Life table parameters of an indigenous strain of Neoseiulus californicus McGregor (Acari: Phytoseiidae) when fed Tetranychus urticae Koch (Acari: Tetranychidae)

The life table of the indigenous Neoseiulus californicus was studied at different temperatures and 65 ± 5% relative humidity under conditions of 16 h light : 8 h dark (LD 16:8). The total developmental period from egg to adult varied from 3.0 to 14.0 days at 15 to 35°C. Survival to adulthood ranges from 86.21 to 93.94%, with the highest rate at 25°C. The lower threshold temperature from egg to adult stages of females and males was 10.84 and 10.72°C, respectively, and the thermal constant was 57.14 degree‐days (DD) for females and 56.18 DD for males. Total number of eggs laid by each female was the highest (70.38 eggs) at 25°C, whereas average daily fecundity was the highest (3.69 eggs/female/day) at 30°C. The net reproductive rate was the highest (48.49) at 25°C and lowest (26.18) at 30°C. Mean generation time decreased from 19.04 to 11.47 days with increasing temperature from 20 to 30°C. Both intrinsic rate of natural increase (0.284) and finite rate of increase (1.32) were maximum at 30°C. Adult longevity was the highest (42.75 days for females and 32.60 days for males) at 20°C and lowest (22.70 days for females and 15.30 days for males) at 30°C. Sex ratio was female biased and was the highest (78.08) at 25°C and lowest (70.24) at 30°C. Developmental data of five constant temperatures, temperature thresholds and thermal requirements may be used to predict the occurrence, number of generations and population dynamics of N. californicus as an important biocontrol agent of Tetranychus urticae.     

Heat tolerance of developmental and seasonal stages of Chilo suppressalis

Global warming means that the ability to withstand heat stress is of crucial importance to insects' survival and reproduction. Insects have various ways of achieving thermal tolerance, which can be affected by thermal history, physiological state, and seasonal cycles. In this study, we compared the thermal tolerance of life stages and seasons of a wild population of the striped stem borer, Chilo suppressalis (Walker) (Lepidoptera: Pyralidae), an economically significant pest of rice crops in Asia. Our results demonstrate that the eggs, larvae, and adults of C. suppressalis collected in rice fields in Yangzhou, China, are able to tolerate extremely high temperatures, in excess of those this species encounters in nature. We found that egg masses had a survival rate of 75% after being kept at 42 °C for 8 h. Egg masses exposed to 39 °C for 8 h had the longest hatching time (3.3 days). LTemp₅₀ and LTemp₉₀ (i.e., the temperatures at which 50 or 90% of individuals died within 2 h) of larvae collected in late summer were 45.4 and 47.3 °C, respectively. LTime₅₀ and LTime₉₀ (i.e., the time required to kill 50 or 90% of individuals) at 44 °C were 6.2 and 9.6 h, respectively. The corresponding values for 46 °C were 1.5 and 2.6 h. We also found that the heat tolerance of adults collected in late summer was lower than that of larvae. For example, LTemp₅₀ of male and female adults was 43.8 and 43.6 °C, respectively. Other measures of the heat tolerance of adults, such as LTime₅₀ at 42 °C, also differed between the sexes, being 5.9 h for males and 7.2 h for females. Although adult survival was robust to heat stress, adult fertility was more sensitive. Our results also indicate that although the second generation of adults (i.e., the summer generation) typically encountered higher temperatures than the overwintering generation, survival of the second generation adults was lower.     

空心莲子草叶甲室内大量繁殖研究

为了大量繁殖供环境释放的空心莲子草叶甲Agasicles hygrophila以实现空心莲子草区域减灾, 我们探索出室内大量饲养与繁殖空心莲子草叶甲的方法与流程, 包括用叶片法或苗水培法孵化卵粒、用盒养法饲养各龄幼虫与成虫并供成虫产卵、用栽培活苗笼养法化蛹羽化。在室内成虫终日均能取食、交配、产卵, 产卵前期约4～5 d, 产卵高峰期在羽化后第7～24 天, 每雌平均产卵21.08块, 约570粒。盒养法叶片平均可着卵4.28块, 叶背与叶面着卵量相近; 笼养法叶片平均着卵为1.46块, 卵主要产于叶背。盒养法与笼养法得到的卵孵化率分别为94.02%与92.50%。空心莲子草叶甲除化蛹需在栽培活苗上完成外, 各龄幼虫与成虫均可用离体新鲜苗盒养法密集饲养。初孵1龄幼虫转株（叶）期、3龄老熟幼虫转化蛹苗期是室内大量饲养与繁殖空心莲子草叶甲的关键时期, 高密度成功饲养与繁殖空心莲子草叶甲的最适化蛹接虫量是每株8头, 产卵期雌虫的最适密度是每株5头。     

Heat tolerance among different strains of the entomopathogenic nematode <Emphasis Type="Italic">Heterorhabditis bacteriophora</Emphasis>

Quality of biological control products based on entomopathogenic nematodes can be severely damaged due to exposure to high temperature surpassing 40°C. The study screened 36 natural populations and 18 hybrid or inbred strains of Heterorhabditis bacteriophora for their response to high temperature. Nematodes were tested with or without prior adaptation to heat at 35°C for 3 h. Five strains of H. indica and one of H. megidis were also included. Molecular identification using nuclear ribosomal DNA sequences confirmed the designation to the three Heterorhabditis spp. The mean tolerated temperature ranged from 33.3°C to 40.1°C for non-adapted and from 34.8°C to 39.2°C for adapted strain populations. H. indica was the most tolerant, followed by H. bacteriophora and H. megidis. No correlation was recorded between tolerance assessed with and without adaptation to heat, implying that different genes are involved. Correlation between heat tolerance and mean annual temperature at place of origin of the strains was weak. A high variability in tolerance among strains and the relatively high heritability (h2 = 0.68) for the adapted heat tolerance recorded for H. bacteriophora provide an excellent foundation for future selective breeding with the objective to enhance heat tolerance of H. bacteriophora.     

Effects of short-term heat stress on the growth and development of Bradysia cellarum and Bradysia impatiens

Bradysia cellarum Frey and Bradysia impatiens Johansen are major pests of vegetable crops, as well as edible mushrooms and ornamental plants, and damage to hosts resulting in economic losses. Temperatures above the optimum levels for these pests have been predicted to regulate their population growth during summer. The aim of the present study was to examine the effects of both heat stress and exposure time on the growth and development of eggs, larvae and pupae for two Bradysia species. The egg stage, egg hatching rate, 4th instar larval stage, pupation rate, pupal stage and adult emergence rate were observed after exposing at high temperatures of 34°C, 37°C and 40°C for 1, 2, 4 and 6 hr. The results showed that 34°C, 37°C and 40°C for 1-, 2-, 4- and 6-hr exposure treatments prolonged the developmental stage of egg, 4th instar larva and pupa, while decreasing the egg hatching rate, pupation rate and adult emergence rate. This suggests that increasing temperature or prolonging exposure time to the heat stress could significantly affect insect survival, growth and development. Our study could provide an ecological basis for pests’ management strategy by using short-term heat stress.     

Effects of heat shock on survival and predation of an important whitefly predator,Serangium japonicum

Climate change is expected to increase the frequency of periods of extreme weather events, including heat waves that are harmful to arthropod natural enemies. We studied the thermotolerance of the ladybeetle Serangium japonicum Chapin (Coleoptera: Coccinellidae), an important native predator of the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) in China. Serangium japonicum eggs, first‐ and fourth‐instar larvae, pupae, and adults were subjected to a range of high temperatures (36, 39, 42, 43.5, and 45 °C) at intervals between 15 and 720 min. Survival was compromised and declined sharply for all life stages at temperatures of 42 °C and higher. First instars were the least heat tolerant, and eggs were typically the most resistant. Egg predation by S. japonicum did not differ whether the adult beetles were subjected to either heat shock or starvation first. Heat shock treatments at 36 °C did not impede adult egg consumption, treatments at 39 °C crippled ladybeetle's egg consumption for 8 h following treatment but recovered predatory capacity within 24 h after treatment. However, treatments at 42 °C greatly impaired ladybeetle's predatory capacity. After experiencing heat shock at 39 and 42 °C, adults significantly increased the amount of time they spent resting, which is the probable cause of predation decline after heat exposure. These results demonstrate that short periods of extreme heat exposures have a detrimental impact on S. japonicum survival and predation, but the effect was dependent on duration and life stage. Overall, these findings can help predict population dynamics and success of biological control of whitefly by S. japonicum in a warming world.     

Effect of temperature on reproduction and embryonic development of the cabbage stem flea beetle,Psylliodes chrysocephala L., (Coleoptera: Chrysomelidae)

The cabbage stem flea beetle, Psylliodes chrysocephala (L.) (Coleoptera: Chrysomelidae), is a major pest of winter oilseed rape. Despite the importance of this pest, detailed information on reproduction to predict risk of crop damage is lacking. This study investigates the effect of temperature on parameters of reproduction, egg development and viability at five constant temperatures. Significant temperature effects were found on the pre‐oviposition period, total number of eggs laid, daily oviposition rate, female longevity, egg‐development rate and viability. The mean length of the pre‐oviposition period ranged from 93.1 days at 4°C to 14.6 days at 20°C. Analysis of total number of eggs laid and daily oviposition rate during female lifespan estimated the highest total number of eggs laid (696 eggs/female) at 16°C and the highest oviposition rate (6.8 eggs/female and day) at 20°C. The daily oviposition rate at 20°C was not significantly higher than 5.4 eggs/female and day at 16°C. Female longevity was significantly longer at 4°C, shorter at 20°C and not significantly different between 8, 12 and 16°C. Estimated 50% survival time of females was 239, 153, 195, 186 and 78 days at 4, 8, 12, 16 and 20°C, respectively. A linear model of egg development at 8–20°C estimated the lower developmental threshold to be 5.1°C and the thermal constant for development 184.9 degree‐days. The percentage of eggs hatching was significantly lower at 4°C than at all other temperatures tested. The estimated mean hatching percentages were 47.3%, 70.0%, 72.4%, 66.2% and 67.9% at 4, 8, 12, 16 and 20°C, respectively. These results can be used to predict the start and intensity of egg‐laying in the autumn and the appearance of larvae in the field from knowledge about time of field invasion and from monitoring the weather.     

Effect of temperature on development and reproduction of Neoseiulus barkeri (Acari: Phytoseiidae) fed on Aleuroglyphus ovatus

The effect of five constant temperatures (16, 20, 24, 28 and 32°C) on the development, survival and reproduction of Neoseiulus barkeri Hughes fed on Aleuroglyphus ovatus Toupeau (Acari: Acaridae) was examined in the laboratory at 85% relative humidity. Development time of different immature stages decreased with increasing temperature, total egg-to-adult development time varied from 5.0 ± 0.13 to 17.5 ± 0.29 days. The lower thermal threshold for development was 9.7 ± 2.48°C and the thermal constant from egg to adult was 111.1 ± 12.34 degree-days. Pre- and post-oviposition period and female longevity all shortened as temperature increased. The longest oviposition period was observed at 24°C with 20.4 ± 1.13 days. At 20, 24, 28 and 32°C, mated females laid on average 0.7 ± 0.08, 1.5 ± 0.04, 1.6 ± 0.11 and 1.5 ± 0.11 eggs per day, respectively, but no eggs were laid at 16°C. Both the maximum fecundity (30.9 eggs per female) and the highest intrinsic rate of increase (r _m = 0.166) were obtained at 28°C. The results of this study indicated that a mass rearing of N. barkeri with A. ovatus as prey is feasible at the appropriate temperature.     

Temperature‐dependent development of the double‐spined spruce bark beetle Ips duplicatus (Sahlberg, 1836) (Coleoptera; Curculionidae)

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Effect of heat stress on survival and reproduction of the olive fruit fly Bactocera (Dacus) oleae

The olive fruit fly Bactrocera (Dacus) oleae Gmelin is a major olive pest in Greece and other Mediterranean countries. Its population density and respective olive infestation is usually low in many areas of northern Greece during summer months. To some extent, this may be due to the prevailing high temperature and low relative humidity conditions. In the present work the effects of short term exposure to high temperatures on the survival and egg production of B. oleae pre‐imaginal stages and adults were studied under laboratory conditions. Different larval instars within infested green olive fruits, adults and pupae and were exposed for 2 h to a series of different high constant temperatures ranging from 34 to 42°C. Subsequently, survival percentages of pre‐imaginal stages and adults as well as the number of eggs laid by females previously exposed to high temperatures were determined. At temperatures up to 38°C high survival percentages of larvae and adults were observed, whereas pupae displayed a relatively increased heat tolerance up to 40°C. Female longevity and egg production were substantially reduced after heat stress. Prior acclimation at 33°C for 1 and 3 days resulted in increased adult survival following heat stress. We discuss the results with respect to the ability of the fly to survive and reproduce under high summer temperatures.     

Effects of heat shock,heat exposure pattern,and heat hardening on survival of the sycamore lace bug,Corythucha ciliata

The sycamore lace bug, Corythucha ciliata (Say) (Hemiptera: Tingidae), is an invasive exotic pest on Platanus trees in China. This study assessed the thermotolerance of C. ciliata in the laboratory. Detailed experiments were conducted on the effects of high temperature (35, 37, 39, 41, 43, and 45 °C), duration of exposure (0.5, 1, 2, 4, 6, and 8 h), and developmental stage (egg, nymph, and adult) on survival of the bug. Meanwhile, the effects of heat hardening on survival at lethal temperature (exposure to 33, 35, 37, 39, and 41 °C for 1 h prior to transfer to 43 °C for 2 h) were also assessed for nymphs and adults. Survival of eggs, nymphs, and adults was not affected by temperatures between 35 and 39 °C, but declined rapidly with increasing duration of exposure (from 0.5 to 8 h) at temperatures ≥41 °C. The lethal temperature that caused mortality of 50% (Ltemp₅₀) of all developmental stages decreased with increasing duration of exposure from 0.5 to 8 h. The Ltemp₅₀ for nymphs was 44.3, 42.0, and 39.0 °C after 0.5, 2, and 8 h exposure, respectively. Thermotolerance was the highest in eggs, followed by adults and then nymphs. Thermotolerance was slightly greater for adult males than for adult females. The ability of nymphs, females, and males to survive exposure to 43 °C for 2 h significantly increased by heat hardening, i.e., by exposure to a non‐lethal high temperature for 1 h; the optimal heat‐hardening temperature was 37 °C. The results indicate that survival of C. ciliata at heat‐shock temperatures depended on both the temperature and the duration of exposure, and the tolerance to heat shock was enhanced by heat hardening. The thermotolerance of C. ciliata may partially explain why C. ciliata has been rapidly spreading on Platanus trees in southern provinces of China.     

High temperature tolerance and thermal-adaptability plasticity of Asian corn borer (Ostrinia furnacalis Guenée) after a single extreme heat wave at the egg stage

Due to ongoing climate change, short-term extreme heat waves in the summer are expected to be more frequent. Insect eggs are sensitive to thermal stress. This raises the question of whether herbivore insects' thermal adaptability would be changed after a single extreme heat wave at the egg stage. In this study, we examined the developmental performance of Ostrinia furnacalis Guenée at 25?°C, 27?°C, 29?°C or 31?°C after a single extreme heat wave (42?°C) for 0?h (control), 1?h, 2?h, or 3?h at the egg stage. The results showed that O. furnacalis at the egg or larval stage was more sensitive to a single heat wave than it was at the pupae or adult stage. After a single heat wave, O. furnacalis showed a reduced egg-hatching rate or reduced larval survival rate, but the optimum temperature for egg hatching and larval survival was higher than that in the control. The upper temperature threshold and optimum temperature for larval development in the control were higher than that after a single extreme heat wave. Both male and female pupal weight decreased with increasing temperature, and pupal weight decreased faster in females than in males. The Cox proportional hazard model showed that when O. furnacalis developed at 25?°C, the instantaneous death risk of adults with a 3?h heat wave at the egg stage was higher than that of the control, but when O. furnacalis developed at 29?°C and 31?°C, the instantaneous death risk of adults after a heat wave was significantly lower than that of the control. Our study highlights the effect of a single heat wave on O. furnacalis eggs and the subsequent development of survival individuals.     

空心莲子草叶甲对越冬保护的响应与控害效能

空心莲子草叶甲Agasicles hygrophila是入侵杂草空心莲子草Alternan thera philoxeroide的重要天敌,冬春季低温冰冻是影响其安全越冬的关键胁迫因子。为了探明采取保护措施是否能提高越冬后的种群基数问题,在低温冰冻天气来临前,用塑料膜覆盖网室构建空心莲子草与空心莲子草叶甲保护生境(PH),分低温期(2009年1月21日至4月9日)、升温期(4月15日至5月1日)与自然生境(NH)中叶甲成虫初现期(从6月1日至29日)3个阶段,调查比较PH与NH两类生境中空心莲子草叶甲种群数量、结构、空间生态位分布特征及控害效能。结果表明:在保护生境中,低温期空心莲子草叶甲不休眠,且能安全越冬,当晴天温度较高时,成虫主要在直立茎或嫩枝上活动取食、补充营养,而在阴雨低温天气则停留在匍匐草层或土壤表层、缝隙中,少活动。随着气温回升,成虫转移到直立茎生态位上活动取食,并于4月上旬开始产卵繁殖,种群数量迅速增加,对空心莲子草的地上部分有较好的控制效果。在自然生境中,直到6月初才见少量成虫活动,此时草生长茂密,较低的空心莲子草叶甲种群难以发挥生防因子的作用。比较两种生境中6月1日与6月15日的控草效果显示,空心莲子草株高增长率分别为:PH-13.91%,NH-2.94%,NH中空心莲子草株高极显著高于PH,且单株生物量的控制率为PH(47.56%)极显著高于NH(4.89%)。在6月15日与29日的调查表明,单株叶片控制效果PH极显著优于NH,PH中的空心莲子草茎上均无叶,叶片或被取食殆尽、或被害后干枯脱落。茎被害率、茎蛀孔数与蛀茎率均为PH极显著高于NH。结果说明覆膜保护能显著提高叶甲越冬种群基数,使其提前进入繁殖期,从而能更有效地控制生境中的空心莲子草。     

Temperature-dependent development and life table parameters of <Emphasis Type="Italic">Typhlodromus bagdasarjani</Emphasis> (Phytoseiidae) fed on two-spotted spider mite

The predatory mite Typhlodromus bagdasarjani Wainstein and Arutunjan (Acari: Phytoseiidae) is an indigenous and widespread species of the Middle East fauna. In this paper we assess the effect of temperature on developmental rate and reproduction potential of T. bagdasarjani under laboratory conditions. The development of this species was determined at 15, 20, 25, 30, 35 and 37.5 ± 1°C, 60 ± 10% RH and L16:D8 h photoperiod. The total developmental time averaged 28.2, 15.0, 8.9, 7.6, 7.2 and 7.4 days at 15–37.5°C, respectively, when feeding on immature stages of two-spotted spider mite, Tetranychus urticae Koch. The lower developmental threshold (T ₀ ) and thermal constant (K) for the development of this predator were estimated 9.2°C and 162 degree-days by the Ikemoto linear model. The life table parameters were estimated at 15–35°C. The shortest life span of females at 35°C was 45.0 days, followed by 50.7, 50.9, 103.3 and 136.8 days at 30, 25, 20 and 15°C, respectively. Mated females laid on average 19.9, 26.3, 41.1, 39.6 and 31.3 eggs per female at 15–35°C, respectively. The intrinsic rate of increase (r _m ) and finite rate of increase (λ) increased significantly with increasing temperature. The r _m values ranged from 0.021 (15°C) to 0.186 (35°C) days⁻¹. The highest value of net reproductive rate (R ₀) was 13.6 females progeny/female/generation at 25°C. The results demonstrated that T. bagdasarjani is well adapted to high temperatures. However, the efficiency to control spider mites may be affected by behavioral characteristics of the predator and its prey under real conditions.     

捕食者对空心莲子草叶甲种群的生物胁迫

广食性捕食者广泛捕食植食性昆虫,常被用于有害生物的生物防治,也因此影响植食性昆虫对杂草的生物效果。空心莲子草叶甲(Agasicles hygrophila)(鞘翅目:叶甲科Chrysomelidae)作为入侵恶性杂草空心莲子草(Alternanthera philoxeroides)(苋科:莲子草属Alternanthera)的专性天敌,从美国的弗罗里达州引入中国,在释放地防治空心莲子草取得了较好的防治效果。虽然空心莲子草叶甲在引入地均已建立田间种群并有一定程度的自然扩散,但丰富的食物资源,并未使空心莲子草叶甲的自然种群数量变得繁荣,因此其未能有效抑制空心莲子草的扩散蔓延。在野外调查时发现空心莲子草生境中存在大量广食性捕食者。这些广食性捕食者是抑制空心莲子草叶甲种群数量扩张的生物胁迫因子吗?为此,选择捕食性昆虫龟纹瓢虫(Propylaea japonica)(鞘翅目:瓢虫科Coccinellidae)、蜘蛛类捕食者拟水狼蛛(Pirata subpiraticus)(蜘蛛目:狼蛛科Lycosidae)与斜纹猫蛛(Oxyopes sertatus)(蜘蛛目:猫蛛科Oxyopidae)为捕食者,分别以空心莲子草叶甲各虫态为猎物,构建简单的捕食者-猎物系统,在室内检测了上述3种捕食者对空心莲子草叶甲各虫态在不同密度下的日捕食量,以期了解捕食者对空心莲子草叶甲的捕食作用,客观评估空心莲子草叶甲的生物防治效能。研究结果表明:捕食者龟纹瓢虫、斜纹猫蛛与拟水狼蛛均捕食空心莲子草叶甲的卵粒及1龄、2龄幼虫,斜纹猫蛛与拟水狼蛛捕食3龄幼虫,捕食者的捕食量均随着猎物密度的升高而增加,寻找效应降低。三者均不捕食成虫。除拟水狼蛛对3龄幼虫的捕食用Holling II模型拟合不呈显著相关关系外,其余捕食反应均拟合Holling II模型并显著相关。通过拟合方程得出捕食者对空心莲子草叶甲卵粒的理论日最大捕食量为:斜纹猫蛛10.9粒,拟水狼蛛为6.2粒,龟纹瓢虫为5.6粒;对1龄幼虫的理论日最大捕食量为:斜纹猫蛛为17.1头;拟水狼蛛为35.8头,龟纹瓢虫为10.4头;对2龄幼虫的理论日最大捕食量为:斜纹猫蛛为6.6头,拟水狼蛛为11.2头,龟纹瓢虫为2.9头;对3龄幼虫的理论日最大捕食量为:斜纹猫蛛捕食12.3头,拟水狼蛛为1.1头。研究结果证实了捕食者可通过捕食作用降低空心莲子草叶甲种群密度,削弱空心莲子草叶甲对空心莲子草的控害效能,是空心莲子草叶甲种群存活的生物胁迫因子。建议在提高空心莲子草叶甲田间种群数量,达到对空心莲子有效的持续控制效果方面开展进一步研究。     

Reproduction of the wedge sole (<Emphasis Type="Italic">Dicologoglossa cuneata</Emphasis> Moreau) in captivity: spawning parameters and influence of the natural temperature

In this work, the wedge sole (Dicologoglossa cuneata) spawning under a natural thermocycle has been studied. The spawning parameters were similar to those of other flatfish in captivity, the relative fecundity being very high (1.7 ± 0.1 × 10⁶ eggs kg female⁻¹ per spawning season). The percentage of floating eggs decreased with time and was directly related to egg diameter, daily relative fecundity and fertilization rate. Nevertheless, the hatching rate variations were not correlated to any other spawning parameter. The temperature range during the spawning season was very wide (11–21°C) though the largest spawns occurred between 12 and 16°C. The natural temperature cycle influenced wedge sole egg production, the winter temperature minimum indicating the onset of spawning, but the variations in the reproductive season did not appear to affect the daily egg production. Future research should focus on the photoperiod and its interaction with temperature as key factor for spawning.     

Effect of cold acclimation and rapid cold-hardening on the survival of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) under cold stress

Spodoptera frugiperda is a highly invasive pest species that recently invaded Africa and Asia causing severe economic losses, primarily related to corn and rice crops. Temperature is one of the most important environmental factors that influence the invasion of pests into new habitats. However, little is known regarding the thermal tolerance characteristics of invasive S. frugiperda. Thus, we investigated the response of four developmental stages of S. frugiperda (i.e., eggs, third and sixth instar larvae, and pupae) to cold acclimation (CA) and rapid cold-hardening (RCH). All individuals suffered high mortality with 24-h temperature treatments at <?5°C and >35 °C. The CA treatment significantly increased the survival rate of the eggs and third instar larvae, although it did not affect the sixth instar larvae and it decreased the pupation rate. The RCH treatment at 5 °C for 5 h or 2 °C for 2 h increased the cold tolerance capabilities of the third and sixth instar larvae, respectively. Thus, the larval stage appears to be crucial for the cold tolerance of S. frugiperda. Our findings improve the current understanding of the cold tolerance characteristics of S. frugiperda and indicate its potential for survival in the newly invaded temperate regions of Asia.     

Effects of down collection on incubation temperature, nesting behaviour and hatching success of common eiders (Somateria mollissima) in west Iceland

Incubating common eiders (Somateria mollissima) insulate their nests with down to maintain desirable heat and humidity for their eggs. Eiderdown has been collected by Icelandic farmers for centuries, and down is replaced by hay during collection. This study determined whether down collecting affected the female eiders or their hatching success. We compared the following variables between down and hay nests: incubation temperature in the nest, incubation constancy, recess frequency, recess duration, egg rotation and hatching success of the clutch. Temperature data loggers recorded nest temperatures from 3 June to 9 July 2006 in nests insulated with down (n = 12) and hay (n = 12). The mean incubation temperatures, 31.5 and 30.7°C, in down and hay nests, or the maximum and minimum temperatures, did not differ between nest types where hatching succeeded. Cooling rates in down, on average 0.34°C/min and hay nests 0.44°C/min, were similar during incubation recesses. Females left their nests 0–4 times every 24 h regardless of nest type, for a mean duration of 45 and 47.5 min in down and hay nests, respectively. The mean frequency of egg rotation, 13.9 and 15.3 times every 24 h, was similar between down and hay nests, respectively. Hatching success adjusted for clutch size was similar, 0.60 and 0.67 in down and hay nests. These findings indicate that nest down is not a critical factor for the incubating eider. Because of high effect sizes for cooling rate and hatching success, we hesitate to conclude that absolutely no effects exist. However, we conclude that delaying down collection until just before eggs hatch will minimize any possible effect of down collection on females.     

Effect of heat treatment on pre-stocking of Turkey eggs and its impact on incubation and hatching

Egg stocking is used to meet housing demands in the hatchery industry. Stocking periods longer than 10 days of occur commonly, despite the fact that this practice causes productive losses during the incubation process. To minimize these losses, eggs are heated before incubation to stimulate the embryo, thereby reducing the range of birth intervals. The objective of this study was to determine whether heat treatment (37.5 °C) prior to incubation would improve hatching rates. We also determined the heat-exposure time necessary to improve productivity. We stored 5376 Nicholas pedigree eggs, aged between 40 and 51 weeks, for seven days. These eggs were distributed in three groups: groups 1 and 2 received 4 and 6 h of heat treatment, respectively; group 3 was used as control (no heat treatment, remaining at 17 °C). After heat treatment, the eggs were stored for 7 days at 17 °C, together with eggs from the control group. We found significant variation in the cumulative dispersion of birds born during the hatch window; greater numbers of birds were born in group 1 that underwent the 4-h heat treatment with a 24-h hatch window and in group 3 that underwent the 6-h heat treatment with a 12-h hatch window. Hatch rate, yolk retention and the relationship between average chick weight/average egg weight did not differ between treatments. These data suggest that heat treatment modulates the hatch window; nevertheless, the treatment did not influence the average weight the chicks, the number of chicks born, the percentage of hatching or yolk retention.