Offspring performance and female preference of Pagiophloeus tsushimanus (coleoptera: curculionidae) on three Lauraceae tree species: A potential risk of host shift caused by larval experience

The weevil Pagiophloeus tsushimanus Morimoto (Coleoptera: Curculionidae), native to Eastern Asia, is a wood-boring pest that causes severe damage to camphor trees (Cinnamomum sp.) in Shanghai, China. Other Lauraceae tree species that grew sympatrically with this pest in close proximity could face a potential threat. To assess the potential risks of host shift, we explored the phenotypic associations between preference and performance in P. tsushimanus reared on three Lauraceae tree species. In a no-choice experiment offering branches of each plant as diet material and oviposition sites, we found that individuals reared on Cinnamomum camphora (L.) Presl (Laurales: Lauraceae) exhibited the strongest performance with shorter development time, higher survival and growth rate in the immature stage, longer longevity and greater fecundity in adults. In contrast, those on novel Lauraceae tree species (Cinnamomum chekiangensis Nakai and Phoebe chekiangensis Shang) had difficulty completing their whole life cycle due to significantly lower survival and reproduction. In a multiple-choice experiment, C. camphora was established as the preferred host. However, we found that the larval experiences on the non-preferred host plants contributed to an increased preference for that plant species. These results indicated that both the preference-performance hypothesis and the Hopkins’ host selection principle are applicable in this weevil under experimental conditions. It is possible that although the weevil performed poorly on two novel Lauraceae tree species, under favourable conditions their surviving offspring could evolve into a new host-specific population. Consequently, this weevil pest needs to be monitored on these novel Lauraceae tree species.     

不同大豆品种上红绿两种色型豌豆蚜的种群参数

【目的】探讨不同大豆品种对红绿两种色型豌豆蚜Acyrthosiphon pisum种群参数的影响,为大豆品种的抗蚜性评价及豌豆蚜的预测预报与综合防治提供试验依据。【方法】在光周期10L∶14D、温度23±1℃,相对湿度60%±10%,光照强度212μmol/m~2·s的人工气候箱中,观察和分析4个大豆品种(汾豆牧绿2号、南夏豆25、南黑豆20和南豆5号)叶片上红绿两种色型豌豆蚜的成虫寿命、繁殖和种群生命表参数。【结果】在大豆品种汾豆牧绿2号上,红绿两种色型豌豆蚜成虫寿命均最短,繁殖力均最弱,且红色型豌豆蚜成虫寿命比绿色型长1.07 d,内禀增长率是绿色型豌豆蚜的29.93倍;在南夏豆25上,红色型豌豆蚜成虫寿命比绿色型长2.46 d,内禀增长率是绿色型豌豆蚜的5.86倍;在南黑豆20上,红色型豌豆蚜成虫寿命比绿色型长2.47 d,内禀增长率是绿色型豌豆蚜的1.54倍;在南豆5号上,红色型豌豆蚜成虫寿命比绿色型短0.02 d,内禀增长率是绿色型豌豆蚜的1.41倍。【结论】不同大豆品种对红色和绿色型豌豆蚜种群参数的影响不同,且两种色型豌豆蚜对不同大豆品种适应性反应也不相同。     

Biology and fertility life table of the greenbug,Schizaphis graminum (Hemiptera: Aphididae) on the resistant winter wheat cultivar (Pishgam) in Iran

The greenbug, Schizaphis graminum (Rondani) (Hemiptera: Aphididae) has been known as a major pest of small grains, particularly wheat, worldwide. In this study, the effect of new wheat cultivar (Pishgam) for cold regions on biological characteristics of greenbug was investigated in a greenhouse at 25 ± 2 °C, 55 ± 10% relative humidity and a photoperiod of 16:8 h (L:D). The raw data were analysed based on the age-stage, two-sex life table. The intrinsic rate of increase (r), the finite rate of increase (λ), the net reproduction rate (R₀) and the mean generation time (T) of greenbug were 0.313 ± 0.0019, 1.36 ± 0.0027 females/female/day, 83.33 ± 0.331 females/female and 14.11 ± 0.09 days, respectively. The life expectancy of a nymph is 43.57 days. The maximum reproductive value of females is on the 16th day which coincides with the total pre-reproduction period counted from birth. Hence, the present results may provide helpful information for comprehensive IPM programme of greenbug on this variety in cold regions of Iran. Result revealed that nymphal survival rate of the aphid was 100% on studied cultivar like that on sensitive host plant cultivar.     

Survival,development and reproduction of Euseius finlandicus (Oudemans) (Acari: Phytoseiidae) fed on various kinds of food substances

Laboratory experiments were conducted to investigate the effect of diet on the biology of the phytoseiid mite, Euseius finlandicus (Oudemans). The predatory mite was able to develop and reproduce better when fed on the eriophyid mites, Aceria olivi (Zaher and Abou-Awad), Aceria dioscoridis (Soliman and Abou-Awad) and Cisaberoptus kenyae (Keifer). The developmental time of immature stages was the shortest when fed on motile stages of eriophyid mite species, followed by the spider mite, Tetranychus urticae Koch, and then pollen grains of Ricinus communis L., Phoenix dactylifera L. and Helianthus annuus L. Total egg production was highest when the predator fed on A. olivi, A. dioscoridis and C. kenyae recording at the rate of 51.0 50.0 and 43.84 eggs/female, respectively, but lowest on pollen grains, R. communis, P. dactylifera and H. annuus at the rate of 11.96, 5.3 and 2.0 eggs/female, respectively. But, the reproduction was nil on the tetranychid mite, T. urticae. Also, sex ratio of the progeny favoured females, when the predatory mite was reared on the eriophyid preys. E. finlandicus recorded the highest intrinsic rate of increase (r_m?=?0.31 females/female/day) when fed on A. dioscoridis, followed by (0.30 and 0.23 females/female/day) when fed on A. olivi and C. kenyae, respectively. In contrast, the lowest intrinsic rate of increase (r_m?=??0.31) was noted when fed on H. annuus pollen grains. The eriophyid mite, as a prey, recorded the shortest developmental time and highest oviposition rate of E. finlandicus.     

Agistemus exsertus Gonzalez (Acari: Stigmaeidae) as a predator of two scale insects of the family Diaspididae (Homoptera: Diaspididae)

Abstract

The predacious mite Agistemus exsertus Gonzalez completed its life-span when fed on eggs and crawlers of the Florida red scale Chrysomphalus ficus Ashmead and the white date scale Parlatoria blanchardi (Targioni). The development was faster when individuals were maintained on eggs and crawlers of C. ficus, compared with both stages of P. blanchardi. The average number of eggs/female/day was 2.5 and 1.1 on eggs and crawlers of C. ficus, respectively. Eggs and crawlers of P. blanchardi were an unsuitable food for egg laying for A. exsertus. Life table parameters showed that A. exsertus preferred eggs of C. ficus to the crawlers as prey. The population of the predator feeding on eggs and crawlers of Florida red scale multiplied 45 and 7 times in a generation time of 23 and 20.5 days, respectively. Under these conditions, the intrinsic rate of increase (r _m) was (0.17 and 0.098) individuals/female/day on eggs and crawlers of C. ficus, while the finite rate of increase (λ) was (1.18 and 1.11) on both stages of C. ficus.     

Life table parameters of large white butterfly Pieris brassicae (Lepidoptera: Pieridae) on different cabbage varieties

Effect of four different cole crops (Brassica oleracea var. botrytis, Brassica oleracea var. capitata, Brassica oleracea var. italica and Brassica oleracea var. viridis) on biological parameters of the large white butterfly Pieris brassicae was evaluated at temperature 26 ± 1 °C, 60 ± 5% R. H. and a photoperiod of 16: 8 (L:D) h. The shortest larval and pupal period stages were recorded on B. oleracea var. botrytis (22.18 ± 0.20 days) and (13.32 ± 0.17 days), respectively. The life span was longest on B. oleracea var. viridis (60.43 ± 2.34 days) and shortest on B. oleracea var. botrytis (50.19 ± 0.51 days). The highest percentage of larval and pupal mortality was observed on B. oleracea var. viridis (74%), and (53%), respectively. We found that P. brassicae prefers B. oleracea var. botrytis and B. oleracea var. capitata among cole crops; it is due to the lowest percentage of larval and pupal mortality and the highest rate of life table parameters, including survival rate (lx) and life expectancy (ex), which makes them to be susceptible varieties to this pest. Contrary, a longer developmental time on B. oleracea var. viridis may be attributed to poor nutritional status and reduced survival of the cohort, resulting in high rates of mortality, which was partial resistance to pest. Knowledge of the biology and life table parameters of P. brassicae on different cole crops could be effective in detecting and monitoring the pest infestation, variety selection and crop breeding.     

Prominence of three diets on life table parameters for Chrysoperla carnea (Neuroptera: Chrysopidae) to mass rearing under laboratory conditions

Chrysoperla carnea (Steph.) is a general predator reared in industrial scale. Different eggs of moth were used to rear C. carnea, but stabled moth colony needed expensive equipment and is costly. In this research, we surveyed appropriate diet to mass rearing. For this purpose, 100 same old (24H) eggs of C. carnea, separately, were selected randomly from the mass culture of C. carnea which was reared on the egg of flour moth Anagasta kuehniella (Zeller), artificial diet and semi-artificial diet under laboratory conditions (25 ± 5°C, 65 ± 5% RH and L–D: 16–8). These results showed reduction process e_x (expectation of life table at age X) and the survival curve was convex (K-Strategy). Also L_x in appearing of adults that fed on egg of flour moth, artificial diet and semi-artificial diet were 0.76, 0.4 and 0.9 which implied that 24, 60 and 10% of cohort were dead before reaching adult stage. Eggs produced by each female were recorded daily until all females died. The parameters were estimated using Carey’s (1993) method. Gross (GRR) and net (R₀) reproductive rates of predator on A. kuehniella, artificial diet and semi artificial diets were 225.5 ± 3.45, 72.4 ± 3.5, 267.8 ± 4.8 and 180.12 ± 2.3, 24.33 ± 4.3, 254.05+3.3 (female/female/generation), respectively. Mean generation time (T), Doubling time (DT), Intrinsic rate of increase (r_m ) and Finite rate of increase (λ) of predator on A. kuehniella, artificial diet and semi artificial diet were 31.9 ± 0.71, 42.87 ± 0.45, 29.79 ± 0.57 (days); 4.27 ± 0.03, 9.36 ± 0.06, 3.74 ± 0.05 (days); 0.162 ± 0.001, 0.074 ± 0.003, 1.185 ± 0.002; and 1.175 ± 0.001, 1.076 ± 0.002, 1.203 ± 0.002 (female/female/day), respectively. This research indicated that semi-artificial diet is a suitable prey for the predator.     

Book Review

Two factors were examined to determine their effect on the life history, reproduction and life table parameters in the predacious mite Paraseiulus talbii (Athias-Henriot), cultured in the laboratory at 32°C and 75% RH, using tydeid mite, Orthotydeus californicus (Banks) as food. The factors investigated included age of mating females and food deprivation periods during adult stage. Age of mating females has an influence on fecundity and adult longevity; old females decreased egg production and shortened adult longevity compared with young females under constant conditions of abundant prey. A significant lower fecundity, shorter oviposition period and adult longevity were recorded on females when exposed to different food deprivation programmes. Old mating females (30-days old) as well as females exposed to severe food deprivation (three days starvation/a week) resulted in the lower net reproductive rate (Ro), intrinsic rate of natural increase (r_m) and finite rate of increase (λ) values (Ro = 7.301 and 7.486, r_m = 0.202 and 0.198, λ = 1.224 and 1.219) compared with young females (0-day old) and without food deprivation (Ro = 41.312, r_m = 0.308, λ = 1.361). The influence of the duration of copulation on egg production was also studied. Artificial curtailment of copulation to half or quarter the average duration resulted in a reduction in the percentage of reproducing females, fecundity, oviposition duration and the proportion of females in the progeny.     

灵空山油松种群年龄结构与动态分析

对山西灵空山自然保护区的油松（Pinus tabulaeformis）种群进行了调查,利用生存分析理论及谱分析理论,分析了油松种群径级结构和静态生命表,绘制了存活曲线,同时分析了种群数量的周期性。主要结果如下：（1）油松种群幼苗幼树个体数较多,中径级的个体数较稳定,而高径级由于种间竞争及环境因子的影响,个体数明显下降。（2）油松种群的存活曲线呈现Deevey-Ⅱ型。动态表现为前期增长,中期稳定,后期衰退。（3）油松种群波动存在小周期,但变化不大,说明油松种群发展较为稳定。     

海南特有种东方琼楠种群结构特征

为探讨海南特有种东方琼楠(Beilschmiedia tungfangensis)种群结构特征,在海南尖峰岭林区设置20.4hm2样地,从种群径级结构、静态生命表、存活曲线、空间分布格局等方面进行分析。结果表明:1)东方琼楠种群径级分布呈倒"J"型,为增长型种群;2)在第Ⅲ级(DBH:10～15cm)时生命期望值最高,向大龄级和小龄级呈递减趋势;3)存活曲线接近DeeveyⅢ型,呈凹型;死亡率曲线和消失率曲线呈"V"型;4)不同分析方法均表明该种群呈聚集分布,且聚群强度较大;5)聚块性指数随径级呈"正余弦"变化。