Developmental Threshold Research Articles

Developmental Thresholds and Thermal Requirements of Two Pupal Parasitoids of the Invasive Fall Webworm

The fall webworm is an injurious pest for many host plants in agriculture, forest, and urban environments. Recent observations showed that the faster spread of this pest can be supported by temperature increases, with a subsequent higher severity of the outbreaks and higher impact on the environment. Traditional chemical control is not effective on this pest, while biological control is a valuable alternative, especially if native natural enemies are used. In this study, the performance of Turkish populations of two parasitoids—Chouioia cunea and Psychophagus omnivorus—at different temperatures is evaluated. Laboratory trials were conducted in climatic chambers under five constant temperatures (10, 15, 20, 25, and 30 °C) and cold storage conditions (6 and 12 °C) for periods of 15, 30, and 45 days. The optimal developmental temperature and the upper thermal threshold of the two parasitoids were similar, while C. cunea showed a lower thermal threshold temperature. Both species could develop and survive between 20 and 30 °C, whereas development below 20 °C for C. cunea, and below 15 °C for P. omnivorus was not possible, respectively. Chouioia cunae was less tolerant to temperature changes than P. omnivorus in terms of offspring survival, development, reproduction, and parasitism. Under cold storage temperatures, the two species did not develop into adults. This study provided relevant eco-biological information that can further support biological control programmes.

Impact of temperature on development and reproduction of the olive black scale Saissetia oleae (Olivier) (Hemiptera: Coccidae).

The olive black scale, Saissetia oleae (Olivier), is a significant pest of olive crops worldwide. The developmental, reproductive, and population growth parameters of S. oleae were evaluated under five constant temperature conditions (18°C to 33°C). Developmental durations significantly decreased with increasing temperatures. Female lifespan decreased from 161.6 days at 18°C to 104.3 days at 33°C, while male lifespan decreased from 96.8 days at 18°C to 49.4 days at 33°C. The highest sex ratio (proportion of females) of 0.35 was observed at 30°C, with pre-adult survival rates of 63%, while survival rates dropped to 28% at 18°C. Parthenogenesis was not observed in females. The total pre-oviposition and post-oviposition periods decreased with increasing temperature, with the longest oviposition period at 33°C (49.6 days). Maximum fecundity was recorded at 33°C (379.0 eggs/female), followed by 30°C (298.6 eggs/female), and decreased sharply at 18°C (90.1 eggs/female). The intrinsic rate of increase (r) was highest at 30 and 33°C (0.038 d⁻1), while the net reproductive rate (R0) peaked at 30°C (104.5 offspring/female). The predicted fecundity of the next generation showed significant potential growth at 27 and 30°C, with the population increasing 65.3 times at 30°C and 39.4 times at 27°C. The developmental threshold for S. oleae was highest for first-instar nymphs (7.58°C), while second-instar nymphs had lower thresholds (1.09-1.65°C), with total pre-adult development requiring 1250 degree-days for both males and females. These findings underscore the significant impact of temperature on the development and reproduction of S. oleae, with implications for pest management in olive orchards.

Thermal Requirement for Spring Emergence of Potter Wasp Parancistrocerus fulvipes: Implications for Population Management Under Climate Change

Parancistrocerus fulvipes (Saussure) (Hymenoptera: Vespidae), a predatory potter wasp, plays a crucial role in ecosystem services by preying on microlepidopteran larvae. This study investigated the effect of the temperature on the spring emergence and survivorship of P. fulvipes. We used seven different temperature regimes ranging from 5 to 38 °C to determine the developmental rate and thermal requirement for the emergence of P. fulvipes at each temperature. The development rates were determined using linear regression and a biophysical model (i.e., the Lactin model). Adult emergence occurred between 22 and 33 °C, and the lower developmental thresholds were 18.5, 17.1, and 17.8 °C for males, females, and both genders combined, respectively. The optimal temperature and upper-temperature threshold for spring emergence were 33 and 38 °C, respectively. The degree-day requirements for adult emergence were 201, 218, and 208 for males, females, and both genders combined. The lowest mortality was observed at 22 °C, while no P. fulvipes emerged at ≤13 °C and ≥38 °C. These findings provide a predictive model for the spring emergence of P. fulvipes, which can optimize ecosystem service programs in various agricultural systems, particularly in the context of climate change and pest management.

Temperature-driven development and reproduction in Cacopsylla citrisuga (Hemiptera: Psyllidae): insights from an age-stage, two-sex life table analysis.

The citrus pest Cacopsylla citrisuga (Yang & Li), a vector for Citrus Huanglongbing (HLB), exhibits distinct sensitivity to temperature variations. This study utilized an age-stage, 2-sex life table to evaluate the development and reproduction of C. citrisuga across 5 temperatures (17, 20, 25, 28, and 31 °C). The findings indicate that Cacopsylla citrisuga can complete its life cycle within the range of 17-28 °C, with optimal temperature at 20 °C, where the highest survival and fecundity rates in females were observed. An increase in temperature correlates with a decrease in developmental duration for all stages, with the shortest at 28 °C. The net reproductive rate (R0) peaked at 20 °C, while the intrinsic rate of increase (r) and the finite rate of increase (λ) increased with the increase of temperature. Conversely, the average generation time (T) decreased with the increase of temperature, underscoring the pivotal role of temperature in population dynamics. The developmental threshold temperature and effective accumulated temperature were determined for each stage, furnishing crucial parameters for pest management strategies. This research highlights the importance of temperature in dictating the distribution and prevalence of C. citrisuga, offering valuable insights for the development of targeted control measures against this HLB vector.

Prediction model of adult flight activities of Synanthedon bicingulata (Lepidoptera, Sesiidae).

Prediction model of adult flight activities of Synanthedon bicingulata (Lepidoptera, Sesiidae).

Development of a Baltimore (MD) population of Calliphora vicina (Diptera: Calliphoridae) reared at several temperatures and estimations of developmental limits and thresholds.

Developmental data for necrophagous Diptera are frequently used in medico-legal investigations to estimate portions of the postmortem interval and interpret periods of insect activity. These applications require baseline developmental data for local populations from geographic locations of interest. For the widely distributed blow fly Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae), detailed developmental data does not exist for many locations in the mid-Atlantic region of the United States. This study examined development of C. vicina collected from a large, metropolitan city (Baltimore) in Maryland utilizing 11 ambient temperatures. The developmental threshold and thermal range of growth and tolerance were also estimated, as well as critical thermal minima and maxima based on thermal injury. For this population, linear growth was observed between 10°C and 25°C, whereas flies failed to complete development at temperatures below 7°C or above 28°C. Growth at low temperatures was not curvilinear, which contrasts with other developmental studies using C. vicina and other calliphorids. The lower developmental threshold was estimated to be 5.9°C and corresponds closely with experimental observations. The implications of these result in reference to phenotypic plasticity in populations of C. vicina and applications in forensic entomology are discussed.

Development of Piophila megastigmata (Diptera: Piophilida) at seven constant temperatures

Development of Piophila megastigmata (Diptera: Piophilida) at seven constant temperatures

A GIS-coupled thermal response model for predicting the population growth potential of the red cotton bug, Dysdercus koenigii (Fabricius) (Hemiptera: Pyrrhocoridae) in India under climate change conditions

A GIS-coupled thermal response model for predicting the population growth potential of the red cotton bug, Dysdercus koenigii (Fabricius) (Hemiptera: Pyrrhocoridae) in India under climate change conditions

Seasonal dynamics of the brown marmorated stink bug (Halyomorpha halys [Stål]) in an urban landscape

ABSTRACT During the 2021–2023 period, we investigated the seasonal dynamics of the brown marmorated stink bug (Halyomorpha halys) at two locations in an urban environment in central Slovenia. We have deployed three funnel traps, in combination with aggregation pheromone at each of the locations. We have recorded daily precipitation and average temperature. The pest was monitored at three different developmental stages, i.e. adults, young nymphs and old nymphs. Based on the average daily temperature, we have calculated degree day values (DD). We found that, accounting for the lower developmental threshold of 12.2°C, overwintered adults can appear in intervals, when DD reaches already 1°C till 11°C. Young nymphs appear when the DD value ranges from 290 to 516°C. Old larvae appear at DD values from 290 to 812°C, and adults of the first generation are observed when the DD value ranges from 809 to 1054°C. Our results revealed that brown marmorated stink bugs have one generation per year in Central Slovenia, and they are present in the landscape from April to the beginning of November. The results of our research are among the first in the field of seasonal dynamics of the brown marmorated stink bug in an urban environment.

First description of immature stages and notes on the biology of the blow fly, Calliphora lopesi Mello, 1962.

Several species of the worldwide distributed genus Calliphora Robineau-Desvoidy (Insecta, Diptera, Calliphoridae) are medically important vectors and agents of myiasis. Furthermore, these flies are relevant in forensics because they are found in corpses. Information regarding the taxonomy, bionomics and distribution of Calliphora species endemic to South America, including Calliphora lopesi Mello, is scarce. To expand knowledge on C. lopesi, this study presents descriptions of eggs, larvae, puparia and developmental data at 14, 17, 20, 23 and 26 ± 1°C for the first time. Adult flies were collected from the field and kept in the laboratory to obtain samples for morphological and biological studies. Immatures were examined using light and scanning electron microscopy. To assess the growth rate, 10 specimens from each temperature group were randomly removed from the diet and weighed every 24 h from larval hatching until pupation. The minimum developmental threshold, thermal constant and linear development-rate equations were calculated for each stage. Considering weight gain records and survival rates, the optimum temperature for the development of C. lopesi ranges from 23 to 26°C. A key to third-instar larvae of known Neotropical species of Calliphora was also provided to assist in identification. The information provided in this study should be useful in expanding knowledge about Neotropical Calliphoridae species of forensic importance.

From research reading and doing to research use: Tracking trajectories of becoming research-informed second language teachers

From research reading and doing to research use: Tracking trajectories of becoming research-informed second language teachers

Age-Stage, Two-Sex Life Table of Atractomorpha lata (Orthoptera: Pyrgomorphidae) at Different Temperatures.

Atractomorpha lata Motschoulsky (Orthoptera: Pyrgomorphidae) has recently emerged as an important agricultural pest in China. Understanding the impact of temperature on its developmental period is crucial for predicting its population dynamics. This study systematically observed the biological characteristics of A. lata at five temperatures (16, 20, 24, 28, and 32 °C) using the age-stage, two-sex life table method. The effects of temperature on the developmental period, survival rate, and fecundity of A. lata were studied using fresh bean leaves as host. The results demonstrated that as temperature increased from 16 °C to 32 °C, the developmental period, preadult time, adult longevity, adult preoviposition period (APOP), and total preoviposition period (TPOP) significantly decreased. The developmental threshold temperatures for various stages were calculated, ranging from 10.47 °C to 13.01 °C, using the linear optimal method. As temperature increased, both the intrinsic rate of increase (r) and the finite rate of increase (λ) also increased, while the mean generation time (T) decreased. The optimal values of the net reproductive rate (R0 = 54.26 offspring), gross reproductive rate (GRR = 185.53 ± 16.94 offspring), and fecundity (169.56 ± 9.93 eggs) were observed at 24 °C. Similarly, the population trend index (I) for A. lata peaked at 24 °C (61.64). Our findings indicate that A. lata exhibits its highest population growth rate at 24 °C, providing a scientific basis for predicting its population dynamics in the field.

Immature development and adult longevity of the soybean tentiform leafminer (Lepidoptera: Gracillariidae).

The leaf-mining microlepidopteran, Macrosaccus morrisella (Fitch) (Lepidoptera: Gracillariidae), has emerged as a new pest of soybean, Glycine max (L.) Merrill (Fabales: Fabaceae), in Canada and the United States, but little is known about its life history traits. Thus, this study was conducted to assess the immature developmental rate of M. morrisella, from egg to adult emergence, on soybean at different temperatures, and the longevity of adults supplied with water and/or honey at different temperatures. The time to 50% emergence of adults was 71.90, 36.33, 24.62, and 17.83 days at 15, 20, 25, and 30 °C, respectively. The lower developmental threshold of M. morrisella was estimated at 8.96 °C, with 425.04 degree-days required for egg-to-adult development. For adult longevity, time to 50% mortality at 25 °C was 15.00, 4.00, and 2.00 days when adults were provided with 25% (v/v) honey-water solution, water, or nothing, respectively. In a follow-up experiment, time to 50% mortality at 25 °C was 24.00, 6.00, 3.00, and 3.00 days when adults were provided with honey and water (offered separately), honey, water, or nothing, respectively, with a synergistic effect when honey and water were offered simultaneously as opposed to honey or water alone. Finally, when fed 25% (v/v) honey-water solution and maintained at 20, 25, and 30 °C, time to 50% mortality of adults was 26.50, 15.00, and 15.00 days. These results inform the understanding of the basic biology of M. morrisella and will help inform the future development of management programs for this insect in soybean.

Mass rearing requirements and ecological zoning of Telenomus remus estimated through life table in different temperatures and relative humidities

Mass rearing requirements and ecological zoning of Telenomus remus estimated through life table in different temperatures and relative humidities

New developmental data for Dermestes maculatus (Coleoptera: Dermestidae) from the Yangtze River Delta region of China under different constant temperatures

New developmental data for Dermestes maculatus (Coleoptera: Dermestidae) from the Yangtze River Delta region of China under different constant temperatures

Diurnal temperature fluctuations improve predictions of developmental rates in the spruce bark beetle Ips typographus

AbstractThe European spruce bark beetle Ips typographus is a widespread pest in Norway spruce-dominated forests in Eurasia. Predicting its phenology and voltinism is crucial to plan forest management measures and to mitigate mass outbreaks. Current phenology models are based on constant temperatures inferred from laboratory experiments; however, insect life cycles under natural conditions are rather driven by diurnal and seasonal temperature fluctuations. Therefore, phenology models based on fluctuating temperatures would reflect field conditions more realistically and might thus improve model predictions. In a laboratory experiment, we investigated the development of I. typographus, applying mean temperatures between 3 and 35 °C and diurnal temperature oscillations of up to ± 15 °C. Subsequently, we calibrated developmental rate models and applied them to climate data, in order to assess the effect of temperature fluctuations on voltinism under field conditions. Our results showed that diurnal temperature oscillations significantly affected developmental rates. Compared to constant temperatures, development was faster at temperature oscillations falling below the lower developmental threshold, and slower at temperature oscillations exceeding the developmental optimum. Furthermore, short exposures to suboptimal temperatures affected I. typographus less than expected from constant conditions. Natural temperature fluctuations thus accelerate development under cool, shaded conditions, whilst slowing it under hot, sun-exposed conditions, thereby ultimately affecting voltinism. Our findings highlight the importance to account for diurnal temperature fluctuations for more accurate predictions of developmental rates of I. typographus in natural thermal environments, and provide the fundament for improving current phenology models to support effective bark beetle management in a warming climate.

The Effects of Temperature on the Development and Survival of Bathycoelia distincta (Hemiptera: Pentatomidae), a Significant Pest of Macadamia in South Africa.

Temperature is the most influential condition affecting insect development and population dynamics. Understanding its impact and other important factors, such as diet, could provide fine-scale predictions of species abundance and distribution in space and time. The two-spotted stink bug, Bathycoelia distincta Distant (Hemiptera: Pentatomidae), is a significant pest of macadamia in South Africa for which limited information on developmental biology exists. Here, for the first time, variations in key developmental parameters of the B. distincta biology were studied systematically. The developmental duration, survival rate, development rate, lower developmental threshold (Tmin), optimum developmental threshold (Topt), upper developmental threshold (Tmax), and thermal constant were quantified for each developmental stage of B. distincta. In addition, the effect of diet (macadamia nut and sweetcorn) on the developmental duration and survival rate were quantified. This study was conducted at five constant temperatures (18, 21, 22, 25, and 29 °C) with relative humidity (RH) variations. The developmental duration from egg to adult decreased significantly with increased temperature: 21 °C (±60 days) to 29 °C (±32 days). The survival rate was significantly different for instar 2 between temperatures. Nymphs (instars 2 and 4) developed faster on the sweetcorn diet than on a macadamia diet, but the total developmental time did not differ significantly between the diets. Development from egg to adult required 783 degree days (DD), with a Tmin of 13.5 °C, Topt of 29.5 °C, and Tmax of 38 °C. Ongoing global warming will increase the population growth of B. distincta through increased development rate, resulting in more damage to macadamia nuts. Understanding the developmental biology and thresholds for the DD model of B. distincta is fundamental for predicting its phenology and outbreaks in macadamia orchards.

Phenology model development for Neodryinus typhlocybae: Evaluation of phenological synchrony with its host, Metcalfa pruinosa

Phenology model development for Neodryinus typhlocybae: Evaluation of phenological synchrony with its host, Metcalfa pruinosa

Studies on the embryonic development and larval infection potential of the stomach bot flies, Gasterophilus pecorum

Studies on the embryonic development and larval infection potential of the stomach bot flies, Gasterophilus pecorum

Effects of temperature on reproduction and development of Cyanopterus ninghais (Hymenoptera: Braconidae), a larval parasitoid of Monochamus alternatus (Coleoptera: Cerambycidae)

AbstractCyanopterus ninghais (Hymenoptera: Braconidae), a newly discovered gregarious ectoparasitoid, is a promising biological control agent against the third‐fifth instar larvae of the Japanese pine sawyer, Monochamus alternatus (Coleoptera: Cerambycidae). Effects of constant ambient temperatures (17, 20, 23, 26, 29 and 32°C) on the reproduction and development of the parasitoid were determined in the laboratory. Results showed that the pre‐oviposition periods of C. ninghais decreased gradually with increasing temperatures, ranging from 8.5 d (at 17°C) to 3.4 d (at 32°C). Both the parasitism rates and the number of offspring exhibited a parabolic trend in relation to increasing temperatures, with the highest parasitism rate being 80% (at 29°C) and the maximum number of offspring reaching 7.2 (at 26°C). Temperature did not significantly affect the emergence rate and sex ratio of progeny. The duration of each developmental stage was inversely correlated with temperature within the range of 20 to 32°C. The egg‐to‐adult development time was 32.3 d at 20°C and 12.5 d at 32°C. The developmental threshold temperatures for the egg, larva, pupa, and the entire generation were 8.6, 12.6, 12.8 and 12.1°C, respectively, and the effective accumulated temperatures were 34.3, 51.3, 148.9 and 240.0 Degree‐days, respectively. We concluded that temperatures in the range of 26 to 29°C are the most suitable for the development and reproduction of C. ninghais. These findings provide important information for improving the artificial rearing efficiency and field release of this parasitoid under different temperature conditions.