不同温度处理对赤拟谷盗的致死作用

采用水浴加热,研究不同温度(35℃、45℃、55℃、60℃、65℃)下处理不同时间(60 s、75 s、90 s、105 s、120 s)后对小麦粉中的赤拟谷盗幼虫、蛹和成虫的致死作用.研究结果表明,不同处理温度、不同处理时间对赤拟谷盗幼虫、蛹和成虫的致死作用效果差异显著.在处理温度为35℃、45℃时,各个处理时间对赤拟谷盗幼虫、蛹和成虫正常发育没有影响,而在处理温度为55℃以上时对赤拟谷盗幼虫、蛹和成虫具有较强的致死作用.在处理温度为65℃时,处理60 s以上对赤拟谷盗成虫的致死作用效果即达到100％,处理75 s可100％抑制赤拟谷盗蛹正常发育为成虫,处理90 s以上能完全抑制赤拟谷盗幼虫正常发育为成虫.     

Temporal dynamics and response to fogging or fumigation of stored-product Coleoptera in a grain processing facility

Stored-product Coleoptera were monitored continuously over 22 months using pitfall traps at an operating food mill and adjacent warehouse in Kansas. Mill management practiced conventional pest management, including monthly crack and crevice applications of a residual insecticide and semi-annual fumigation with methyl bromide in the mill, and application of dichlorvos+pyrethrin (commonly called fogging) in the warehouse. The dynamic temporal changes in insect captures and effect of the global interventions on insect captures were analyzed. Data show that more Trogoderma variabile individuals were captured in the warehouse than any other species, but Tribolium castaneum was captured with greater frequency. Trogoderma variabile captures inside the warehouse tended to mirror outside captures suggesting immigration from the outside. The food mill was infested year round with T. castaneum but developed substantial populations of Typhaea stercorea during the warm months from May through October. Stored-product insects were nearly always captured during the first trapping interval following methyl bromide or dichlorvos+pyrethrin applications, but it was not clear if the insects were surviving inside the structure or if they were rapidly recolonizing after treatment. Population increases immediately following fumigation or fogging occurred only in fungus-feeding species in late spring or summer. The most successful fumigation was conducted late in the autumn when environmental conditions prevented insect activity outside. Information contained in this study provides data that could be used to improve insect management programs for milling and processing facilities.     

细叶亚菊挥发油化学组成及其对赤拟谷盗和烟草甲的杀虫活性研究

本实验研究了细叶亚菊挥发油的化学组成及其对2种常见粮储害虫—赤拟谷盗和烟草甲成虫的杀虫活性及驱避作用。采用水蒸气蒸馏法提取挥发油,GC/MS法分析挥发油的成分及其相对含量;采用熏蒸、触杀、驱避3种不同的测试方法评价挥发油对害虫的防治作用。从细叶亚菊挥发油中鉴定出了17种化合物,主要成分为(+)-樟脑(28.92%)、1,8-桉油精(23.64%)、冰片(6.52%)。挥发油对赤拟谷盗和烟草甲表现出较强熏蒸活性,LC_(50)分别为15.88 mg/L和25.67 mg/L;同时,对2种昆虫表现出一定触杀活性,LD_(50)分别为52.37μg/头和17.56μg/头;另外,在78.63 nL/cm~2和15.73 nL/cm~2测试浓度下作用2 h或4 h后,对赤拟谷盗均具有与阳性对照DEET相近的驱避效果,对烟草甲作用2 h后具有一定驱避活性。结果表明,细叶亚菊挥发油对赤拟谷盗和烟草甲具有较好防治作用,能够为细叶亚菊挥发油防治常见粮食仓储害虫提供参考。     

12种植物精油对两种仓储害虫熏蒸活性的研究

采用水蒸气蒸馏法提取12种香料植物精油,密闭容器熏蒸法测定精油对赤拟谷盗和花斑皮蠹的熏蒸活性,为仓储害虫的生物防治提供依据。结果表明:精油熏蒸处理24 h后,在3个筛选浓度(166.67、33.33、6.67μL/L)下,5种植物精油(大蒜、花椒、小茴香、肉桂和八角茴香)对赤拟谷盗表现出较好的熏蒸活性,在高浓度(166.67、33.33μL/L)时,熏蒸致死率达到90%,在低浓度6.67μL/L时,致死率依然在60%以上;5种精油对赤拟谷盗的LC_(50)分别为0.71、1.15、1.39、1.58、1.73 mg/L。4种植物精油(大蒜、肉桂、小茴香和八角茴香)对花斑皮蠹的熏蒸活性最好,在高浓度(166.67μL/L、33.33μL/L)时,致死率高达100%,在低浓度(6.67μL/L)时,致死率均在80%以上;4种精油的LC_(50)分别为0.41、1.03、2.92、3.28 mg/L。12种植物精油中,大蒜精油对两种仓储害虫的熏蒸活性最好,且大蒜精油资源丰富,原料易得,对人类安全无毒,可成为理想的绿色环保仓储害虫熏蒸剂。     

两种昆虫生长调节剂对赤拟谷盗的控制效果

选取氟啶脲(Chlorfluazuron)和灭幼宝(Pyriproxyfen)两种昆虫生长调节剂对储藏物害虫赤拟谷盗进行了控制效果的研究。结果表明,在402、0、10 mg/kg剂量下,氟啶脲对赤拟谷盗幼虫有较高的校正死亡率,依次为94.44%8、8.89%、83.33%,幼虫均不能化蛹,表明该药剂可能作用于几丁质合成酶,抑制了几丁质合成酶的活性。在相同浓度下,灭幼宝对赤拟谷盗幼虫没有明显的致死效果,但其能延长赤拟谷盗幼虫的发育历期,使其不能正常化蛹,最终导致畸形死亡,表明灭幼宝有类似保幼激素的作用。     

苦皮藤素乳油对三种储粮害虫的熏蒸作用

采用密闭熏蒸法研究了苦皮藤素乳油对储粮害虫的熏蒸作用。研究结果表明,处理24h后,苦皮藤素乳油对玉米象、赤拟谷盗和锯谷盗的LD50分别为3.606 97、2.773 78和2.048 87μg/ml;玉米象、赤拟谷盗和锯谷盗的回归方程分别为Y=3.972 64 X+2.786 68、Y=4.319 64 X+3.086 09和Y=4.095 70 X+3.724 13。三种储粮害虫对苦皮藤素乳油的敏感度由强到弱依次为锯谷盗、赤拟谷盗、玉米象。     

Detection of Tribolium castaneum (Herbst) volatile defensive secretions by solid phase microextraction–capillary gas chromatography (SPME-CGC)

The solid phase microextraction (SPME) technique was used for the collection of the volatile defensive secretions released by Tribolium castaneum (Herbst), the red flour beetle. The detection of the major components methyl-1,4-benzoquinone (MBQ) and ethyl-1,4-benzoquinone (EBQ), together with 1-pentadecene (C15:1), was performed by capillary gas chromatography (CGC). SPME samples were identified by CGC coupled to mass spectrometry (MS). Volatile organic compounds (VOC) released from insects were compared employing different SPME fibers. The relative amounts of the major volatiles collected varied with the fiber coating. Quinones accounted for 75% of the volatiles trapped by the carboxen/polydimethylsiloxane (CAR/PDMS) fiber, whereas they only represented 45% of the volatiles trapped with the PDMS fiber. The PDMS/divinylbenzene (DVB) coating exhibited intermediate affinity. In a 15-min extraction period, the highest amounts of VOC extracted from disturbed insects with CAR/PDMS were 349±107 ng/beetle of MBQ, 780±290 ng/beetle of EBQ, and 144±69 ng/beetle of C15:1. The total VOC amounts extracted by SPME were estimated by adding the disturb-released VOC to heat-released VOC of the same insects, resulting in 742±93 ng/beetle of MBQ, 1672±244 ng/beetle of EBQ, and 946±237 ng/beetle of C15:1. SPME-CGC is a simple method to detect and estimate T. castaneum volatiles. This method has the potential to detect insect infestation in stored products.     

The red flour beetle Tribolium castaneum allows for the convenient determination of fitness and survival as a measure of toxic effects of the food contaminant acrylamide

Acrylamide is a toxic ingredient generated as a by-product of the Maillard reaction in starchy foods processed at temperatures above 120°C. Here we used the red flour beetle Tribolium castaneum as a model organism to test the effects of acrylamide on fitness and survival. Beetles were fed on flour spiked with acrylamide between 0.5% and 10% at 32°C over 2 weeks. Fitness of the beetles was tested by measuring the running distance and survival was recorded after 2 weeks of feeding at increased temperatures at 42°C. Both parameters were dose-dependent reduced by acrylamide. Knockdown of gene homologues of ahr, the arylhydrocarbon receptor, and of nrf-2, the nuclear factor erythroid 2-related factor 2, both reduced fitness and survival. Application of 0.5% acrylamide under knockdown of each factor further reduced fitness and survival, suggesting that ahr and nrf-2 are important for an adequate response to the toxicant. RNA-interference for ahr blocked completely the increase in nrf-2 mRNA levels, suggesting that the actions of ahr on acrylamide detoxification are mediated via Nrf-2.     

大黑粉盗与赤拟谷盗和锈赤扁谷盗对磷化氢的耐受力比较研究

潜在危害的储粮害虫大黑粉盗Cynaeus angustus研究缺乏,掌握其磷化氢耐受力有助于科学治理。采用快速击倒和FAO推荐方法测定了磷化氢对大黑粉盗的KT50值和毒力方程,并与赤拟谷盗Tribolium castaneum和锈赤扁谷盗Cryptolestes ferrugineus进行了比较,测定了100、200、300、400、500 mL/m3磷化氢模拟熏蒸中3种害虫卵、幼虫、蛹和成虫不同时间的死亡率。磷化氢对大黑粉盗、赤拟谷盗和锈赤扁谷盗的KT50值分别为7、127和3 736 min,相应毒力方程斜率值b为3.67、8.28和9.94,相应LC50值为0.008、1.34和5.88 mg/L。害虫不同虫态在100~500 mL/m3浓度下的半数致死时间LT50值于大黑粉盗卵为4~2 h、幼虫4~1 h、蛹4~1 h、成虫3~1 h,于赤拟谷盗为卵12~5 d、幼虫11~5 d、蛹13~7 d、成虫10~4 d,于锈赤扁谷盗为卵28~13 d、幼虫为18～9 d,蛹26～11 d,成虫17~9 d。相应的完全致死时间（LT100）于大黑粉盗卵为21~6 h、幼虫8~3 h、蛹9~6 h、成虫5~3 h,于赤拟谷盗卵为21~18 d、幼虫21~15 d、蛹27~18 d、成虫21~12 d,于锈赤扁谷盗卵为54~30 d、幼虫42~30 d、蛹48~30 d、成虫36~25 d。所测大黑粉盗为磷化氢敏感品系,其各虫态对磷化氢的耐受力为卵>蛹>幼虫>成虫,其耐受力远小于赤拟谷盗和锈赤扁谷盗磷化氢抗性品系。