花生播种期施用绿僵茵防治蛴螬的研究

本文研究金龟子绿僵菌MetarhiziumanisopliaeM202．1菌株对花生蛴螬的防治效果。室内生物测定表明,在含有绿僵菌5×10^6、10×10^6和20~10。孢子．g^-1土壤中,暗黑鳃金龟Holotrichiaparallela幼虫死亡率分别为22．4％、41,1％和74．4％,高浓度下LT50为11．9d。盆栽试验中,在播种花生时进行土壤施菌。施药处理,并在花生开花时进行接虫对比处理,结果显示：对照土壤中接虫处理的蛴螬为害可造成花生好果数减少29．2％,果重减轻26．1％,虫果增加率达28．1％;土壤施菌后接虫条件下虫果增加率为20．7％,比对照减少7．4％;但不论接虫与否,花生好果数及果重与对照土壤不接虫处理的差异均不显著;辛硫磷处理对蛴螬有较好的直接控制作用,但使花生结荚数减少;1／2剂量绿僵菌加1／2剂量辛硫磷混合处理不能很好控制虫害。田间试验显示,播种时绿僵菌能有效控制蛴螬为害,收获期花生的好果数和果重都提高40％左右,显著高于对照,虫果率降低10．9％;绿僵菌的防治效果显著高于辛硫磷。     

Ingestion of Artemia nauplii by Chinese mitten crab Eriocheir sinensis zoea larvae

A series of ingestion trials were conducted to determine the ingestion rate of Artemia nauplii by Eriocheir sinensis zoea larvae with increasing densities of Artemia and with or without rotifers as a co-feed. At each zoeal stage, 10 groups of 10 larvae were reared individually in glass beakers and fed with increasing densities of newly hatched Artemia nauplii (0.5, 2.5, 5, 10 and 20 individual (ind.) mL⁻¹) with or without rotifers (15–25 ind. mL⁻¹) as a co-feed. The average number of ingested Artemia was measured over 24 h. In addition, the average larval development rate (Larval Stage Index, LSI) over a longer period (time needed for the best treatment to reach 100% moult or metamorphosis to the next larval stage) was compared. The results showed that Artemia ingestion rate of E. sinensis larvae increased with increasing prey densities and larval development, and had a significantly negative correlation with rotifer consumption for all zoeal stages. Rotifers as an alternative prey significantly affected the intake of Artemia at early larval stages (Z1 and Z2) and promoted LSI at a lower Artemia density. Further experiments are needed to clarify the effect of prey density on survival and larval development when larvae are reared communally.     

Effect of live algae used as green water on survival,growth, behaviour,ontogeny and bacterial profile of lobster larvae (Homarus americanus Milne Edwards)

Green water is a technique commonly used in aquaculture, that consists of adding live algae in the water culture and its benefits have been shown for several species. Several hypotheses exist to explain the benefits of green water: increase in nutritional value; action as a probiotic; increase in contrast to reveal preys for larvae; or increase in predator behaviour of larvae. Green water produced with a mix of strains Isochrysis galbana and Chaetoceros muelleri (50:50, cells:cells) applied in four different ways was tested. The survival and the growth of American lobster (Homarus americanus) between stage I and stage IV post‐larvae were not affected by the addition of live algae. The lipid classes were not affected by the addition of algae and limited variation was observed in the fatty acids and bacterial profiles. Furthermore, the green water techniques had a limited effect on the behaviour of post‐larvae stage IV lobster at releasing. Behaviour was mostly affected by the age of post‐larvae. The bacteria Lewinella sp., Leucothrix sp. and Thiothrix sp. appeared to represent a common and core component of Stage IV lobster post‐larvae microflora. The results show that the algae do not increase either nutritional value or feed intake of the lobster larvae. Probiotic effect may be more important when larvae are raised in a close system where potential bacterial pathogens could have more chances to colonize the culture. Also, the dark green colour of the larval tank used in this study may have mimicked the effect of green water in the control group. Biochemical results suggest that dietary supplementation with phospholipids and DHA is needed in a lobster hatchery using frozen Artemia and our open formula Dry mix.     

Incorporating early life stages of fishes into estuarine spatial conservation planning

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文蛤浮游期发病幼虫细菌群落分析和致病菌的分离鉴定

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