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

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

Temperature effects on reproduction and adult lifespan of the smaller fruit tortrix,Grapholita lobarzewskii

The effects of temperature on adult lifespan, reproduction, and oviposition behaviour of Grapholita lobarzewskii Nowicki (Lepidoptera: Tortricidae) were studied under controlled and semi‐field conditions to improve the basis for phenological forecasting. The average female lifespan ranged from 18.9 days at 25.1 °C to 65.3 days at 11.0 °C. For adult female ageing, a lower thermal threshold (THR) of 8.6 °C and a thermal constant (K) of 298 degree days (dd) were established. At constant temperatures, fecundity ranged from 0.3 eggs per female at 11.0 °C to 107 eggs per female at 21.2 °C. The highest fecundity of 127 eggs per female was observed at fluctuating temperatures. Oviposition lasted on average 350 dd, but 50% of the eggs were laid within the first 100 dd after adult emergence. Grapholita lobarzewskii had a distinct circadian rhythm for oviposition. Females began to lay eggs at ca. 16:00 hours and ceased at 24:00 hours with the peak occurring generally at 19:00 hours. Females reacted very sensitively to sudden temperature changes. A temperature drop of 3.1 °C could cause a 1‐day interruption of oviposition.     

Studies on the oviposition and longevity ofIlione albiseta [Dipt.: Sciomyzidae] — Potential biological control agent of liver fluke

The effect of 5 constant temperatures (10, 14, 17, 20 and 23°C) on the oviposition and longevity ofIlione albiseta was investigated. Most eggs were laid at 14–17°C and mean oviposition period declined progressively above and below 14°C. There was no significant difference between oviposition rates or preoviposition periods at each constant temperature, but the mean number of days between egg laying for each female was significantly greater at 10 °C than at 17, 20 and 23 °C than at 20 °C. The percentage of infertile eggs laid ranged from 9.2% at 23 °C to 17.9 % at 20 °C and these eggs tended to be laid at the beginning and end of each oviposition period. A possible association between sex ratio of the emergent adult and temperature is also discussed.      

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

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

Age‐ and temperature‐dependent oviposition model of Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) with Tetranychus urticae as prey

In this study, we developed an oviposition model of Neoseiulus californicus (McGregor) with Tetranychus urticae Koch as prey. To obtain data for the model, we investigated the longevity, fecundity and survivorship of adult female N. californicus at six constant temperatures (16, 20, 24, 28, 32 and 36°C), 60–70% RH and a photoperiod of 16 : 8 (L : D) h. Longevity (average ± SE) decreased as temperature increased and was longest at 16°C (46.7 ± 5.25 days) and shortest at 36°C (12.8 ± 0.75 days). Adult developmental rate (1/average longevity) was described by the Lactin 1 model (r² = 0.95). The oviposition period (average±SE) was also longest at 16°C (29.8 ± 2.93 days) and shortest at 36°C (6.7 ± 0.54 days). Fecundity (average±SE) was greatest at 24°C (43.8 ± 3.23 eggs) and lowest at 36°C (15.9 ± 1.50 eggs). The oviposition model comprised temperature‐dependent fecundity, age‐specific cumulative oviposition rate and age‐specific survival rate functions. The temperature‐dependent fecundity was best described by an exponential equation (r² = 0.81). The age‐specific cumulative oviposition rate was best described by the three‐parameter Weibull function (r² = 0.96). The age‐specific survival rate was best described by a reverse sigmoid function (r² = 0.85).     

Temperature-driven models of Aculops pelekassi (Acari: Eriophyidae) based on its development and fecundity on detached citrus leaves in the laboratory

This study was carried out to develop temperature-driven models for immature development and oviposition of the pink citrus rust mite Aculops pelekassi (Keifer). A. pelekassi egg development times decreased as the temperature increased, ranging from 6.6 days at 16 °C to 1.9 days at 35 °C. Total nymph development times decreased from 8.2 days at 16 °C to 3.3 days at 35 °C. The egg-to-adult development durations were 14.8, 11.6, 9.7, 8.0, 7.3, 6.1, and 5.2 days at 16, 20, 24, 26, 28, 32, and 35 °C, respectively. The lower developmental threshold temperatures for eggs, nymphs, and total egg-to-adult development were calculated as 9.3, 4.3, and 6.9 °C, respectively. The thermal constants were 54.0, 101.8, and 153.8 degree days for each of the above stages. The non-linear biophysical model fitted well for the relationship between the development rate and temperature for all stages. The Weibull function provided a good fit for the distribution of development times of each stage. Temperature affected the longevity and fecundity of A. pelekassi. Adult longevity decreased as the temperature increased and ranged from 24.2 days at 16 °C to 14.6 days at 35.0 °C. A. pelekassi had a maximum fecundity of 33.1 eggs per female at 28 °C, which declined to 18.8 eggs per female at 16 °C. In addition, three temperature-dependent components for an oviposition model of A. pelekassi were developed with sub-models estimated: total fecundity, age-specific cumulative oviposition rate, and age-specific survival rate. The oviposition model, coupled with the stage emergence model, should be useful to construct a population model for A. pelekassi in the future.     

Effect of constant temperatures on development of the walnut husk fly,Rhagoletis completa

The developmental rates of various life stages ofRhagoletis completa Cresson (Diptera: Tephritidae) were determined in the laboratory at seven different constant temperatures: 8, 12, 16, 20, 24, 28, and 32±1°C, RH 80±10%, photoperiod L 16∶D8. Preoviposition developmental rate was fastest at 28°C (10±1 days, mean±SD) and slowest at 12°C (26±1 days). About 83% of the females deposited eggs at 20 and 24°C and only 25% oviposited at 32°C. Females laid the highest number of eggs at 24°C and the lowest at 8°C. Egg development increased with increasing temperatures up to 28°C, then declined. The fastest egg development was noticed at 28°C (55±1 h) and slowest at 8°C (389±2 h). Over 90% egg hatch was observed at temperatures between 12 and 32°C, but decreased to 73% at 8°C. Larval development was fastest also at 28°C (20±0.2 days). Over 65% pupation was recorded at 20 and 24°C, but decreased to 15% at 32°C and 12% at 8°C. Pupal development was most rapid at 24°C (53±1 days) and slowest at 8°C (162±2 days). More than 70% of adult emergence was noticed in treatments between 16 and 24°C but decreased to 20% at 8°C. Based on a linear regression model of temperature-development rate relationship, the lower developmental thresholds were determined to be 6.6, 5.3, 2.9, and 5°C for preoviposition, egg, larval, and pupal stages, respectively. Based on a non-linear developmental rate model, the upper developmental thresholds were 34°C for preoviposition, egg, and larval stages and 30°C for pupal stage.     

Impact of increasing temperatures and exposure duration on egg hatch in the hemlock looper,Lambdina fiscellaria

As the growing season is expected to begin earlier under climate change, insects should initiate reproduction several days or weeks earlier than they used to. In eastern Canada, hemlock looper (HL) Lambdina fiscellaria (Guenée) (Lepidoptera: Geometridae) females generally oviposit in September, with eggs entering an obligatory diapause quickly after their deposition. We therefore simulated an early start of the HL reproduction cycle of 2, 4, 6, or 8 weeks to examine the extent to which freshly laid eggs from two populations (island and mainland) can withstand exposure to four temperature conditions (15, 20, 25 °C, or fluctuating temperature in an outdoor insectary), with all treatments ending on 1 September 2007. On this date, half the eggs from each population were immediately incubated at 15 °C, while the rest were stored in an outdoor insectary until their incubation at 15 °C the following spring. In a separate experiment, the effect of temperature on pre‐diapause duration was determined from the number of days required for eggs to change colour after oviposition. The pre‐diapause phase was completed faster as temperature increased. Regardless of incubation date and population, percent hatch decreased significantly after 6‐8 weeks of exposure to 25 °C or in the outdoor insectary. Under most treatments, the odds of dying as pharate larvae increased with exposure duration. When eggs were incubated at 15 °C immediately after treatment, time to hatch and diapause duration remained constant over treatments, except at 25 °C when they both decreased. After 8 weeks of exposure to 15 or 20 °C, eggs transferred outdoors were more likely to hatch precociously than those exposed to 25 °C or insectary conditions. Globally, mortality seemed greater among eggs stored outdoors than among those kept indoors. Most eggs that survived the winter hatched synchronously after incubation in spring. Overall, larger eggs from the island population survived better than smaller eggs from the mainland population.     

Age-specific fecundity and life table of Trissolcus semistriatus, an egg parasitoid of the sunn pest Eurygaster integriceps

The effects of temperature on age‐specific fecundity and life table parameters of the egg parasitoid Trissolcus semistriatus (Nees, 1834) (Hymenoptera: Scelionidae) were examined under four constant temperature conditions (17, 20, 26 and 32°C), using eggs of the sunn pest Eurygaster integriceps Puton, 1881 (Hemiptera: Scutelleridae), an important pest of wheat, as hosts. The intrinsic rate of increase increased linearly, while the mean generation time and the doubling time decreased with increases in temperature. The net reproductive rate, however, varied without clear correlation with temperature. Fecundity tended to be higher at higher temperatures. The total number of eggs per female was estimated as 52.0 and 116.4 eggs, respectively, at 17°C and 32°C, with the highest fecundity rate during the first day of oviposition. The oviposition rate fluctuated from 4.4 to 14.3 eggs per day. Oviposition and postoviposition periods and longevity decreased when temperature increased. Maximum longevity for females was 21.6 days at 20°C, and female parasitoids lived longer than males at all temperatures. The development period ranged from 7.1 days (32°C) to 35.6 days (17°C) for males and from 8.4 days (32°C) to 37.2 days (17°C) for females. The development of female T. semistriatus required 166.7 degree‐days (DD) above a theoretical threshold of 11.8°C and the development of males required 142.9 DD above 13.1°C. The numbers of generations per year for female and male T. semistriatus, given the temperature in Tekirdag, Turkey, were estimated to be 9.0 and 8.8, respectively. The potential of the egg parasitoid for the control of E. integriceps is discussed.     

Induction of adult diapause and of low and high reproductive states in a parasitoid wasp,Ooencyrtus nezarae, by photoperiod and temperature

Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) was reared on eggs ofRiptortus clavatus (Thunberg) (Heteroptera: Alydidae) at various temperatures under long-day (L16:D8) or short-day (L10:D14) conditions. There was no diapause during egg, larval or pupal stages under any set of conditions examined. However, at 15°C under short-day conditions, vitellogenesis was arrested in all adult females and they entered diapause. At 15°C under long-day conditions, or at 20°C under short-day conditions, some adult females entered diapause. Under the latter set of conditions, the adult females laid eggs but they laid fewer eggs than under long-day conditions, Even at 25°C, under short-day conditions, adult females laid fewer eggs than under long-day conditions, and this low rate of oviposition was attributed to the retarded development of ovaries. Diapause adults reared at 15°C were more resistant to low temperature than nondiapause adults reared at 25°C.     

Geographic mosaics of phenology,host preference,adult size and microhabitat choice predict butterfly resilience to climate warming

The climate‐sensitive butterfly Euphydryas editha exhibited interpopulation variation in both phenology and egg placement, exposing individuals to diverse thermal environments. We measured ‘eggspace’ temperatures adjacent to natural egg clutches in populations distributed across a range of latitudes (36°8′–44°6′) and altitudes (213–3171 m). Eggs laid > 50 cm above the ground averaged 3.1°C cooler than ambient air at 1 m height, while eggs at < 1 cm height averaged 15.5°C hotter than ambient, ranging up to 47°C. Because of differences in egg height, eggs at 3171 m elevation and 20.6°C ambient air experienced mean eggspace temperatures 7°C hotter than those at 213 m elevation and ambient 33.3°C. Experimental eggs survived for one hour at 45°C but were killed by 48°C. Eggs laid low, by positively geotactic butterflies, risked thermal stress. However, at populations where eggs were laid lowest, higher oviposition would have incurred incidental predation from grazers. Interpopulation variation in phenology influenced thermal environment and buffered exposure to thermal stress. At sites with hotter July temperatures, the single annual flight/oviposition period was advanced such that eggs were laid on earlier dates, with cooler ambient temperatures. The insects possessed two mechanisms for advancing egg phenology; they could advance timing of larval diapause‐breaking and/or shorten the life cycle by becoming smaller adults. Mean weight of newly‐eclosed females varied among populations from 92 to 285 mg, suggesting that variable adult size did influence phenology. Possible options for in situ mitigation of thermal stress include further advancing phenology and raising egg height. We argue that these options exist, as evidenced by current variation in these traits and by failure of E. editha to conform to restrictive biogeographic constraints, such as the expectation that populations at equatorial and poleward range limits be confined to higher and lower elevations, respectively. This optimistic example shows how complex local adaptation can generate resilience to climate warming.     

An investigation into the reproductive characteristics ofMicroctonus hyperodae (Hym.: braconidae), a parasitoid ofListronotus bonariensis (Col.: Curculionidae)

The reproductive tract of the parasitoidMicroctonus hyperodae was found to comprise 6.1±0.2 ovarioles containing a total of 40–60 oöcytes. After oviposition into its hostListronotus bonariensis, the parasitoid's egg volume increased by 205 times prior to hatching. At 19.1°C ovipositingM. hyperodae survived for a mean 21±4 days and laid a mean of 48±8 eggs.M. hyperodae collected from Colonia, Uruguay laid a mean of 62±15 eggs which was significantly more than the other ecotypes. Under caging conditions with an ample supply of hosts,M. hyperodae laid 51% of its eggs in the first 72 hours and on average 41% of the species' life-span occurred after the exhaustion of its egg supply. Minimum temperature forM. hyperodae oviposition was found to be c. 5°C; beyond this the rate of increase in egg-laying was approximately linear until 30°C whereafter the rate fell abruptly. There was effectively no egg-laying at 39°C. The parasitoid showed no preference for one host sex or the other either in the laboratory or under field conditions. Compared to otherMicroctonus spp.,M. hyperodae appeared to show low fecundity and high longevity. The adaptive implications of this are discussed.     

Effects of temperature on the fecundity and longevity of Zeugodacus cucurbitae (Coquillet) (Diptera: Tephritidae) on artificial diet

The melon fruit fly, Zeugodacus cucurbitae (Coquillett), is an important polyphagous pest that damages to various agricultural crops, whose distribution has become global as a result of human activity. In this study, we investigated the fecundity, pre-oviposition and oviposition periods, and the longevity of adult Z. cucurbitae at various constant temperatures ranging from 15 to 35.2°C. One newly emerged one virgin female and two males of Z. cucurbitae were used, and the longevity of both sexes and the fecundity of the females were examined daily. The longevity of female Z. cucurbitae ranged from 183.8 days at 15.0°C to 30.8 days at 35.2°C, and the maximum fecundity per female was 1204 eggs at 24.5°C. The lower development threshold (LDT) and thermal constant (K) of females were estimated as 14.8°C and 781.13 degree-days, respectively. Female reproduction was modeled using a two-phase oviposition model. Oviposition was estimated using females in the oviposition phase, which had a complete pre-oviposition phase. The oviposition model consisted of two reproductive components (total fecundity and age-specific cumulative oviposition rate during oviposition) and a survival component (age-specific survival rate). The daily egg production of Z. cucurbitae was estimated in relation to adult age and temperature.     

绿盲蝽成虫的产卵行为与习性

本文观察记录了绿盲蝽Apolygus lucorum(Meyer-Dür)雌性成虫的产卵行为,并研究了其产卵习性。结果发现,绿盲蝽卵主要产在植物组织中,单次产卵平均历时31.4 s;产卵主要在夜间进行,白天的产卵量仅占全天的6.6%。成虫交配后主要产可育卵,后期偶产不育卵;而未交配个体大部分能产不育卵。在25℃下,成虫从7日龄起开始产卵,16日龄前产卵量占总产卵量的48.9%;17～40日龄间产卵量约占40%。在棉株上,约65%卵分布在中部(第4到第7果枝),同时94.3%卵集中在叶柄、叶脉、蕾柄和铃柄上。     

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.     

Effect of food and temperature on the reproduction of the blowfly, <Emphasis Type="Italic">Calliphora vicina</Emphasis> R.-D. (Diptera,Calliphoridae), a popular model object in biological research

Egg maturation in Calliphora vicina is known to occur within a wide range of temperatures, from 12°C to nearly 30°C (Vinogradova, 1991). Photoperiodism has no effect on this process. Some females enter diapause already at 20°C; their fraction increases at lower temperatures and reaches 100% at 6°C. Reproducing females with eggs can survive for a long time and even lay eggs at low temperatures (4–5°C). Experiments with C. vicina from Leningrad Province revealed some effects of the diet (liver or fish) and temperature on the fly reproduction. At 20 and 25°C, 7–10-day old females begin to oviposit, but at 20°C egg maturation is observed in 98% of females feeding on liver and in only 5% of females feeding on fish. On the liver diet, the mean daily fecundity is significantly correlated with the day of oviposition but not with the temperature. At 20°C a significant correlation is observed between the mean daily fecundity and both the day of oviposition and food. The total number of eggs laid by flies after feeding on fish is half that produced after feeding on liver. The optimal conditions for Calliphora vicina cultivation are a 16-h light day, temperatures within the range from 20 to 25°C, and liver as food.     

Field and laboratory studies in a Neotropical population of the spinose ear tick, Otobius megnini

Abstract One ear of each of five cows on a property close to Dean Funes, province of Córdoba, Argentina, was inspected monthly from December 2004 to November 2006 to determine the presence of Otobius megnini (Dugès) and to ascertain its seasonality. Ticks were collected to study the biological parameters of larvae, nymphs and adult ticks. Groups of nymphs were also maintained at three different photoperiods at 25 °C. The abundance of immature stages was greatest during January–April and August–October in the first and second years of the study, respectively. No larvae successfully moulted. Nymphs weighing < 17 mg also failed to moult, but 89% of heavier nymphs moulted into adults. Nymphs moulting to males weighed less (49.5 ± 16.09 mg) than nymphs moulting to females (98.1 ± 34.08 mg). The pre‐moult period was similar for nymphs moulting to either sex and significantly longer (P < 0.01) for female nymphs maintained at 25 °C compared with nymphs kept at 27 °C. No effect of photoperiod on the pre‐moult periods of nymphs was detected. Female ticks produced a mean of 7.0 ± 1.94 egg batches after a preoviposition period of 16.4 ± 8.41 days for the first batch. The mean oviposition period was 61 ± 20.8 days and the duration of oviposition for each batch varied from 1 to 6 days. The mean number of eggs per batch was 93.1 ± 87.53. The minimum incubation period for the first egg batch was 13.6 ± 2.77 days. The total number of eggs laid by each female was 651.6 ± 288.90. Parthenogenesis was not observed. The reproductive efficiency index (REI) (number of eggs laid/weight of female in mg) was 5.5 ± 1.26. Pearson’s correlations showed a significant direct relationship between the weight of the female and number of eggs laid (P < 0.01) and REI (P < 0.05). Several of the biological values presented above for the tick population from the Neotropical zoogeographic region showed marked differences to equivalent values for O. megnini populations from the U.S.A. (Nearctic) and India (Oriental). Nevertheless, the only two sequences of 16S rDNA deposited in GenBank from ticks originating in Argentina and allegedly in the U.S.A. indicate that they are conspecific (99.8% agreement). We tentatively consider the biological differences among populations of this tick species to represent adaptations for survival at different conditions.     

Humidity‐controlled cold storage of Neoseiulus californicus (Acari: Phytoseiidae): effects on male survival and reproductive ability

Humidification can suppress water loss from an organism and has great potential for improving the cold storage of short‐lived arthropods, such as predatory mites. The effectiveness of humidity‐controlled cold storage was recently verified for Neoseiulus californicus (McGregor) females but was not examined for males. Combining both males and females in one storage protocol might increase the predator population because it would enhance the opportunity for multiple mating, which is necessary for females to maximize their egg production. Newly emerged adult males were stored at an air temperature of 5°C and relative humidity (RH) of 100% or 80%. The median survival time (LT₅₀) was 32 days at 100% RH and 14 days at 80% RH; the survival curves differed significantly. Males stored at 100% RH for 0, 10, 20 and 30 days were introduced to virgin females for mating at 25°C to evaluate their reproductive ability. The pre‐oviposition period was significantly prolonged in the females mated with males stored for ≥20 days. No negative effects of storage were observed on the oviposition period, total number of eggs or net reproduction rate (R₀) in the females mated with males stored for ≤20 days or on the mean generation time (T) for those stored for 30 days. A slight decrease in the intrinsic rate of increase (r_m) was observed in the females mated with males stored for ≥20 days. Our storage method can preserve N. californicus males for 20 days with only a minor reduction in their survival and reproductive ability.     

Effects of temperature and soil moisture on survival of eggs of the mosquito Psorophora columbiae (Diptera: Culicidae)

The results of laboratory tests indicated the average survival rates for Psorophora columbiae eggs remained quite high for all of the egg populations exposed to a temperature of 27°C (range 83.0–100.0% survival) after 96 days of exposure, except for the non‐diapausing eggs on dry soil (66.3%). In regard to the exposure of egg populations to moderately cold temperatures (i.e. 8°C, 4°C and ?2°C) for periods of up to 16 days, survival rates for egg populations exposed to 8°C continued to remain relatively high (average >85%) for the remainder of the experimental exposure period (i.e. 96 days). Diapausing Ps. columbiae eggs were more tolerant (82.0% survival) to low temperatures (?2°C) than non‐diapausing eggs (2.4% survival) for 64 days, particularly at temperatures of and below 4°C. Diapausing and non‐diapausing eggs were similar in their ability to survive under high temperatures (34°C and 38°C). High soil moisture (30–40%) or substrate moisture (95% relative humidity) content appeared to enhance the ability of the mosquito eggs to survive both low and high temperature extremes.