克里角梢小蠹生物学特性及防治

克里角梢小蠹TrypophloeusklimeschiEggers为国内新记录种 ,近年来成为新疆杨 (PopulusalbawyPyramidalis)的重要害虫 ,在短期内可导致新疆杨死亡。该虫在新疆阿拉尔 1年发生 2代 ,主要以成虫在树干蛀盲孔越冬。危害部位集中于距地面高 40～ 2 0 0cm的主干。成虫出树活动 1年中有 3个高峰 ,即 :5月上旬至 5月中旬 ,7月下旬至 8月中旬 ,9月下旬。第 1代幼虫历期约为 3 0d。成虫出孔活动盛期是防治该害虫的关键时期。     

In situ determination of food daily ration in fish: review and field evaluation

Synopsis A literature review showed that numerous studies have dealt with the estimation of fish daily ration in the field. Comparisons of results from different studies are often difficult due to the use of different approaches and methods for parameter estimations. The objective of the present study was to compare the most commonly used approaches to estimate fish daily ration and to propose a standardized procedure for their estimation in the field. Comparisons were based on a field experiment specifically designed to investigate these questions and on data and theoretical considerations found in the literature. The results showed that (1) the gut fullness computed with entire digestive tract content is preferable to the stomach content only, supporting recent research done on other fish species; (2) it is important to consider the data distribution before estimating parameters; (3) estimates of experimental evacuation rates should be used rather than maximum evacuation rate for species showing no feeding periodicity; (4) it is necessary to exclude parasites from gut content in the computation of daily ration as they may significantly decrease daily ration estimates (by an average of 29.3% in this study); and (5) the Eggers (1977) model is as appropriate as, and less complex than, the Elliott & Persson (1978) model for estimating fish daily ration in the field, again supporting recent experiments done on other fish species.