifetime, adult preoviposition period was 0 days, total preoviposition period was 10.03 days, and the ratio of female and male offspring was 0.495 and 0.421, respectively. In addition, most females emerged from 24 h-old eggs, whereas most males emerged from 48 h-old eggs. The intrinsic rate of increase, finite rate of increase, net reproductive rate, mean generation time, and population doubling time were 0.3506 d–1 1.4199 d–1 92.45 offspring/individua, 12.91 days and 1.98 days, respectively. The net killing rate of T.remus on S.litura was 101.49 eggs/female, indicating the high capacity of T.remus to parasitize S.litura eggs. Moreover, the higher the egg density, the higher the parasitism rate by female T.remus, although there was a trend of parasitism stabilization at an egg density of 100, indicating a type II functional response curve for this parasitoid.ConclusionOverall, these findings suggest that T.remus can be efficiently reared on S.litura eggs and shows potential as biocontrol agent for this economically important pest species.

Insecticidal treatment is a common practice for the control of stored-product insect pests. Most studies are focused on the direct effects of insecticides on target insects, while there are no data on the indirect effects on adults in terms of progeny fitness. This study deals with the effect of pirimiphos-methyl on adults of Tribolium castaneum (Coleoptera: Tenebrionidae), investigating their exposure time cost to progeny fitness. For this purpose, females of T. castaneum were exposed for 1, 3, 8, 16, 24, and 72h to pirimiphos-methyl and progeny birth or death rates were calculated. The fecundity, as well as the survival of progeny, was affected by the parental exposure to the insecticide. When females were exposed for 1 and 3h to pirimiphos-methyl, the net reproductive rate of the progeny was 4.1 and 4.3 females/female, respectively, which did not statistically differ with the progeny in control treatment (6.3 females/female). Further exposure time to pirimiphos-methyl affected significantly the progeny net reproductive rate, where the lowest value was observed at the 72-h exposure time (0.97 females/female). The intrinsic rate of increase, as well as the finite rate of increase, did not differ between the progeny of the control treatment (0.029 females/female/day and 1.029, respectively) and the progeny of exposed females at 1h (0.021 females/female/day and 1.021, respectively) or 3h (0.023 females/female/day and 1.023, respectively). By increasing the time of exposure to pirimiphos-methyl, a detrimental effect to progeny fitness was revealed based on the values of the intrinsic and finite rate of increase. The lowest values of these parameters were observed at the 72-h exposure time (0.001 females/female/day and 1.000, respectively). The same trend was observed in the values of the doubling time. In contrast, the mean generation time did not statistically differ between control and all insecticide treatments. The fact that the exposure of parental females of T. castaneum to pirimiphos-methyl negatively affects the demographic parameters of their offspring production should be seriously taken into account when management strategies are applied against this notorious stored-product insect species since it could reduce the repeatedly insecticidal applications in storage facilities.

Demographic toxicology is recommended for toxicity determination of the long term effects of a pesticide since it gives a more accurate and efficient measure of the effect of a pesticide. Thus, in the current study the sublethal effects of pirimicarb (carbamate insecticide) two concentrations of LC30and LC10were used against third instar larvae of Hippodamia variegata (Goeze) in order to determine the effects of the pesticide on demographic parameters of the predator under laboratory conditions. Results showed that pirimicarb did not affect individual life parameters such as development time of larva, pupa, adult longevity, female and male longevity, adult preoviposition period (APOP), and total preoviposition period (TPOP). However, population parameters such as intrinsic rate of increase (r), net reproductive rate (R0), mean generation time (T), and finite rate of increase (λ) was affected by sublethal treatment. For example, intrinsic rate of increase (r) was 0.18 day-1in the controls but it was 0.13 and 0.14 day-1in the treated insects with LC10and LC30concentrations, respectively. Also, there were significant differences between mean generation time (T) of the treatments and the controls i.e. mean generation time of the controls was 29.03 days while mean generation time in the two treatments of LC10and LC30was 33.93 and 31.66 days, respectively. The finite rate of increase was also significantly affected by sublethal effects of the pesticide. The results showed that pirimicarb, even at low concentrations, has potential to adversely affect the predatory ladybird, therefore care should be taken when this insecticide is used in the Integrated Pest Management (IPM) program.

Aphis gossypii Glover and Acyrthosiphon gossypii Mordvilko (Hemiptera: Aphididae) are important pests of cotton (Gossypium hirsutum L.) in Xinjiang, China, that reduce yield and lint quality. We studied competition between the two aphid species in laboratory arenas to better understand population change and competitive advantage between the two and to provide a theoretical basis for the observed population outbreak of aphids in cotton fields. To study intraspecific competition, densities of 5, 10, and 15 aphids per 5-cm-diameter leaf disc were established in individual 6-cm-diameter arenas. Equal numbers of each species were placed on leaf discs in the arenas to establish densities of 3, 5, and 10 aphids of each species per leaf disc to assess interspecific competition. In intraspecific competition assays, the mean generation time (T) and the net reproductive rate (Ro) of both species decreased as aphid density increased, while the intrinsic rate of increase (r) and finite rate of increase (λ) of Acy. gossypii increased as density increased. In interspecific competition assays, population growth of A. gossypii was higher than with Acy. gossypii at the same density, while the mean generation time of A. gossypii was less than with Acy. gossypii. The net reproductive rate, intrinsic rate of increase, and finite rate of increase were higher in A. gossypii than in Acy. gossypii. Density is a key factor affecting competition between A. gossypii and Acy. gossypii. The higher the density, the more intense the interspecific competition, with interspecific competitiveness of A. gossypii stronger than that of Acy. gossypii.

Side effects of chlorantraniliprole, phosalone and spinosad on the egg parasitoid, Trichogramma brassicae.

Proprioseiopsis asetus (Chant) (Acari: Phytoseiidae) is a newly developed and commercialized predatory mite that can prey on various phytophagous mites and small insects. To evaluate its potential as a biocontrol agent against pest thrips (Thysanoptera: Thripidae), we constructed age-stage, two-sex life tables and investigated the biological characteristics of P. asetus fed on two economically important thrip species, Megalurothrips usitatus and Thrips flavus (Thysanoptera: Thripidae), both of which cause significant crop damage. Our results show that P. asetus successfully develops and reproduces when fed on both thrips species, indicating its biocontrol potential against these pests. However, P. asetus reared on T. flavus exhibits shorter preadult duration, mean generation time (T), and population doubling time (DT), along with obviously reduced longevity, compared to P. asetus reared on M. usitatus. Despite the shorter lifespan, P. asetus fed on T. flavus shows significantly higher fecundity (F = 36.35 eggs/female), intrinsic rate of increase (r = 0.1816 d-1) and finite rate of increase (λ = 1.1991 d-1) than on M. usitatus (F = 30.75 eggs/female, r = 0.1375 d-1 and λ = 1.1474 d-1). Notably, no significant differences were observed in net reproductive rate (R0), adult preoviposition period (APOP), total oviposition period (TPOP), or oviposition duration between the two prey species. These findings indicate that P. asetus is a promising biological control agent for both thrip species, with T. flavus being a more suitable prey to support its rapid development, high fecundity and faster population growth, despite the trade-off in adult longevity. Based on these results, we propose tailored biocontrol strategies: frequent releases of P. asetus for T. flavus management to compensate for its shorter lifespan, and early release for M. usitatus to establish a population before the pest reaches damaging levels, aiming for more efficient and sustainable pest management in crop production systems.