真水狼蛛的生物学和田间种群动态研究

真水狼蛛在湖北武汉1a发生3个不完整的世代,以第2代历期最短,第3代(越冬代)历期最长。主要以亚成蛛越冬。雌、雄均可多次交配。真水狼蛛1生最多可产4个卵袋,平均2.8个,含卵量较大(平均90粒)。雌蛛有较强的护卵、护幼习性。卵的孵化率较高,平均孵化率为91.36％。真水狼蛛共蜕皮6次,有7个龄期。性比各个世代均为雌蛛多于雄蛛。真水狼蛛捕食叶蝉、飞虱等多种水稻害虫,捕食量与龄期、蜕皮和性别有关。真水狼蛛在6月5日左右开始由田埂向稻田内迁移,1a有2个发生高蜂,分析了影响真水狼蛛种群动态因素。     

真水狼蛛胚胎发育过程中形态和主要化学物质含量的变化

采用常规石蜡切片和液体石蜡透明卵壳的方法,系统地观察了真水狼蛛的胚胎早期,体节期,胚胎速转期和幼虫期4个发育阶段的形态特征和发育过程,并测定了胚胎发育过程中卵的内主要化学物质含量的变化,在28度时,真水狼蛛的卵从产卵到孵化共需144小时,其中胚胎早期42小时,体节期33小时,胚胎逆转期27小时,在胚胎逆转期后进入前幼虫期,前幼虫期42小时,真水狼蛛的胚胎逆转现象很明显,表明真水狼蛛的进化程度较高,在胚胎发育过程中,卵的含水量,含脂量和卵重在胎发育24hr后开始下降,卵的蛋白质含量在48小时后也开始下降,含糖量下降不明显。     

温度对真水狼蛛发育和繁殖的影响

报道了具水狼蛛发育和繁殖的影响,２０～３２℃恒温条件,随着温度的升高历期变句。真永恒蜂在武泽地区一可发生２～３代。幼蛛发育到成熟所蠕蜕皮次数与温度有关,在各种温度下,均以蜕皮６次的个体最多,２７℃恒温条件下,产卵率最高,化率最高;３０』下单此产卵量最大。每蛛携带幼蛛的时间随温度和升高的而缩短。根据真水蛛蛛在６种恒温下的的幼蛛存活率,雌蛛产卵率,产量量和孵化率组了真水狼蛛在不同温度条件下的实验种各增     

真水狼蛛对褐飞虱捕食作用的初步研究

应用二次正交旋转组合的设计方法,研究了在不同的天敌密度、害虫密度、温度和光照时间的动态系统中,真水狼蛛对稻田主要害虫褐飞虱的捕食作用。得出其控制作用的数学模型为:y=27.4087 3.1667 x_1 6.8333 x_2-1.1667 x_3 0.5000 x_4-0.4258 x_1~2-0.9258 x_2~2-3.1758 x_3~2 .2500 x_1x_2 0.5000 x_1x3-1.5000 x_3x_4通过模型的主效应分析.得出了各环境因子对天敌捕食作用的影响。真水狼蛛对褐飞虱的日捕食量为19.372头。     

温度对细毛水狼蛛个体发育和繁殖力的影响

本研究结果证明:(1)细毛水狼蛛(Pirata tenuisetae)的卵粒在15℃恒温条件下,不能孵化;(2)在20—32℃恒温条件下随着温度升高历期逐渐缩短;其中以25—30℃恒温条件下幼蛛的成活率较高。在同一温度梯度下雄蛛的历期均短于雌蛛;(3)在28—32℃恒温条件下产卵率为最高,产卵量最大,25—30℃时孵化率最高;(4)母蛛携带卵袋的时间随着温度的升高而缩短,在35℃条件下,有取食自产卵粒习性。     

温湿度对稻纵卷叶螟卵的联合作用

为了探讨温湿度在稻纵卷叶螟Cnaphalocrocis medinalis （Guenée）种群发展中的作用, 通过室内实验调查了不同温度和湿度组合下该蛾卵的发育历期、 胚胎发育情况、 孵化率和卵粒重量的变化。结果表明： 在相同温度下卵历期随相对湿度的增大而缩短, 孵化率随相对湿度的加大而提高。在22℃下低于46%的相对湿度显著降低了卵的孵化率, 而在25～34℃下低于66%的相对湿度会引起孵化率的显著降低, 37℃下卵无论在何种湿度中均不能孵化。在50%左右的低湿条件下, 温度高于28℃后卵也不能孵化。温度在22～31℃和相对湿度在77%～100%范围内, 卵的孵化率无显著差异, 这属于稻纵卷叶螟卵的适宜温湿度范围。稻纵卷叶螟卵的发育起点温度和有效积温分别为10.1±0.6℃和63.7±3.5日度。卵的孵化率（Y）与温湿系数（RH/T）间呈显著的逻辑斯蒂曲线关系Y=0.8662/[1+exp(17.4084-7.5714×RH/T)]。温湿系数在2.34以下时卵孵化率将低于50%, 而达到3.0左右时孵化率接近最高值。结论认为, 低湿造成的稻纵卷叶螟卵重量显著降低、 卵粒干瘪、 胚胎发育受阻是致死卵的主要原因。     

温度变化对家蟋蟀卵孵化率的影响

对低温萌动温度和高温孵化温度变化条件下家蟋蟀Acheta domesticus卵的孵化率变化进行研究,旨在探讨温度变化对家蟋蟀卵孵化的影响,为温度影响昆虫卵孵化提供一个新的证据。在低温萌动温度(4℃和7℃)和高温孵化温度(25℃和29.5℃)下观察记录家蟋蟀卵孵化的个体数量,采用方差分析方法检验温度变化对卵孵化率的影响。结果表明,低温萌动温度显著影响家蟋蟀卵的孵化率,而高温孵化温度对家蟋蟀卵的孵化率则无显著作用,但二者存在显著的互作效应。在同一孵化时间内,不同温度处理下家蟋蟀卵孵化率之间的差异有统计学意义。在不同温度处理下,家蟋蟀卵达到最大孵化率的时间不同。说明低温萌动和高温孵化是家蟋蟀卵孵化的重要影响因素。本研究为家蟋蟀人工饲养的较有利的温度条件设置提供一定的理论指导。     

间斑寇蛛幼蛛过冬及其早期饲养管理

间斑寇蛛幼蛛过冬和早期饲养管理是人工饲养的关键。通过比较不同保存温度和不同保存时间下过冬幼蛛的孵化率、存活率和平均体质量,研究了间斑寇蛛幼蛛过冬的规律,并探讨了相对湿度、环境温度和食物种类对幼蛛离开卵囊后的早期生长发育的影响。结果表明:4℃左右是比较理想的卵囊保存过冬温度,但在此温度下保存7个月后存活率开始下降,到13个月幼蛛存活率降为零;卵囊放入低温保存前需在室内放置一段时间(约2个月)以使卵粒孵化成幼蛛;4℃左右下过冬的幼蛛离开卵囊后,在相对湿度55%~60%、环境温度25℃~30℃的条件下,用黄粉虫喂养4周后体质量增长40余倍,成活率达80%以上。     

基于响应面法分析温度和盐度对虎斑乌贼受精卵孵化的联合影响

根据中心复合试验设计(CCD)原理,在单因素试验的基础上,采用响应曲面分析法,观察了温度(24~32℃)与盐度(25~35)对虎斑乌贼受精卵孵化率及平均孵化时间的联合影响。结果表明:温度和盐度的一次、二次及互作效应对孵化率与平均孵化时间均有显著影响(P0.05),随着温度的升高,孵化率呈先上升后下降的趋势,平均孵化时间呈减少的趋势;随着盐度的上升,孵化率呈先上升后下降的趋势,平均孵化时间呈先下降后上升的变化;所考察的因子与孵化率、平均孵化时间之间二次多项模型的决定系数分别达到0.9791和0.9774;回归方程优化结果显示,温度为27.6℃和盐度31.1时,孵化率最大值为88.11%;温度26.2℃和盐度29.6时,平均孵化时间最小值为21.8 d,两模型的可信度均高达0.985。建议虎斑乌贼受精卵在温度26~28℃,盐度29~31条件下进行孵化,以提高生产效率。     

高温对粘虫Leucania separata Walker发育与生殖的作用——Ⅰ.卵的发育与孵化

本文报导了几种相对湿度下25—46℃高温对粘虫卵发育与孵化的作用。卵发育及孵化的适温上限为31.0-32.5℃,其致死高温限为32.0-33.5℃。在25.0—32.0℃间,孵化率不因温度而有显著变化,发育速率则随温度升高而加快:湿度仅在大幅度下降时才对孵化率有显著影响,但对发育速率的影响则随温度增高而加大,在接近适温上限时湿度又成为决定卵发育与孵化的主要因素。高温的致死作用,因温度强度、处理时间及相对湿度而异。温度越高,忍受时间越短,41℃以上高温处理2小时,即使绝大部分卵死亡。高温下饱和湿度,对卵的发育与孵化不利。受精卵处于第一步分裂前期,抗高温能力较差。温度驯化略可提高卵的耐高温能力。文中还讨论了高温致死的原因及湿度的作用。     

Influence of temperature, photoperiod and humidity on oviposition and egg hatch of the root-feeding flea beetle Longitarsus bethae (Chrysomelidae: Alticinae), a natural enemy of the weed Lantana camara (Verbenaceae)

The root-feeding flea beetle Longitarsus bethae Savini & Escalona, was introduced into South Africa as a candidate biological control agent for the noxious and invasive weed, Lantana camara L. As part of the study to predict the beetles' survival in its new range, the influence of climatic conditions on its egg development and reproductive performance were investigated in the laboratory. The threshold temperature (T degrees) and degree-days (DD) required for egg hatch were determined after exposing the eggs to various constant temperatures (12, 17, 22, 27 and 32 degrees C) in separate growth chambers. The DD required for egg hatch was 178.6, and the temperature threshold required for egg hatch was 11.3 degrees C. Survival of eggs varied from 27 to 56% at 32 and 17 degrees C, respectively, and was optimum between 17 and 25 degrees C. Oviposition was examined under high and low relative humidity (RH) regimes while egg hatch was determined at six RH levels, each maintained in a separate controlled growth chamber set at a constant temperature (25 degrees C). Whilst RH had no influence on oviposition, eggs were highly susceptible to aridity, and continuous exposure to relative humidity below 63% for more than three days was wholly lethal at 25 degrees C. Optimum egg hatch occurred at RH between 85 and 95% for up to 12 days. The effect of day length on oviposition and subsequent egg hatch was investigated under two photoperiod regimes. Neither oviposition nor subsequent egg hatch was influenced by photoperiod. The knowledge obtained will be useful for mass rearing as well as field release programmes for L. bethae.     

Studies on the biology of Argas (A.) reflexus (Fabricius, 1794) (Acari: Ixodida: Argasidae). 2. Effect of alternating temperatures on embryonic development and egg hatch.

The paper presents the results of observations on the effect of temperature alterations between 9 degrees C and 30 degrees C every 6 and 12 hours, respectively, on the embryonic development and egg hatch of Argas (A.) reflexus. No effect of the frequency of temperature changes on the percentage of egg mortality, embryo mortality, abnormal egg hatching, or egg hatching into morphologically normal larvae was observed. The experiments showed that in changes temperature have a particularly detrimental effect on the eggs prior to blastulation.     

Influence of temperature and photoperiod on embryonic development in the dragonfly Sympetrum striolatum (Odonata: Libellulidae)

Temperature and photoperiod play major roles in insect ecology. Many insect species have fixed degree‐days for embryogenesis, with minimum and maximum temperature thresholds for egg and larval development and hatching. Often, photoperiodic changes trigger the transfer into the next life‐cycle stadium. However, it is not known whether this distinct pattern also exist in a species with a high level of phenotypic plasticity in life‐history traits. In the present study, eggs of the dragonfly Sympetrum striolatum Charpentier (Odonata: Libellulidae) are reared under different constant and fluctuating temperatures and photoperiodic conditions in several laboratory and field experiments. In general, and as expected, higher temperatures cause faster egg development. However, no general temperature or light‐days for eyespot development and hatching are found. The minimum temperature thresholds are distinguished for survival (2 °C), embryogenesis (6 °C) and larval hatching (above 6 °C). Low winter temperatures synchronize hatching. Above 36 °C, no eyespots are visible and no larvae hatch. In laboratory experiments, light is neither necessary for eyespot development, nor for hatching. By contrast to the laboratory experiments, the field experiment show that naturally changing temperature and photoperiod play a significant role in the seasonal regulation of embryonic development. The post‐eyespot development is more variable and influenced by temperature and photoperiod than the pre‐eyespot development. This developmental plasticity at the end of the embryogenesis might be a general pattern in the Libellulidae, helping them to cope with variation in environmental conditions.     

Diapause and prolonged development in the embryo and their ecological significance in two cicadas, Cryptotympana facialis and Graptopsaltria nigrofuscata

The seasonal timing mechanism of egg hatching was examined in two cicadas, Cryptotympana facialis and Graptopsaltria nigrofuscata, with different but overlapping geographical distributions. These species lay eggs in summer, and nymphs hatch in the summer of the following year after egg durations of 10-12 months. When eggs were maintained at 25 °C from oviposition, both the species entered embryonic diapause within 60 days irrespective of photoperiod, but at different developmental stages between the two species. The optimal temperature for diapause development was approximately 15 °C in both the species. The development rate for postdiapause morphogenesis increased linearly with temperature in the range of 20-27.5 °C in C. facialis, and of 15-25 °C in G. nigrofuscata. The lower development threshold and the sum of effective temperatures were computed as 14.3 °C and 715.3 day-degrees in C. facialis and 12.1 °C and 566.6 day-degrees in G. nigrofuscata, respectively. The hatching dates predicted by these large thermal constants accorded with the hatching dates observed in the field, i.e., late June and mid-July in G. nigrofuscata and C. facialis, respectively. Therefore, the high thermal requirements for postdiapause development compel the cicadas to hatch in summer.     

Development rates of two Xenopsylla flea species in relation to air temperature and humidity

The rate of development of immature fleas, Xenopsylla conformis Wagner and Xenopsylla ramesis Rothschild (Siphonaptera: Xenopsyllidae) was studied in the laboratory at 25 degrees C and 28 degrees C with 40, 55, 75 and 92% relative humidity (RH). These fleas are separately associated with the host jird Meriones crassus Sundevall in different microhabitats of the Ramon erosion cirque, Negev Highlands, Israel. This study of basic climatic factors in relation to flea bionomics provides the basis for ecological investigations to interpret reasons for paratopic local distributions of these two species of congeneric fleas on the same host. Both air temperature and RH were positively correlated with duration of egg and larval stages in both species. Change of humidity between egg and larval environments did not affect duration of larval development at any temperature. At each temperature and RH, the eggs and larvae of X. ramesis did not differ between males and females in the duration of their development, whereas female eggs and larvae of X. conformis usually developed significantly faster than those of males. For both species, male pupae developed slower than female pupae at the same air temperature and RH. Air temperature, but not RH, affected the duration of pupal development. At each humidity, duration of the pupal stage was significantly longer at 25 degrees C than at 28 degrees C: 15.3+/-1.7 vs. 11.7+/-1.2 days in X. conformis; 14.1+/-2.0 vs. 11.5+/-1.7 days in X. ramesis, with a significantly shorter pupal period of the latter species at 25 degrees C. These limited interspecific bionomic contrasts in relation to basic climatic factors appear insufficient to explain the differential habitat distributions of X. conformis and X. ramesis.     

The adaptive value of hatching towards the end of the night: lessons from eggs of the haematophagous bug Rhodnius prolixus

Abstract. The daily hatching rhythm of Rhodnius prolixus eggs is established under an LD 12 : 12 h photoperiod. The endogenous nature of this rhythm is demonstrated under continuous darkness. Hatching takes place during the last half of the night, when the maximum environmental relative humidity (RH) and minimum temperature (i.e. the combination that yields the lower water vapour saturation deficits) occur in wild habitats. This temporal window of approximately 7 h recurs at 24‐h intervals, producing a hatching rhythm in the population. The effects of the RH upon egg‐hatching are analysed. In agreement with previous studies, hatching success is strongly affected by environmental RH. Although 88% of eggs hatch at 75% RH, only 4% and 10% hatch at 0% or 100% RH, respectively. These results support the hypothesis that temporal synchronization is related to the avoidance of low environmental RHs, high environmental temperatures, or high water vapour saturation deficit during hatching, thus minimizing their deleterious effects. Given that eggs cannot choose optimum microclimatic conditions, selective pressures appear to have originated from an adaptive temporal rather than spatial hygropreference.     

Abiotic factors influencing embryonic development, egg hatching, and larval orientation in the reindeer warble fly, Hypoderma tarandi

Wild-caught, tethered females of the reindeer warble fly, Hypoderma tarandi (L.) (= Oedemagena tarandi (L.)), (Diptera, Oestridae) were stimulated to oviposit on hairs of a reindeer hide. Newly laid eggs incubated at constant temperatures and relative humidities hatched within 3 days to 2 weeks, depending on the experimental conditions. Over a range of 7-40 degrees C, hatching only occurred between 20 and 37 degrees C. Eggs held at 100% relative humidity had lower hatchability and longer time to hatch relative to eggs held at 77% relative humidity. The average number of degree-days for hatching was 50.35. Between 20 and 33 degrees C there was a temperature-dependent linear trend in developmental rate, and the proportion of eggs hatching was highest, and least variable, at the mid-temperature ranges. The temperature range found in the natural host micro-habitat where H. tarandi commonly affix their eggs (close to the skin at the base of a host hair) was consistent with the experimental temperature treatments that produced the highest hatching rate. Newly emerged larvae displayed positive thermotaxis, while showing no phototaxic or geotaxic behaviour. Results indicate that constraints of the host environment, coupled with temperature-dependent hatching success, may impose a selective pressure on oviposition behaviour.     

Laboratory studies of factors affecting egg hatch of triops longicaudatus (LeConte) (Notostraca : Triopsidae)

Egg hatch was greatest (78.33%) for eggs not previously desiccated. A reduction in numbers hatched occurred as the relative humidity at which they were dried decreased. Some eggs hatched (0.67–79.33%) at pH levels of 3.10–10.01 with the highest hatch at pH 5.60. Water temperature greatly affected egg hatch. No hatch occurred until temperatures were above 14°C. A constant 29°C significantly inhibited hatching. Egg hatch increased 13.00 to 43.42% as salinity decreased from 2200 to 9.24 micromhos/cm. As little as 13 mm of flooded soil covering the eggs prevented them from hatching for 14 days. Eighteen percent hatch resulted when soil and eggs were redistributed to a 1 mm soil layer. Egg samples from the same parent, even though treated similarly, often hatched at greatly varying rates and only rarely was hatching 100% within a replication.     

Necator americanus: temperature, pH, light, and larval development, longevity, and desiccation tolerance

The effect of incubation temperature and pH on the hatch rate of eggs of Necator americanus, and the desiccation tolerance of the resulting infective stage-3 larvae were investigated in the laboratory under controlled conditions. Hatching did not occur below 15 C and above 35 C. A 21% hatch rate was obtained at 15 C while a 10.6% hatch rate was obtained at 35 C. The highest hatch rate (93.7%) was obtained at 30 C. The optimum pH for hatching was 6.0, but the larvae did not reach the infective stage. Incubation temperature of the eggs affected the longevity and desiccation tolerance of resultant infective larvae. Larvae hatched at 30 C and maintained at 26 C under bright fluorescent light had a 50% survival time (S50) of 4 days. In the dark or shade, the S50 for larvae raised at 30 C was 5 weeks, while that of larvae hatched at 20 C was 7 weeks. Incubation temperature also affected the desiccation tolerance of larvae. Larvae developed at 20 C were more resistant to desiccation at various relative humidity values than larvae hatched at 30 C.