Biological studies including population growth parameters of the predatory miteAmblyseius barkeri [Acarina.: Phytoseiidae] at 25°C in the laboratory

Amblyseius barkeri (Hughes) fed onThrips tabaci (Lind.) at 25°C showed an average duration of 2.2, 0.8 and 3.2 days for the egg, larval and nymphal stages, with mortalities at 1.0, 1.0 and 3.1%, respectively. Females represented 63% of the population and required multiple matings for optimal fertility. The oviposition period was 20.3 days and the average oviposition rate 2.3 eggs per day. The intrinsic rate of increase was 0.22 per day. The expected life span was 29.6 days for ♀♀ and 27.4 days for ♂♂.A. barkeri ♂♂ and ♀♀ both consumed 3.3 nymphs of thrips per day (mean value for the feeding stages). The larva does not take up food. In the absence of thripsA. barkeri was able to consume two-spotted spider mites,Tetranychus urticae (Koch), and their eggs, adult broad mites,Polyphagotarsonemus latus (Banks), and pollen of various plants. Cannibalism was observed when food was lacking. Certain morphological features, egglaying, mating and predatory behaviour are described.      

A laboratory-based method to measure relative pesticide and spray oil efficacy against broad mite, Polyphagotarsonemus latus (Banks)(Acari: Tarsonemidae)

Six pesticides and two spray oils were tested against Polyphagotarsonemus latus. The chemicals were evaluated under laboratory conditions, requiring the development of a novel bioassay method, which is reported here. The pesticide toxicities fell into three distinct groups, namely abamectin, conventional pesticides and oils. The relative pesticide toxicities at the LC₅₀ level were abamectin 4.9×10^-8 g ai l^-1, endosulfan 1.1×10^-3 g ai l^-1, fenpyroximate 2.3×10^-3 g ai l^-1, pyridaben 4.1×10^-3 g ai l^-1, tebufenpyrad 4.4×10^-3 g ai l^-1, dicofol 4.5×10^-3 g ai l^-1, petroleum spray oil 3.4×10^-1 g ai l^-1 and canola oil 4.1×10^-1 g ai l^-1. The calculation of the LC_99.9 values allows for resistance monitoring in P. latus and the suggested discriminating concentrations are abamectin 1.0×10^-4 g ai l^-1; endosulfan, pyridaben and dicofol 1.0×10^-1 g ai l^-1 fenpyroximate and tebufenpyrad 5.0×10^-1 g ai l^-1.     

宽额螯蜂的幼期形态及生物学特性研究

宽额螯蜂Dryinus latus Olmi在山东商河寄生恶性席瓢蜡蝉Sivaloka damnosus Chouet Lu若虫,具有捕食和寄生的双重控制作用。首次明确该蜂寄主,记述其幼期形态特征、生活史、生活习性。在山东商河1年发生2代,以4龄老熟幼虫在茧内越冬。翌年4月下旬至5月上旬为化蛹盛期,5月中旬越冬代成虫开始出现,捕捉寄主若虫补充营养。成虫主要产卵于恶性席瓢蜡蝉3～5龄若虫前后翅芽下紧贴体背的淡绿色组织上。第1代卵历期平均78.1h,幼虫孵化至脱囊平均历时209.5h,产卵至脱囊平均历时280.0h,蛹期平均386.4h。幼虫作茧于枝条、叶片或地面枯叶上,茧外缀有枝条表皮或叶片碎屑。7月下旬至8月上旬出现第1代成虫,第2代幼虫8月上旬开始脱囊结茧越冬。野外寄生率27.8%～45.7%,控制作用显著。     

茄子叶片绒毛与侧多食跗线螨抗性的关系

研究了27 个茄子品种叶片绒毛对侧多食跗线螨(Polyphagotarsonemus latus)的田间种群密度、叶片为害指数、种群增长倍数的影响.结果表明：不同品种茄子叶片绒毛密度和长度存在一定差异;同一品种叶片正面绒毛密度小于背面,正面绒毛长度大于背面;7个抗性较强品种叶片背面平均绒毛密度显著高于6个抗性较弱品种的平均绒毛密度.茄子叶片背面绒毛密度越高,螨的田间种群密度、叶片为害指数越低,茄子的抗性越强.     

环境因子对温室白粉虱携播 侧多食跗线螨的影响

侧多食跗线螨Polyphagotarsonemus latus(Banks)能够附着在温室白粉虱Trialeurodes vaporariorum胫跗节上进行远距离扩散,即携播。笼罩试验表明：温室白粉虱对侧多食跗线螨的携播是它们在正常情况下普遍发生的一种现象,18～25℃,50%～75%RH是其发生的最适条件;高温(32～39℃)虽能加速携播,使得1～2 h达到携播高峰,但携播率低,白粉虱不易存活;光照强度对携播率没有显著影响。适温高湿有利于温室白粉虱携带多个跗线螨,随着螨密度的增加,温室白粉虱的携播率和携螨数明显增大。85%携播螨采取翘式附着(呈45°)。显微镜照片清晰显示,携播中侧多食跗线螨的口针插入温室白粉虱足内。     

黄鳍鲷弧菌病病原特性及其全菌苗的研究*

自湛江市发病养殖黄鳍鲷分离一株致病菌。对该菌的基本特征、药物筛选、灭活全菌苗等进行了研究。结果表明该病原菌为溶藻弧菌,且对四环素、土霉素、氯霉素、氟哌酸、氧氟沙星等药物敏感,pH6．0比pH8．4时灭活效果好,加入福尔马林可以提高灭活效果;全菌苗能够提高鱼体的免疫能力,减少攻毒时的死亡率。     

黄瓜钝绥螨对茶黄螨雌成螨和腐食酪卵的功能反应

研究黄瓜钝绥螨Amblyseius cucumeris 对茶黄螨Polyphagotarsonemus latus (Banks)雌成螨和腐食酪螨Tyrophagus putrescentiae卵的功能反应。结果表明,黄瓜钝绥螨的第1若螨,第2若螨,雌成螨捕食茶黄螨雌成螨和腐食酪螨卵的功能反应均属于Holling II型,其中,雌成螨的捕食能力最强,对腐食酪螨卵和对茶黄螨雌成螨的攻击系数a大,处理时间th短,第2若螨也具有较强的捕食能力,对静态的腐食酪螨卵比对动态的茶黄螨捕食能力强,黄瓜钝绥螨对茶黄螨雌成螨具有很强的捕食能力。     

Dispersal of the broad mite, Polyphagotarsonemus latus (Acari: Tarsonemidae) on Bemisia argentifolii (Homoptera: Aleyrodidae)

The broad mite Polyphagotarsonemus latus (Banks) and silverleaf whitefly Bemisia argentifolii Bellows & Perring (=B strain of Bemisia tabaci (Gennadius)) have many common host plants. It was found that broad mites can attach themselves to B. argentifolii adults and use them as a carrier for their dispersal. In a cage experiment, we observed that more than 80% of B. argentifolii adults had more than one broad mite attached within 4 h after B. argentifolii landed on broad mite-infested plants. Overall, 97.5% of the broad mites examined were attached to the legs, mostly on the tibiae and tarsi of B. argentifolii adults, and 99.5% of the broad mites attached to B. argentifolii were adult females. The successful dispersal of broad mite via B. argentifolii was also demonstrated with a cage experiment.     

Physiological responses of Yellowfin seabream (Acanthopagrus latus) to acute salinity challenge

ABSTRACT

One hundred and eight juvenile Acanthopagrus latus were transported from their natural habitat and kept in tanks (300 L) with 20 ppt salinity for 14 days. After 24h starvation, the fish were exposed to salinity of 34, 12, and 5 ppt; then, blood samples were taken after 0, 2, 24, and 48h after the exposure. Blood electrolytes did not show significant changes in response to variation in the environmental salinities. Cortisol and ALP increased (not significantly) in all groups after 2h (P<0.05) and returned to the basal value within 24 h. Glucose and lactate levels increased significantly in all experimental groups after 2h (P<0.05) and returned to the basal value within 48 and 24h, respectively. Triglyceride did not show any significant change during the trial. Our findings showed juvenile A. latus could acclimate to a range of salinities from 5% to 35% within 48h. Also, the metabolic changes were more related to the time of sampling than the salinity challenge, suggesting that adaption occurred during the time of the study.     

Biological studies of the predacious mite Amblyseius swirskii,a predator of the broad mite Polyphagotarsonemus latus on pepper plants (Acari: Phytoseiidae: Tarsonemidae)

The predatory phytoseiid mite Amblyseius swirskii (Athias-Henriot) completed its lifespan when fed on females of the broad mite, Polyphagotarsonemus latus (Banks). The development was the quickest and the number of prey consumed was highest when individuals were reared at 28?°C compared with 19?°C. The average number of eggs/female/day was 2.36 and 1.69, respectively. Life table parameters showed that the population of A. swirskii multiplied 16 and 20 times in a generation time of 22 and 18?days at 19 and 28?°C, respectively. Under these conditions, the intrinsic rate of increase (rm) was 0.139 and 0.170 individuals/female/day, respectively.