Development, survivorship, and reproduction of Helicoverpa armigera (Lepidoptera: Noctuidae) under constant and alternating temperatures

Laboratory studies were conducted to assess the effect of temperature on the survival, development, fecundity, and longevity of Helicoverpa armigera (Hübner) at 11 constant temperatures ranging from 12.5 to 40 degrees C, as well as at five alternating temperature regimes (25-10, 30-15, 32.5-17.5, 35-20, and 35-27.5 degrees C) and under a photoperiod of 16:8 (L:D) h. H. armigera reared at constant temperatures did not develop from egg to adult (emergence) outside the temperature range of 17.5-32.5 degrees C. The alternating conditions expanded this range from 10 to 35 degrees C. The lowest developmental thresholds of the immature stages were estimated by a linear model and ranged from 10.17 (pupal stage) to 11.95 degrees C (egg stage) at constant temperature regimes and from 1.1 to 5.5 degrees C, respectively at alternating temperatures. The values of developmental thresholds estimated using the nonlinear (Lactin-2) model were lower than those estimated by the linear model for constant and alternating temperature regimes except for larval and pupal stages at constant temperatures. Mean adult longevity fluctuated from 34.4 d at 15 degrees C to 7.6 d at 35 degrees C. Females reared under all alternating temperature regimes laid more eggs than females reared at any, except the 25 degrees C, constant temperature treatment. The intrinsic rate of increase was highest at 27.5 degrees C, at both the constant and the corresponding alternating temperature regimes (0.147 and 0.139, respectively). Extreme temperatures had a negative effect on life table parameters.     

Effect of temperature and relative humidity on the development and fecundity of Chilo partellus (Swinhoe) (Lepidoptera: Crambidae)

The spotted stemborer, Chilo partellus (Swinhoe) (Lepidoptera: Crambidae), is one of the most important insect pests attacking maize and sorghum in Ethiopia. Recent studies have indicated that the pest is spreading to new locations where it was not reported before. In the current study, laboratory investigations were carried out to determine the combined effect of different levels of relative humidity and temperature regimes on the development and fecundity of C. partellus, as these physical factors are known to play an important role in the life cycle of insects and adaptability to local climate. Developmental time, longevity, potential fecundity and realized fecundity of C. partellus were measured under controlled conditions. Three temperature regimes (22°C, 26°C and 30°C) and three relative humidity levels (40%, 60% and 80%) were tested. It was found that temperature, relative humidity (RH) and their interaction significantly affected the developmental time, adult longevity, potential fecundity and realized fecundity of the pest. Developmental time was inversely related to temperature. Mean duration of C. partellus life cycle was 70.2 days at 22°C and 80% RH, whereas it took only 26.5 days to complete its life cycle at 30°C and 40% RH. Male and female longevity were similar in most cases. The adult life span ranged between 6.9-11.1 days at 22°C and 3.1-7.2 days at 30°C for different levels of relative humidity. The most suitable conditions for C. partellus development and fecundity were 26-30°C temperatures regimes and 60-80% RH levels.     

Developmental times and age-specific life tables for Lygus lineolaris (Heteroptera: Miridae), reared at multiple constant temperatures

Developmental times and survivorship of tarnished plant bug nymphs, Lygus lineolaris (Palisot de Beauvois), and longevity and reproduction of adult tarnished plant bug adults reared on green beans were studied at multiple constant temperatures. The developmental time for each life stage and the total time from egg to adult decreased with increasing temperature. Eggs required the longest time to develop followed by fifth instars and then first-instars. Total developmental time from egg to adult was shortest at 32°C, requiring 18.0 ± 0.3 d and 416.7 ± 31.3 DD above 7.9°C, the estimated minimum temperature for development from egg to adult. Sex did not affect total developmental times and did not affect median survival time. Adults lived significantly fewer days at high temperatures (30-32°C: 17-19 d) compared with temperatures below 30°C (range: 24.5-39.4 d) and the number of eggs laid per day increased from ≈ 4 at 18°C to a maximum of 9.5 eggs per day at 30°C. Total egg production over the lifetime of female tarnished plant bugs increased with temperature reaching a maximum of 175 eggs on average at 27°C, total egg production declined at temperatures above 27°C (30°C: 110.8, 32°C: 77.3 eggs per female). The highest net reproductive rate 74.5 (R(0)) was obtained from insects maintained at 27°C. The intrinsic rate of natural increase (r(m)) increased linearly with temperature to a maximum value of 0.1852 at 30°C, and then decreased at 32°C. Generation and doubling times of the population were shortest at 30°C, 21.0 and 3.7 d, respectively.     

Influence of temperature on the development, reproduction and longevity of Ceratothripoides claratris (Thysanoptera: Thripidae) on tomatoes

Ceratothripoides claratris (Shumsher) is a serious pest attacking tomatoes in Thailand. Temperature-dependent development of C. claratris was studied at seven constant temperatures, i.e. 22, 25, 27, 30, 34, 35 and 40 degrees C. Pre-adult survivorship was greatest (95%) at 25 and 30 degrees C and shortest at 22 degrees C. Egg-to-adult time decreased within the range of 20 to 30 degrees C and at 34 degrees C it started to increase. The lower thermal threshold for egg-to-adult development was estimated at 16 and 18 degrees C by linear regression and the modified Logan model, respectively. The optimum temperature for egg-to-adult development was estimated at 32-33 degrees C by the modified Logan model. The influence of temperature on reproduction and longevity of C. claratris was determined at 25, 30 and 35 and 40 degrees C. Both inseminated and virgin females failed to reproduce at 40 degrees C. Virgin females produced only male offspring, confirming arrhenotoky. The sex ratio of the offspring of fertilized females was strongly female-biased, except at 25 degrees C. Mean total fecundity per female and mean daily total fecundity per female were highest for both virgin and inseminated females at 30 degrees C. Female longevity was longest at 25 degrees C and shortest at 40 degrees C. Male longevity was longest at 30 degrees C and shortest at 40 degrees C. The net reproductive rate (R0) and intrinsic rate of natural increase (rm) was greatest at 30 degrees C while, mean generation time (G) and the doubling time (t) were highest at 25 degrees C. The finite rate of increase (lambda) was fairly constant (1.1-1.5 days) over the three temperatures tested. The pest potential of C. claratris for tropical Asia is discussed.     

Influences of temperature and humidity on the life history parameters and prey consumption of <Emphasis Type="Italic">Anthocoris minki</Emphasis> Dohrn (Heteroptera: Anthocoridae)

Anthocoris minki Dohrn is a promising indigenous Anthocoris species for the biological control of Agonoscena pistaciae Burck. and Laut. (Homoptera: Psyllidae) in pistachio orchards in Turkey. The adult longevity, fecundity, life table parameters and prey consumption of A. minki fed on Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs were studied at combinations of three constant temperatures (20, 25 and 30 ± 1°C) with two relative humidity (RH) levels (40 and 65 ± 5%). Studies indicated that temperature and RH significantly affected adult longevity, fecundity and prey consumption of A. minki. The greatest adult female longevity was 116.0 days at 20°C and 65% RH; the shortest adult female longevity was 27.5 days at 30°C and 40% RH. At all tested temperatures, the oviposition period and prey consumption of both females and males significantly decreased at low RH compared to high RH. The highest and lowest total fecundities were 276.0 eggs (at 20°C and 65% RH) and 42.4 eggs (at 25°C and 40% RH), respectively. The intrinsic rates of natural increase (r _m) at 40 and 65% RH were 0.049 and 0.076 at 20°C, 0.072 and 0.096 at 25°C and 0.076 and 0.112 at 30°C, respectively. The highest mean numbers of E. kuehniella eggs consumed by females and males were 859.6 (at 20°C) and 515.3 (at 25°C) at 65% RH, respectively; the lowest were 183.3 (at 20°C) and 95.5 (at 25°C) at 40% RH, respectively.     

Developmental and reproductive biology of Scirtothrips perseae (Thysanoptera: Thripidae): a new avocado pest in California

The developmental and reproductive biology of a new avocado pest, Scirtothrips perseae Nakahara, was determined in the laboratory at five constant temperatures, 15, 20, 25, 27.5 and 30 degrees C. At 20 degrees C, S. perseae exhibited greatest larval to adult survivorship (41%), and mated females produced a greater proportion of female offspring at this temperature when compared to 15, 25, 27.5 and 30 degrees C. Average lifetime fecundity and preoviposition period was greatest at 15 degrees C at 39.6 eggs per female and 17.6 days, respectively. Jackknifed estimates of net reproduction (Ro), capacity for increase (rc), intrinsic rate of increase (rm), and finite rate of increase (lambda) were all significantly greater at 20 degrees C than corresponding values at 15, 25 and 27.5 degrees C. Population doubling time (Td) was significantly lower at 20 degrees C, indicating S. perseae populations can double 33-71% faster at this temperature in comparison to 15, 25 and 27.5 degrees C. Mean adult longevity decreased with increasing temperature, from a maximum of 52.4 days at 15 degrees C to a minimum of 2.4 days at 30 degrees C. Developmental rates increased linearly with increasing temperatures for eggs and rates were non-linear for development of first and second instar larvae, propupae, pupae, and for egg to adult development. Linear regression and fitting of the modified Logan model to developmental rate data for egg to adult development estimated that 344.8 day degrees were required above a minimum threshold of 6.9 degrees C to complete development. An upper developmental threshold was estimated at 37.6 degrees C with an optimal temperature of 30.5 degrees C for egg to adult development. Unmated females produced only male offspring confirming arrhenotoky in S. perseae.     

Temperature dependent development of the parasitoid Colpoclypeus florus (Hymenoptera: Eulophidae) in the laboratory

Development, fecundity, and longevity of Colpoclypeus florus (Walker), a parasitoid of Adoxophyes orana (Fischer von R?slerstamm) (Lepidoptera: Tortricidae), were studied under laboratory conditions at different constant temperatures. Developmental time from egg to adult was inversely related to temperature and at 25 degrees C was 12.81 +/- 0.19 d. No adults emerged at 30 degrees C. The thermal units required for development from egg to adult were 232.56 +/- 19.5 degree-days. Female C. florus oviposited (mean +/- SEM) on average 30.7, 57.4, 46.6, and 34.1 eggs at 15, 17, 20, and 25 degrees C. respectively. Adult longevity was 11 +/- 1.25 d at 17, whereas it decreased to 4.5 +/- 0.4 at 25 degrees C. Honey significantly increased longevity for both males and females. The highest net reproductive rate was 30.739 at 17 degrees C, whereas the highest intrinsic rate of increase and the shortest doubling time occurred at 25 degrees C.     

Life table studies of Elasmopalpus lignosellus (Lepidoptera: Pyralidae) on sugarcane

The lesser cornstalk borer, Elasmopalpus lignosellus (Zeller) (Lepidoptera: Pyralidae) is an important pest of sugarcane (a complex hybrid of Saccharum spp.) in southern Florida. Reproductive and life table parameters for E. lignosellus were examined at nine constant temperatures from 13 to 36 °C with sugarcane as the larval food source. The pre- and postoviposition periods decreased with increasing temperatures and reached their minimums at 33 and 36 °C, respectively. The oviposition period was longest at 27 °C. The mean fecundity, stage-specific survival, stage-specific fecundity, intrinsic rate of increase, and finite rate of increase were greatest at 30 °C and decreased with increasing or decreasing temperature. The net reproductive rate was greatest at 27 °C. The Logan-6 model best described the relationship between temperature and intrinsic rate of increase. The generation and population doubling times were longest at 13 and shortest at 33 and 30 °C, respectively. The most favorable temperatures for E. lignosellus population growth were between 27 and 33°C. Life table parameters for E. lignosellus reared on sugarcane were greater than for the Mexican rice borer [Eoreuma loftini (Dyar) (Lepidoptera: Crambidae)] reared on an artificial diet at 30 °C. The intrinsic rates of increase for the sugarcane borer [Diatraea saccharalis (F.) (Lepidoptera: Crambidae)] reared on sugarcane or corn were the same as for E. lignosellus reared on sugarcane at 27 °C, but the net reproductive rate was four times higher for the former than the latter borer species.     

Temperature-related development and population parameters for Typhlodromus pyri (Acari: Phytoseiidae) found in Oregon vineyards

The beneficial mite Typhlodromus pyri is a key predator of grapevine rust mite Calepitrimerus vitis in Pacific coastal vineyards. Rust mite feeding has been associated with damage such as stunted, deformed shoot growth and reductions in fruit yield. The life history traits of T. pyri were assessed at seven constant temperatures (12.5, 15, 17.5, 20, 25, 30 and 35 °C) to determine population parameters providing data to better predict biological control of C. vitis populations by T. pyri in vineyards. Successful development from the egg to adult stage was observed at temperatures ranging from 15 to 30 °C. Constant exposure to 12.5 and 35 °C resulted in 100 % mortality in immature T. pyri. Developmental times, fecundity and longevity were highest at 25 °C. The estimated minimum and maximum developmental thresholds were 7.24 and 42.56 °C, respectively. Intrinsic rate of increase (r ( m )) was positive from 15 to 30 °C indicating population growth within this range of temperatures. Net reproductive rate and intrinsic rate of increase were greatest at 25 °C. These developmental parameters can be used to estimate population growth, determine seasonal phenology and aid in conservation management of T. pyri. Results presented in this study will aid in evaluating the effectiveness of T. pyri as a key biological control agent of C. vitis during different periods of the growing season in Pacific Northwest vineyards.     

Life history study of Thrips setosus

Development, reproduction and population growth of Thrips setosus Moulton (Thysanoptera, Thripidae), reared on a leaf of kidney bean, was studied under six different constant temperatures, and the effect on reproduction of short photoperiod during immature stages was examined. Survival rates from hatch to adult were more than 67.5% at temperatures between 17.5 and 27.5 °C, but less than 55% at 30 °C. Developmental rates increased linearly as rearing temperature increased. A total of 181.1 degree-days, above a developmental zero of 12.5 °C, were required to complete development from egg to adult oviposition. These data were related to records of field temperatures in Kurashiki in western Japan, and an estimate produced that, under outdoor conditions, a maximum of between seven and 12 generations could have developed annually between 1990 and 1999. There were no significant differences in mean adult longevity and mean fecundity among three temperatures (20, 22.5 and 25 °C). The intrinsic rate of natural increase (r _m) was 0.1997 at 25 °C. Reproductive diapause was induced by a photoperiod less than 12 h at 20 °C.     

Influence of temperature on life-table parameters of Stethorus gilvifrons (Mulsant) (Coleoptera: Coccinellidae) fed on Tetranychus urticae Koch

The influence of temperature on life-table parameters, fecundity and survivorship of the predatory ladybird, Stethorus gilvifrons , fed on Tetranychus urticae was determined at seven constant temperatures of 15°C, 20°C, 25°C, 28°C, 30°C, 35°C and 40°C. No development was observed at 40°C, thus being regarded as the threshold for the development of S. gilvifrons . The results indicate a significant decrease in male and female longevity with increasing temperature from 15°C to 35°C. The longest and shortest longevity were 18.40 and 12.75 days for males and 17.40 and 8.80 days for females, respectively. The intrinsic rate of natural increase ( r _m ) and the net reproductive rate ( R ₀) of S. gilvifrons linearly increased with increasing temperatures from 15°C to 35°C, while the mean generation time ( T ) and doubling time (DT) decreased linearly within this temperature range. The highest values of r _m (0.240 females/female/day) and R ₀ (59.27 females/female) and the lowest mean generation time (17.01 days) and DT (2.88 days) were recorded at 35°C. The maximum (185.50 eggs) and minimum (25.50 eggs) measurement of total fecundity was also recorded at 35°C and 15°C, respectively. The results indicate that temperature greatly affected fecundity, survivorship and life-table parameters of S. gilvifrons , and that 35°C is a suitable temperature for population growth of this predator.     

不同温度下稻螟赤眼蜂在黏虫卵上的种群生命表

稻螟赤眼蜂Trichogramma japonicum Ashmead是水稻二化螟Chilo suppressalis(Walker)的优势卵寄生蜂。本文构建了以黏虫卵为中间寄主,稻螟赤眼蜂在20℃、25℃、30℃、33℃四个温度条件下的生命表。研究结果表明利用黏虫卵繁育稻螟赤眼蜂时,不同温度下其生长发育和繁殖均存在显著差异,雌蜂平均寿命随温度的升高呈下降趋势,在20℃条件下,雌蜂平均寿命为1.44 d,显著长于其它温度,当温度为30~33℃时,雌蜂寿命最短,平均为0.59 d。在温度为20℃和25℃时,稻螟赤眼蜂的羽化率显著高于温度较高的30℃和33℃,平均为94.73%。在25℃条件下,黏虫卵繁育的稻螟赤眼蜂的净生殖力(R 0)最大,达到31.9176,单雌寄生卵数最多,为32.88个,表现出最强的繁殖能力,而在30℃条件下,瞬时增长率r m和周限增长率λ达到最大值。综合生命表参数、单雌寄生黏虫卵数、寿命、羽化率等指标,利用黏虫卵工厂化繁殖稻螟赤眼蜂的最佳温度为25℃。本研究为利用黏虫卵大量繁殖稻螟赤眼蜂提供了有价值的参考。     

Effect of temperature on life table parameters of predatory thrips Scolothrips longicornis (Thysanoptera: Thripidae) fed on twospotted spider mites (Acari: Tetranychidae)

Environmental variables such as temperature are important factors that affect the efficiency of biological control agents. This study examined the effect of temperature on the sex ratio, longevity, oviposition periods, fecundity and life table parameters of the predatory thrips Scolothrips longicornis Priesner (Thysanoptera: Thripidae) fed on twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), at six constant temperatures: 15, 20, 26, 30, 35, and 37 degrees C. Approximately 75% of the progeny were female, except at 37 degrees C, at which temperature the proportion of males increased. Adult longevity as well as the preoviposition, oviposition, and postoviposition periods decreased significantly with temperature. Thus, adults lived for approximately 5 wk at 15 degrees C and < 1 wk at 37 degrees C with preoviposition, oviposition, and postoviposition periods ranging from 6.4 to 0.4, 24.4-3.1, and 7-0.8 d between the two temperature extremes, respectively. The maximum (56.48 eggs) and minimum (11.69 eggs) value of total fecundity was recorded at 26 and 37 degrees C, respectively. The intrinsic rate of natural increase (r(m)) of S. longicornis increased linearly with increasing temperature from 0.056 d(-1) at 15 degrees C to 0.310 d(-1) at 35 degrees C. The lower temperature threshold for the population increase of S. longicornis was estimated to be around 5 degrees C. The data suggest that the upper temperature threshold for the predatory thrips is approximately 37 degrees C. The results showed that populations of S. longicornis are able to develop at a broad range of temperatures and that this predator is well adapted to the high temperatures that occur in the Mediterranean region.     

Life table study of Sitotroga cerealella (Lepidoptera: Gelichiidae), a strain from West Africa

Life table studies for the Angoumois grain moth, Sitotroga cerealella (Olivier), a pest on stored maize, Zea mays L., in West Africa, were conducted as part of the expansion of a mathematical simulation model that has been developed for two pests of stored maize. The effects of four temperatures (20, 25, 30, and 35 degrees C) and two relative humidity levels (44 and 80%) on developmental time, age-specific survivorship and fecundity, sex ratio, and intrinsic rate of natural increase (r(m)) of S. cerealella were investigated. Sex ratio was close to 1:1 at all temperatures and humidity. Minimum development time occurred close to 32 degrees C and 80% RH for both males and females, and developmental time of females was significantly shorter than that of males. Immature survivorship was highest between 25 and 30 degrees C and 80% RH and lowest at 35 degrees C under both humidity conditions. A similar low level was found at 20 degrees C and 44% RH. The greatest fecundity (124 eggs per female) occurred at 20 degrees C, 80% RH. The maximum r(m) value was 0.086 d(-1) at 30 degrees C and 80% RH, but the growth rate declined dramatically at 35 degrees C. If compared with the few other life table studies conducted on this species on maize in India and North America, some variation among the strains becomes evident. A common conclusion for the current study and previous ones is that optimal population development for S. cerealella occurs at approximately 30 degrees C and at high humidity.     

Temperature-dependent development and demography of Scymnus subvillosus (Coleoptera: Coccinellidae) reared on Hyalopterus pruni (Homoptera: Aphididae)

The development, survival, and fecundity of Scymnus subvillosus (Goeze) (Coleoptera: Coccinellidae) were studied at 20, 25, 30, and 35 degrees C, 60 +/- 5% RH, and a photoperiod of 16:8 (L:D) h (5,000 lux) under laboratory conditions. The total developmental time from egg hatch to adult eclosion ranged from 22.6 d at 20 degrees C to 10.6 d at 35 degrees C. The developmental rates of the egg stage, the larval stage, and total preadult stage at different temperatures increased linearly with increasing temperature. The thermal summation of the egg stage, the larval stage, and the total preadult stage was 77.5, 145.8 and 300 degree-days (DD), respectively. The developmental threshold of the egg stage, the larval stage, and the total preadult stage was 7.4, 4.1, and 7.1 degrees C, respectively. The life history raw data were analyzed using the age-stage, two-sex life table. The intrinsic rate of increase was 0.0845, 0.1138, 0.1395, and 0.0668 d(-1) at 20, 25, 30, and 35 degrees C, respectively. The net reproductive rate was highest at 25 degrees C (R0 = 78.7), and lowest at 35 degrees C (R0 = 4.7). The mean generation time was shortest at 35 degrees C (T = 23.9 d). The life table data can be used for the projection of population growth and designing mass rearing programs.     

Biological parameters of Thripobius semiluteus Bouček (Hym., Eulophidae), a larval endoparasitoid of Heliothrips haemorrhoidalis (Bouché) (Thysan., Thripidae)

Abstract:  The endoparasitoid Thripobius semiluteus Bouček was recently introduced to Italy from Israel for the biological control of Heliothrips haemorrhoidalis (Bouché). In this study, some aspects of the biology of T. semiluteus were determined in the laboratory. Developmental time (egg to adult), potential fecundity, realized fecundity, progeny, daily rate of deposition of eggs and several demographic growth parameters were evaluated. Studies of the longevity of fed and starved adults at seven temperatures (3, 10, 15, 20, 23, 25 and 30 ± 1°C) showed that fed T. semiluteus lived longest at 15°C (36.45 days) and shortest at 3°C (1.45 days). Longevity was reduced significantly at higher and lower temperatures than 15°C and when honey was not provided. Development time was measured at six temperatures. Pupae did not complete development at 10°C. The lower theoretical temperature threshold was 9.0°C; the optimum developmental temperature and the upper lethal threshold were 28.0°C and 34.1°C respectively. The most rapid development was found at 30°C, but waSPS suffered significantly higher mortality at this temperature than at other temperatures. Ovigeny index showed that T. semiluteus is synovigenic, with a mean realized fecundity of 78.8 eggs per female. The mean progeny was 68.2 adults per female on fed adults.     

Life table and biological characteristics of Macrolophus pygmaeus when feeding on Myzus persicae and Trialeurodes vaporariorum

The life table and biological characteristics of the predatory bug Macrolophus pygmaeus Rambur (Hemiptera: Miridae) were studied when the bugs were fed with Myzus persicae (Sulzer) (Homoptera: Aphididae) feeding on eggplant and with Trialeurodes vaporariorum Westwood (Homoptera: Aleyrodidae) feeding on tomato plants. The tests were done at five temperatures between 15 and 30 °C, using a L16:D8 photoperiod and 65 ± 5% r.h. Most eggs (range 85 to 90%) hatched at 15 and 20 °C. Incubation period was shortest at 27.5 °C (8.45 and 8.38 days on eggplant and tomato, respectively). Preoviposition was also shortest at 27.5 °C (5.10 and 4.75 days on eggplant and tomato, respectively) whereas fecundity was highest at 20 °C (213.90 and 228.25 eggs on eggplant and tomato, respectively). Maximum longevity of females was at 15 °C (122.40 and 129.35 days on eggplant and tomato, respectively). Mean generation time was longest at 15 °C on both host plants (122.75 and 124.64 days, respectively). The intrinsic rate of increase of M. pygmaeus was highest at 27.5 °C with similar values on eggplant (0.0981 day^–1) and tomato (0.1040 day^–1). Doubling time was shortest at 27.5 °C (7.06 and 6.67 days on eggplant and tomato, respectively) and, also, finite rate of increase was highest at 27.5 °C (1.1031 and 1.1096 on eggplant and tomato, respectively). The results show that the predator M. pygmaeus develops well on the aphid M. persicae or on the whitefly T. vaporariorum, both of which are important pests of vegetable crops. This predator is also well adapted to the temperatures that occur both in greenhouses and in the open field in the Mediterranean region. Compared to other natural enemies of whiteflies, such as Encarsia formosa Gahan (Hymenoptera: Aphelinidae), Macrolophus pygmaeus can increase at relatively low temperatures.     

Effect of temperature on pupa development and sexual maturity of laboratory Anastrepha obliqua adults

The effect of four temperatures (18, 20, 25 and 30°C) on pupa development and sexual maturity of Anastrepha obliqua adults was investigated under laboratory conditions. The results showed that the duration of the pupal stage decreased with an increase in temperature (29, 25, 13 and 12 days, respectively), and maintaining the pupae at 18°C and 20°C results in a low percentage of pupation, pupa weight loss and lesser flying ability. However, it significantly favored sexual behavior, a higher proportion of sexual calls and matings. While enhanced pupa development was observed at a temperature of 30°C, adults had low sexual efficiency, as well as a lower proportion of calls and matings. Gas chromatography-mass spectrometry (GC-MS) analysis of male volatiles showed that the amount of (Z,E)-α-farnesene did not vary among males from pupae reared at different temperatures; however, less (E,E)-α-farnesene was emitted by males obtain from pupa reared at 30°C. Male flies kept at 30°C during their larval stage had more (Z)-3-nonenol and, also, an unknown compound was detected. The fecundity of the females was higher at low temperatures. Regarding fertility, no significant differences were found between temperatures. The optimal temperature on pupa development was 25°C when males displayed ideal attributes for rearing purposes.     

Effect of temperature on development, survival, and fecundity of Microplitis manilae (Hymenoptera: Braconidae)

Microplitis manilae Ashmead (Hymenoptera: Braconidae), a larval parasitoid, is a potential biological control agent of both Spodoptera exigua (Hübner) and Spodoptera litura (F.) (Lepidoptera: Noctuidae). Aspects of the climatic requirements for development, including survival, longevity, and fecundity of M. manilae were studied at six constant temperature regimes (17, 20, 23, 26, 29, and 32°C) in the laboratory. The results showed that developmental duration for egg, larva, pupa, and the entire immature stages shortened in response to temperature increasing from 17 to 32°C. Survival rates of different developmental stages were higher at 20-29°C than at other temperatures. Longevity of M. manilae adults shortened with increasing temperature. The maximum fecundity of M. manilae female equaled 261.0 eggs/female at 26°C. Minimum threshold temperature and effective accumulated temperature for completing a generation of M. manilae were 11.04°C and 205.98 degrees-days, respectively. Both intrinsic rate of increase (r) and finite rate of increase (λ) of M. manilae did not differ between 26 and 29°C, but those were significantly higher at 26 and 29°C than at any other temperatures. The highest net reproduction rate (r(0)) was observed at 26°C, with the value of 97.77, but the lowest was 11.79 at 32°C. These results suggest that the parasitoid is well adapted to temperate and subtropical climates, which implies a significant potential for using M. manilae to control S. exigua because most of areas occupied by these two pests belong to temperate and subtropical regions in southeastern Asia.     

Developmental times and life table statistics of Aulacorthum solani (Hemiptera: Aphididae) at six constant temperatures, with recommendations on the application of temperature-dependent development models

Aulacorthum solani (Kaltenbach) (known as foxglove aphid or glasshouse potato aphid) is a pest of increasing economic importance in several agricultural crops worldwide, including greenhouse vegetables and ornamentals. Developmental rates and age-specific life tables for a North American population of A. solani on pansy (Viola × wittrockiana) (Gams.) were determined at six constant temperatures, and comparisons were made to previous studies of A. solani from differing geographic regions and host crops. On pansy, A. solani developed fastest at 25°C, passing through the four nymphal instars in an average of 6.9 d. The highest intrinsic rates of population increase (0.410 and 0.445) and shortest population doubling times (1.69 and 1.56 d) were recorded at 20 and 25°C, respectively. Average total fecundity remained high from 10 to 20°C (74-68 nymphs/adult); a significant decrease to 39 nymphs/adult occurred at 25°C. For calculating developmental thresholds, we present here a method of adjusting the lower developmental threshold (t(min)) using estimates from nonlinear models to provide an improved estimate of the thermal constant (K, in degree-days). We also call attention to the necessity of using a simulation method to estimate the true upper developmental threshold (t(max)) and optimum developmental temperature (t(opt)) from the Lactin-2 model of temperature-dependent development.