Predicting spring emergence of blackcurrant leaf midge (Dasineura tetensi) from air temperatures

The mean duration of post-diapause development of overwintered Dasineura tetensi larvae (in cocoons) was 72.8 (SD=11.4), 45.9 (SD=8.6), 28.7 (SD=6.0), 15.9 (SD=4.3), 10.4 (SD=1.9) and 10.2 (SD=1.8) days at constant temperatures of respectively 10, 12.5, 15, 17.5, 20 and 25 °C in the laboratory. No perceptible development occurred at 5 or 7.5 °C and complete mortality occurred when larvae were held at 30 °C for prolonged periods. The relationship between development rate (r days^–1) and temperature (T °C) was sigmoidal between 10 and 25 °C, the logistic equation r=0.0158+0.085/(1+exp(–0.696(T–17.0))) accounting for 98% of the variation. Larvae entered the winter in diapause. Populations of cocoons were greatest in the surface soil in the centre of bushes adjacent to the crown, 69, 15, 9 and 6% of cocoons occurring in the top 0–1, 1–2, 2–3 and 3–4 cm of the soil, respectively. The time of termination of diapause in the field varied greatly between individuals and from season to season but a significant proportion (>40%) had broken diapause by the end of January in each of the three seasons studied. Diapause was not terminated in the laboratory by chilling over-wintered larvae in cocoons at –2.5, 2.5 or 10 °C for up to 28 days nor when held in a L16:D8 photoperiod. A computer-based phenological forecasting model was constructed using the development rate values (using the INSIM software developed at The Agricultural University, Wageningen, The Netherlands). The model accumulated daily development amounts calculated from daily maximum and minimum air temperatures from 1 February, the end of the coldest period of the year on average and before significant post-diapause development occurred. The model uses boxcar trains to simulate dispersion. The model predicted the time of first emergence of D. tetensi adults in spring at HRI-East Malling generally to within 6 days of the observed time of emergence, and to within 11 days at worst. There was poorer agreement between observed and predicted times of emergence when daily maximum and minimum soil temperatures (depth ca. 3 cm) were used. The use of the model to time insecticidal sprays in relation to the flowering time of blackcurrant is discussed.     

The Comparative Susceptibility of the Diamondback Moth Plutella xylostella and Some Other Major Lepidopteran Pests of Brassica Crops to a Range of Baculoviruses

The susceptibility of larvae of the Diamondback moth (DBM), Plutella xylostella to infection by three baculoviruses was evaluated in the laboratory using a microdroplet feeding assay. The viruses tested were a granulovirus (GV), originally isolated in Taiwan from P. xylostella larvae (Px GV-Taiwan); the nucleopolyhedrovirus (NPV) from Galleria mellonella (Gm NPV), and the NPV from Autographa californica (Ac NPV). Neonate P. xylostella larvae were susceptible to infection by all three viruses. In an extensive series of bioassays carried out over a 21-month period, LD 50S for neonate DBM larvae ranged from 1.0-8.9 viral occlusion bodies (OB) for Px GV-Taiwan, and 9.5-30.2 OB for Gm NPV and Ac NPV. LT 50S for the three viruses ranged from 3.8-6.0 days at 27 C, with Gm NPV having a significantly shorter LT 50 than the other two viruses. Second and third instar larvae of P. xylostella were significantly less susceptible to infection by Px GV-Taiwan (LD 50 s ranging from 18-57 OB/larva) than were neonate larvae. Gm NPV also initiated infection in several other lepidopterous pest species that colonize brassica crops. In particular, neonate Crocidolomia binotalis larvae proved highly susceptible to Gm NPV, with mean LD 50 s ranging from 2.1 to 9.3 OB/larva and a mean LT 50 of 4.8 days at a dose of 8.08 OB. Heliothis virescens neonate larvae were also highly susceptible to Gm NPV (LD 50 , 7.1 OB), but Mamestra brassicae larvae were less so (LD 50 , 80-270 OB). The results of the bioassays suggest that Px GV-Taiwan is highly infective and could be developed as a selective microbial pesticide for DBM. While Gm NPV has a higher LD 50 in DBM larvae, its wider host range may be of considerable value in situations where DBM occurs on cruciferous crops together with a complex of other lepidopterous pests.     

NaCl胁迫对甘薯叶片叶绿体超微结构及一些酶活性的影响

随ＮａＣｌ 胁迫浓度的提高,甘薯叶片叶绿体数目逐渐减少, 类囊体膜片层松散、扭曲、破裂并逐渐解体, 叶绿素含量下降。与此同时,Ｈ２Ｏ２ 、ＭＤＡ 含量增加, ＡＳＰ、ＳＯＤ 活性表现出先上升后下降的趋势。耐盐品种在ＮａＣｌ 胁迫下能维持较强的Ｈ２Ｏ２ 清除能力和较低的ＭＤＡ 水平     

野生朱鹮的种群数量和分布现状

2012年9-10月,我们对野生朱鹮（Nipponia nippon）的分布区和潜在分布区进行了调查,共发现其游荡期夜宿地23个,其中20个有朱鹮夜宿,分布在洋县（16个）、宁陕县（3个）和城固县（1个）。对这些夜宿地进行了的同步调查,共统计到野生朱鹮1 090只,其中97.2%分布在洋县境内。最大的夜宿集群数量为184只,集群数量超过40只的夜宿地共11个,累计停歇的朱鹮占总数的91.7%,表明野生朱鹮在游荡期有趋于集结较大群体夜宿的习性。朱鹮野生种群中当年出生的幼鸟占19.0%,据此估算,截至秋季朱鹮幼鸟的存活率约为67.2%。加强对保护区以外,尤其是野生朱鹮新扩散地区的的保护管理,将促进野生朱鹮种群的扩散,进一步增加这一濒危物种抵御风险的能力。     

Do upstream migrating,juvenile amphidromous shrimps,provide a marine subsidy to river ecosystems?

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