Effects of temperature, age and body size on moulting and growth in the freshwater amphipods Gammarus fossarum and G. roeseli

1. The total body length, cephalic length, wet weight and dry weight was measured in juveniles, males and females of Gammarus fossarum and G. roeseli kept in the laboratory. Numbers of flagellar segments on the first and second pairs of antennae of G. fossarum and G. roeseli were quantitatively related to body size and in stars. The addition of segments cannot be used to identify particular instars of individuals or to determine their ages in natural populations. 2. At experimental temperatures ranging from 3.8 to 20.2°C, the number of moults, duration of intermoults, maturation times and specific growth rates were studied from birth in isolated specimens. Sexual maturity was reached after 9 or 10 moults, at a mean wet weight of c. 5mg for females and c. 7mg for males of G. fossarum, and at c. 10 mg for females and c. 13 mg for males of G. roeseli. At 3.8°C neither species reached sexual maturity within 550 days. 3. The mean interval between moults was observed from birth to sexual maturity and was linearly related to moult number and exponentially related to age. The relationship between each intermoult interval, or the maturation time, and the experimental water temperature was described by a power function. Maturation times increased from 96 days at 20.2°C to 355 days at 7.9°C in G. fossarum, and 85 days to 403 days in G. roeseli. 4. Over the range 3.8–20.2°C there was a log—log relationship between temperature and specific growth rates. Growth was maximal at 20.2°C in newborn animals as well as in small sexually mature animals; interspecific differences were highly significant. 5. Increase in body wet weight of G. fossarum and G. roeseli fed ad libitum on a constant mixture of autumn-shed, naturally decaying, tree leaves and aquatic macrophytes was followed to senescence and death. The instantaneous or specific growth rate was maximal near birth, at c. 7.98% wet weight day^?1 in G. fossarum and 9.03% in G. roeseli. At ≥12°C, growth conformed to a logistic curve; maximum absolute increments in weight occurred about half-way through a life span of 280–300 days at 20°C, 380–420 days at 16°C and 550–600 days at 12°C. Some individuals lived longer than 850 days at ≤12°C. The wet weight at birth was 0.112mg for G. fossarum and 0.123mg for G. roeseli. Asymptotic mean body weights of males and females were, respectively, 61 and 41 mg for G. fossarum and 87 and 58 mg for G. roeseli. However, G. roeseli reached the inflection point of the logistic curve significantly faster than G. fossarum. In the latter species, growth and maturation were relatively faster at temperatures below 12°C, whereas they were faster in G. roeseli at 16–20°C. Thus G. fossarum is adapted to summer-cool streams and G. roeseli is adapted to summer-warm streams.     

Number of flagellar segments and moulting in the amphipod Gammarus pulex

SUMMARY. The number of flagellar segments on the antennules of Gammarus pulex was quantitatively related to body size in animals from natural populations and to moulting and instar number of isolated animals grown from birth in the laboratory. The number of segments was 5.0 at birth increasing to means of 19–20 in females and 21–22 in males at sexual maturity or c. 5 mg wet wt reached after nine or ten moults. Addition of segments to the paired flagellae of juveniles was not regular and the number of segments cannot be used to identify particular instars of individuals or to determine their age. The mean interval (days) between moults progressively increased in the later juvenile instars and was exponentially related to moult number, age and the number of flagellar segments; the moult interval is also exponentially related to these variables in adults.     

Effects of temperature on the development and survival of an endangered butterfly,Lycaeides argyrognomon (Lepidoptera: Lycaenidae) with estimation of optimal and threshold temperatures using linear and nonlinear models

The effects of temperature on the development and survival of Lycaeides argyrognomon were examined in the laboratory. The eggs, larvae and pupae were reared at temperatures of 15, 17.5, 20, 25, 30 and 33°C under a long‐day photoperiod of 16‐h light and 8‐h darkness. The survival rates of the first–third instars ranged from 40.0 to 82.4%. The mortalities of the fourth instar were lower than those of the first–third instars. The development time of the overall immature stage decreased from 78.33 days at 15°C to 21.07 days at 30°C, and then increased to 24.33 days at 33°C. The common linear model and the Ikemoto–Takai model were used to estimate the thermal constant (K) and the developmental zero (T₀). The values of T₀ and K for the overall immature stages were 10.50°C and 418.83 degree‐days, and 9.71°C and 451.68 degree‐days by the common model and the Ikemoto–Takai model, respectively. The upper temperature thresholds (T_max) and the optimal temperatures (T_opt) of the egg, the first–third instars and the overall immature stages were estimated by the three nonlinear models. The ranges of T_opt estimated were from 30.33°C to 32.46°C in the overall immature stages and the estimates of T_max of the overall immature stages by the Briere‐1 and the Briere‐2 models were 37.18°C and 33.00°C, respectively. The method to predict the developmental period of L. argyrognomon using the nonlinear models was discussed based on the data of the average temperature per hour.     

Effects of diet, body size, age and temperature on growth rates in the amphipod Gammarus pulex

SUMMARY. Increase in body wet weight of Gammarus pulex fed on decaying elm leaves was followed to senescence and death. Growth in juveniles was approximately exponential; from birth to death it conformed to a logistic growth curve, with maximum absolute increments in weight about half-way through a life span of 350–450 days at 15°C. Some individuals lived longer, for up to 640–700 days. The instantaneous or specific growth rate was maximal near birth, at c. 5–6% wet wt day^?1, and declined exponentially with increasing size and age. Over the range 4.7–14.8°C there was a log-log relationship between temperature and specific growth rate. Growth was maximal at 20°C in newborn animals and at 15°C in 6–9-mg animals. The specific growth rate of young individuals was fastest on decaying leaves of elm with a well developed flora of fungi and other microorganisms. Leached elm leaves without this flora supported growth at a lower rate. The latter diet was sufficient for survival and growth of newborn individuals; detritus, faeces or other food items were not needed. Isolated specimens grew as fast as those kept in groups. Growth was generally slower on leached leaves of oak and sycamore. In newborn animals fed on the fine roots of aquatic plants (Veronica, Rorippa and Glyceria), growth was as fast as on decaying elm leaves; growth on the green living leaves of the plants was slower, as on detritus from two streams and on a pure culture of an aquatic fungus. Consumption of leached elm leaves was related to leaf thickness. In a full gut the wet weight (1.34–1.37 mg) and volume (3.8–4.1 mm³) (for 20-mg animals) was independent of leaf thickness but dependent on animal size, increasing 4-fold over the range 2–50 mg body wt. Daily consumption (dry wt) was approximately equivalent to 50% body dry wt at 5 mg and 20% at 50 mg body wet wt. Individuals fed on thick leaves ingested 50% more dry weight per day and absorbed more in the gut than when fed on thin leaves, but the relative efficiency of absorption was the same at 36–59% for 10–20-mg animals. Weight-specific absorption in the gut was highest in juveniles and decreased with increasing body weight; relative efficiency of absorption was generally lower in the larger individuals. Assuming an energy value of 5 cal mg^?1 dry wt for elm leaves, daily mean energy intake by absorption in thegutof G. pu/ex was2.2 cal mg^?1 animaldry wt (9.2 J mg^?1) in individuals of 0.4 mgdry wt (2 mg wet wt), decreasing to 0.3 cal mg^?1 (1.3 J mg^?1) at 10 mg dry wt (50 mg wet wt). Growth in Gammarus is briefly reviewed in the hght of work on other animals and it is emphasized that all aspects of feeding, growth and metabol-ism should be specifically related to size and age of the individuals, using well defined diets.     

Temperature‐dependent demography of Agriphila aeneociliella (Lepidoptera: Crambidae), a new insect pest of wheat in China

相似文献   

The effect of temperature on the development times of eggs,naupliar and copepodite stages of five species of cyclopoid copepods

The duration times of eggs, combined naupliar instars and of the different copepodite stages of five species of cyclopoid copepods — Acanthocyclops robustus, Cyclops vicinus, Diacyclops bicuspidatus, Mesocyclops leuckarti, and Thermocyclops crassus — were investigated at five different temperatures. The five species can be divided in two groups: two species, C. vicinus and D. bicuspidatus, adapted to cold water conditions and three species, A. robustus, M. leuckarti and T. crassus adapted to warm water conditions. The cold water species showed a faster egg development than M. leuckarti and T. crassus at 5–15 °C. The eggs and instars of the warm water species M. leuckarti tend to develop faster than those of the former two species at higher temperatures. A. robustus showed the shortest egg and instar development at 10–25 °C. The warm water species T. crassus produced no eggs at 10 °C and temperatures below. At higher temperatures (20, 25 °C) the egg and instar duration times were similar or longer than those of the other species. When cultured in total darkness a great part of the C_IV respectively C_V copepodites of the summer forms entered arrest and the percentage of copepodites that showed an arrest of development was highest at lowest temperatures. The present results are compared with data from literature and differences are discussed.     

Germination and emergence of Sorghum bicolor. genotypic and environmentally induced variation in the response to temperature and depth of sowing

Abstract The germination of Sorghum bicolor seeds of 9 genotypes was tested at temperatures between 8°C and 48°C on a thermal gradient plate. Samples were tested from three regions of the panicle expected to differ in temperature during grain filling. Seeds of a tenth genotype, SPV 354, produced in controlled-environment glasshouses at different panicle temperatures, were tested similarly. In addition, the emergence of SPV 354 was measured from planting depths of 2 and 5 cm at mean soil temperatures of 15, 20 and 25°C. Four methods of calculating mean germination rate for the nine genotypes were compared. Germination characters like base, optimum and maximum temperature (T_b, T_o, T_m), thermal time (θ)and the germination rate at T_o(R_max showed only small differences between methods. There was a range of genotypic variation in all characters: T_b 8.5–11.9°C; T_o, 33.2–37.5°C; T_m, 46.8–49.2°C; θ, 23.4–38.0°Cd; R_max, 0.69–1.14-d_-1. In contrast, mean germinability (G) was between 90% and 100% over the temperature range 13–40°C. Panicle temperature had no effect on any germination character in SPV 354. However, deeper burial increased θ for emergence and decreased G, irrespective of soil temperature except at 5 cm. Increasing panicle temperature, by reducing seed size, reduced G and increased θ by about 10% only at 15°C and 5 cm depth.     

The life stages and population dynamics of an arid zone scorpion Urodacus yaschenkoi (Birula 1903)

The arid zone scorpion Urodacus yaschenkoi (Birula 1903) is shown to have six instars. Instars can be recognized by measuring the claws and the carapace plus first five tail segments. A population study, carried out at Coombah, NSW, showed that the life history consisted of mating in September–October, 18 month gestation, birth in February-March, moult to second instar March-April and annual moults to sixth instar in December–February. The minimum generation time was 6 y, and the population appeared to be stable. The calendar of catches method was used to determine the population size (about 400 animals in 2240 m²) but required some extra assumptions to cope with loss of marks from individuals when they moulted.     

Impact of heat shock on heat shock proteins expression, biological and commercial traits of Bombyx mori

We report the thermotolerance of new bivoltine silkworm, Bombyx mori strains NB₄D₂, KSO₁, NP₂, CSR₂ and CSR₄and differential expression of heat shock proteins at different instars. Different instars of silkworm larva were subjected to heat shock at 35°C, 40°C and 45°C for 2 hours followed by 2 hours recovery. Heat shock proteins were analyzed by SDS‐PAGE. The impact of heat shock on commercial traits of cocoons was analyzed by following different strategies in terms of acquired thermotolerance over control. Comparatively NP₂ exhibited better survivability than other strains. Resistance to heat shock was increased as larval development proceeds in the order of first instar > second instar > third instar > fourth instar > fifth instar in all silkworm strains. Expression of heat shock proteins varies in different instars. 90 kDa in the first, second and third instars, 84 kDa in the fourth instar and 84, 62, 60, 47 and 33 kDa heat shock proteins in fifth instar was observed in response to heat shock. Relative influence of heat shock on commercial traits that correspond to different stages was significant in all strains. In NB₄D₂, cocoon and shell weight significantly increased to 17.52% and 19.44% over control respectively. Heat shock proteins as molecular markers for evaluation and evolution of thermotolerant silkworm strains for tropics was discussed.     

Interactive effects of low atmospheric CO2 and elevated temperature on growth, photosynthesis and respiration in Phaseolus vulgaris

For most of the past 250 000 years, atmospheric CO₂ has been 30–50% lower than the current level of 360 μmol CO₂ mol^–1 air. Although the effects of CO₂ on plant performance are well recognized, the effects of low CO₂ in combination with abiotic stress remain poorly understood. In this study, a growth chamber experiment using a two-by-two factorial design of CO₂ (380 μmol mol^–1, 200 μmol mol^–1) and temperature (25/20 °C day/night, 36/29 °C) was conducted to evaluate the interactive effects of CO₂ and temperature variation on growth, tissue chemistry and leaf gas exchange of Phaseolus vulgaris. Relative to plants grown at 380 μmol mol^–1 and 25/20 °C, whole plant biomass was 36% less at 380 μmol mol^–1× 36/29 °C, and 37% less at 200 μmol mol^–1× 25/20 °C. Most significantly, growth at 200 μmol mol^–1× 36/29 °C resulted in 77% less biomass relative to plants grown at 380 μmol mol^–1× 25/20 °C. The net CO₂ assimilation rate of leaves grown in 200 μmol mol^–1× 25/20 °C was 40% lower than in leaves from 380 μmol mol^–1× 25/20 °C, but similar to leaves in 200 μmol mol^–1× 36/29 °C. The leaves produced in low CO₂ and high temperature respired at a rate that was double that of leaves from the 380μmol mol^–1× 25/20 °C treatment. Despite this, there was little evidence that leaves at low CO₂ and high temperature were carbohydrate deficient, because soluble sugars, starch and total non-structural carbohydrates of leaves from the 200μmol mol^–1× 36/29 °C treatment were not significantly different in leaves from the 380μmol mol^–1× 25/20 °C treatment. Similarly, there was no significant difference in percentage root carbon, leaf chlorophyll and leaf/root nitrogen between the low CO₂× high temperature treatment and ambient CO₂ controls. Decreased plant growth was correlated with neither leaf gas exchange nor tissue chemistry. Rather, leaf and root growth were the most affected responses, declining in equivalent proportions as total biomass production. Because of this close association, the mechanisms controlling leaf and root growth appear to have the greatest control over the response to heat stress and CO₂ reduction in P. vulgaris.     

Strong thermal acclimation of photosynthesis in tropical and temperate wet‐forest tree species: the importance of altered Rubisco content

Understanding of the extent of acclimation of light‐saturated net photosynthesis (A_n) to temperature (T), and associated underlying mechanisms, remains limited. This is a key knowledge gap given the importance of thermal acclimation for plant functioning, both under current and future higher temperatures, limiting the accuracy and realism of Earth system model (ESM) predictions. Given this, we analysed and modelled T‐dependent changes in photosynthetic capacity in 10 wet‐forest tree species: six from temperate forests and four from tropical forests. Temperate and tropical species were each acclimated to three daytime growth temperatures (T_growth): temperate – 15, 20 and 25 °C; tropical – 25, 30 and 35 °C. CO₂ response curves of A_n were used to model maximal rates of RuBP (ribulose‐1,5‐bisphosphate) carboxylation (V_cmax) and electron transport (J_max) at each treatment's respective T_growth and at a common measurement T (25 °C). SDS‐PAGE gels were used to determine abundance of the CO₂‐fixing enzyme, Rubisco. Leaf chlorophyll, nitrogen (N) and mass per unit leaf area (LMA) were also determined. For all species and T_growth, A_n at current atmospheric CO₂ partial pressure was Rubisco‐limited. Across all species, LMA decreased with increasing T_growth. Similarly, area‐based rates of V_cmax at a measurement T of 25 °C (V_cmax²⁵) linearly declined with increasing T_growth, linked to a concomitant decline in total leaf protein per unit leaf area and Rubisco as a percentage of leaf N. The decline in Rubisco constrained V_cmax and A_n for leaves developed at higher T_growth and resulted in poor predictions of photosynthesis by currently widely used models that do not account for T_growth‐mediated changes in Rubisco abundance that underpin the thermal acclimation response of photosynthesis in wet‐forest tree species. A new model is proposed that accounts for the effect of T_growth‐mediated declines in V_cmax²⁵ on A_n, complementing current photosynthetic thermal acclimation models that do not account for T sensitivity of V_cmax²⁵.     

Life history and production of the predatory caddisfly Rhyacophila vao Milne in a spring-fed stream

1. The predatory caddisfly Rhyacophila vao Milne (Rhyacophilidae) displayed a 2-year, semivoltine life cycle in a small, spring-fed stream in southern Alberta, Canada. Three overlapping cohorts were identified throughout the 2-year sampling program, with five larval instars recognized. Larvae overwintered in instars I —ELI, developed to instar IV by summer and instar V by autumn. The second winter was spent in instar V, Pupation occurred from late May to August and did not commence until stream temperature exceeded 3°C. Adults were collected from mid-June to early September. 2. Larvae displayed a diphasic growth pattern: Phase I, a positive, non-linear growth rate for instars I-IV; Phase II, a constant growth rate during instar V. Phase I coincided with increasing stream temperatures in late winter and spring, where mean instantaneous growth rates (maximum of 2.78% dry wt day^?1) were significantly correlated with stream temperatures. Although the duration of Phase II spanned a temperature range similar to that in Phase I, the instantaneous growth rate remained temperature-independent at 0.87% dry wt day^?1. 3. Larvae exhibited a type III survivorship curve (i.e. an exponential decrease on an arithmetic scale), with the finite rate of mortality averaging 0.80% larvae day^?1. 4. Cohort 1 (later part of 1983 year class) displayed lower total production compared with the equivalent growth phase in the 1984 year class (Cohort 2). In contrast, production of the non-linear and linear growth phases of Cohort 2 was similar. Periods of similar growth characteristics for Cohorts 1 and 2 had comparable P/B ratios for both the unadjusted and time-adjusted annual estimates, although higher ratios were observed for the non-linear growth phase of Cohort 2. Total cohort production (linear + non-linear growth phases) could only be calculated for Cohort 2, and was 870.2 ± 1011.4 mg dry wt m^?2. The corresponding cohort P/B ratio was 5.01 and the adjusted annual P/B, 3.01. 5. Annual larval production (±SE) for the first and second years of the study was similar (Year 1, 480.0 ± 387.5mg dry wt m^?2; Year 2, 526.9 ± 967.5mg dry wt m^?2) as were unadjusted and annual P/B ratios.     

Effects of temperature on biology and life table parameters of the Asian citrus psyllid, Diaphorina citri Kuwayama (Homoptera: Psyllidae)

The development, survivorship, longevity, reproduction, and life table parameters of the Asian citrus psyllid, Diaphorina citri Kuwayama were evaluated at 10°C, 15°C, 20°C, 25°C, 28°C, 30°C and 33°C. The populations reared at 10°C and 33°C failed to develop. Between 15°C and 30°C, mean developmental period from egg to adult varied from 49.3 days at 15°C to 14.1 days at 28°C. The low‐temperature developmental thresholds for 1st through 5th instars were estimated at 11.7°C, 10.7°C, 10.1°C, 10.5°C and 10.9°C, respectively. A modified Logan model was used to describe the relationship between developmental rate and temperature. The survival of the 3rd through 5th nymphal instars at 15–28°C was essentially the same. The mean longevity of females increased with decreasing temperature within 15–30°C. The maximal longevity of individual females was recorded 117, 60, 56, 52 and 51 days at 15°C, 20°C, 25°C, 28°C and 30°C, respectively. The average number of eggs produced per female significantly increased with increasing temperature and reached a maximum of 748.3 eggs at 28°C (P<0.001). The population reared at 28°C had the highest intrinsic rate of increased (0.199) and net reproductive rate (292.2); and the shortest population doubling time (3.5 days) and mean generation time (28.6 days) compared with populations reared at 15–25°C. The optimum range of temperatures for D. citri population growth was 25–28°C.     

Growth and annual production of the brown alga Laminaria religiosa introduced into the Uwa Sea in southern Japan

Recently, aquaculture of Laminaria japonica has expanded to the southern coast of Japan and to China along the East China Sea. The southerly distribution of L. religiosa, compared to that of L. japonica, indicated that the aquaculture of L. religiosa along the southern coasts of Japan might be feasible. Thus, we examined the growth, biomass and productivity of L. religiosa cultivated in the Uwa Sea, in southwestern Japan over a period of two years. The seawater temperature ranged from 12.9 to 27.4°C in 2003/2004 and from 12.2 to 28.3°C in 2004/2005. In 2003/2004, the maximum mean density, maximum mean length, and maximum mean wet weight of L. religiosa was 7.8 ± 5.0 ind. m⁻¹ (mean ± SD), 14.8 ± 4.6 cm, and 1.2 ± 0.8 g wet wt., respectively. In 2004/2005, no germination was confirmed through the study period. The maximum biomass and annual production in 2003/2004 were estimated to be 6.9 ± 5.2 g wet wt. m⁻¹ and 8.9 g wet wt. m⁻¹ year⁻¹, respectively. The present study revealed that L. religiosa cultivated in the Uwa Sea were much smaller compared with those of Hokkaido Island, where the alga is naturally found. For the growth of L. religiosa, a relatively long period of seawater temperatures below 13.5°C is required. In the study area, seawater temperatures were below 13.5°C only 11 days in 2003, and 12 days in 2004. As a result, it is thought that expanding the cultivation of L. religiosa to southern areas including the Uwa Sea will be difficult.     

Predation capacity and prey preference of <Emphasis Type="Italic">Chrysoperla carnea</Emphasis> on <Emphasis Type="Italic">Pieris brassicae</Emphasis>

The predation capacity and prey preference of larvae of Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) on eggs or larvae of Pieris brassicae (Linnaeus) (Lepidoptera: Pieridae) in the absence and presence of cabbage aphids as an alternative prey were evaluated in laboratory experiments at 25°C. Both instars preyed upon butterfly eggs and larvae as well as on cabbage aphids with the third instar being the most voracious. The lacewings had a strong preference for caterpillars to butterfly eggs. In the presence of the aphids the predation on P. brassicae eggs or larvae was either completely abandoned or reduced by about 70%, respectively, by second instar lacewings and either reduced by about 80% or maintained, respectively, by third instar lacewings. Both instars thus had a clear preference for aphids compared to eggs of P. brassicae. However, second instar lacewings preferred aphids to caterpillars whereas the opposite was the case for third instar lacewings. The results indicate that 3rd instar C. carnea has a potential as biocontrol agent against P. brassicae.     

Reproductive potential and lifetime potential fecundity of the freshwater amphipods Gammarus fossarunt and G. roeseli in Austrian streams and rivers

• 1 Fecundity of Gammarus fossarum populations at six stream sites (S1-S6) and G. roeseli populations at two sites (S5 and S6) was studied monthly during 1985–1988, distinguishing seven morphological stages of embryonic development. Mean survival of G. fossarum eggs was 65% (60–70%) in nature and 60% (57–63%) in the laboratory; egg survival of G. roeseli was 52% (46–58%) in nature and 41% (35–47%) in the laboratory. Regressions of egg numbers per clutch against body wet weight (WWT) decreased significantly for egg developmental stages 2 to 7 (hatching).
• 2 In stream populations, ovigerous females of G. fossarum were absent in October (six sites) and November (five sites); ovigerous G. roeseli were usually absent from October until March.
• 3 Overall mean egg volume (EV) increased significantly from 0,08 ± 0.001 mm³ and 0.075 ± 0.001 mm³ for stage 2 eggs, to 0.174 ± 0.012mm³ and 0.160 ± 0.013 mm³ for stage 6 eggs of G. fossarum and G. roeseli, respectively. The dry weights of stage 2 eggs, stage 6 eggs and neonates (stage 7) were not significantly different, within and between species; mean dry weight was 36 ± 3 μg.
• 4 Egg volumes and fecundity indices (FI, weight-specific number of eggs per clutch) were not significantly different between the same months of four successive years, so the data were pooled to give a single representative ‘year’. At most sites there were marked seasonal fluctuations in these variables. In both species, mean EV was largest for ‘winter’ eggs in December/January and smallest for ‘summer’ eggs in May, EV decreased during some months of the year when FI increased, and vice versa. Mean reproductive effort (RE = EV × FI) declined from high ‘winter’ values to low ‘summer’ values, and this difference was most marked at sites where the major foodstuff available was seasonally limited (autumn-shed tree leaves). Overall (‘annual’) mean RE was also lowest at these sites (S3 and S4) but was some 13% greater at sites where nutrients and food were present in the greatest quantifies (S5 and S6). Specific maximum potential body sizes and hence maximum potential fecundities (fifty-nine eggs for G. fossarum and eighty-seven eggs for G. roeseli) were attained only at S5 and 56. Mean RE was nearly identical for G. fossarum and G. roeseli from the same sites.
• 5 At experimental temperatures (T) in the range 3.8–20.2°C, females of the same body weight carried significantly different egg numbers per clutch. The relationship between FI and T was described by a second-order polynomial. The calculated optimum T was 12.1°C for G. fossarum and 16.3°C for G. roeseli. Interspecific differences were highly significant.
• 6 Theoretical lifetime potential fecundity was approximately 194 eggs for G. fossarum

     

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

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

Functional response of Chrysoperla carnea (Neuroptera: Chrysopidae) to Helicoverpa armigera (Lepidoptera: Noctuidae): Effect of prey and predator stages

Abstract Understanding predator–prey interactions has a pivotal role in biological control programs. This study evaluated the functional response of three larval instars of the green lacewing, Chrysoperla carnea (Stephens), preying upon eggs and first instar larvae of the cotton bollworm, Helicoverpa armigera Hübner. The first and second instar larvae of C. carnea exhibited type II functional responses against both prey stages. However, the third instar larvae of C. carnea showed a type II functional response to the first instar larvae of H. armigera, but a type III functional response to the eggs. For the first instar larvae of C. carnea, the attack rate on H. armigera eggs was significantly higher than that on the larvae, whereas the attack rate of the second instar C. carnea on H. armigera larvae was significantly higher than that on the eggs. For the third instar larvae of C. carnea, the attack rate on the larvae was 1.015 ± 0.278/h, and the attack coefficient on the eggs was 0.036 ± 0.005. The handling times of the third instar larvae on larvae and eggs were 0.087 ± 0.009 and 0.071 ± 0.001 h, respectively. The highest predation rate was found for the third instar larvae of C. carnea on H. armigera eggs. Results of this study revealed that the larvae of C. carnea, especially the third instar, had a good predation potential in controlling H. armigera eggs and larvae. However, for a comprehensive estimation of the bio‐control abilities of C. carnea toward H. armigera, further field‐based studies are needed.     

Life history studies of anisocentropus kirramus neboiss (trichoptera: Calamoceratidae) in a tropical Australian rainforest stream

Eggs and larvae of Anisocentropus kirramus were collected from leaf packs in riffles and pools in a small upland rainforest stream in tropical Queensland. Adults were collected in floating emergence traps. Egg masses contained 80–100 eggs. None developed in water at 12–15°C but at 22–25°C larvae hatched in 3–10 days. There were five larval instars and complete development appeared to take several months. Instars II‐V were present in all nine months sampled; instar I was present in all but one month. Adults emerged in all ten months sampled, but there was clear seasonality with peak emergence in the summer. The sex ratio of adults was 1:1.