硫酰氟对烟仓不同虫态烟草粉螟的熏杀效果

硫酰氟是国内外新推的一种安全、高效的害虫熏蒸剂。笔者采用薄膜密闭法,研究了硫酰氟对烟垛4 种虫态烟草粉螟的熏杀效果。研究结果表明,硫酰氟对4 种虫态烟草粉螟均具有很高的熏杀活性。用15 g/m³硫酰氟分别熏杀幼虫、蛹及成虫12 h,试虫的校正死亡率均为100.00%,以15 g/m³硫酰氟熏杀卵48 h,卵的校正死亡率为93.46%。4 种虫态的烟草粉螟以成虫和幼虫对硫酰氟的敏感性最高,蛹次之,卵的敏感性最低。硫酰氟可作为一种有效的熏蒸剂用于防治烟仓烟草粉螟。     

高良姜根茎粉剂对烟草甲的毒杀作用

为明确高良姜根茎粉剂对储烟害虫烟草甲的毒杀作用,采用药膜法测定了5种不同浓度下高良姜根茎粉剂对烟草甲卵、幼虫、蛹、成虫4种虫态的毒力作用.结果表明,高良姜根茎粉剂对烟草甲成虫具有一定的触杀作用,并且随着处理浓度增大、处理时间的延长而增强,但对其幼虫无触杀作用.在处理浓度范围内,在16 g/ m2的处理浓度下对烟草甲成虫的校正死亡率最高可达45%以上.高良姜根茎粉剂对烟草甲卵和蛹也都有较强的触杀作用,最高校正死亡率均达到60%以上.因此,高良姜根茎粉剂是一种具有较大应用潜力的植物源杀虫剂.     

温度对高氮气调中米象各虫态致死时间和发育的影响

明确氮气气调中温度对隐蔽性害虫各虫态致死时间的延迟程度及差异,可为气调杀虫时间的科学掌控提供参考。研究了在98%氮气浓度和(75±5)%RH下18、23和28℃时米象Sitophilus oryzae(L.)成虫和隐蔽于粮粒内的卵、幼虫和蛹在不同时间的死亡率、致死时间以及羽化出成虫的时间。18℃温度下达到100%死亡率的时间为25 d,比23℃和28℃时相应延迟了6 d和12 d。18℃下气调致死虫卵、幼虫、蛹和成虫的LT_(50)值(半数致死时间)分别为9、8、11和7 d,LT_(99)值(99%个体致死所需时间)分别为24、21、26和17 d;23℃时相应LT_(50)值为6、5、7和5 d,LT_(99)值为19、16、21和11 d;28℃时LT_(50)值为3、3、4和3 d,LT_(99)值为11、10、12和7 d。98%氮气气调后残存米象隐蔽虫态均可发育,与正常气体环境相比18℃时从卵发育至成虫的历期最大可延迟27 d,温度降低可导致发育历期延长更为明显。米象不同虫态对氮气气调耐力由大到小为:蛹卵幼虫成虫,氮气气调杀除米象时应以完全杀死隐蔽发生的蛹为目标。     

温度对高氮气调中米象各虫态致死和发育的影响

明确氮气气调中温度对隐蔽性害虫各虫态致死时间的延迟程度及差异,可为气调杀虫时间的科学掌控提供参考。研究了在98％氮气浓度和（75±5）% RH下18、23和28 ℃时米象Sitophilus oryzae（L.）成虫和隐蔽于粮粒内的卵、幼虫和蛹在不同时间的死亡率、致死时间以及羽化出成虫的时间。18 ℃温度下达到100%死亡率的时间为25 d,比23 ℃和28 ℃时相应延迟了6 d和12 d。18 ℃下气调致死虫卵、幼虫、蛹和成虫的LT50值（半数致死时间）分别为9、8、11和7 d,LT99值（99%个体致死所需时间）分别为24、21、26和17 d;23 ℃时相应LT50值为6、5、7和5 d,LT99值为19、16、21和11 d;28 ℃时LT50值为3、3、4和3 d,LT99值为11、10、12和7 d。98%氮气气调后残存米象隐蔽虫态均可发育,与正常气体环境相比18 ℃时从卵发育至成虫的历期最大可延迟27 d,温度降低可导致发育历期延长更为明显。米象不同虫态对氮气气调耐力由大到小为：蛹＞卵＞幼虫＞成虫,氮气气调杀除米象时应以完全杀死隐蔽发生的蛹为目标。     

高温、真空回潮及烟叶复烤杀虫工艺研究

为有效控制贮烟害虫,提高防治的安全性,进行了高温、真空回潮对烟草甲的杀虫效果、烟叶复烤杀虫工艺参数确定以及复烤温度对烟叶吸味品质的影响试验.结果表明:烘箱内温度100℃,历时4min各虫态烟草甲全部死亡;真空回潮具有杀死各种虫态烟草甲的作用,真空度越高(真空回潮机温度越低),烟草甲成虫、幼虫和蛹的死亡率越高,卵孵化率越低,当真空回潮机内真空度为99.02%,温度50℃,保压1 min时,各种虫态烟草甲全部被杀死;在打叶复烤线上,烟草甲成虫和幼虫耐高温的能力强,适当调整复烤干燥阶段的工艺参数,不能完全杀死烟草甲.采用真空回潮与适当提高复烤干燥温度相结合的方法,可100%杀死烟草甲.     

电子束处理对不同虫态烟草粉螟的辐照效应

为控制烟草粉螟对烟叶、卷烟的危害,利用不同剂量的电子束对烟草粉螟卵、幼虫、蛹、成虫进行辐照处理,研究了其辐照效应.结果表明:不同虫态的烟草粉螟对电子束辐照的敏感性不同,其敏感性依次为:卵＞幼虫＞蛹＞成虫;完全阻止卵、幼虫和蛹发育为成虫的辐照剂量分别为175,325和1000 Gy;幼虫、蛹和成虫经电子束辐照处理后在一定时期内全部死亡,幼虫、蛹和成虫的致死率与辐照剂量呈正相关;成虫经600 Gy剂量辐照后其繁殖力为0,即无法产生下一代成虫,并且600 Gy的剂量辐照下可以阻止烟草粉螟卵、幼虫发育为成虫,600 Gy剂量辐照处理烟草粉螟蛹虽然其仍可以羽化,但羽化的成虫在辐照后第6d就完全死亡.因此,600 Gy的剂量可以作为辐照防治烟草粉螟的最低有效剂量.     

不同虫态的烟草甲对磷化氢的敏感性及其电导率的测定

就不同虫态的烟草甲对PH3敏感性以及CO2效应进行了研究,测定了不同虫态的烟草甲匀浆液的电导率.结果表明,烟草甲对PH3的敏感性,以成虫最强,蛹和幼虫次之;CO2对PH3气体有增效作用.烟草甲的电导率以成虫最小,蛹和幼虫无明显差别,PH3处理后,烟草甲的匀浆液电导率上升,但加入CO2后,电导率则下降.     

2%和5%低氧处理赤拟谷盗不同虫态的乳酸测定研究

用乳酸测试盒测定了正常大气下5%和2%氧浓度处理24 h的赤拟谷盗(Tribolium castaneum Herbst)卵、幼虫、蛹和成虫的体内乳酸含量.结果表明:正常大气下,4种虫态试虫体内的乳酸含量明显不同,成虫的乳酸含量最高,蛹次之,幼虫较小,卵最低;雌成虫和雄成虫体内的乳酸含量,差异不显著(P>0.05).在5%氧浓度下处理24 h,前述4种虫态的乳酸含量分别是对照组相同虫态乳酸含量的2.1倍、2.5倍、2.3倍和1.1倍.2%氧浓度下处理24 h,4虫态的乳酸含量明显比5%氧浓度处理组各相同虫态的高,分别是对照组相同虫态乳酸含量的4.7倍、3.4倍、4.5倍和1.5倍.低氧条件下,四种虫态的乳酸含量都明显增加,卵和蛹的乳酸含量增加的最快,幼虫次之,成虫最慢.因此,低氧导致害虫各个虫态体内乳酸量的增加与低氧致死机理有一定的关系.     

不同温度对氮气气调锈赤扁谷盗各虫态致死时间比较研究

掌握温度对氮气气调中害虫不同虫态致死时间的影响程度对科学控制气调时间和成功杀虫具有重要意义。测定了18℃、23℃和28℃温度时锈赤扁谷盗的卵、幼虫、蛹和成虫在98%氮气气调过程中不同时间的死亡率及完全致死时间。温度18℃时锈赤扁谷盗卵、幼虫、蛹和成虫的完全致死时间分别为28、18、28和14 d，23℃时完全致死时间分别为22、14、24和8 d，28℃时完全致死时间分别为16、9、18和5 d。温度18℃时卵、幼虫、蛹和成虫的完全致死时间比23℃时相应延迟6、4、4和6 d，比28℃时相应延迟12、9、10和9 d。实验温度下98%氮气气调时锈赤扁谷盗耐受力最强的虫为蛹期，其后依次为卵、幼虫和成虫期。锈赤扁谷盗蛹在18、23和28℃温度下的死亡率-时间回归方程分别为y = 3.85x - 3.85、y = 4.01x - 3.53和y = 4.72x - 3.71。温度降低显著延迟98%氮气气调杀虫时间，氮气气调锈赤扁谷盗时应以杀死其耐受力最强的蛹为目标。     

烟草甲的研究

烟草甲在安徽一年发生２～３代，主要以高、中龄幼虫越冬，越冬代成虫高峰期为５月下旬。７月下旬至９月下旬为第１、２代成虫混合盛发期。第１代卵、幼虫和蛹的平均历期分别为７．５、５８和４ｄ；第２代卵、幼虫和蛹的平均历期分别为５．２、５２和６ｄ。另外，烟草甲在年生活史中可分为４个时期：入冬期——各虫态转为以幼虫虫态为主，发育速度逐渐变慢；冬眠期——低温引起发育停滞，死亡率大；复苏期——越冬幼虫恢复发育，后期各虫态混发；盛发期——各虫态呈高虫口密度。     

烟草甲幼虫高毒力病原真菌的筛选

为筛选出对烟草甲2龄幼虫具有较好防治效果的病原真菌,在实验室条件下,采用浸渍法测定5株蜡蚧轮枝菌和5株球孢白僵菌对烟草甲2龄幼虫的毒力,筛选出2株对烟草甲2龄幼虫具有高毒力的白僵菌菌株Bb05和Bbr81,将2株菌株配置成不同浓度的孢子悬浮液,测定其毒力并对Bb05菌株的侵染过程进行观察。结果表明,接种孢子浓度1.0×10⁸mL^-1条件下,菌株Bb05处理烟草甲的累积死亡率最高,达77.78%,LT₅₀为8.18 d;菌株Bbr81处理烟草甲的累积死亡率为74.44%,LT₅₀为7.60 d。用不同浓度孢子悬浮液处理烟草甲2龄幼虫后,其累积死亡率随孢子浓度和接种时间的增加而增加,Bb05菌株的LC₅₀为8.3×10⁷ mL^-1,菌株Bbr81的LC₅₀为1.2×10⁷ mL^-1。筛选所得的2个菌株对烟草甲虫2龄幼虫的毒力较高,具有一定的开发应用潜力。     

Damage characteristics produced by insect pests in packaging film

This study investigated the morphology of damage produced by three important stored-product pest species, Rhyzopertha dominica, Sitophilus oryzae and Lasioderma serricorne, in food packaging film. Three different types of plastic film (polypropylene 25 μm, polyethylene 50 μm and polyester 12 μm), a multilayer film (paper, polyethylene 15 μm, aluminium 7 μm and polyethylene 30 μm), and cigarette paper were compared. Damage was examined using a stereomicroscope at 20× to 40× magnification and a scanning electron microscope. All three species produced several different types of damage on the surface of the side where insects perforated the plastic film. This damage consisted of scratches and tears on the contours of the holes. In comparison, damage around the holes was much less pronounced on the exit side. In polypropylene, holes produced by adults of S. oryzae and R. dominica and larvae of L. serricorne could be identified by the large damaged area, the small scratches produced and the deep scars left around the holes. Scratches on polyethylene produced by R. dominica were deeper and more marked than damage produced by the other two species. Holes covered with filaments were characteristic of the damage produced by S. oryzae. Conversely, in polyester it was difficult to differentiate between holes produced by S. oryzae and R. dominica: the easiest way to distinguish between damage by these species was on the basis of hole size. Larvae of L. serricorne did not produce holes in polyester. In cigarette paper the presence of filaments differentiated the holes produced by S. oryzae from those produced by the other two species. All three species were able to produce holes in multilayer film with a 7 μm thickness of aluminium foil. In this film, the morphology of damage was similar to that produced in paper because the first layer of this film was made of paper. The diameter of the perforations, including the damaged area around the holes, ranged from 0.58 to 1.86 mm for all three species.     

Incorporation of Lactobacillus acidophilus in Minas fresh cheese and its implications for textural and sensorial properties during storage

The effect of Lactobacillus acidophilus on instrumental texture profile and related properties of Minas fresh cheese during storage at 5 °C and on sensory performance was investigated. Four cheese-making trials were prepared, two supplemented with a mesophilic type O culture (T1, T2) and two with lactic acid (T3, T4). L. acidophilus was added in T2 and T3. The viability of L. acidophilus, instrumental texture profile analysis and related properties were monitored during storage for up to 21 days. Probiotic cheeses T3 were firmer by the end of storage, due to higher values of pH and hardness. Differences detected were attributed to the starter, rather than to L. acidophilus. Viability of L. acidophilus during storage ranged from 6.04 to 6.93 for T2 and from 5.46 to 6.53 log cfu g⁻¹ for T3, which performed better in sensory evaluation. Minas fresh cheese is a suitable food system for the delivery of L. acidophilus.     

Prediction of Listeria spp. growth as affected by various levels of chemicals, pH, temperature and storage time in a model broth

The effects of concentration of NaCl (0.5 to 12.5%), methyl paraben (0.0 to 0.2%), sodium propionate (0.3%), sodium benzoate (0.1%), potassium sorbate (0.3%), pH (>5.9) temperature (4 to 30°C), storage time (up to 58 d) and inoculum (>10⁵ to >10⁻² per ml) on the log₁₀ probability percentage of one cell of Listeria spp. to initiate growth in a broth system were evaluated in a factorial design study. At pH 5.96 and temperature ranging from 4 to 30°C the concentrations of sodium propionate, potassium sorbate, and sodium benzoate examined allowed growth of L. monocytogenes with lag phases at 4°C of 18, 27 and 21 days, respectively. For 0.1 and 0.2% methyl paraben growth of all Listeria spp. was initiated at 8°C and 30°C, respectively. At pH 6, concentration of 12% NaCl supported the growth of L. monocytogenes at 8 to 30°C, whereas 12.5% inhibited all Listeria species. Four regression equations were derived relating probability of growth initiation to temperature, concentrations of NaCl and preservatives storage time, and Listeria species specific effects. From these equations, the number of cells needed for growth initiation can be calculated. The impact of this type of quantitative study and its possible application on the development of microbial standards for foods is discussed.     

Listeria innocua and aerobic mesophiles during chill storage of inoculated mechanically recovered poultry meat treated with high hydrostatic pressure

Mechanically recovered poultry meat (MRPM) was inoculated with Listeria innocua 910 CECT at a level of approximately 10⁸ CFU g⁻¹. Vacuum-packaged samples were treated by combinations of pressure (350, 400, 450 and 500 MPa), time (5, 10, 15 and 30 min) and temperature (2, 10 and 20°C) and later stored at 2°C for 2 months. Counts of L. innocua and aerobic mesophilic bacteria were determined 1, 4, 7, 15, 30 and 60 days after pressurisation. For mesophiles, in most treatments, pressurization at 2°C gave the significantly best results. High pressure caused a marked bactericidal effect on L. innocua: reductions higher than 7.5 log units were achieved in several cases. Some cells were just sublethally injured by pressure. Samples treated at 500 MPa for 30 min at 2°C had counts of only 2.3 log units after 60 days of chill storage. Noninoculated pressurised MRPM did not show Listeria growth throughout storage. These results suggest that high pressure processing can enhance the microbiological quality of MRPM.     

A novel use of modified atmospheres: Storage insect population control

The research described here aimed to establish the feasibility of using modified atmospheres (MA) to protect commodities throughout their storage life by using oxygen (O₂) levels that disrupt the life cycles of the target beetle species. Rather than achieving complete mortality of all stages, the aim was to identify more easily obtainable MAs that would kill the most susceptible stage and prevent population growth. Simulated burner gas and nitrogen (N₂) atmospheres with O₂ contents between 3% and 6%, were tested, along with a N₂-based MA with elevated carbon dioxide (CO₂) (10–20%).

Laboratory tests were carried out on five species of stored-product beetles, Cryptolestes ferrugineus, Oryzaephilus surinamensis, Sitophilus granarius, S. oryzae and Tribolium castaneum. After exposure to the MAs for 28 d an assessment was made of the mortality of adults, the number of adults from progeny produced under the MAs and, for the simulated burner gas, the number of adults from progeny produced in a 28-d period after exposure to the MA. The tests were carried out at 20 and 25 °C with 75% and 85% r.h. at each temperature.

The O₂ content preventing population growth varied with species and temperature. For simulated burner gas or N₂ it was about 4% for O. surinamensis, S. granarius and S. oryzae, and about 3% for C. ferrugineus and T. castaneum at 25 °C. At 20 °C it was about 3% for all species tested. When CO₂ was increased to 10% or 20%, reducing O₂ to 5% was sufficient to eliminate emergence of S. granarius at 20°C, but a few individuals emerged at 25 °C. For C. ferrugineus there was a 95% reduction with 5% O₂ plus 20% CO₂ at 20 °C, but not at 25 °C.     

Probiotic white cheese with Lactobacillus acidophilus

The objective of the present study was to determine the effects of Lactobacillus acidophilus on the sensory attributes, ripening time, and composition of Turkish white cheese and to investigate the survival of L. acidophilus during ripening of the cheese stored in vacuum or in brine. Two types of white cheeses, traditional cheese (control, made with Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. cremoris) and probiotic cheese (made with Lactococcus lactis ssp. lactis, Lactococcus lactis ssp. cremoris and L. acidophilus 593 N), were produced and ripened in vacuum pack or in brine at 4°C for 90 days. Cheese samples were assessed for microbiological and compositional properties, proteolysis, and sensory evaluation at different ripening stages. On ripening in vacuum pack, L. acidophilus survived to numbers >10⁷ cfu g⁻¹, which is necessary for positive effects on health. Protein, dry matter, salt content, and percentage of lactic acid in the vacuum-packed and brine-salted probiotic cheeses were significantly different. Also, the lactic acid content of probiotic cheeses was slightly higher than that of the controls for both vacuum- and brine-packed cheeses. Vacuum-packed probiotic cheese had the highest levels of proteolysis and the highest sensory scores of all cheeses. Consequently, L. acidophilus could be used for the manufacturing of probiotic white cheese to shorten ripening time and vacuum packaging is the preferred storage format.     

Accelerated ripening of low fat Ras cheese by attenuated lactobacilli cells

Thirteen Ras cheese were made from 4% fat raw milk; 3% raw and heat treated; 2% raw and heat treated milks in order to study the effect of freeze-shocked or heat-shocked L. casei NIH 334 or L. helveticus CNRZ 53 on the quality of the resultant cheeses. The soluble nitrogen, soluble tyrosine, soluble tryptophan, total volatile fatty acids, titratable acidity and organoleptic evaluation scores increased as ripening period progressed, while moisture decreased. Neither strain nor the heated lactobacilli had significant effects on moisture content of cheeses, while increasing their acidity. Cheeses with freeze-shocked L. casei or L. helveticus had higher titratable acidity than cheeses in which heat-shocked cells were added. However, cheeses added L. helveticus had higher acidity than those with L. casei. Ripening indices (soluble nitrogen, soluble tyrosine, soluble tryptophan and total volatile fatty acids) and organoleptic evaluation scores had similar trends. Cheeses with attenuated lactobacilli had higher ripening indices and cheese scores than cheeses without lactobacilli. Addition of either freeze-shocked L. casei or L. helveticus yielded cheeses having higher ripening indices and organoleptic scores than cheeses made with heat-shocked lactobacilli. The best cheeses were made from 3% fat milk heated to 70 °C, and containing freeze-shocked L. helveticus followed by cheeses made from 2% fat milk heated to 75 °C and containing freeze-shocked L. helveticus.     

Comparison of the hydrophobic grid-membrane filter DNA probe method and the Health Protection Branch standard method for the detection of Listeria monocytogenes in foods

The standard Health Protection Branch (HPB) method for the detection of L. monocytogenes in foods involves lengthy enrichment, selection and biochemical testing, requiring up to 8 days to complete. A hydrophobic grid-membrane filter (HGMF) method employing a digoxigenin-labelled listeriolysin O probe required 5 days to complete, and included an image-analysis system for electronic data acquisition. A total of 200 food samples encompassing 8 high-risk food groups (soft and semi-soft cheeses, packaged raw vegetables, frozen cooked shrimp, ground poultry, ground pork, ground beef, jellied meats, and pâté) were screened for the presence of L. monocytogenes by the two methods. Overall, 32 (16%) and 30 (15%) of the naturally-contaminated food samples tested positive for L. monocytogenes by the HPB and DNA methods, respectively. The DNA probe method was highly specific in discriminating L. monocytogenes from other Listeria spp. present in 50 of the samples tested. Results showed 94% sensitivity and 100% specificity between the two methods. The HGMF DNA probe method is an efficient and reliable alternative to the HPB standard method for detecting L. monocytogenes in foods.     

低温冷藏对烟草粉螟亲代和子代适合度的影响

为明确低温冷藏对烟草粉螟亲代和子代适合度的影响,根据年龄-龄期两性生命表理论,对5℃冷藏160d后的烟草粉螟5龄幼虫亲代生殖适合度及其子代发育历期、存活率、繁殖率和种群参数进行研究。结果表明,低温冷藏160d后烟草粉螟F₀代的蛹期显著长于对照,雌雄成虫寿命、平均繁殖力和产卵时间均显著低于对照;但在F₁代中,除了低温处理的平均繁殖力（148.29粒）显著高于对照（113.93粒）外,其他参数均无显著差异。研究表明,低温冷藏显著降低烟草粉螟亲代的适合度,对子代的适合度则无显著影响。