Life history parameters for Nesidiocoris tenuis (Reuter) (Het., Miridae) under different temperature regimes

The development time for eggs and nymphs and female fertility were determined for Nesidiocoris tenuis Reuter (Het., Miridae: Dicyphini) at 15, 20, 25, 30, 35 and 40 ± 1°C, using tomato, Solanum esculentum (Miller), as substrate and eggs of Ephestia kuehniella Zeller as substitute prey. At 40°C, N. tenuis was unable to develop and barely reproduced. Egg development ranged from 30.8 days at 15°C to 6.3 days at 35°C. The cumulative thermal requirements for the eggs were 148.6 degree days (°d) and the lower thermal threshold, 10.3°C. The duration of the nymphal instar decreased from 55.9 days at 15°C to 8.6 days at 35°C. The thermal constant for the nymphs was 182.3 °d and the lower thermal threshold 11.7°C. No nymphs survived at 40°C, and the highest mortalities were at extreme temperatures (15 and 35°C). Female and male weights were influenced significantly by temperature. The fertility of N. tenuis females was reduced greatly at 15 and 40°C. The highest fertility during an observation period of 18 days following female emergence (79.5–60.0 nymphs per female) was within the temperature range of 20 to 35°C. Fertility was related directly to female weight and temperature (r² = 0.932). Based on development, reproduction data and thermal requirements, the optimum temperature range for N. tenuis was established as being between 20 and 30°C. Overall, N. tenuis is the most thermophilous of all dicyphines from vegetable crops in the Mediterranean area studied so far.     

The effect of relative humidity on the behaviour and development of Triatoma brasiliensis

Abstract The preference for relative humidity (RH) and suitability of different levels of this environmental parameter were investigated in the haematophagous bug Triatoma brasiliensis Neiva, 1911 (Hemiptera, Reduviidae). The hygropreference of T. brasiliensis was studied using a RH gradient and the effect of different RHs on the egg hatching, nymph mortality and moulting success was also analysed. The results show that egg hatching in first-instar nymphs of T. brasiliensis was lower at extreme RHs and, particularly, it was lowest at 9.3% RH. The survival of starved nymphs was not affected by RH, but the percentage of engorged nymphs and the ecdysis success of these nymphs once fed was diminished strongly by high humidity. Fourth-instar nymphs preferred to stay at the lowest RH during the first 5 days after feeding and during ecdysis. This preference changed markedly during starvation. Fifteen days after ecdysis, the bugs moved towards intermediate humidities, and 30 days after ecdysis they even preferred the most humid sectors of the gradient. Females preferred to lay eggs in dry environments, suggesting that they may not have a particular hygropreference for oviposition, but that they simply lay their eggs at the RHs where they prefer to stay.     

Effect of Temperature on Development and Fecundity of the Predaceous Plant Bug <Emphasis Type="Italic">Deraeocoris brevis</Emphasis> Reared on <Emphasis Type="Italic">Ephestia kuehniella</Emphasis> Eggs

Temperature-dependent development and oviposition component models were developed for Deraeocoris brevis (Uhler) (Hemiptera: Miridae). Egg development times decreased with increasing temperature and ranged from 35.8 d at 15 °C to 6.7 d at 32 °C. Total development times of nymphs reared on frozen Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs decreased from an estimated 55.6 d at 15 °C to 9.2 d at 32 °C and 10.0 d at 34.6 °C. By fitting linear models to the data the lower developmental threshold temperatures for eggs, small nymphs (1st to 3rd instar), large nymphs (4th to 5th instar), and all nymphs combined were calculated as 10.5, 12.5, 11.8, and 11.9 °C, respectively. The thermal constants were 144.1, 90.3, 95.0, and 190.8 degree-days for each of the above stages. The non-linear model was based on a Gaussian equation, which fit the relationship between development rate and temperature well for all stages. The Weibull function provided a good fit for the distribution of development times of each stage. Adult longevity decreased with increasing temperature and ranged from 52.9 d at 21.7 to 16.8 d at 32.0 °C. D. brevis had a maximum fecundity of 471 eggs per female at 24 °C, which declined to 191 eggs per female at 32 °C. Also, three temperature-dependent components for an oviposition model of D. brevis were developed including models for total fecundity, age-specific cumulative oviposition rate, and age-specific survival rate.     

Host instar suitability and life-history parameters under different temperature regimes of Necremnus artynes on Tuta absoluta

Necremnus artynes is native to the Mediterranean region where it has been observed in greenhouses parasitising Tuta absoluta on tomato. In this study, we evaluated the suitability of the different instars of T. absoluta as hosts for N. artynes and the life-history traits of N. artynes at three different temperature regimes (20, 25 and 30°C) on third instar T. absoluta larvae infesting tomato. N. artynes females preferred third instar T. absoluta larvae for oviposition, whereas host-feeding was significantly higher on the second instar larvae. Duration of life stages was no different between sexes but was affected by temperature, being significantly reduced as temperature increased. Pre-imaginal survival also decreased with temperature and the percentage of females was ca. 70% under all temperature regimes. Adult longevity was 1.5-fold significantly greater at 25°C compared to 30°C with no differences between 20 and 25°C. Fecundity was estimated at 36.3±7.80, 51.8±10.65 and 52.1±10.03 eggs/female and host-feeding at 59.5±8.50, 71.6±12.07, 51.4±7.89 hosts/female at 20, 25 and 30°C, respectively, although these differences among temperatures were not significant. However, oviposition and feeding rate were significantly higher at 30 and 20°C, respectively. The estimated intrinsic rate of increase (r _m) was significantly higher as temperature increased from 20 to 30°C and it was greater than those reported for T. absoluta on tomato, indicating the potential of N. artynes to control this pest.     

Thermal effects on the biological parameters of the predatory mirid Pilophorus gallicus (Hemiptera: Miridae)

Pilophorus gallicus Remane (Hemiptera: Miridae) is a predatory mirid reported in deciduous trees in the western Mediterranean area. This work aimed to determine the biological and demographic parameters for this species at different temperatures (15, 20, 25 and 30°C). Egg hatching times shortened from 57.8 days at 15°C to 9.2 days at 30°C, and nymphal development times declined from 62.8 days at 15°C to 11.1 days at 30°C. The hatching and nymphal survival rates were low at 15 and 30°C. The lower thermal thresholds for the egg and nymphal development were 12.4 and 12.0°C, respectively. These high thermal thresholds could be a safety mechanism to avoid the emergence of nymphs in the unfavorable winter period. Female weight increased between 15 and 25°C and decreased at 30°C. The fecundity increased from 70.2 eggs per female at 15°C to 212.4 eggs per female at 25°C, and decreased to 88.5 eggs per female at 30°C. Fertility ranged from 9.4% at 15°C to 40.9% at 25°C, being 24.9% at 30°C. The intrinsic rate of natural increase (r_m) rose from 0.001 to 0.081 between 15 and 25°C and decreased to 0.05 at 30°C. In summary, this species performs poorly at low temperatures and has a relative tolerance of high temperatures (30°C); its performance was best at 25°C. Knowledge of the variation in the biological parameters with temperature may be very useful for the understanding of its ecology and population dynamics.     

Effects of acclimation on the thermal tolerance of the brown planthopper Nilaparvata lugens (Stål)

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Effect of temperature on the morphometric development of eggs in the prawn Macrobrachium americanum (Caridea: Palaemonidae) and larval success under experimental conditions

Abstract

This study evaluated the effect of temperature on morphometric features of the egg during the embryonic development of the prawn Macrobrachium americanum and the relationship with hatching and the survival of the larvae. Berried females were grouped (n = 3) and reared at three different temperatures, 26, 29, and 33 °C, for which seven developmental stages were recognized. At each stage, the apical and sagittal diameters of the eggs were measured, the volume was calculated, and the weights were recorded. Additionally, the duration of embryonic development, hatching percentage, and larval survival were determined. At 29 and 33 °C, the eggs’ volume increased by 50%, but at 26 °C, the increase was 25%. Larvae from eggs incubated at 33 °C died one day after hatching. At 29 °C, larvae survived until Zoea VII. Larvae from eggs incubated at 26 °C died at the end of Zoea I. The number of days of embryonic development was 20.5 ± 1.5 (26 °C), 15 ± 1 (29 °C), and 12 ± 1 (33 °C). A temperature of 29 °C was the most favorable for embryonic development in M. americanum.     

Effects of temperature experienced during embryonic development on biomass and C and N composition at hatching in Palaemon serratus (Pennant, 1777)

In decapod crustaceans, the conditions experienced during embryonic development trigger phenotypic plasticity of the larvae at hatching. The objective of this study was to test the effects of temperature during embryonic development of Palaemon serratus on the phenotypic plasticity of hatching larvae. We incubated egg-bearing females from eggs laying to hatching at four temperatures (10, 15, 18 and 20°C). Weight, carbon and nitrogen contents were measured on newly laid eggs and on freshly hatched larvae. The duration of embryonic development was negatively correlated with incubation temperature. At 20°C, all females abandoned their eggs during development. Incubation temperature had no effect on the weight and the percentage of N of the larvae at hatching, while it did affect their percentage of C and their C/N ratio. Embryos incubated at 10°C seemed to produce larvae with fewer lipid reserves than those incubated at 15 and 18°C. They probably overconsumed their lipid reserves to compensate for the metabolic losses due to the low temperature. These results provide information on the link between maternal investment per egg and larval development in P. serratus.     

Biological studies ofDiadegma semiclausum (Hym., Ichneumonidae), a parasite of diamondback moth

Laboratory studies were conducted on certain aspects of biology ofDiadegma semiclausum Hellén, a larval parasite of a crucifer pest,Plutella xylostella (L.). Within the range of 15°C to 35°C, the higher temperature, the shorter was the duration of larval and adult stages. Egg hatching and adult emergence were high at 15°C to 30°C but were significantly reduced at 35°C. The higher the temperature, the higher was the proportion of males produced. Temperature threshold was 5.74°C for eggs, 3.80°C for larvae, 5.91°C for pupae and 6.60°C for adults.D. semiclausum oviposition in the first threeP. xylostella larval instars produced more parasite males than females but oviposition in the fourth instar produced significantly more females than males. Parasite adults tended to emerge from their pupae from 06∶00 to 09∶00 hours although some emerged at other hours during the photophase. Adult longevity and production of eggs increased when adults were provided with a food source (honey) compared with no food or provision of water alone. Parasite adults survived and laid eggs for 28 days when provided with food but for only three days when deprived of food.     

Development times and fecundity of three important arthropod pests of strawberry in the United Kingdom

The development rates and fecundity of three important pests of strawberry in the UK were determined over a range of temperatures. Development time of the strawberry tarsonemid mite, Phytonemus pallidus, from egg lay to adult, ranged from a mean of 28.4 days at 12.5°C to 8.8 days at 25°C. No nymphs developed to adult at 10°C. Females lived for up to 45 days and laid a mean of 24.3 and 28.5 eggs at 20°C and 25°C respectively. Total development time from egg lay to adult for the strawberry blossom weevil, Anthonomus rubi, ranged from a mean of 95.7 days at 10°C to 18.2 days at 25°C. Mean fecundity at 20°C was 157.6 eggs, and the oviposition period averaged 71.6 days. When nymphs were reared on strawberry, development of the European tarnished plant bug, Lygus rugulipennis, from egg lay to adult, ranged from 83.8 days at 15°C to 28.8 days at 25°C. Development times on groundsel were shorter and ranged from 65.6 to 22.2 days at 15°C and 25°C. Only two nymphs developed to adults at 10°C; no eggs hatched at that temperature. Mean fecundity at 20°C was 75.4 eggs, but ranged from 23 to 179. Under a fluctuating temperature regime of 10°C for 12 h:20°C for 12 h, nymphs of L. rugulipennis took 40.3 days to become adult on strawberry, and 33.4 days on groundsel. Simple linear models fitted the developmental rate ‐ constant temperature relationship well for all species, accounting for 95–98% of the total variation in observed developmental rates. Development under fluctuating temperatures illustrated the potential problem of extrapolating linear models beyond the conditions of the experiment.     

Effects of brief exposures to low temperature on the development, longevity and fecundity of the grain aphid Sitobion auenae (Hemiptera: Aphididae)

First instar nymphs and adults of the grain aphid Sirobion auenae that had been reared at 10°C and 20°C over a number of generations, were cooled to -5°C and -10°C for 1 h and 6 h and returned to 20°C to assess the effects of brief exposures to low temperatures (cold-pulses) on their survival. rate of development, longevity and fecundity. A strong acclimation response was observed in first instar nymphs, with significantly less mortality in groups reared to 10°C compared to 20°C. Mean development time from first instar to adult was not significantly affected by low temperature exposure at the first nymphal stage. Longevity in all groups cooled as first instars was reduced by the sub-zero cold-pulses, and was also dependent on temperature and exposure time. Acclimated aphids survived longer than non-acclimated individuals. Reproductive rate, in terms of the number of nymphs born per aphid per day, was unaffected by cold stress applied at the first instar stage. Total fecundity was however reduced, being a function of the number and longevity of the survivors. Adult aphids were less cold hardy than nymphs; mortality was higher at -10°C than -5°C increasing with duration of exposure from 1 h to 6 h. Mean fecundity was reduced significantly in aphids cooled at the adult stage, the number of aphids born per day decreasing as the exposure period of the cold-pulse increased, suggesting that low temperature had affected embryogenesis. All the nymphs born to adults surviving exposure to -5°C for 6 h died within 48 h of birth, indicating that low temperature has a pre-natal effect on mortality.     

Response of diapausing eggs hatching to changes in temperature and the presence of fish kairomones

It has been hypothesized that the production of diapausing eggs in Daphnia can be induced by fish kairomones. A population of Daphnia could survive severe predation using this predator avoidance strategy. However, in changing environments, diapausing eggs experience various temperature conditions, and hatchlings at emergence may be exposed to the same predation risks as their mothers. Therefore, staying in diapause or an immediate response upon hatching to available environmental information could be important for hatchling survival. For this study, we investigated the impact of water temperature (10, 15, 20, and 25°C) in the presence and absence of fish kairomones (Lepomis macrochirus) on the hatching success of resting eggs (D. galeata). Results show that no diapausing eggs hatched at the lowest temperature (10°C), and the highest hatch percentage occurred at 15°C. Although higher water temperatures reduced hatching success, diapausing eggs hatched more quickly. The number of hatchlings was significantly higher after exposure to fish kairomones, and this was more noticeable at higher temperatures (20 and 25°C). The present results suggest that the diapausing eggs were produced as a predator avoidance strategy in Daphnia; however, the presence of fish works as a positive signal to increase hatchlings when the diapausing stage is terminated.     

Preimaginal development,adult longevity and fecundity ofEncarsia inaron (Hym.: Aphelinidae) parasitizingSiphoninus phillyreae (Hom.: Aleyrodidae) in California

A laboratory study of preimaginal development, adult longevity and fecundity ofEncarsia inaron (Walker) was conducted. Preimaginal developmental times varied with temperature, from 55–60 d at 15±1°C to 14–17 d at 30±1°C. No development took place at 10°C, which was approximately the developmental minimum estimated from regression analysis of developmental rates vs. temperature in the range 15–30°C. Development was slowed and survival was reduced at 32°C. Females lived an average of 18.6 days and laid a average of 159 eggs/female at 25°C. At 25°C, average preimaginal survival was 59.3%, and the sex ratio was 73.5% female. The net reproductive rate (R₀) forE. inaron calculated from these studies was 69.3, while the intrinsic rate of natural increase was 0.1686 individuals per individual per day. Oviposition was concentrated slightly in third instar nymphs of the host.     

Temperature effects on induction of parasitization by females of Trichogramma principium (Hymenoptera, Trichogrammatidae)

The effects of temperature on induction and stability of parasitization of less preferred factitious host (the Angoumois grain moth, Sitotroga cerealella) eggs by Trichogramma principium females were studied under laboratory conditions. The percentage of parasitizing females at 15°C was significantly lower than that at 20, 25, and 30°C. At constant temperatures of 15, 20, 25, and 30°C, mean durations of pre-oviposition periods were 6.5, 2.1, 0.9, and 0.6 days, respectively (differences were significant between all regimens). In most of females, parasitization induced by high temperature (25°C) continued after the temperature decrease to 15°C. These results suggest that although emerged females are ready to lay eggs, rather prolonged pre-oviposition period may precede parasitization of less preferred hosts, and the duration of this period may depend on temperature.     

黄杨绒蚧的生物学特性及卵期预测预报

黄杨绒蚧Eriococcus abeliceae Kuwana是危害园林树木的重要害虫之一。该蚧在西宁地区1年发生1代,以2龄若虫在树干裂皮缝中越冬。翌年3月下旬2龄若虫蜕皮变为3龄若虫,开始为害,雌虫5月上旬开始产卵,卵期18~23d,每雌虫产卵量134~424粒,平均287粒。6月上旬卵开始孵化,孵化率100%。雌虫3龄,雄虫2龄。在室内自然变温条件下,对黄杨绒蚧卵的发育起点温度和有效积温进行测定。结果表明:卵发育起点温度12.98℃,有效积温39.03日.度;预测式为N=(39.03±2.66)/T-(12.98±0.18)。     

Independent and joint action of cis- and trans-permethrin in Triatoma infestans (Hemiptera: Reduviidae)

The toxicity of pure cis- and trans-permethrin or mixtures of the two isomers topically applied to first, third, and fifth instar nymphs of Triatoma infestans (Klug) at 26°C was determined. The cis-isomer was more active than the trans-isomer in the three stages evaluated. When the two isomers were simultaneously applied to first instar nymphs, an additive effect was observed. Similar treatments of third and fifth instar nymphs resulted in an antagonistic effect. In third instar nymphs, the cis-isomer was more active than trans-isomer at all the three temperatures assayed (16°, 26°, and 36°C). The toxicity of the cis-isomer was lower at 36°C than at either 16° or 26°C. Temperature had no significant effect on the toxicity of the trans-isomer within the temperature range assayed. The toxicity of either isomer to third instar nymphs was not affected by pretreatment of nymphs with PBO (an inhibitor of mixed-function oxidases activity) or TPP (an inhibitor of esterase activity), suggesting that these detoxification pathways are not relevant in the metabolism of cis- or trans-isomers. Arch. Insect Biochem. Physiol. 37:225–230, 1998. © 1998 Wiley-Liss, Inc.     

Biology of Doryctobracon brasiliensis at different temperatures: development of life table and determining thermal requirements

Doryctobracon brasiliensis (Szépligeti) is a parasitoid larval–pupal of fruit flies and has great potential to be used in biological control programmes as it feeds on other Anastrepha species in addition to Anastrepha fraterculus (Wiedemann). This study investigated the biology of D. brasiliensis at different temperatures to design a life fertility table and determine thermal requirements. The parasitoids were multiplied in larvae of A. fraterculus in air‐conditioned chambers at 15, 18, 20, 22, 25, 28 and 30°C, 70 ± 20% RH and photophase of 12 h. We determined the number of offspring, sex ratio, longevity of males and females and duration of egg–adult period. The temperature range 18–22°C ensures higher fecundity and at 20°C, and the average number of offspring per female was 152.77 parasitoids. The sex ratio of offspring produced was reduced with increasing temperatures. Longevity of males and females of D. brasiliensis was reduced by increasing temperatures. At 15, 28 and 30°C, there was no development of immature stages. For the temperature range 18–25°C, the duration of egg–adult period of D. brasiliensis was inversely proportional to temperature. At 20 and 22°C, we observed the highest values of net reproduction rate (Ro) and finite reason of increase (λ), meaning that at the estimated optimum temperature (21°C), the population of D. brasiliensis increased 47 times each generation. The lower temperature threshold for development was 10.01°C and the thermal constant (K) 303.21 degree/days. This information confirms that D. brasiliensis is better suited to temperate environments, which implies a significant potential for the use of D. brasiliensis in the control of A. fraterculus, because most areas occupied by this pest are in temperate regions. In addition, D. brasiliensis is useful in mass rearing systems in laboratory.     

Effect of temperature on the survival and infectivity of <Emphasis Type="Italic">Pseudotheraptus devastans</Emphasis> vector

The aim of this study was to investigate under a controlled environment, the effect of temperature on the survival and infectivity of Pseudotheraptus devastans Distant, a cassava anthracnose disease vector. The insect P. devastans was collected from young cassava (Manihot esculenta Crantz) field plots, at the International Institute of Tropical Agriculture, (IITA), Ibadan, Nigeria. A mixture of the different developmental stages of eggs, first to fifth instar nymphs, and adults, were incubated in controlled environment chambers, under various constant temperatures of: 15, 17, 22, 25, 27, 30, and 35°C. Relative humidity at different temperature conditions were recorded and maintained at 90%, 85%, 80%, 75%, 70%, 65%, and 60%, respectively. A significant increase in insect survival was observed between 22 and 27°C temperature conditions while a significant decrease in survival was observed at 15°C and above 30°C. Lesion number, lesion diameter and infectivity among the insect stages varied as a function of temperature and relative humidity. Infectivity was highest at 22–25°C maintained at 75–80% RH and lowest at 15°C and above 30°C maintained respectively, at 65% RH and 90% RH. There was considerable low vector infectivity due to low survival of the insects at extreme temperatures.     

Sexual reproduction and diapause of Hexarthra sp. (Rotifera) in short-lived ponds in the Chihuahuan Desert

1. In the life cycle of monogonont rotifers it is generally assumed that diapausing eggs invariably hatch into amictic stem females which produce female offspring parthenogenetically. Diapausing eggs are only produced by later generations after sexual reproduction has been induced by environmental cues. 2. We show that populations of an undescribed Hexarthra species inhabiting small temporary ponds in the Chihuahuan Desert deviate from this life cycle pattern. These ponds may dry within days and up to 85% of females were mictic. Females producing male offspring and diapausing eggs were observed 1 or 2 days, respectively, after ponds had filled with water. 3. Under laboratory conditions, 7–46% of females hatching from re‐hydrated sediments were sexual. Male offspring of these females can fertilise other mictic stem females leading to diapausing egg formation. In laboratory experiments, females produced fully developed diapausing eggs within 1.9 days at 20 °C and 1.2 days at 30 °C. 4. In addition, embryonic development time (1.1–0.3 days at temperatures between 12 and 30 °C) and juvenile period (2.1–0.5 days for the same temperature range) are shorter than those of other rotifer species. In short‐lived habitats, the potential for rapid population development and production of new diapausing eggs may be crucial in the long‐term survival of populations.     

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.