Laboratory survival of Drosophila suzukii under simulated winter conditions of the Pacific Northwest and seasonal field trapping in five primary regions of small and stone fruit production in the United States

BACKGROUND: Drosophila suzukii was first found in Oregon in August 2009. The threat of this pest to regional small and stone fruit production industries led to investigations on its overwintering capabilities in fruit‐growing regions in the Pacific Northwest. Knowledge of its cold tolerance will help in the development of computer models to forecast seasonal population growth and decline. RESULTS: Of 1500 adults or pupae, 22 (1.4%) individuals survived the 84 day experimental chilling period. Most (86%) of the survivors were subjected to 10 °C temperature treatments. Survival decreased significantly at lower temperature treatments. Freezing temporarily increased the mortality rate but did not significantly affect overall mortality over the trial period. Flies that emerged from pupae are estimated to survive for up to 103–105 days at 10 °C and for shorter periods at lower temperatures. Field trapping in five fruit production areas has demonstrated overwintering survival in California and Oregon, but lower survival is predicted in Eastern Washington and Michigan. CONCLUSION: The experiments reported here indicate that long‐term survival of D. suzukii is unlikely at temperatures below 10 °C. Field data from five climatic regions indicated extended low initial D. suzukii field presence in 2010 in all regions except California, where field presence was recorded earlier. Copyright © 2011 Society of Chemical Industry     

塔克拉玛干沙漠腹地两处高地的地质地貌对比研究——麻扎塔格山和北民丰隆起

文章论述了沙漠腹地两处高地的地质地貌特点,并作对比分析。它们之间既有受构造控制的共性,又有发育历史差异带来的个性,认为它们之间同受东西向构造控制,长期以来经历缓慢的隆升与长期同受沙漠包围经受剥蚀;它们的存在的地貌效应,导致南北侧许多自然环境因子的差异,同时对丝路兴衰和西域文明的进展也具有影响。     

高产油葵光合特性的初步研究

北疆沿天山一带高产油癸光合特性的初步研究结果表明,油葵单叶光合速率日变化呈双峰曲线,值分别出现在１２：００和１６：００左右。油葵群体光合速率日变化呈单峰曲线,峰值一般出现在１２：００￣１３：００,光合持续时间为１３ｈ左右,略低于同期单叶光合持续时间。不同时层群体的我率及光合速率均以中上层叶片较大,占群体总光合量的８２％。各生育期中,群体光合的最高值出现在盛花期,同时植株干物质积累也最大。灌浆期光合     

东南太平洋公海智利竹筴鱼年龄与生长研究

智利竹筴鱼是一种重要的中上层经济鱼类,对其生活史关键过程的认识还相当有限。根据2006年5-8月在智利公海采集的智利竹筴鱼样本,利用其中963尾智利竹筴鱼耳石对其年龄进行了鉴定,估算了智利竹筴鱼叉长体重关系以及von Bertalanffy生长方程参数,并分析了智利竹筴鱼耳石重量(OW)与年龄的关系。研究结果表明,样本最大年龄9龄,最小年龄2龄,样本年龄组成以4龄为主(71.5%)。智利竹筴鱼叉长体重方程参数a、b分别为0.000 03和2.801 9,von Bertalanffy生长方程参数L∞为738.4 mm,k为0.107,t0为-1.08。耳石重量与年龄呈显著线性关系(r=0.74,P<0.001),表明耳石重量可用于智利竹筴鱼年龄鉴定。     

The influence of life history dynamics and environment on the determination of year class strength in North Sea herring (Clupea harengus L.)

The inter-annual variability in year class strength (1976–2000) of North Sea herring (Clupea harengus) was investigated using Paulik diagrams based on survey data and Virtual Population Analysis. The herring life cycle was split into five stages: spawning stock biomass (SSB), egg production, larvae, fish with 0 winter rings on the otolith (0-wr), 1-wr and 2-wr. Surveys were used as indices and Paulik analysis revealed relationships between stages. In 80% of the years, year class strength reflected SSB. Poorer than expected year classes were determined during the larva to 0-wr phase, whilst stronger than expected year classes were apparently determined during the 0-wr to 1-wr stage. There was no clear relationship between survival of young stages of herring and the abundance of Calanus finmarchicus but the year class strength of 0-wr and 1-wr had a negative relationship to bottom water temperature. Lower sea water temperatures in the North Sea are associated with higher Calanus abundance. The analysis shows that the strength of aberrant year classes of North Sea herring is determined between the pelagic larval and the juvenile stages.     

An assessment of the west winter–spring cohort of neon flying squid (Ommastrephes bartramii) in the Northwest Pacific Ocean

In the Northwest Pacific, the squid jigging fisheries targeted the west winter–spring cohort of neon flying squid (Ommastrephes bartramii) from August to November. Total annual catch by the Chinese mainland squid jigging fleet during 2000–2005 ranged from 64,100 to 104,200 t. The unique life history of this squid species makes the use of traditional age- or length-structured models difficult in evaluating the effect of intensive commercial jigging on this stock. We fitted a modified depletion model to the Chinese jigging fisheries data to estimate the squid stock abundance during 2000–2005. Monthly biological data were randomly sampled from the five squid jigging vessels during the fishing seasons. Effects of using different natural mortality rates (M) and three different error assumptions were evaluated in fitting the depletion model. Based on sensitivity analyses, the log-normal error model was found to be preferred for the squid assessment. The assessment results indicated that the initial (pre-fishing season) annual population sizes ranged from 199 to 704 million squid with the M value of 0.03–0.10 during 2000–2005. The proportional escapement (M = 0.03–0.10) for different fishing seasons over the time period of 2000–2005 ranged from 15.3% (in 2000) to 69.9% (in 2001), with an average of 37.18%, which was close to the management target of 40%. Thus, the current fishing mortality of the squid jigging fishery was considered to be sustainable. We inferred its annual maximum allowable catch ranging from 80,000 to 100,000 t. This study suggests that the modified depletion model provides an alternative method for assessing short-lived species such as O. bartramii.     

Visual acuity of Pacific Saury <Emphasis Type="Italic">Cololabis saira</Emphasis> for understanding capture process

ABSTRACT:   To understand the mechanism of the behavioral response in the capture process of how fish recognize fishing gear and then how they can avoid the gear, the visual acuity of Pacific saury Cololabis saira was investigated by histological examination of the retina of individuals in the size range of 75–365 mm fork length (FL). The contour map of cone density distribution shows that the highest cone density is located in the temporal area of the retina, which indicated the visual axis as the forward direction. The visual acuity (VA) depends both on the focal length of the lens and the number of cones in the retina. The lens diameter increased linearly from 1.40 to 4.73 mm with fish growth, while the cone density decreased gradually from 765 to 378 cells/0.01 mm². Our results show that the visual acuity increases proportionately from 0.057 to 0.140 for individuals ranging in FL from 75 to 365 mm as expressed by the equation VA  = 0.0065 ×  FL ^0.5271 ( r ² = 0.9624).     

The spatial structure of the oceanic spawning of jack mackerel (Trachurus murphyi) off central Chile (1998–2001)

The jack mackerel population has a widespread oceanic spawning habitat off central Chile, extending more than one thousand nautical miles offshore. In this paper, the spatial structure of jack mackerel eggs density is analyzed on the basis of four surveys carried out in oceanic waters (32°S–39°S, 75°W–92°W), from 1998 to 2001. In each survey, a grid of plankton stations was sampled through vertical hauls with WP2 plankton nets by using several purse-seine fishing ships sampling simultaneously along the E–W transects. With the aim of finding the bulk of the egg distribution within the surveyed area, an exploratory analysis between jack mackerel egg densities, latitude, longitude, and sea surface temperature (SST) was carried out. The spatial structure of the egg distribution was studied using geostatistical techniques. The bulk of the jack mackerel spawning tends to occur offshore between 80°W and 92°W, is maximal at 35°S and associated to SST warmer than 15–16 °C. All of the variograms showed clear spatial autocorrelations without anisotropy, with the range fluctuating between 125 and 252 nautical miles. The range of variograms suggests that the spawning of jack mackerel is a large scale process, probably reflected in the adult behavior of the spawning by favoring a high dispersion of eggs and/or associated with sea surface temperature characterizing the subtropical frontal zone (16–18 °C) off central Chile.     

Seasonal change in the relationship between otolith radius and body length in age-zero Pacific saury <Emphasis Type="Italic">Cololabis saira</Emphasis>

We examined seasonal changes in the relationship between otolith radius and body length in age-zero Pacific saury Cololabis saira collected from June to December 2002–2004, based on 12,164 specimens. Results of the analysis using a generalized linear model indicated that there were differences in the intercepts among months, but no difference was seen in the slopes. In addition, post hoc analysis showed that the intercepts got larger as the month progressed from June to December. These results suggested that although the body length growth rate decreased, the growth of the otolith does not decrease to the same degree as the body after September, so the ratio of otolith radius to body length becomes larger as the months pass. Consequently, we consider that the seasonal change in relation between otolith radius and body length affects the back-calculation of body length based on otolith radius.