Effect of temperature on development, mortality, fecundity, and reproduction of Aphis rumicisL. (Homoptera: Aphididae) on broadleaf dock (Rumex obtusifolius) and Swiss chard (Beta vulgaris vulgaris var. cida)

Temperature effects on developmental period, survival rate, and reproductive capacity of Aphis rumicis L. were studied on Broadleaf dock and Swiss chard at four constant temperatures (17.5°C, 20°C, 22.5°C, and 25°C). The developmental time of immature stages ranged from 10.9 days at 17.5°C to 6.5 days at 25°C on Broadleaf dock, and 11.8 days at 17.5°C to 6.5 days at 25°C on Swiss chard. The total percentage of survivorship of immature stages varied from 54.2% and 67.6% 17.5°C–25°C on Broadleaf dock, and 49.7% and 62.4% at 17.5°C–25°C on Swiss chard. The largest r _m value occurred with 0.2845 at 25°C on Broadleaf dock and with 0.2785 at 25°C on Swiss chard. The results obtained on this study indicated that Swiss chard was a less favorable host of the A. rumicis than Broadleaf dock. The optimal temperature for A. rumicis growth, developmental time, and reproduction was 22.5°C–25°C.     

Effects of temperature on reproductive capacity and longevity of Trissolcus simoni, an egg parasitoid of Eurygaster integriceps

In order to understand the effects of temperature on Trissolcus simoni, some parameters of the life tables of adult parasitoids were investigated under laboratory conditions. The following parameters were measured (the values in parentheses were obtained at 20, 26, and 32 °C temperatures, respectively): net reproductive rate (R_o=37.785, 40.301, and 58.299), intrinsic rate of population increase (r_m=0.111, 0.221, and 0.325), generation time (T=32.77, 16.60, and 12.49 days), doubling time (DT=6.245, 3.136, and 2.133), and finite rate of increase (=1.117, 1.247, and 1.385). Fecundity increased with increasing temperature. The values for total number of eggs deposited per female were 50.1, 64.1, and 68.1, and average female longevity was 24.2, 13.8, and 11.1 days at 20, 26, and 32°C, respectively. Temperature had a significant effect on longevity and oviposition and post-oviposition periods. The results of the study are discussed and compared with life-table parameters of other scelionids.     

Temperature-dependent functional response of two aphid parasitoids, Aphidius colemani and Aphidius matricariae (Hymenoptera: Aphidiidae), on the cotton aphid

The functional response of two aphid parasitoids, Aphidius colemani Viereck and Aphidius matricariae (Haliday) (Hymenoptera: Aphidiidae), on the cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae), was examined. Five constant temperatures (10, 15, 20, 25, and 30°C) and six host densities (2, 4, 8, 16, 32, and 64) were used during a 24-h period. At each temperature, 2–64 third-instar nymphs of A. gossypii were exposed to individual wasp mating pairs. A type II functional response model for both parasitoid wasps was fit separately for each temperature. The results showed that instantaneous attack rate (a) in A. colemani increased linearly as the temperature increases from 10 to 30°C, but in A. matricariae, (a) increased almost linearly with temperature to reach a maximum at 25°C, and then decreased at 30°C, displaying an asymmetrical dome-shaped pattern. The highest instantaneous attack rate for A. colemani and A. matricariae were calculated 0.940 ± 0.144 day⁻¹ at 30°C and 0.687 ± 0.157 day⁻¹ at 25°C, respectively. Handling time (T _h) for A. colemani was inversely proportional to temperature and ranged from 0.093 ± 0.026 day at 10°C to 0.032 ± 0.004 day at 30°C, but in A. matricariae, (T _h) was between 0.078 ± 0.015 day at 10°C and 0.036 ± 0.014 day at 20°C. A. colemani achieved higher parasitism rate than A. matricariae at higher temperatures. This observation suggests that A. colemani maybe more effective for biological control of the cotton aphid during warmer periods.     

Effect of soybean cultivar on life history parameters of <Emphasis Type="Italic">Tetranychus urticae</Emphasis> Koch (Acari: Tetranychidae)

The two-spotted spider mite, Tetranychus urticae Koch, is a very polyphagous pest with a worldwide distribution. In order to appraise population growth parameters of this pest, samples of two-spotted spider mites were taken from soybean (Glycine max) fields of Moghan region, Iran in June 2007 and are reared on bean plants var. Derakhshan (Phaseolus vulgaris) in a growth chamber. The life table parameters of this pest were calculated on three commercial soybean cultivars (Zane, Hach, and L17) and one hybrid (Hob × Will) at 25 ± 1°C, 60 ± 10%RH, and 16 h photophase. The developmental times of immature stages varied from 9.69 on Hach to 9.82 days on L17, whereas the immature survival was 57–79% on Hach and Hob × Will, respectively. On average, there were 65.5, 40.8, 38.8 and 34 eggs produced per female on L17, Hach, Hob × Will and Zane, respectively. The intrinsic rate of natural increase (r _m ) for T. urticae on Hob × Will was the highest, whereas the values for r _m ranged from 0.211 (females/female/day) on Zane to 0.292 on Hob × Will. Also, jackknife values of other life table parameters such as net reproductive rate (R ₀), generation times (T), doubling time (DT), and finite rate of increase (λ) on these cultivars were estimated. Overall, the two-spotted spider mite indicated a better performance on Hob × Will than on the other soybean cultivars.     

Prey consumption preferences of<Emphasis Type="Italic"> Serangium parcesetosum</Emphasis> Sicard (Col., Coccinelidae) for different prey stages,species and parasitized prey

Serangium parcesetosum Sicard (Col., Coccinellidae) is considered one of the important predators of whiteflies. However, knowledge about its preferences for different prey stages, species and parasitized prey is still lacking in the literature. The present work investigated the preferences of S. parcesetosum for different stages of B. tabaci, different prey species and B. tabaci parasitized by Encarsia formosa Gahan (Hym., Aphelinidae) by prey consumption at different temperatures in the laboratory. Results showed that L₂ and L₄ predatory instars of S. parcesetosum preferred puparia to nymphs and eggs of Bemisia tabaci (Genn.) (Hom., Aleyrodidae). The mean daily prey consumption was 5.1–9.0, 4.5–6.2 and 3.6–4.3 by L₂ and 6.4–9.7, 5.5–8.5 and 2.5–7.5 by L₄ for puparia, nymphs and eggs, respectively. Adult females, however, indicated a significantly greater preference for both puparia and nymphs, consuming a daily mean of 6.4–7.5 puparia and 5.1–6.7 nymphs, but only 3.0–4.7 eggs. At 18 and 30 °C, all S. parcesetosum stages tested significantly preferred B. tabaci and Trialeurodes vaporariorum Westwood (Hom., Aleyrodidae) over the other three prey species offered. At both temperatures, all predatory stages preferred B. tabaci to T. vaporariorum, the L₂ instar at 18 °C, showing significantly more preference for B. tabaci than T. vaporariorum. In contrast, very few individuals were consumed from Aphis gossypii Glover (Hom., Aphididae), Frankliniella occidentalis (Pergande) (Thys., Thripidae) and Tetranychus urticae Koch (Acari, Tetranychidae). At 18 °C, a daily mean of 7.5–8.0, 6.6–9.0 and 6.7–8.1 B. tabaci as well as 5.3–6.4, 5.4–7.8 and 5.6–6.3 T. vaporariorum was consumed by L_2, L₄ and adult females, respectively, while at 30 °C, L₂, L₄ and adult females consumed a mean of 9.3, 8.8–9.7 and 8.3–9.7 B. tabaci/day as well as 8.3–9.0, 7.8–9.1 and 5.5–8.4 T. vaporariorum/day, respectively. S. parcesetosum L₂ and L₄ instars as well as adult females and males at both studied temperatures showed a significant tendency to avoid B. tabaci puparia after 5 days of parasitism by E. formosa and preferred to feed on unparasitized whiteflies. At 18 °C, the mean daily consumption was 8.7 and 0.2 (L₂), 11.1 and 0.6 (L₄), 12.1 and 1.0 () as well as 10.5 and 0.2 (), while at 30 °C the means were 15.9 and 0.5 (L₂), 19.8 and 1.0 (L₄), 18.9 and 1.2 () as well as 17.4 and 0.6 () from unparasitized and parasitized B. tabaci puparia, respectively.This paper is gratefully dedicated to Prof. Dr. W Schwenke on his 83rd birthday, 22 March 2004     

Gas exchange,water relations and morphology of yellow-cedar seedlings and stecklings before planting and during field establishment

Information is lacking on how yellow-cedar (Chamaecyparis nootkatensis (D. Don.) Spach) stecklings compare with seedlings in their response to potentially limiting field site environmental conditions. Before planting, yellow-cedar seedlings and stecklings were characterized at 5 and 22°C root temperatures for gas exchange parameters (n=6), root growth capacity (n=12) and plant water movement (n=6) using a fully randomized design in a controlled environment growth room. Seedlings, compared with stecklings (t-test), showed a faster (p=0.01) recovery of net photosynthesis (P_n) and stomatal conductance (g_wv) after root temperature increased from 5 to 22°C. Seedlings had greater (p=0.05) root growth capacity (number of new roots 0.5 cm in length) than stecklings after 14 days at 22°C and after 14 days at 5°C followed by 15 days at 22°C. Seedlings had a lower (p=0.01) resistance to plant water movement measured after 29 days (14 days at 5°C followed by 15 days at 22°C root temperature).Seedlings and stecklings were planted on a coastal British Columbia field site and monitored for 1) morphological development and physiological response to ambient site conditions throughout the first growing season, and 2) physiological response to drought conditions during late summer. Both trials used a fully randomized design and stock type means were compared using t-tests (p=0.10, 0.05, and 0.01). Initially, seedlings were taller (p=0.01) than stecklings but otherwise morphologically similar (n=20). Over a 35 week period after planting, stecklings had greater incremental height growth, while seedlings produced a greater (p=0.01) number of roots extending out of the root plug. Seedlings and stecklings (n=6) had similar P_n and g_wv patterns under late spring environmental conditions. However, seedlings had greater P_n and g_wv under cold temperature (p=0.05 and p=0.1, respectively) and drought conditions (p=0.05 and p=0.01, respectively), but during conditions of high evaporative demand and adequate soil moisture, stecklings had greater (p=0.01) P_n and g_wv. Seedlings had higher (p=0.01) daily integrated shoot water potential values (D) at different times during the growing season, and maintained higher (p=0.05) predawn (_pd) shoot water-potential values, higher (D) (p=0.01) and lower (p=0.01) resistance to plant water movement (R_SPAC) during drought conditions.     

Zur Bekämpfung des Reiszünslers,Corcyra cephalonica (Stainton) (Lep., Pyralidae) unter Ausnutzung der Kälteempfindlichkeit der Eier und Larven

Zusammenfassung Experimente mit Eiern und Larven verschiedenen Alters des MehlzünslersCorcyra cephalonica (Staint.), welche unterschiedlich langen Temperaturen von 5, 0 und –10°C ausgesetzt wurden, ergaben, daß Eier bei Kurzzeitbehandlung (10h) mit –10°C oder bei Langzeitbehandlung (10 Tage mit 0°C, 15 Tage mit 5°C) zu 100% abstarben. Die Kältebehandlung von Erstlarven führte bei 2 h mit –10°C oder 5 Tagen mit 5°C zum völligen Absterben. Wurde mit verschiedenen Entwicklungsstadien (außer Puppen) vonC. cephalonica befallenes Weizenmehl 5 Tage lang 0°C oder 15 Tage lang 5°C ausgesetzt, starben alle Stadien ab, so daß keine Falter schlüpften. Somit ist unter diesen Bedingungen eine wirksame Bekämpfung des Schädlings in befallenem Mehl möglich, solange noch keine Puppen ausgebildet sind.

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Use of cold susceptibility of eggs and larvae of the rice mothCorcyra cephalonica (Stainton) (Lep., Pyralidae) for their control

Experiments were conducted to evaluate the effect of storing wheat flour for various length of time at –10°, 0°, and 5°C, on the mortality of the egg and larval stages ofCorcyra cephalonica (Stainton). Treating eggs with –10°C for 10 h, 0°C for 10 and more days, or 5°C for 15 days, stopped all embryonic development, and hence 100% mortality of eggs was obtained. Also, 100% mortality was observed when first-instar larvae were treated with –10°C for 2 h and more; or 0°C or 5°C for 5, 10, or 15 days.Storing wheat flour infested with different stages at 0°C for 5 days and more, or at 5°C for 15 days prevented the development of immature stages and thus no adults emerged. It can be concluded that storing small quantities of flour at 5°C for 15 days, or at 0°C for 10 or 15 days would be effective in controllingC. cephalonica, if no pupae are present at the time of treatment.

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Mit 2 Tabellen     

Wirkungen der Fotoperiode und Temperatur auf die Entwicklungsstadien von Acrotylus insubricus Scop. (Orthopt., Acrididae)

Effect of photoperiod and temperature on the developmental stages of Acrotylus insubricus Scop. (Orth., Acrididae) The effect of different temperatures and photoperiods on the developmental stages ofAcrotylus insubricus Scop. was studied. The species has no embryonic or nymphal diapause. The relatively low temperature of the winter months prolonges the incubation period as well as the nymphal development. By rising temperature both eggs and nymphs began to continue their development. The shortest nymphal duration at 27 °C (63.9 days) was obtained when rearing nymphs at long photoperiod (16L:8D), while the longest duration (92 days), was recorded at short photoperiod (8L:16D). In intermediate photoperiod (12L:12D), the nymphal duration was 82.8 days, between the long and the short photoperiods. At 37 °C, the nymphal durations were shorter than at 27 °C and still the shortest at a long day (4310 days) than the two other conditions. The total nymphal mortality was higher at short day-length than that at the other photoperiods tested. The incubation period as well as the percentage of hatching were not affected by the different photoperiodic regimes while the low temperature prolonges the incubation period and nymphal development. The higher temperature (37 °C) tended to mask or abolish the effect of the photoperiod while the moderate temperature (27 °C) clarified this effect when the two factors were combined together.     

Apple cultivars acceptance by Dysaphis plantaginea Passerini (Homoptera: Aphididae)

The development time, longevity, and fecundity of Dysaphis plantaginea were measured on six apple cultivars (Golden delicious, Red delicious, Renetta canada, Florina querina, Golden lasa, and Golden orange) under controlled conditions, in order to establish the life tables of D. plantaginea on the different cultivars and to evaluate the tolerance of the cultivars against this pest. The intrinsic rates of increase (r _m) were 0.07 and 0.11 day⁻¹ on F. querina and G. orange, respectively. On the other four cultivars, rates ranged between 0.22 and 0.26 day⁻¹, with the maximum value registered on G. lasa. All the biological and demographic parameters evaluated, i.e. survival of larvae (M = 5.8–72.2%), mean generation time (T = 14.94–20.62 days), and net reproduction rate (R ₀ = 4.23–47.37), show that G. orange and F. querina are tolerant cultivars while R. delicious, R. canada, G. lasa, and G. delicious are susceptible hosts.     

Effects of light radiation intensity on photosynthetic characteristics and water use efficiency of Platycladus orientalis and Pinus tabulaeformis seedlings

In order to offer a scientific basis for cultivation and management of forests, effects of light radiation intensity on photosynthetic characteristics and water use efficiency of Platycladus orientalis and Pinus tabulaeformis were studied under different soil moisture contents. By adopting artificial control methods to soil moisture, and under simulated photosynthetic radiation (SPR), the net photosynthetic rate (P _N), transpiration rate (T _r), water use efficiency (WUE) and intercellular CO₂ concentration (C _i) of Platycladus orientalis and Pinus tabulaeformis in the semi-arid region of the Loess Plateau, were studied. Results are as follows: within the photon range of 0–2,200 μmol/(m²·s), P _N, T _r and WUE were enhanced with an increase in SPR in both species. P _N and WUE of Platycladus orientalis and Pinus tabulaeformis, however, declined with continued increase in SPR. P _N, T _r, WUE and light saturation point (LSP) of Platycladus orientalis were higher than those of Pinus tabulaeformis, while light compensation point (LCP) of Platycladus orientalis was lower than that of Pinus tabulaeformis at the same soil moisture content. The efficiency of light energy utilization of Platycladus orientalis was higher than that of Pinus tabulaeformis; P _N, T _r and C _i of Platycladus orientalis and Pinus tabulaeformis were enhanced by increasing soil moisture content, whereas WUE declined. At soil moistures of 7.90%, 13.00% and 19.99%, LSP of Platycladus orientalis was 1,275, 1,450 and 1,675 μmol/(m²·s) respectively, and LCP was 42, 25 and 13 μmol/(m²·s) respectively, with corresponding maximal net CO₂ photosynthetic rates (P _max) of 3.04, 4.06 and 5.53 μmol/(m²·s). At soil moistures of 7.83%, 13.04% and 20.15%, the LSP of Pinus tabulaeformis was 1,100, 1,325 and 1,500 μmol/(m²·s) respectively, and LCP was 60, 30 and 23 μmol/(m²·s), with P _max of 1.08, 3.35 and 4.36 μmol/(m²·s) respectively. __________ Translated from Science of Soil and Water Conservation, 2006, 4(3): 108–113 [译自: 中国水土保持科学]     

Influence of leaf portion and plant species on the egg-laying behaviour of the predatory ladybird Serangium parcesetosum Sicard (Col., Coccinellidae) in the presence of a natural enemy

The effectiveness of natural enemies against arthropod herbivores can depend on the characteristics of the plant on which they are found. The influence of the plant on the egg-laying behaviour of the promising whitefly predator, Serangium parcesetosum Sicard (Col., Coccinellidae) was examined in order to be able to use it effectively in biological control programs. The present work investigated the possible influence of the portion of the leaf on the number of eggs laid as well as the effect of plant species on the way in which eggs are deposited by S. parcesetosum. The experiments were conducted on cucumber and cotton leaves with Bemisia tabaci (Genn .) (Hom., Aleyrodidae) as prey in the absence and presence of a natural enemy, the lacewing, Chrysoperla carnea (Stephens) (Neur., Chrysopidae) at two different temperatures. The results showed that at 18°C, S. parcesetosum females significantly preferred to lay their eggs between the veins and close to the veins of cucumber leaves, mean of 10.1 and 7.5 eggs, in the absence of C. carnea, respectively, while in its presence significantly more eggs were deposited close to the veins and close to the petiole. On cotton leaves, close to the petiole, a mean of 8.4 eggs in the absence of the lacewing, as well as close to the veins, mean of 6.3 eggs in the presence of the lacewing, were found to be the most suitable leaf portions for egg-laying. At 30° C, the females laid their eggs preferentially close to the veins of cucumber leaves in the absence and presence of C. carnea. On cotton leaves, S. parcesetosum females significantly preferred to lay their eggs close to the petiole, mean of 7.6 and 6.1 eggs, as well as close to the veins, mean of 6.2 and 8.7 eggs, in the absence and presence of the lacewing, respectively. At both temperatures, the ladybird females laid their eggs singly on cucumber leaves in the absence and presence of C. carnea. While on cotton leaves, the females had a tendency to deposit their eggs together in the absence and presence of the lacewing, except at 30°C in its absence. Within the same plant species, significant differences were found in the total number of eggs laid by S. parcesetosum females on cotton leaves at 18°C as well as on cucumber leaves at 30°C in the absence and presence of the natural enemy. In addition to the effects of presence and absence of C. carnea, and where eggs were laid, some significant differences due to plant species was found at both temperatures.This article is dedicated to Prof. Dr Wolfgang Schwenke on his 84th birthday.     

Effect of Lecanicillium muscarium on Eretmocerus sp. nr. furuhashii (Hymenoptera: Aphelinidae), a parasitoid of Bemisia tabaci (Hemiptera: Aleyrodidae)

Pathogenicity of Lecanicillium muscarium, against Eretmocerus sp. nr. furuhashii (Hymenoptera: Aphelinidae), was investigated under laboratory conditions to determine if the fungal infection of the whitefly host can effect the survival, longevity and fecundity of female parasitoid. The results indicated that the number of parasitized larvae surviving a L. muscarium treatment after 6 days of oviposition decreased with increasing concentrations of L. muscarium and in later stages of development (12 days post oviposition) were not affected by fungal application. There were no significant differences on adult parasitoid survivorship after 7 days among all treatments. Maximum survivorship (73.33%) was observed for control and it was minimum (60%) at 1 × 10⁸ conidia/ml. L. muscarium showed a non significant effect on longevity and next offsprings of female parasitoids. The percentage emergence of parasitoids from the whitefly nymphs produced by the females emerged from treated pupae was almost similar. Maximum emergence (69.77%) was observed at 1 × 10⁶ conidia/ml and it was lowest (61.02%) at conidial concentration of 1 × 10⁸ conidia/ml. Maximum longevity of adult Eretmocerus sp. emerging from whitefly nymphs when treated after 12 days of postoviposition was observed for 1 × 10⁵ conidia/ml having a mean value of 5 days whereas the lowest longevity was 4.9 days observed at 1 × 10⁸ conidia/ml. The results mentioned above indicate that the interaction among biocontrol agents is positive to a greater extent with minimum risk hazards.     

Chlorophyll fluorescence as an indicator of frost hardiness in white spruce seedlings from different latitudes

This study examined the utility of variable chlorophyll fluorescence (F_var) to detect freezing damage in white spruce seedlings of four seedlots. Logistic regression analysis done for freezing tests in September showed that visible needle damage from freezing could be estimated by the F_var attributes F_o/I_ABS(r²=0.94), F_p(r²=0.98), F_v/F_m (r²=0.99), and F₁(r²=0.86). The regression curves indicated that for all four fluorescence attributes, inflection points occurred between 10 and 20% visible needle damage. The lack of a relationship between fluorescence attributes and visible seedling needle damage in October through December is because the minimum temperature (–18 and –24°C respectively) applied was insufficient to cause needle damage. Freezing-induced changes to F_var attributes can be detected which also result in photosynthetic rate decreases when no visible needle damage, and even electrolyte conductivity changes are evident. F_var attribute differences due to freezing can be resolved to the seedlot level. The Fvar curve feature manifested 5 seconds after dark-adapted seedlings have been exposed to light (F_5s) will estimate (r²=0.76) photosynthetic rate after freezing.     

Some biological interactions between the parasitoid <Emphasis Type="Italic">Anagyrus pseudococci</Emphasis> (Girault) (Hymenoptera: Encyrtidae) and its host <Emphasis Type="Italic">Planococcus ficus</Emphasis> (Signoret) (Hemiptera: Coccoidea: Pseudococcidae)

The development, longevity, fecundity and life-table parameters of the endoparasitoid Anagyrus pseudococci (Girault) (Hymenoptera: Encyrtidae), 15 d.o. (3rd-instar nymphs) and 21 d.o. (young adult females) of the vine mealybug, Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) at 28 ± 1°C, 65 ± 10%RH and 16:8h L:D under laboratory conditions. The developmental time of female parasitoids within the host was 17.7 ± 0.39 days in 15 d.o. and 16.65 ± 0.25 days in 21 d.o. hosts; for males, development time was 16.85 ± 0.29 and 15.25 ± 0.09 days, respectively. The average number of offspring per female was 22.35 ± 1.68 in 15 d.o. and 34.8 ± 2.56 in 21 d.o. vine mealybugs. The longevity of female parasitoids was 14.8 ± 0.98 days in 15 d.o. and 15.65 ± 0.92 days in 21 d.o. mealybugs, respectively; for males, longevity was determined as 7.3 ± 0.43 and 6.7 ± 0.54 days, respectively. The mean time of pupation was 7.85 ± 0.003 days in 15 d.o. mealybugs and 8.65 ± 0.003 days in 21 d.o. mealybugs. The aggregate encapsulation rate in the parasitized 15 d.o. mealybugs was 49.73 and 60.36% in 21 d.o. mealybugs. Furthermore, effective encapsulation was 24.82% in 15 d.o. mealybugs and 37.50% in 21 d.o. mealybugs. Population growth rate (r _m) for A. pseudococci was 0.0999 female/female/days in 15 d.o. mealybugs and 0.1269 female/female/days in 21 d.o. mealybugs. The mean population generation time was 23.49 days for parasitoids reared in 15-days-old and 22.39 days when reared in 21 d.o. mealybugs.     

Feeding activity and life history characteristics of the generalist predator,<Emphasis Type="Italic"> Chrysoperla carnea</Emphasis> (Neuroptera: Chrysopidae) at different prey densities

Larvae of the common green lacewing, Chrysoperla carnea (Stephens) (Neuroptera :Chrysopidae) were fed with different densities of Hyalopterus pruni (Geoffer) (Homoptera: Aphididae) in Petri dishes under laboratory conditions. Functional response, developmental time, mortality rate and fecundity of the predator were measured. Treatments were carried out at 25±1°C, 65±5% RH and a 16L:8D photoperiod in a controlled temperature cabinet. Prey was given at densities of 5, 10, 20, 40, 80, 160 and 250 aphids per larva per day and the number of consumed prey, developmental time and mortality rate of the predator were recorded daily. Larvae of C. carnea responded to increasing prey densities with increasing food consumption and older larval stages displayed a higher rate of predation than younger ones. The behaviour of each of the three larval stages matched Hollings type II functional response. Larvae were able to complete their development in each of the seven prey densities, although increased prey densities reduced developmental time and mortality rate. Increased prey consumption in immature stages resulted in a higher net reproduction rate (R ₀) and the intrinsic rate of increase (r _m) of adult females.     

Variation in chemical contents of seed,and foliage inAlbizia lebbek (L.) Benth. of different provenances

Protein, oil, carbohydrate and starch contents of seed, which were collected from places with latitude 9° N to 32° N, longitude 72° E to 85° E and rainfall 40 to 400 cm, varied significantly (P<0.05) among 12 provenances. Interestingly, seed protein was positively correlated (r=0.838,P<0.05), and on the contrary, carbohydrate and starch were negatively correlated (r=–0.755,r=–0.623, respectively,P<0.05), with the latitude of the seed source. Significant variation for N, P, K, Ca and Mg in stems and leaves of one-year and three-year-old plants was also observed when these provenances were grown at Hisar (29°10 N, 75° 46 E, 215 m alt.), an arid region in north India. In general, provenances from north India at the age of three years had greater chemical and mineral contents than those from south India. Chlorophyll content was highly correlated with the latitude of the seed source, at the ages of one and three years (r=0.742,r=0.659,P<0.05, respectively), while crude protein of foliage at the age of three years was significantly correlated (r=0.673) with latitude. Dehradun, Jammu and Hisar provenances, from the north had comparatively greater concentrations of N, P and K at the age of three years as compared to those from south India. The results are useful from the points of view of genetical variation, and selection of superior provenances for arid conditions in north India.     

Development and population growth of <Emphasis Type="Italic">Stephanitis pyri</Emphasis> (F.) (Heteroptera: Tingidae) at five temperatures

Pear lace bug, Stephanitis pyri (F.) (Heteroptera: Tingidae) is a pest of apple and pear trees and ornamental Rosaceae plants in Mediterranean countries and palearctic region. The aim of this study is to determine the effects of temperatures on S. pyri in the laboratory. Development and fecundity of S. pyri reared on apple leaves (Pyrus malus L.) were investigated at five constant temperatures (20, 23, 26, 29 and 32 ± 1°C) and a 16L:8D photoperiod. Longevity was determined to be 12.6 days at 32°C and 58.7 days at 20°C for females, and 9.7 and 37.7 days for males. Females laid 186.9 eggs per female with the highest number achieved during 28.5 days of oviposition period at 26°C. Female lifetime fecundity was reduced at 32°C (40.0 eggs per female). While the net reproductive rate (R ₀) was highest at 26°C, the intrinsic rate of natural increase (r _m ) was highest at both 26 and 32°C. The mean generation time (G) was estimated to be 27.2–78.4 days at 20 and 32°C, respectively. The longest development times for egg and total nymph stages were obtained as 22.0 and 24.9 days, respectively, at 20°C. S. pyri developed fastest from egg to egg in 24.3 days at 32°C. The lower developmental threshold (T ₀) was 9.7°C and the thermal constant (K) was 517.3 degree-days for S. pyri. Thus, S. pyri is calculated to have 3.8 theoretical generations in Tekirdag. The optimum developmental temperature for S. pyri was 26°C.     

Soil–atmosphere CO2, CH4 and N2O fluxes in boreal forestry-drained peatlands

Greenhouse gas emissions from managed peatlands are annually reported to the UNFCCC. For the estimation of greenhouse gas (GHG) balances on a country-wide basis, it is necessary to know how soil–atmosphere fluxes are associated with variables that are available for spatial upscaling. We measured momentary soil–atmosphere CO₂ (heterotrophic and total soil respiration), CH₄ and N₂O fluxes at 68 forestry-drained peatland sites in Finland over two growing seasons. We estimated annual CO₂ effluxes for the sites using site-specific temperature regressions and simulations in half-hourly time steps. Annual CH₄ and N₂O fluxes were interpolated from the measurements. We then tested how well climate and site variables derived from forest inventory results and weather statistics could be used to explain between-site variation in the annual fluxes. The estimated annual CO₂ effluxes ranged from 1165 to 4437 g m⁻² year⁻¹ (total soil respiration) and from 534 to 2455 g m⁻² year⁻¹ (heterotrophic soil respiration). Means of 95% confidence intervals were ±12% of total and ±22% of heterotrophic soil respiration. Estimated annual CO₂ efflux was strongly correlated with soil respiration at the reference temperature (10 °C) and with summer mean air temperature. Temperature sensitivity had little effect on the estimated annual fluxes. Models with tree stand stem volume, site type and summer mean air temperature as independent variables explained 56% of total and 57% of heterotrophic annual CO₂ effluxes. Adding summer mean water table depth to the models raised the explanatory power to 66% and 64% respectively. Most of the sites were small CH₄ sinks and N₂O sources. The interpolated annual CH₄ flux (range: −0.97 to 12.50 g m⁻² year⁻¹) was best explained by summer mean water table depth (r² = 64%) and rather weakly by tree stand stem volume (r² = 22%) and mire vegetation cover (r² = 15%). N₂O flux (range: −0.03 to 0.92 g m⁻² year⁻¹) was best explained by peat CN ratio (r² = 35%). Site type explained 13% of annual N₂O flux. We suggest that water table depth should be measured in national land-use inventories for improving the estimation of country-level GHG fluxes for peatlands.     

The optimum temperature–humidity combination for the feeding activities of Japanese subterranean termites

Two species of Japanese subterranean termite, Coptotermes formosanus Shiraki and Reticulitermes speratus (Kolbe), were used in an investigation of the optimum temperature–relative humidity (RH) combination for their feeding activities. Daily wood consumption per worker and survivals were measured, and the protozoan fauna in the hindgut were observed under 15 temperature–RH combinations for 1 week. Five temperatures (20°, 25°, 30°, 35°, and 40°C) and three RH conditions (50%, 70%, and 90% RH) were examined. The activities of the workers were highest at around 30°C for both species, and workers died at 40°C within 5 days and 2 days for C. formosanus and R. speratus, respectively. The optimum RH condition for feeding activity was 90% RH for C. formosanus and 70%–90% RH for R. speratus. The optimum temperature–RH combinations for feeding activities were 30°C at 90% RH for C. formosanus and 30°C at 70%–90% RH for R. speratus.     

Changes in Buprestidae (Coleoptera) community with successional age after fire in a Pinus brutia forest

Fire is a frequent and common disturbance factor in Mediterranean ecosystems. It is a most spectacular ecological force because it destroys ecosystems in a very short time. Pinus brutia Ten. forests, which are one of the most widespread ecosystems in the eastern Mediterranean rim, have developed adaptations against fire. The adaptations evolved by plant species have been studied extensively. However, the response of insects, which are an important part of the ecosystem, has received little attention. In this study, we investigated the effects of fire on the community structure of Buprestidae over the long term and along a successional gradient. The study was carried out at the Marmaris National Park (N 36°50, E 28°17), which is located in southwestern Turkey. Four sites were selected to represent the different stages of succession. Buprestids were sampled using sweep nets with a 32-cm diameter that were swung 200 times while walking along a 100-m transect in three sampling lines. Total abundance, species richness and the Shannon diversity index were used in order to compare the Buprestidae community at different successional stages. Twenty-seven individuals belonging to 11 species were found. Total abundance and species richness decreased with successional age. Both parameters were significantly and negatively correlated with time since fire (respectively r_s=–0.547, P=0.013, n=20; r_s=–0.479, P=0.033, n=20). The results showed that fire affects the Buprestidae community through food supply and changes of habitat. Buprestidae species benefited from conditions that occurred after fire. Weakened trees, spread branches and trunks constituted suitable food resources for the wood-boring beetles in early successional sites. In addition, because of the low abundance of Buprestidae species, no damages were observed on pine seedlings in early successional sites.