Developmental Threshold Temperature Research Articles

Predicting the development of critical biological stages of Sunn pest,Eurygaster integriceps Put. (Hemiptera: Scutelleridae), by using sumof degree-days for timing its chemical control in wheat*

This investigation was carried out for possible use of sum of degree-days (total effective temperatures) in order to predict the critical biological stages in chemical control of Sunn pest, Eurygaster integriceps Put. (Hemiptera: Scutelleridae), in 28 wheat fields of Adiyaman, Diyarbakir, and Sanliurfa provinces from 2007 to 2010, and in climate chamber conditions. Development threshold temperature (°C) of Sunn pest in terms of the life span, starting from egg to new generation of adults, was found as 13.30 °C. Sums of degree-days starting from 1 January to appearance of the eggs, first-stage nymphs (n 1 ), second-stage nymphs (n 2 ), and fourth-stage nymphs (n 4 ) were found with the averages of 44.6, 84.4, 123.3, and 223.1 degree-days, respectively. The results from the field studies reflected that developmental biological data on sum of degree-days as a predictive tool could be useful in better decision making to start chemical applications as soon as the appearance of n 1 until n 4 for Sunn pest control.

Effect of temperature on the development of the Common Grass Yellow, Eurema hecabe

The developmental responses of insects to temperature are important considerations in gaining a better understanding of their ecology and life histories. Temperature-dependent phenology models permit examination of the effects of temperature on the geographical distributions, population dynamics, and management of insects. Measurements of insect developmental and survival responses to temperature pose practical challenges that depend on the chosen modality, variability among individuals, and high mortality rates near the lower and upper threshold temperatures. Different temperature levels can significantly affect larval development of Eurema hecabe. The development of E. hecabe reared on leaves of Lespedeza cuneata was investigated at three temperature regimes (20, 25, and 30°C), a relative humidity of 60%, and a light:dark photoperiod of 14:10 h. The developmental time from larva to adult was 34.3, 20.6, and 17.9 d at temperatures of 20, 25, and 30°C, respectively. Pupal rate was 47.6%, 47.6%, and 61.9% at temperatures of 20, 25, and 30°C, respectively. The developmental threshold temperature estimated from larva to pupae was 8.1°C with 381.7 degree-days. There is an increasing need for a standardized manual for rearing this butterfly species based on adequate knowledge of its ecology.

Fenologia e acúmulo térmico em videiras viníferas na região da Fronteira Oeste do Rio Grande do Sul

Resumo: O objetivo deste trabalho foi avaliar a exigência térmica, obtida por diferentes métodos de cálculo, para caracterizar a fenologia das videiras (Vitis vinifera) 'Cabernet Sauvignon', 'Tannat', 'Ruby Cabernet' e 'Merlot', cultivadas na Fronteira Oeste do Rio Grande do Sul. O desenvolvimento fenológico foi acompanhado durante cinco safras - 2005/2006 a 2009/2010. As temperaturas mínimas e máximas do ar foram coletadas diariamente e foram testados oito métodos de soma térmica: M1.1, M1.2 e M1.3, que utilizaram somente a temperatura base inferior (10°C); M2.1 e M2.2, que consideraram também a temperatura ótima de desenvolvimento de 25°C; e M3.1, M3.2 e M3.3 que, além das anteriores, utilizaram 35°C como temperatura base superior do desenvolvimento. Estes métodos foram comparados pelo erro-padrão das estimativas de soma térmica. O teste SNK foi utilizado para a comparação da exigência térmica entre as cultivares. O método M3.3 foi o que melhor simulou o desenvolvimento em 'Tannat' e 'Merlot' (1.823,1 e 1.780,8 graus-dia respectivamente). No entanto, o menor desvio foi obtido em 'Cabernet Sauvignon' e 'Ruby Cabernet', pelo método M3.1 (1.958,9 e 1.944,8 graus-dia respectivamente). Os métodos que empregaram as três temperaturas cardinais apresentaram maior precisão. 'Tannat' e 'Merlot' são as cultivares de videira que apresentam a menor exigência térmica para completar o ciclo.

Lower development threshold temperatures and thermal constants for four species of Asphondylia (Diptera: Cecidomyiidae) in Japan and their larval developmental delay caused by heat stress

Lower development threshold temperatures (LDT) of gall midges (Diptera: Cecidomyiidae) were directly determined by comparing developmental stages before and after incubation of galls for a definite period under a range of temperatures sufficient to cover the borders of the linear response. The LDT was determined to be 15 and 17 °C, respectively, for the soybean-pod gall midge, Asphondylia yushimai Yukawa and Uechi, and the ampelopsis fruit-gall midge, A. baca Monzen. They are host-alternating multivoltine species, but their LDT did not differ between generations on winter–spring and summer–autumn hosts, supporting the hypothesis that the value of LDT is stable and species specific. Based on the LDT and the 50 % emergence dates (ET50) of an overwintered generation, we estimated the thermal constants from first instars to adults to be 47.4 day-degrees for A. yushimai and 164.9 day-degrees for A. baca. The estimated thermal constant enables A. yushimai to repeat many generations annually, which may support the possibility that the gall-midge infestation range expands every summer and autumn from southern to northern Honshu, where winter–spring hosts have never been detected. The larval development of A. yushimai and A. baca, as well as those of two other univoltine congeners, A. aucubae Yukawa and Ohsaki and A. sphaera Monzen, was delayed at temperatures of 26, 28, or 29 °C. Global warming, when it becomes more prominent, will reduce the number of generations and the survival rate of multivoltine gall midges that spend summer without diapause.

Correction: Identification and Risk Assessment for Worldwide Invasion and Spread of Tuta absoluta with a Focus on Sub-Saharan Africa: Implications for Phytosanitary Measures and Management

To support management decisions, molecular characterization of data and geo-reference of incidence records of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) were combined with data on the biology and ecology of the pest to estimate its climatic suitability and potential spread at regional and global scale. A CLIMEX model was developed and used for the global prediction of current and future climate-induced changes in the distributional shifts of T. absoluta. Results revealed that temperature and moisture characterized T. absoluta population growth while the pest ability to survive the cold, hot, wet and dry stress conditions are the primary characteristics defining its range frontiers. Simulated irrigation also played an important role in the model optimization. Model predictions suggest that T. absoluta represents an important threat to Africa, Asia, Australia, Northern Europe, New Zealand, Russian Federation and the United States of America (USA). Under climate change context, future predictions on distribution of T. absoluta indicated that the invasive nature of this pest will result in significant crop losses in certain locations whereas some parts of Africa may witness diminution in ranges. The following scenarios may occur: 1) T. absoluta damage potential may upsurge moderately in areas of Africa where the pest currently exists; 2) a range diminution in temperate to Sahel region with moderate upsurge in damage potential; 3) a range expansion in tropical Africa with reasonable upsurge of damage potential. These possible outcomes could be explained by the fact that the continent is already warm, with the average temperature in majority of localities near the threshold temperatures for optimal development and survival of T. absoluta. Outputs from this study should be useful in helping decision-makers in their assessment of site-specific risks of invasion and spread of T. absoluta with a view to developing appropriate surveillance, phytosanitary measures and management strategies.

Temperature-Dependent Development ofXyleborus glabratus(Coleoptera: Curculionidae: Scolytinae)

Redbay ambrosia beetle, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae), is a nonnative pest that transmits the pathogenic fungus Raffaelea lauricola T.C. Harr., Fraedrich & Aghayeva (Ophiostomatales: Ophiostomataceae), which causes laurel wilt disease in trees of the family Lauraceae. Laurel wilt is present in the commercial avocado (Persea americana Mill.; Laurales: Lauraceae) growing areas of Florida and poses a potential threat to the avocado industries of California and Mexico. The life cycle of X. glabratus was studied in avocado logs at 16, 20, 24, 28, and 32 °C. Xyleborus glabratus successfully completed its life cycle at 24, 28, and 32 °C, with the greatest oviposition and development rate at 28 °C. Development of the egg and pupal stages was studied at 12, 16, 18, 20, 24, 28, 32, and 36 °C. One linear and 7 nonlinear developmental models were used to estimate the temperature-dependent development of both stages. The linear model estimated the lower threshold temperatures for egg and pupal development to be 13.8 °C and 11.1 °C, respectively, and the degree-days (DD) for egg and pupal development to be 55.1 DD and 68.2 DD, respectively. The Brier-2, Ratkowsky, Logan, and polynomial models gave the best estimates for the temperature-dependent development of the egg stages, whereas the Brier-1, Logan, and polynomial models gave the best estimates of temperature-dependent development of the pupal stages. Our results suggested that the optimal temperature for development of X. glabratus was around 28 °C, and that temperature will play an important role in the spread and successful establishment of X. glabratus.

EMERGENCE TIMING OF OVERWINTERED ADULTS LAID EGGS AND CONTROL EFFECT BY ECO-FRIENDLY MATERIALS TO CACOPSYLLA PYRICOLA

The pear sucker (Cacopsylla pyricola) is the most important insect pest in Korea. The hatching rates of eggs of overwintered adults were observed at 10, 13, 18, and 22°C. The liner model about temperature and the developmental rate of the eggs was drawn as Y=0.00277X+0.00146 (Y = developmental rate, X = temperature). The developmental threshold temperature for eggs was assumed about -0.83°C. The egg hatching timing over 50% in function of the accumulated temperature by day maximum temperature of 6°C from 1 February in 2011, 2012 and 2013 was 424.3, 367.8, and 429.8°C, respectively. This was 3 to 7 days before full blooming in pear orchard. Otherwise, the abamectin 1.8Ec, lime sulfer, machine oil and 13 kinds of eco-friendly materials did not show the control effect to the eggs. On mixed stages of pear suckers, there were 4 kinds of eco-friendly materials with over 90% control values such as the mixture of Azadiractin A+B, Nimbin, Salanin, Meliantriol and Vepol after two applications on 21 May and 5 June in the pear growing season in 2012.

Influence of Temperature on Some Biological Characteristics of <I>Trichogramma evanescens</I> (Westwood) (Hymenoptera:Trichogrammatidae) on the Egg of Lesser Date Moth <I>Batrachedra amydraula</I> Meyrick

The egg parasitoids Trichogramma spp. were used in a large scale application in different agriculture systems and the species Trichogramma evanescens (Westwood) showed a very promising results when used against lesser date moth Batrachedra amydraula Meyrick (Lepidoptera: Cosmopterygidae). The efficiency of the parasitoids is affected by many environmental factors including temperature. The effect of different temperature regimes on some biological characteristics of T. evanescens was investigated when reared on the egg B. amydraula under laboratory conditions. The longest life span was 35 days recorded at 15°C while the shortest one was 7 days at 33°C. The optimum temperature for the development of this parasitoid ranged between 22 and 27°C. The upper development threshold temperature was 38.4°C and the lower was 11.14°C. Results also showed that the highest parasitism rate was 94.4% recorded at 25±2°C. Adult emergence and female longevity were also influenced by temperature. The feasibility of the results in mass production and the use of the parasitoid for the control of lesser date moth also discussed.

Identification and Risk Assessment for Worldwide Invasion and Spread of Tuta absoluta with a Focus on Sub-Saharan Africa: Implications for Phytosanitary Measures and Management.

To support management decisions, molecular characterization of data and geo-reference of incidence records of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) were combined with data on the biology and ecology of the pest to estimate its climatic suitability and potential spread at regional and global scale. A CLIMEX model was developed and used for the global prediction of current and future climate-induced changes in the distributional shifts of T. absoluta. Results revealed that temperature and moisture characterized T. absoluta population growth while the pest ability to survive the cold, hot, wet and dry stress conditions are the primary characteristics defining its range frontiers. Simulated irrigation also played an important role in the model optimization. Model predictions suggest that T. absoluta represents an important threat to Africa, Asia, Australia, Northern Europe, New Zealand, Russian Federation and the United States of America (USA). Under climate change context, future predictions on distribution of T. absoluta indicated that the invasive nature of this pest will result in significant crop losses in certain locations whereas some parts of Africa may witness diminution in ranges. The following scenarios may occur: 1) T. absoluta damage potential may upsurge moderately in areas of Africa where the pest currently exists; 2) a range diminution in temperate to Sahel region with moderate upsurge in damage potential; 3) a range expansion in tropical Africa with reasonable upsurge of damage potential. These possible outcomes could be explained by the fact that the continent is already warm, with the average temperature in majority of localities near the threshold temperatures for optimal development and survival of T. absoluta. Outputs from this study should be useful in helping decision-makers in their assessment of site-specific risks of invasion and spread of T. absoluta with a view to developing appropriate surveillance, phytosanitary measures and management strategies.

A Model for Predicting Spring Emergence of Monochamus saltuarius (Coleoptera: Cerambycidae) from Korean white pine, Pinus koraiensis.

Monochamus saltuarius Gebler is a vector that transmits the pine wood nematode, Bursaphelenchus xylophilus, to Korean white pine, Pinus koraiensis, in Korea. To reduce the damage caused by this nematode in pine forests, timely control measures are needed to suppress the cerambycid beetle population. This study sought to construct a forecasting model to predict beetle emergence based on spring temperature. Logs of Korean white pine were infested with M. saltuarius in 2009, and the infested logs were overwintered. In February 2010, infested logs were then moved into incubators held at constant temperature conditions of 16, 20, 23, 25, 27, 30 or 34°C until all adults had emerged. The developmental rate of the beetles was estimated by linear and nonlinear equations and a forecasting model for emergence of the beetle was constructed by pooling data based on normalized developmental rate. The lower threshold temperature for development was 8.3°C. The forecasting model relatively well predicted the emergence pattern of M. saltuarius collected from four areas in northern Republic of Korea. The median emergence dates predicted by the model were 2.2-5.9 d earlier than the observed median dates.

Technical note: Development of Hemipyrellia ligurriens (Wiedemann) (Diptera: Calliphoridae) at constant temperatures: Applications in estimating postmortem interval

Blowflies (Calliphoridae) are recognized as a powerful tool for estimating the minimum postmortem interval (PMImin). The times for blowflies to develop from oviposition to eclosion is mainly controlled by temperature, which can differ between even closely related species. Hemipyrellia ligurriens (Wiedemann) (Diptera: Calliphoridae) is a blowfly distributed throughout Asia and Australia. However, a systematic determination of the developmental times of H. ligurriens under constant temperature, necessary for estimating the PMImin, is lacking. Such an examination would broaden the forensic importance of the species. Thus, this study explored the growth curves of larval H. ligurriens at 7 constant temperatures (16, 19, 22, 25, 28, 31, and 34°C). Isomegalen and isomorphen diagrams were successfully constructed, depicting the time of larval length or developmental event, respectively, at different temperatures. A thermal summation model was also constructed via regression analysis, by estimating the developmental threshold temperature t and thermal summation constant K. The thermal summation model indicated that t at 8.3°C and K at 5747.5 degree-hours (°Ch) are required for complete development from oviposition to eclosion, and suggested an optimum temperature range of 16–28°C for the development of H. ligurriens. These data establish for the first time the temperature-dependent developmental time of H. ligurriens for forensic entomology application. The 3 developmental models are provided.

Impact of fluctuating temperatures on development of the koinobiont endoparasitoid Venturia canescens

The effect of temperature on the biology of Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae) is well understood under constant temperature conditions, but less so under more natural, fluctuating conditions. Herein we studied the influence of fluctuating temperatures on biological parameters of V. canescens. Parasitized fifth-instar larvae of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) were reared individually in incubators at six fluctuating temperature regimes (15–19.5°C with a mean of 17.6°C, 17.5–22.5°C with a mean of 19.8°C, 20–30°C with a mean of 22.7°C, 22.5–27.5°C with a mean of 25°C, 25.5-32.5°C with a mean of 28.3°C and 28.5–33°C with a mean of 30°C) until emergence and death of V. canescens adults. Developmental time from parasitism to adult eclosion, adult longevity and survival were recorded at each fluctuating temperature regime. In principle, developmental time decreased with an increase of the mean temperature of the fluctuating temperature regime. Upper and lower threshold temperatures for total development were estimated at 34.9 and 6.7°C, respectively. Optimum temperature for development and thermal constant were 28.6°C and 526.3 degree days, respectively. Adult longevity was also affected by fluctuating temperature, as it was significantly reduced at the highest mean temperature (7.0 days at 30°C) compared to the lowest one (29.4 days at 17.6°C). Survival was low at all tested fluctuating temperatures, apart from mean fluctuating temperature of 25°C (37%). Understanding the thermal biology of V. canescens under more natural conditions is of critical importance in applied contexts. Thus, predictions of biological responses to fluctuating temperatures may be used in population forecasting models which potentially influence decision-making in IPM programs.

Effect of temperature on life history traits during immature development of Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae) from Córdoba city, Argentina

We investigated how ambient temperature under fluctuating conditions affects the larval–pupal immature traits of Aedes aegypti and Culex quinquefasciatus mosquitoes from Córdoba city, Argentina, and established each species development threshold and physiological time. Based on life tables, three cohorts of each mosquito species were reared in the laboratory under small fluctuating temperatures conditions of 15.2±1.7°C, 17.9±1.6°C, 21.6±0.7°C and 25.3±0.4°C for Ae. aegypti, and 16.6±1.7°C, 18.7±1.7°C and 25.2±0.3°C for Cx. quinquefasciatus. Immature development time and survival values, and also thermal development threshold and physiological time were estimated. Development times of all larval and pupal stages of Ae. aegypti and Cx. quinquefasciatus were significantly affected by the rearing temperatures, decreasing when temperature increased. Mean Ae. aegypti total (larva+pupa) development time ranged from 21.9 to 8.6 days, at 15.2 and 25.3°C, whereas, for Cx. quinquefasciatus varied between 23.5 to 9.2 days at 16.6 and 25.2°C, respectively. Larval and pupal survival of both species was affected by different rearing temperatures, increasing in general as temperature increased. For Ae. aegypti the total immature survival ranged from 26% at 15.2°C to 92% at 21.6°C; however, temperature did not have significant effect on this variable. The total immature survival of Cx. quinquefasciatus was significantly and positively affected by temperatures, ranging from 32 to 88%, at 16.6 and 25.2°C. The temperature development threshold and the physiological time estimated for Ae. aegypti and Cx. quinquefasciatus were 11.11°C and 93.74 degree-days, and 10.96°C and 136.87 degree-days, respectively. The results of the present study showed that temperature significantly affects the larval–pupal immature traits of these mosquito species of sanitary importance, from the central region of Argentina. All the parameters recorded are useful for the development of mosquito management models.

有效积温对郁金香生长发育影响的研究初报

研究郁金香生长发育与温度的关系，为郁金香的设计和配置提供依据。本实验以15个郁金香品种作为试验材料，主要研究露地栽培时郁金香生长发育与温度变化强度、有效积温的关系。试验结果表明：郁金香植物配置应根据品种的生物学特性和种植方法进行配球。低矮、窄冠幅品种应适当增加种植密度，株型高、冠幅大品种应适当降低用球数量，适度的种植密度能降低种植成本。供试郁金香品种发育阈温度6℃~7℃；以萌芽–开花积温为依据，栽培时通过调控积温，使不同类群的郁金香品种花期保持一致。 Studying the relation between temperature and growth provides the basis for designing. Taking 15 species as the test material, this paper is mainly to research the relationship between growth and intensity of changes in temperature and effective accumulated temperature of the relationship in land. The results show that designing should be carried out according to the biological characteristics and planting way. Low varieties should be appropriate to increase the planting density and high varieties should be appropriate to reduce the ball number. Appropriate planting density can reduce the cost of planting. The developmental threshold temperatures of different tulips are among 6˚C - 7˚C; based on sprout-blossom accumulated temperature, through controlling the effective accumulated temperature, the tulip cultivars will flower at the same time.

Development, Survival, and Reproduction of Megacopta cribraria (Heteroptera: Plataspidae) at Different Constant Temperatures.

The plataspid Megacopta cribraria (F.), an economic pest of soybeans, Glycine max (L.) Merrill, in Asia recently invaded North America and has become not only an important pest of soybean but also a nuisance pest. Although much is reported about M. cribraria in its native and invasive range, little information has been documented on the effect of temperatures on its development, longevity, and reproduction. We evaluated the influence of five constant temperatures (17-33°C) on the development, survival, fecundity, and population growth of M. cribraria in the laboratory. The developmental time for egg and nymph stages was shortened significantly with increasing temperature. The developmental time from egg to adult emergence was 114.81, 76.26, 44.54, and 38.54 d at 17, 21, 25, and 29°C, respectively. The nymphs of M. cribraria could not complete full development at a constant 33°C. The developmental threshold temperature estimated for egg to adult was 14.25°C, with a thermal constant of 849.56 degree-days. Females had the longest preoviposition period at 21°C (54.33 d), and the preoviposition period was shortened significantly as the temperature increased. Females had the longest oviposition period (35.33 d) and the highest fecundity (159.67 eggs per female) at 25°C and did not lay any eggs at 17°C. Female longevity was found to be shortest (44.0 d) at 29°C, and similar (75.67-81.50 d) at 17-25°C. The population trend index of M. cribraria was the highest (46.47) at 25°C, followed by 29°C (10.84) and 21°C (6.70). The results will be useful for predicting the phenology and population dynamics of M. cribraria and will provide some biological information on the invasive species in its nonnative range.

Biological and genetic characteristics of Glyptotendipes tokunagai (Diptera: Chironomidae) on the basis of successive rearing of forty-two generations over seven years under laboratory conditions.

Members of the nonbiting midge family Chironomidae have been used worldwide as water-quality indicators or toxicity test organisms. The purpose of this study was to establish the chironomid Glyptotendipes tokunagai Sasa as a new test species by conducting successive rearing under laboratory conditions. We monitored biological and genetic aspects of >42 successive generations over 7 yr, and also compared the development of the 39th generation with the fourth generation under five constant temperatures of 15, 20, 25, 30, and 35°C. We observed that the number of eggs in an egg mass and the adult body sizes decreased rapidly in the early generations, and thereafter tended to stabilize from the fifth generation to the 42nd generation. In all generations, the mean hatching rate was >75%. Males were predominant in the early generations, but the sex ratio increased to 0.5 (ranged 0.24-0.61) in later generations. The genetic divergence of the reared generations, analyzed by using the mitochondrial cytochrome c oxidase subunit I gene, decreased from 0.0049 to 0.0004 as the generations progressed. In comparison with the fourth generation, the mortality and developmental time of the 39th generation were generally greater, and the adult body sizes were generally smaller. The estimated low developmental threshold temperatures of eggs, male larvae to male adults, and female larvae to female adults were 9.6, 11.3, and 9.7°C, respectively. The optimal rearing temperature was determined to be 25°C. This is the first record of domesticated rearing of a wild chironomid species under laboratory conditions for >7 yr.

Development and thermal requirements of the Nearctic predator Geocoris punctipes (Hemiptera: Geocoridae) reared at constant and alternating temperatures and fed on Anagasta kuehniella (Lepidoptera: Pyralidae) eggs

Knowledge of the optimal temperatures for development and survival of biological control agents is essential for efficient mass-rearing and introduction of natural enemies in augmentative biological control programs. We studied the effect of constant and alternating temperatures on development and survival of immature stages and the sex ratio at emergence of adults of the Nearctic generalist predator Geocoris punctipes (Say). We also determined its thermal requirements. They were reared in climatic chambers at alternating (21/11°C, 24/18°C, 27/21°C and 30/26°C ± 1°C) and constant temperatures (16.8°C, 21.5°C, 24.5°C and 28.3°C ± 1°C), RH 70 ± 10% and a 14 h photophase. Survival and development of G. punctipes were the same when reared at constant and alternating temperatures. Five instars were recorded in all temperature regimes. The duration of the egg stage and each instar, as well as that of total larval development were longer, and larval survival lower when reared at 16.8°C, 21/11°C, 21.5°C and 24/18°C than at 24.5°C, 27/21°C, 28.3°C and 30/26°C. The optimal temperature range for development and survival of G. punctipes is 24.5°C to 30°C, its lower development threshold temperature is 13.5°C and its thermal constant 295.9 DD. Sex ratios were not significantly different from 1 : 1 male : female ratio in all temperature regimes. There is an excellent match between the temperature regimes at which the prey Tuta absoluta (Meyrick) and predator G. punctipes are active, which indicates that this predator will function well in crops where this pest is present.

Population dynamics of aphids on cereals: digging in the time-series data to reveal population regulation caused by temperature.

Aphid populations show periodic fluctuations and many causes are attributed to their dynamic. We investigated the regulation by temperature of the aphid populations composed of Metopolophium dirhodum, Sitobion avenae, and Rhopalosiphum padi on winter wheat using a 24 years long time series data. We computed the sum of daily temperatures above 5°C, the threshold temperature for aphid development, and the sum of daily temperatures within the [0(threshold for wheat development),5] °C interval. Applying Generalised Additive Model framework we tested influences of temperature history expressed via degree days before the start of the aphid immigration on the length of their occurrence. We aimed to estimate the magnitude and direction of this influence, and how far to the past before the start of the aphid season the temperature effect goes and then identify processes responsible for the effect. We fitted four models that differed in the way of correcting for abundance in the previous year and in specification of temperature effects. Abundance in the previous year did not affect the length of period of aphid population growth on wheat. The temperature effect on the period length increased up to 123 days before the start of the current season, i.e. when wheat completed vernalization. Increased sum of daily temperatures above 5°C and the sum of daily temperatures within the [0,5] °C interval both shortened the length of period of aphid population growth. Stronger effect of the latter suggests that wheat can escape from aphid attacks if during winter temperatures range from 0 to 5°C. The temperature influence was not homogeneous in time. The strongest effect of past temperature was about 50 to 80 and 90 to 110 days before the beginning of the current aphid season indicating important role of termination of aphid egg dormancy and egg hatching.

Comparative study of thermal reaction norms for development in ants

AbstractThis is the first compilation of our research and data from the literature on the duration and thermal reaction norms for development in ants. Altogether, 97 regression lines characterizing the linear dependence of ant brood (egg, larval, prepupal and pupal) development on temperature were obtained for 33 species from 15 genera and three subfamilies. Significant positive correlations between the durations of different immature stages were revealed. We found differences between thermal reaction norms for development for various immature stages, some taxonomic groups, and southern and northern groups of species. All immature stages appeared to be shorter on average at 25°C in northern ants compared to southern species; this difference is insignificant only for eggs. Highly significant negative correlations were revealed between the temperature threshold for development (TTD) and the sum of degree‐days (SDD) for all immature stages. The latitudinal trends in intraspecific variation of thermal constants appeared to be opposite to those we observed at the interspecific level. At the latter, the coefficient of thermal sensitivity of development (i.e. the coefficient of linear regression of development rate on temperature) and TTD tends to decrease and SDD to increase from the south to the north. In contrast, at the intraspecific level, development became more temperature‐sensitive in northern populations, i.e. characterized by higher slopes of regression lines of development rate on temperature, and higher TTDs. The species of the genus Formica are characterized by the shortest and the most temperature‐sensitive immature development among all the ant species studied.

An empirical predictive model for the spring emergence of Thecodiplosis japonensis (Diptera: Cecidomyiidae): model construction and validation on the basis of 25 years of field observation data.

The reliability of the empirical phenology model proposed by Nam et al. (2013) was tested using spring emergence data of Thecodiplosis japonensis Uchida et Inouye (Diptera: Cecidomyiidae) from 1986 to 2011 in Yeongcheon, Korea. First, the lower developmental threshold temperature (LDT) was estimated using spring emergence of T. japonensis and field temperatures. Then a degree-day model to predict spring emergence of T. japonensis was constructed, based on LDTs estimated from field observations and laboratory temperature-dependent development data. Based on field observations, the estimated LDT value for postdiapause development of T. japonensis was 6.1 degrees C, only 0.2 degrees C higher than that estimated from laboratory data. The explanatory power of the empirical degree-day model constructed on the basis of LDT from field observations was 87.2%, similar to the 87.0% of a degree-day model based on laboratory data, suggesting that both models had similar explanatory power. Furthermore, the predictions of median date of emergence in both models were only five days earlier than the observed median date in 2011. These results show that the empirical phenology model based on field observations is a reliable method for predicting the phenology of insects.