Overwintering success in adults of the Japanese common grass yellow Eurema mandarina

The evolution of reproductive diapause is controversial in males as compared to females that must overwinter to leave offspring, because late‐autumn males can obtain offspring by pre‐overwintering copulation. The Japanese common grass yellow Eurema mandarina is suitable to examine the evolution of male reproductive diapause, because direct comparisons are possible between males that do and do not exhibit reproductive diapause. Approximately one‐half of males are insensitive to diapause‐inducing conditions, and emerge as non‐diapause summer‐form. Most autumn‐form females mate with summer‐form males in late autumn. Females that have overwintered re‐mate with autumn‐form males before the onset of oviposition. Because last‐male‐precedence is general in sperm competition in Lepidoptera, it is unclear why half of males emerge as summer‐form in late autumn. A potential adaptive benefit for emerging as summer‐form is increased sperm overwintering success, if autumn‐form females have a higher overwintering success than autumn‐form males. In the present study, overwintering success was estimated for both sexes of autumn‐form adults by rearing under seminatural conditions and a mark–release–recapture technique. Both approaches estimated an overwintering success of approximately 5% for both sexes. The absence of difference in overwintering success between the sexes suggests that pre‐overwintering copulation does not increase sperm overwintering success. However, a considerably low overwintering success may explain, at least partly, the presence of summer‐form males in late autumn. The degree of overwintering success might be more important than the sexual differences of overwintering success in the evolution of male reproductive diapause.     

A cyanogenic glucoside of Trifolium repens deters oviposition by the common grass yellow Eurema mandarina

The common grass yellow Eurema mandarina (Pieridae, Coliadinae) widely inhabits Japan, feeds on various fabaceous plants such as silktree (Albizia julibrissin) and uses d ‐pinitol, a cyclitol omnipresent in Fabaceae, as a primary oviposition stimulant. However, E. mandarina has a clear host preference within the Fabaceae; for example, white clover (Trifolium repens) is a nonhost despite containing d ‐pinitol. The present study aims to identify plant chemicals in white clover that inhibit oviposition of E. mandarina. Females lay very few eggs on T. repens foliage and plastic plant models treated with a methanolic extract of the foliage. The foliage extract is fractionated by successive extraction with chloroform, isobutanol and water. None of these fractions induce egg‐laying responses. The aqueous fraction is further separated into four subfractions (Tr‐3‐1 to Tr‐3‐4) by column chromatography. Among these subfractions, females show high egg‐laying responses to Tr‐3‐1, which is known to contain d ‐pinitol. Interestingly, Tr‐3‐2, when mixed with Tr‐3‐1, significantly decreases egg‐laying responses, indicating that it contains oviposition deterrents. Chemical analyses reveal that two cyanogenic glucosides, linamarin and lotaustralin, are the major constituents of Tr‐3‐2. Authentic linamarin does not elicit egg‐laying responses and significantly inhibits female oviposition when mixed with Tr‐3‐1 at the natural concentration. Although these cyanogenic glucosides are reported to synergistically induce oviposition of a coliadine species Colias erate on white clover, we conclude that linamarin acts as an oviposition deterrent for E. mandarina, restricts its host range and regulates their differential host acceptance.     

Effect of mating status on the fecundity of a cricket,Teleogryllus emma

Abstract Fecundity in some insects is affected by mating status. The effect of mating status on the fecundity and total egg production of Teleogryllus emma (Ohmachi et Matsumura) (Orthoptera: Gryllidae) was examined in this study. The results showed that the pre‐oviposition period was shorter for amphigonic females than that for virgin females. However, no significant difference in pre‐oviposition was found between amphigonic females and those that had mated with a male with either the phallodeum or testes extirpated. There is no difference in adult longevity between the above four groups. The fecundity and total egg production were much higher in amphigonic females than in those controlled under the three non‐amphigonic treatments. The females of T. emma that mated with the testes‐extirpated males produced more eggs (up to two‐fold more) than both the virgin females and those that mated with the phallodeum‐extirpated males, but there was no difference between them. The fecundity‐enhancing substances transferred from male to female can stimulate the female to produce more eggs, but this stimulation has to occur in collaboration with sperm.     

Egg concealment in ascidians by females of the Japanese tubesnout, Aulichthys japonicus (Gasterosteiformes), and its subsequent copulation

The reproductive behaviors of the Japanese tubesnout, Aulichthys japonicus, the only fish among gasterosteiform fish that conceals eggs in ascidians, were observed in aquaria. Yellow nuptial-colored males attending at ascidian courted gravid females. The nuptial color could be an advertisement to females for depositing sites, and courtships seemed to facilitate female spawning. The females spawned eggs above the ascidian and immediately placed their eggs with their mouths into the peribranchial cavity. Males never ejaculated on eggs after spawning, but attempted to copulate with females during a period of several minutes, and one or a few males with the remarkable nuptial color frequently copulated using their urogenital papilla. An evolutionary scenario of unique egg concealment and subsequent copulation is proposed.     

Seasonal changes of glycogen/trehalose contents,supercooling points and survival rate in mature larvae of the overwintering soybean pod borer Leguminivora glycinivorella

The mature larvae of the soybean pod borer Leguminivora glycinivorella, spend over 9 months (October-next August) in the inactive state until pupation down to 3 cm below the surface in soil. Trehalose content of inactive larvae increases in early winter, attaining a maximum (ca 30 mg/g), and decreases in spring, with a concomitant decrease and increase of glycogen. The median supercooling points seasonally change from ?19.8°C (October) to ?25.0°C (February), and to ?17.0°C (June). The lower supercooling points in winter are in part due to the absence of unusually high values (> ?18°C). The increase in trehalose does not seem to be effective in depressing the supercooling points. The larvae are freeze-intolerant, but ambient temperatures in outdoor conditions are always above the supercooling points. The survival rates are very high throughout the inactive period.     

Female polyandry and size‐assortative mating in isolated local populations of the Japanese common toad Bufo japonicus

In anurans, female polyandry under male harassment is distributed across taxa because of external aquatic fertilization. According to the sexual selection theory, male–male competition for access to females is affected by the operational sex ratio (OSR) and population density. The Japanese common toad, Bufo japonicus, is widespread in mainland Japan, and like the European common toad, B. bufo, it engages in explosive breeding. In this study, we observed the breeding behaviour of B. japonicus in isolated local populations for over four years in two breeding ponds with different population sizes and densities: large‐low (L‐pond) and small‐high (S‐pond). We analysed the relative polyandry ratio in egg clutches laid by females and estimated the size‐assortative mating pattern to be an indicator of male–male competition in the two ponds. Both ponds tended to exhibit a size‐assortative mating pattern; however, the frequency of polyandry was different in the two ponds (L‐pond = 20% and S‐pond = 90%). Our results showed that polyandry could occur without multiple amplexus with a high population density, i.e. eggs were often fertilized by free‐swimming sperm in the small shallow pond. We propose that high female polyandry ratios without continuous male harassment are generated because of a male‐biased OSR and a high population density in the small pond. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 236–242.     

Expression of heat shock proteins in response to high and low temperature extremes in diapausing pharate larvae of the gypsy moth,Lymantria dispar

Diapausing pharate first instars of the gypsy moth, Lymantria dispar, respond to high temperature (37–41°C) by suppressing normal protein synthesis and synthesizing a set of seven heat shock proteins with M_rs of 90,000, 75,000, 73,000, 60,000, 42,000, 29,000, and 22,000 as determined by SDS-PAGE. During recovery at 25°C from heat shock, synthesis of the heat shock proteins gradually decreases over a period of 6 h, while normal protein synthesis is restored. A subset of these same heat shock proteins is also expressed during recovery at 4°C or 25°C from brief exposures to low temperature (-10 to 20°C), and its expression is more intense with increased severity of cold exposure. During recovery at 4°C after 24 h at ?20°C, both 90,000 and 75,000 M_r heat shock proteins are expressed for more than 96 h. While normal protein synthesis is suppressed during heat shock and recovery from heat shock, normal protein synthesis coincides with synthesis of the heat shock proteins during recovery from low temperatures, thus implying that expression of the heat shock proteins is not invariably linked to suppression of normal protein synthesis. Western transfer, using a monoclonal antibody that recognizes the inducible form of the human 70,000 M_r heat shock protein, demonstrates that immunologically related proteins in the gypsy moth are expressed at 4°C and during recovery from cold and heat shock.     

The effect of female mating history on sperm precedence in the two-spot ladybird, Adalia bipunctata (Coleoptera, Coccinellidae)

Effects of two different mating regimes on sperm precedencein the two-spot ladybird, Adalia bipunctata, were studied usingthe polymorphic gene for melanism as a marker for paternity.Virgin nonmelanic females (homozygous recessive) were matedto nonmelanic male(s) and then, after laying fertilized eggs,were mated to a melanic male of known genotype. The resultsafter the two successive single matings showed a highly variabledegree of paternity of the second male. Initial multiple matingwith nonmelanic males did not alter the pattern of paternityafter the subsequent single mating with a melanic male, butit had two other effects: (1) the female showed an increasein rejection behavior, and (2) a longer copulation was requiredfor high success of the melanic male. Additional observationsin which families were reared from beetles collected in copulain the field demonstrated that sperm competition also occursunder natural conditions. The outcome of the competition wasvariable with frequent sperm mixing.     

温湿度对中华通草蛉越冬成虫存活的影响

室内研究了不同温湿度对中华通草蛉 (Chrysoperla sinica)越冬成虫存活的影响。试验采用因子二次正交旋转组合设计的要求安排 ,研究了越冬成虫在不同的温度组合条件下储存不同时间后的存活率 ,并得到了在不同时间后 ,成虫存活率与温湿度间的二次回归模型。结果表明 ,在试验条件下 ,越冬成虫存活的最佳条件组合是温度为 5℃和相对湿度为 75 % ,此条件下储存90 d的越冬成虫存活率达 85 %以上 ;温度对成虫存活率的影响最大 ,湿度次之 ,温湿度的交互作用最不重要。利用温湿度与存活率之间的回归方程 ,分析并得出了适宜于越冬中华通草蛉成虫存活的条件为温度 5～ 9℃ ,相对湿度 70 %～ 85 % ,温度和湿度过高或过低均不利于成虫的存活     

Impact of short‐term exposure to low subzero temperatures on egg hatch in the hemlock looper,Lambdina fiscellaria

The frequency of extreme events, such as cold spells, is expected to increase under global warming. Therefore, the ability of insects to survive rapid changes in temperature is an important aspect to investigate in current population ecology. The hemlock looper (HL), Lambdina fiscellaria (Guenée) (Lepidoptera: Geometridae), a defoliator of boreal balsam fir forests in eastern Canada, overwinters at the egg stage on tree trunks and branches where eggs can be exposed to very low subzero air temperatures. Using eggs from the island of Newfoundland (NL) and Quebec mainland (QC), we undertook field and laboratory experiments to determine: (1) their supercooling point (SCP) in mid‐January and mid‐February; (2) overwintering mortality; (3) cold tolerance to various combinations of subzero temperatures (?25, ?30, ?33, ?35, or ?37 °C) and exposure durations (2, 4, 8, 12, or 16 h); and (4) potential causes of death at subzero temperatures above the SCP. Regardless of population or sampling date, eggs supercooled on average at ?40.1 °C. In the field, 59% of eggs from either population that overwintered in Sainte‐Foy (QC) and Corner Brook (NL) hatched successfully, whereas none did in Armagh (QC) or Epaule (QC). In the laboratory, 50% of eggs survived after 4 h at ?34.4 °C or after 14 h at ?32.9 °C. In contrast, regardless of exposure duration, >50% of eggs hatched at temperatures ≥?33 °C, but <50% did so at ≤?35 °C, suggesting high pre‐freeze mortality. However, when eggs were attached to thermocouples and exposed to temperatures ranging from ?25 to ?37 °C for 16 h, 69% froze at temperatures of ?35 to ?37 °C, but only 2% did at ?25 or ?30 °C. Time to freeze decreased as subzero temperatures declined, and this was more evident in island eggs than in mainland eggs. Overall, eggs can freeze after a brief exposure to subzero temperatures higher than the standard SCP, and are thus highly vulnerable to cold spells.     

Russian Wheat Aphid,Diuraphis noxia in the Czech Republic – cause of the significant population decrease

Diuraphis noxia is a newly established alien pest in the Czech Republic. There were two population explosions during the period 1993–2012. A successful overwintering of the anholocyclic populations of D. noxia was the cause of a population explosion in the oncoming growth season. Viviparous parthenogenetic females of the anholocyclic populations and diapausing eggs of holocyclic populations could overwinter at the same time. Analysis of the course of winter temperatures showed that a complete winter mortality of anholocyclic populations depended mainly on the duration of the freezing period, when temperature dropped below ?5°C, and on the intensity of the frost. We proposed the cumulative effective freeze (in minus degree days) as a key parameter for the aphid anholocyclic population's mortality during overwintering. This parameter equalled ?10.1 degree days for relatively warm winter period 2006–2007, whereas in the relatively cold winter period of 2009–2010, this parameter reached ?87.1 DD, which caused complete mortality of anholocyclic populations. A cumulative effective freeze could be used for short‐time prognosis of D. noxia population explosion.     

Effect of temperature on egg production in the common housefly

Musca domestica L. (Diptera: Muscidae), better known as the common housefly, is increasingly considered to be a new, alternative protein source for animal nutrition. By transferring low-value organic side streams into high-value protein products, its commercial production contributes to a circular economy. Next to technical innovations for scaling-up the production capacity, efficient egg production has been identified as one of the bottlenecks of housefly production systems. We investigated egg production in two strains, one originally from Spain (SPA) and one from The Netherlands (GK), at 25 and 32 °C. At 25 °C, duration of preoviposition period, laying phase, and adult longevity was longer than at 32 °C. Lifetime egg production was lower at 32 °C, but the number of clutches laid per female was unaffected by temperature. Daily egg production at 32 °C was higher during the first 7 days, revealing a trade-off between higher early-in-life reproductive effort and adult longevity. The combination of shorter sexual maturation period and higher daily egg-laying rate resulted in reaching 50% of total egg production only 6 days after emergence at 32 °C for both strains, compared to 13 and 14 days at 25 °C for SPA and GK, respectively. We conclude that, in the absence of a need for high adult survival rates, houseflies have favourable production performances at higher temperature, and that efficacy and yield of the production process could be maximized by increasing the rearing temperature to 32 °C.     

Modelling the time–temperature relationship in cold injury and effect of high-temperature interruptions on survival in a chill-sensitive collembolan

1. Temperature- and time-dependent mortalities were studied and modelled in insects exposed in regimes with constant and alternating temperatures. In these experiments, freezing was not a cause of death.
2. Survival rates at a range of constant low temperatures (– 5 to + 1 °C) and for different exposure periods (1–14 days) were measured in the summer acclimated springtail Orchesella cincta .
3. Daily interruptions of the cold exposure with short intervals at high temperature reduced mortality or slowed the increase of mortality. This effect was stronger at higher temperature (19 vs 5 and 12 °C) and increased with the duration of the interruption (0·25–2 h).
4. The injury was reversible when the cold exposure was limited to 2 days.
5. Survival in desiccated animals (14% water loss) was reduced.
6. It is suggested that the mortality of summer acclimated springtails is caused by a complex metabolic disorder and membrane changes at low temperatures.     

Effect of growth at low temperature on the alternative pathway respiration in Acanthamoeba castellanii mitochondria

Mitochondria of amoeba Acanthamoeba castellanii in addition to the conventional cytochrome pathway possess, like plant mitochondria, a cyanide-resistant alternative quinol oxidase. In mitochondria isolated from amoeba batch culture grown temporarily at low temperature (6 degrees C), higher respiration was accompanied by lower coupling parameters as compared to control culture (grown at 28 degrees C). In the presence of benzohydroxamate, respiratory rates and coupling parameters were similar in both types of mitochondria indicating that growth in cold conditions did not disturb the cytochrome pathway. Increased contribution of alternative oxidase in total mitochondrial respiration in low-temperature-grown amoeba cells was confirmed by calculation of its contribution using ADP/O measurements. Furthermore, in mitochondria from low-temperature- grown cells the content of the alternative oxidase was increased and correlated with the increase in the unstimulated and GMP-stimulated cyanide-resistant respiratory activity. A possible physiological role of higher activity of alternative oxidase as response to growth at a low temperature in unicellular organisms, such as amoeba, is discussed.     

Assessing the effects of low temperature on the establishment potential in Britain of the non-native biological control agent Eretmocerus eremicus

Abstract. Eretmocerus eremicus is a parasitoid wasp that is not native to Britain. It is a biological control agent of glasshouse whitefly and has recently been released under licence in Britain for the first time. This study assessed the effect of low temperature on the outdoor establishment potential of E. eremicus in Britain. The developmental threshold calculated by three linear methods was between 6.1° and 11.6 °C, with a degree‐day requirement per generation between 256.3 and 366.8° day^?1. The supercooling points of non‐acclimated and acclimated larvae were similar (approximately ?25 °C). Non‐acclimated and acclimated larvae were subject to considerable pre‐freeze mortality, with lethal temperature (LTemp₅₀₎ values of ?16.3 and ?21.3 °C, respectively. Lethal time experiments indicated a similar lack of cold tolerance with 50% mortality of both non‐acclimated and acclimated larvae after 7 days at ?5 °C, 10 days at 0 °C and 13 days at 5 °C. Field trials showed that neither non‐acclimated nor acclimated larvae survived longer than 1 month when exposed to naturally fluctuating winter temperatures. These results suggest that releasing E. eremicus into British greenhouses would pose minimal risk because typical British winter temperatures would be an effective barrier against establishment in the wild.     

Effects of the corpora allata on sexual receptivity and completion of oocyte development in females of the cricket, Gryllus bimaculatus

Abstract Allatectomy of young penultimate nymphs of Gryllus bimaculatus De Geer (Gryllidae) resulted in prothetelic creatures which exhibited reproductive competence. The same operation performed on young last instar nymphs resulted in moulting to morphologically normal adults. Allatectomized morphologically normal adult females, as well as prothetelic ones, showed the same level of sexual receptivity as untreated control females. Allatectomized morphologically normal and prothetelic females laid viable eggs, but rate of egg laying and number of eggs produced by these females were much reduced in comparison with the controls. Administration of methoprene (a Juvenile Hormone analogue) to allatectomized females restored egg production to a more or less normal rate. Removal of the spermatophore within 10 min of copulation had no effect on subsequent sexual receptivity of the females, nor on the reduced rate of egg laying by the allatectomized females, but did affect the rate of egg laying by control females.
It is suggested that the corpora allata (CA) and the Juvenile Hormone (JH) play no major role in controlling basic sexual receptivity of G.bimaculatus females, and do not have an all-encompassing control on egg production, though they do exert a marked quantitative effect on the rate of egg production.     

Effect of culture age, pre-incubation at low temperature and pH on the thermal resistance of Aeromonas hydrophila

S. CONDON, M.L. GARCIA, A. OTERO AND F.J. SALA. 1992. The thermal resistance of Aeromonas hydrophila strain NCTC 8049 was determined within the range 48°-65°C with a thermoresistometer TR-SC and McIlvaine buffer. The effects of culture age, pre-incubation at 7°C and the pH of the heating menstruum were evaluated. The pattern of thermal death was dependent on culture age. Cells heated in the late logarithmic growth phase (15 h at 30°C) were twice as resistant as those in the early stage (5 h at 30°C), and the maximum D -value was obtained after 72 h incubation (5.5 total increase). The age of the cells did not affect z -values significantly. The heat resistance of cells incubated for 48 h at 30°C increased (twice) after holding at 7°C for 72 h. Pre-incubation at low temperature of older cultures (72 h, 30°C) did not influence their D -values. Maximum heat resistance was found at pH 6.0 and minimal at pH 4.0. Decreasing the pH from 6.0 4.0 reduced D -values by a factor of 5. Although the strain studied was heat-sensitive ( D _55°C= 0.17 min; z = 5.11°C), survivor curves of cultures older than 50 h showed a significant tailing. Organisms surviving in the tails were only slightly more resistant than were the original population.     

短时间高温处理对棉蚜存活的影响

为探索棉蚜Aphis gossypii Glover种群动态与高温的关系,研究了不同温度(30、34、38、42、46℃)、不同处理时间(1、2、5、8h)对棉蚜存活的影响。结果表明:在同一处理时间条件下,棉蚜的存活率随着温度的升高而降低;在同一处理温度下,棉蚜的存活率随处理时间的延长而降低。30～38℃温度范围内,棉蚜存活率降低缓慢,从42℃开始棉蚜的存活率迅速降低。棉蚜半数致死温度随着处理时间的延长而降低;相同处理时间条件下,若蚜半数致死温度高于成蚜,若蚜较成蚜更耐高温。     

Variation in food availability mediate the impact of density on cannibalism,growth, and survival in larval yellow spotted mountain newts (Neurergus microspilotus): Implications for captive breeding programs

In this study, we examined cannibalistic behavior, growth, metamorphosis, and survival in larval and post‐metamorph endangered yellow spotted mountain newts Neurergus microspilotus hatched and reared in a captive breeding facility. We designed a 2 × 2 factorial experiment, crossing two levels of food with two levels of density including high food/high density, high food/low density, low food/high density, and low food/low density. The level of cannibalistic behavior (including the loss of fore and hind limbs, missing toes, tail, gills, body damage, and whole body consumption) changed as the larvae grew, from a low level during the first 4 weeks, peaking from weeks 7 to 12, and then dropped during weeks 14–52. Both food level and density had a significant effect on cannibalism. The highest frequency of cannibalism was recorded for larvae reared in the low food/high density and lowest in high food/low density treatments. Growth, percent of larval metamorphosed, and survival were all highest in the high food/low density and lowest in low food/high density treatment. Food level had a significant effect on growth, metamorphosis, and survival. However, the two levels of density did not influence growth and metamorphosis but showed a significant effect on survival. Similarly, combined effects of food level and density showed significant effects on growth, metamorphosis, and survival over time. Information obtained from current experiment could improve productivity of captive breeding facilities to ensure the release of adequate numbers of individuals for reintroduction programs. Zoo Biol. 35:513–521, 2016. © 2016 The Authors. Zoo Biology published by Wiley Periodicals, Inc.     

Effect of increasing the surface area of primary sludge on anaerobic digestion at low temperature

Two sets of reactors were operated at 15 °C and at sludge retention times (SRTs) of 65 days and 30 days, respectively. Each set was operated at six different mixing velocities. Shear forces provided by mixing affected particle size distribution and resulted in different sludge surface areas. The aim was to investigate the effect of increasing primary sludge surface area on anaerobic digestion at low temperature. The maximum surface areas at the applied mixing velocities were 5926 cm²/cm³of sludge and 4672 cm²/cm³ of sludge at SRTs of 65 days and 30 days, respectively. The corresponding calculated methanogenesis were 49% and 15% at SRTs of 65 days and 30 days, respectively. Maximum total solids (TS) reductions were 26% and 11% at 65 days and 30 days SRTs, respectively. Lipase activity increased with increasing SRT and sludge surface area. Results clearly showed that increasing sludge surface area improved sludge digestion at 15 °C.