The predatory mite Hypoaspis miles: biological and demographic characteristics on two prey species, the mushroom sciarid fly, Lycoriella solani, and the mould mite, Tyrophagus putrescentiae

The biology of Hypoaspis miles Berlese (Acarina: Hypoaspidae) fed on mushroom sciarid larvae (Lycoriella solani Winnertz) (Diptera: Lycoriidae) and mould mites (Tyrophagus putrescentiae Schrank) (Acari: Acaridae), was investigated by laboratory experiments at 20 °C, 75% r.h. and LD16:D8 hours. H. miles had a significantly shorter development time and a significantly lower juvenile mortality when fed on sciarid larvae than on mould mites, the development time being 14.5 days and the mortality 3.5% on the former prey. The preoviposition and postoviposition periods of H. miles were not uninfluenced by the prey species and were 5–9 and 32–37 days, respectively. Oviposition periods of 53.2 and 68.5 days and female longevities of 82 and 109.6 days were observed on diets of sciarid larvae and mould mites, respectively. Male longevity (168–219 days) was uninfluenced by the prey species. The egg production of H. miles on sciarid larvae was estimated to be 44.4 ± 4.33 eggs per female, as compared to 22.43 ± 1.79 eggs per female on mould mites. The sex-ratio of the offspring was significantly influenced by the prey species, the ratios (/(+)) being 0.66 on sciarid larvae and 0.54 on mould mites. The net reproductive rate (R₀) for H. miles fed on sciarid larvae was approximately 27 which was three times higher than for mites feeding on mould mites. The innate capacity of increase (r_m) was highest (0.0747 day^–1) when sciarid larvae served as food, giving a doubling time of 9.3 days as compared to 12.8 days on mould mites. The generation times were 44.28 on sciarid larvae and 40.67 days on mould mites. The daily food consumption rate of juvenile and adult H. miles was 0.24 and 0.86 sciarid larvae and 10.8 and 21.7 mould mites, respectively. In terms of weight consumed, however, the consumption of sciarid larvae was 2–3.5 times the weight of mould mites. The ratio of females to males influenced the oviposition period and egg production of H. miles, with virgin females laying fewer eggs over a longer period of time as compared with females with access to males. The egg production in relation to the sex-ratio was described by models predicting a maximum number of eggs per female of 22.3 to be attained at a sex ratio of 0.69 (/(+)) and a maximum daily number of eggs per female of 0.33 to be attained at a sex ratio of 0.37 (/(+)).     

Biological control of glasshouse sciarid flies (Bradysia spp.) with the predatory mite,hypoaspis miles on cyclamen and poinsettia

The predatory mite Hypoaspis miles was released from laboratory cultures into young crops of pot‐grown cyclamen and poinsettia in six small glasshouses. Five different rates of release were used together with a control house. In both crops, rates of 55 mites per pot and above gave satisfactory control of glasshouse sciarids with no later resurgence of the pest. Mites persisted on the pots until the end of the trial, probably feeding on a residual population of sciarids. In separate tests H. miles was found mostly in the top 1 cm of compost and persisted in horticultural compost for up to 7 weeks in the absence of food.     

温度对矩形龟甲轮虫生命表统计学参数和形态特征的影响

应用单个体培养方法研究了温度(10℃、15℃、20℃和25℃)对双后棘刺、单后棘刺和无后棘刺矩形龟甲轮虫的净生殖率、内禀增长率、世代时间、平均寿命和后代混交率等生命表统计学参数以及后代体长、体宽、前中棘刺长、左右两前侧棘刺长、左右两后棘刺长、后棘刺数目等形态参数的影响.结果表明,各生命表统计学参数和后代形态参数在3种形态型轮虫间的差异因温度的不同而异,它们对温度升高的反应也因轮虫形态型的不同而异.温度显著影响轮虫的内禀增长率、世代时间、平均寿命和后代所有的形态参数(P＜0.05);形态型显著影响轮虫后代的体长、前中棘刺长和左右两后棘刺长(P＜0.05),但对轮虫的生命表统计学参数均无显著影响(P＞0.05);而温度和形态型的交互作用显著影响轮虫的世代时间和后代的形态参数(P＜0.05).3种形态型轮虫间,双后棘刺轮虫后代的体长(122.1±0.6μm)显著短于无后棘刺和单后棘刺轮虫后代的体长(分别为126.3±0.7μm和125.1±0.7 μm),前中棘刺长(32.5±0.3 μm)显著长于无后棘刺和单后棘刺轮虫后代的前中棘刺长(分别为31.l±0.3μm和30.8±0.3μm),左后棘刺长(31.2±1.0μm)和右后棘刺长(32.3±0.9 μm)均与单后棘刺轮虫后代的(分别为29.5±0.8 μm和31.5±0.6 μm)相似,但显著短于无后棘刺轮虫后代(分别为36.7±1.5 μm和37.3±1.6μm).矩形龟甲轮虫后代的棘刺长、体宽和体长之间的关系也受温度和形态型的影响.     

胡瓜钝绥螨捕食茶橙瘿螨的实验种群生命表及捕食作用初探

本在25℃条件下初步研究了胡瓜钝绥螨捕食茶橙瘿螨的实验种群生命表、各螨态取食量及猎物－－卵转化率。25℃时胡瓜钝绥螨的净增殖率R0＝21．7862,世代平均周期T＝16．1822,内禀增长率rm＝0．1904,周限增长率λ＝1．2097,种群倍增所需时间t＝3．6405。日平均产卵量2．19粒／天,总产卵量36－48粒／雌,平均38．97粒／雌。胡瓜钝绥螨雌螨－生取食量1978．49头。雄螨取食量879．56头。猎物：卵转化率为79．78头茶橙瘿螨：2．19粒胡瓜钝绥螨卵。     

Effect of Verticillium lecanii on biological characteristics and life table of Serangium japonicum (Coleoptera: Coccinellidae), a predator of whiteflies under laboratory conditions

Effects of entomopathogenic fungus Verticillium lecanii on biological characteristics and life table of Serangium japonicum , a predator of whiteflies against five different conidial concentrations (1×10⁴, 1×10⁵, 1×10⁶, 1×10⁷, and 1×10⁸ conidia/mL) were studied under laboratory conditions. The developmental periods for all immature stages (from eggs, 1st, 2nd, 3rd, 4th instar nymph and pupae up to emergence) among the treatments were significantly different when compared to that of control, and the longest development period was observed as treated with 1×10⁸ spore/mL. However, no significant difference on the percent survival of all immature stages was observed among the treatments and control. Also, there were no significantly different effects of V. lecanii on mean generation time, intrinsic rate, the finite rate of increase and longevity of S. japonicum among the treatments and control.     

The effects of temperature, relative humidity and hostplant on the behaviour of Stethorus punctillum as apredator of the two-spotted spider mite, Tetranychusurticae

The predatory behaviour of Stethoruspunctillum larvae was studied on the two-spottedspider mite (Tetranychus urticae), in order toassess how it responded to temperatures and relativehumidities typical of glasshouse conditions on fouredible crop plant species. Locomotory activity(distance covered, time spent walking, walking speed,angular velocity, and turning rate) was recorded at20, 25 and 30 °C and relativehumidity levels of 33%, 65% and 90% RH on tomato,pepper, aubergine and cucumber and analysed usingvideo/computer techniques. The results show thatactivity of S. punctillum significantly increased athigher temperatures. Host plant species also stronglyinfluenced the performance of the predator, which wasmost active on pepper and tomato and least active onaubergine. Relative humidity had no significantinfluence.     

温度对草小卷蛾发育的影响及其实验种群生命表

【目的】研究温度对草小卷蛾Celypha flavipalpana Herrich-Schaffer种群动态和繁殖情况的影响。【方法】本研究在不同条件下(20~32℃,16L︰8D,RH=70%~80%)对草小卷蛾的发育起点温度和有效积温进行系统研究,并于26℃下建立实验种群生命表和生殖力表。【结果】经统计分析,其卵、幼虫、蛹、成虫及全世代的发育起点温度(℃)分别为14.30±2.43、6.45±1.57、11.01±1.78、12.40±2.7和9.48±2.19,有效积温(日·度)分别为45.05±8.88、492.01±42.48、107.53±13.63、65.51±12.39和671.86±94.19;实验种群趋势指数I>1,次代种群数量呈12.13倍趋势增长,净增值率R0=15.85,世代平均周期T=39.99,内禀增长率rm=0.0691,周限增长速率λ=1.0715,种群倍增时间t=10.0331。【结论】在20~28℃,草小卷蛾各虫态发育历期随着温度的升高而逐渐缩短,32℃下幼虫期和蛹期发育速率减慢,部分幼虫出现休眠状态;26℃下次代实验种群数量呈增长趋势。     

The effects of colony characteristics on life span and foraging behavior of individual wasps (Polybia occidentalis,Hymenoptera: Vespidae)

Summary We studied the effects of intrinsic colony characteristics and an imposed contingency on the life span and behavior of foragers in the swarm-founding social waspPolybia occidentalis. Data were collected on marked, known-age workers introduced into four observation colonies.To test the hypothesis that colony demographic features affect worker life span, we examined the relationships of colony age and size with worker life span using survivorship analysis. Colony age and size had positive relationships with life span; marked workers from two larger, older colonies had longer life spans (¯X = 24.7 days) than those from two smaller, younger colonies (¯X = 20.1 days).We quantified the effects of experimentally imposed nest damage on forager behavior, to determine which of three predicted behavioral responses by foragers to this contingency (increased probability of foraging for building material, increased rate of foraging, or decrease in age of onset of foraging) would be employed. Increasing the colony level of need for materials used in nest construction (wood pulp and water) by damaging the nests of two colonies did not cause an increase in either the proportion of marked workers that gathered nest materials or in foraging rates of marked individuals, when compared with introduced workers in two simultaneously observed control colonies. Instead, nest damage caused a decrease in the age at which marked workers first foraged for pulp and water. The response to an increase in the need for building materials was an acceleration of behavioral development in some workers.