Biology of the House Fly Predator <Emphasis Type="Italic">Carcinops pumilio</Emphasis> (Erichson) (Coleoptera: Histeridae)

Two larval instars of Carcinops pumilio (Erichson) were identified from a frequency distribution of the head capsule measurements. The total developmental time from egg to adult emergence averaged 20.5 ± 0.1 days at 30 °C. The 2nd instar was the longest, accounting for 39% of the total development time. The 1st instar larvae sustained the highest mortality of 26% whilst there was no mortality in the pupal stage. The immature stages sustained about 50% mortality before adult emergence. The adult females of C. pumilio can live for 140 days and the rate of survival was high in the young adults but decreased as the beetles aged. Newly emerged adults survived for 25.5 ± 0.4 days without feeding. The sex ratio was 0.48 females: 0.52 males. The intrinsic rate of natural increase (r_m) was 0.065, the generation time (T) was 50.019 days and the net reproduction rate (R_o) was 20.191.     

Effect of Azo Dyes on Survivorship,Oxygen Consumption Rate,and Filtration Rate of the Freshwater Cladoceran Moina macrocopa

Toxicity of the azo dyes Procion Red MX-5B (PR), Procion Yellow HE-4R (PY), and Congo Red (CR) on the freshwater cladoceran Moina macrocopa was studied. The 4-day LC₅₀ values for PR, PY, and CR were 59.0, 9.50, and 0.16 mg/L, respectively. Reproduction was a more sensitive endpoint than mortality. The onset of reproduction was delayed at azo dye concentrations ≥ 0.01 mg/L. The total number of young produced over 7 days was reduced by 49.8% in PR, 44.5% in PY, and 69.0% in CR. No reproduction was recorded at PY concentrations ≥ 100 mg/L and CR concentrations ≥ 1.0 mg/L. A significant decrease in oxygen consumption rate was observed after 4 days of exposure to azo dyes at concentration equivalent to 25% of the 4-day LC₅₀. The effect of CR on oxygen consumption rate was observed after 4 days of exposure to a concentration equivalent to 10% of the 4-day LC₅₀. Filtration rate was a more sensitive endpoint than oxygen consumption rate. For all three dyes, filtration rate was reduced after 4 days of exposure to concentrations equivalent to 10% of the 4-day LC₅₀. Based on mortality, reproduction, oxygen consumption, and filtration, the order of toxicity was CR > PY > PR.     

Life Tables of Phytoseiulus Macropilis (Banks) (Gamasida: Phytoseiidae) at Different Temperatures

The biology of Phytoseiulus macropilis (Banks) fed on Tetranychus urticae Koch was studied at different temperatures. The total development times averaged 7.5, 5.7, 4.2, 4.2 and 5.6 days at 20, 25, 28, 30 and 32°C, respectively at 78 ± 2% RH and 16 h photoperiod daily. The intrinsic rate of natural increase (r _m) and the net reproduction (R _o) reached maximum values 0.47 and 88.9, respectively, at 28°C. The mean generation time decreased (20.0-8.8 days) with increasing temperature 20-28°C.     

Development and reproduction of Stratiolaelaps scimitus (Acari: Laelapidae) with fungus gnat larvae (Diptera: Sciaridae), potworms (Oligochaeta: Enchytraeidae) or Sancassania aff. sphaerogaster (Acari: Acaridae) as the sole food source

Stratiolaelaps ( = Hypoaspis) miles (Berlese) (Acari: Mesostigmata: Laelapidae) is a polyphagous soil-dwelling predatory mite that is widely marketed for use in greenhouse production systems to manage populations of dark-winged fungus gnats, Bradysia spp. (Diptera: Sciaridae) and for supplemental control of thrips. The suggestion by Walter and Campbell (2003, Biol. Control 26: 253–269) that North American commercial cultures of S. miles may actually be S. scimitus was confirmed. The development and reproduction at 21–23 °C of S. scimitus provided ad libidum with one of three different prey – the fungus gnat Bradysia aff. coprophila (Lintner), potworms (Enchytraeidae), or Sancassania aff. sphaerogaster (Zachvatkin, 1937) (Acari: Astigmata: Acaridae) – were compared. Developmental duration of the egg and non-feeding larval stages were 2.47 and 1.11 days, respectively; mortalities were 8.3 and 5.5%. Stratiolaelaps scimitus failed to develop beyond the protonymphal stage when provided with S. aff. sphaerogaster alone, although some feeding was observed. Development and reproduction of S. scimitus was successful on both fungus gnat larvae and enchytraeids, with no influence of prey on protonymphal duration (4.70 days) and mortality (8.3%), or on deutonymphal duration (4.61 days) and mortality (6.1%). Adult female S. scimitus feeding on potworms, compared to those feeding on fungus gnat larvae, had a significantly shorter pre-oviposition period (2.69 vs. 4.59 days). However, diet did not influence other adult female developmental or reproductive characteristics (oviposition period, 18.6 days; post-oviposition period, 6.2 days; total adult longevity, 27.3 days; total number of eggs, 26.5). S. scimitus reared on potworms tended (p = 0.06) to have a higher intrinsic rate of increase, a higher finite rate of increase and a shorter doubling time (r _m = 0.142 day⁻¹, λ = 1.153, Dt = 4.85 days) than those reared on fungus gnat larvae (r _m = 0.105 day⁻¹, λ = 1.110, Dt = 6.58 days), but differences in net reproductive rate (R ₀) and generation time (G) were not significant.     

醉马草水浸液对豌豆蚜触杀活性及种群增长的影响

为探讨醉马草水浸液对豌豆蚜触杀活性及种群增长的影响,采用带虫浸叶法比较不同生育期醉马草带菌（E+）和不带菌（E-）水浸液对豌豆蚜触杀活性及种群生命表,测定了豌豆蚜的死亡率及触杀后对其生殖期,平均繁殖力,繁殖率及生命表参数的影响。结果表明,不同生育期醉马草带菌（E+）水浸液触杀豌豆蚜后对其各项指标均有显著影响。在苗期时,E+水浸液触杀豌豆蚜后校正死亡率最高,繁殖力最低,内禀增长率（r_m=0.145 d^-1）和净生殖率（R₀=4.802头）均为最小值。在成熟期时,E+水浸液触杀豌豆蚜24 h、48 h和72 h后校正死亡率分别为26.15%,19.01%,9.07%;繁殖期（3.87 d）,平均繁殖力（8.80头）,繁殖率（1.40%）,内禀增长率（r_m=0.208 d^-1）和净生殖率（R₀=8.820头）。在枯黄期时,E+水浸液触杀豌豆蚜后校正死亡率最低,繁殖力最强,内禀增长率（r_m=0.247 d^-1）和净生殖率（R₀=13.647头）均为最大值。不同生育期醉马草E-水浸液触杀豌豆蚜后对其种群繁殖无显著影响,与对照差异不显著（P>0.05）。综上,苗期醉马草E+水浸液对豌豆蚜有较好的触杀效果,校正死亡率高,且触杀后当代繁殖力减弱,种群扩建时间延长,不利于其种群繁殖和增长;故苗期醉马草E+水浸液具有很好的杀虫潜力,所采用水浸液方法制备简单,成本低,可为新型植物源农药研发提供重要理论依据。     

Effect of avermectin and dicofol on the immatures of the predacious miteAmblyseius gossipi with a special reference to the secondary poisoning effect on the adult female [Acari: Phytoseiidae]

Avermectin at 1 ppm was slightly toxic by contact to the different immature stages of the predacious miteAmblyseius gossipi El-Badry. When immatures ofA. gossipi ingested treated prey on clean leaf discs, the toxicity increased and the resulted ΦΦ oviposited at a significantly lower rate. In contrast, dicofol at 250 ppm was extremely toxic by contact and caused a significant mortality to the immatures when it was ingested. Female mortality increased and fecundity decreased as the time of feeding treated prey increased from 24 h to 192 h. In case of dicofol a permanent depression in reproduction was recorded after feeding treated prey for 144 h. Females ofA. gossipi suffered a depression in reproduction when fed on prey formerly kept on plant leaves treated with avermectin. This depression was reported, only, after 192 h of feeding on prey previously reared on leaves treated with dicofol.      

Population parameters and reproduction of the piranha Serrasalmus marginatus in the Negro river,Pantanal, Brazil

This paper aimed to define the reproductive period and population parameters of Serrasalmus marginatus relative to local environmental features, such as day length, rainfall and mean river level. The study site was a floodplain in the Negro river, Pantanal, Brazil, and samples were collected bimonthly using gill nets and cast nets with meshes from 1.5 to 8 cm between adjacent knots. The reproduction period, as determined by gonadosomatic index (GSI) and percentage of gonad stages, varied significantly along the year (F_4,116 = 77.5; p < 0.01), but it was well defined from October to December. Reproduction period was positively correlated with rainfall (rs = 0.97; p < 0.01) and photoperiod (rs = 0.92; p = 0.02), but not with the rise of river level (rs = 0.10; p = 0.86). Rainfall and photoperiod may act as predictive factors, providing cues to fish to begin reproduction in order to find the best conditions for offspring in the following months, during the flooding season, when the river level reaches its peak and extends to the plain. We have herein reported the first population parameters described for this species in the Brazilian Pantanal, including growth rate (k = 0.53/year), asymptotic length (L∞ = 32.74), lifespan (A_0.95 = 5.65) and mortality (M = 1.11), showing that this population has better growth performance when compared to data reported for this same species in the Paraná river since the population in the Negro river is characterized by lower growth and mortality rates, and S. marginatus achieved longer lengths and lifespan. This latter parameter was compatible with six cohorts estimated by Electronic Length Frequency Analysis (ELEFAN). The size at first maturity (L50 = 18.26 cm A50 = 1.56 years) was also larger and later than the population in the Paraná river, likely a consequence of the the lower mortality and the maintenance of larger specimens in the Negro river.     

Quantitative observations on the population ecology of Branchiura sowerbyi (Oligochaeta,Tubificidae)

Cohorts of Branchiura sowerbyi were reared at different temperatures and initial population densities in order to obtain data suitable for the interpretation of population dynamics in field populations. Percent hatching from cocoons reaches its maximum at 25 °C and decreases towards lower and higher temperatures. Embryonic development time, T_E, was measured and the relative threshold temperature, 10 °C, calculated by extrapolation. The degree day requirement for embryo development is 195 °C d. The time of first cocoon laying (T_gm) was observed and the ratio T_E/T_gm was seen to fit with that of other tubificid species cultured so far. Embryo mortality is rather high, while worm mortality is low or very low. Fecundity increases from 15 to 20 °C but decreases at 25 °C. A mathematical model for the simulation of population densities with four size-stage compartments is suggested. It could be used for the optimization of worm uptake (simulated as stage specific mortality) in mass cultures reared for the production of Branchiura, to be used as food for fish fingerlings.     

The effects of a temperature shock on zooplankton

Summary Exposure of 4–5 day oldDaphnia hyalina to temperatures of 32° C and higher caused substantial mortality when the exposure time was an hour or more. The tolerance ofBosmina sp. to temperature shocks appears to be about that ofD. hyalina. Naupllus larvae ofCyclops sp. were much more tolerant.Survival and reproduction ofD. hyalina at high temperatures were strongly influenced by the food concentration. In a high food concentration the reproduction is at 28° C as high as at 20° C.     

Effects of maternal parasite load on offspring life-history traits in the common lizard (Lacerta vivipara)

We studied the effect of maternal ectoparasite load (measured at parturition) on the life-history traits of the offspring of the host Lacerta vivipara, the European common lizard. The ectoparasite, a mite belonging to the family Laelapidae, had a detrimental effect on its host: parasite load was associated with increased host mortality, and was negatively correlated with host body mass. Parasite load was persistent over time, suggesting that parasite load can be predictable. Offspring of highly parasitised mothers had higher values of several fitness components early in life than offspring of parasite-free mothers or lightly infested mothers. This was expressed in terms of increased F₁ yearling growth rate, and reproductive investment at first reproduction (measured as F₂ hatchling mass). These results are interpreted as a host adaptation to attenuate the impact of parasites. Indeed, if high parasite loads arise from long exposure time to a constant population of parasites, and if the negative effects of parasites are additive over time, hosts could reduce the impact of parasites simply by investing more during the earlier stages of life. Naturally, having better performance early in life should lead to higher mortality rates and/or lower fecundity later in life.     

Effects of temperature on acaricidal and insecticidal activities of the benzoylureas flucycloxuron and diflubenzuron

Effects of temperature on the activity of flucycloxuron on larval stages of Panonychus ulmi (Koch), based on LC₅₀ values, were highly significant (P < 0.001) with temperature coefficients of-1.7 in both the ranges of 15° to 25°C and 20° to 30°C. The slopes of probit regression lines at 15° and 20°C were significantly steeper than those at 25° and 30°C. As a consequence the temperature coefficients based on LC₉₀ values were-4.4 and-2.2, for the 2 temperature ranges. The ovicidal activity of flucycloxuron on P. ulmi was low and was only statistically detectable at 20°C (LC₉₀ of 84 mg a.i./l). In studies with larvae of Aedes aegypti (Linnaeus), Leptinotarsa decemlineata (Say), Plutella xylostella (Linnaeus), Spodeptera exigua (Hübner) and Spodoptera littoralis (Boisduval) probit regression lines were parallel over temperature. The activity of flucycloxuron on these five insect species was not affected by temperature. Based on LC₅₀ values, diflubenzuron showed positive temperature coefficients on P. xylostella of + 2.1 at 15° to 25°C and + 2.5 at 20° to 30°C. For S. littoralis the temperature coefficient was positive (+ 2.4) at 15° to 25°C but negative (-1.9) at the 20° to 30°C range. Temperature coefficients of diflubenzuron were neutral for A. aegypti, L. decemlineata and S. exigua. In the design and analysis of these studies special allowance was made for date effects and variation in natural mortality over temperature.     

Life History of Kampimodromus aberrans as a predator of Phytoptus avellanae (Acari: Phytoseiidae, Phytoptidae)

The biology of Kampimodromus aberrans (Oudemans), a predator of the big bud mite, Phytoptus avellanae Nalepa, was studied under laboratory conditions. All experiments were conducted on hazelnut leaf discs in an incubator at 25 ± 1 °C, with 16:8 h L:D, at an average daily relative air humidity of 76%. Observations were made twice daily for the immature stages and daily for the adults to determine developmental time, survival and fecundity. The mean developmental time for females was 6.90 days and for males was 7.10 days, and mean adult longevity for females was 11.67 days. The mean total and daily egg production were 12.67 and 1.85 eggs, respectively. The net reproduction rate (R₀) was 7.09 females/female, intrinsic rate of increase (r_m) was 0.153 female/female/day and mean generation time (T₀) was 12.80 days. The mortality rate of immature stages was 0.66% and the sex ratio was 0.51 female.     

Stem turnover strategy of multiple-stemmed woody plants

We have investigated stem turnover strategy for Lindera umbellata, an understory shrub that sprouts from its rootstock under natural conditions to replace constituent stems, on the basis of the hypothesis that the multiple-stemmed form of woody species is an adaptation enabling efficient reproduction in high-stress environments. We tested the hypothesis that the timing of stem replacement maximizes sexual reproduction for the shrub. We developed a model for the time of optimum replacement of a stem by a daughter stem which maximizes the sexual reproduction of a shrub and tested the model using L. umbellata growing in the field. From the model, the optimum time of replacement of a stem with a daughter stem is when cumulative sexual reproduction per unit time for the stem is maximum. In practice, this will be the last age (t _opt) at which annual sexual reproduction in a stem can potentially exceed cumulative sexual reproduction per unit time for the stem. Half of the stems died at almost t _opt and had sexually mature daughter stems at that time. Other stems, however, died at times more remote from t _opt when daughter stems were sexually immature. It is thought that normal replacement of the latter stems was prevented by accidents such as breakage. We conclude that clumps of L. umbellata achieve efficient sexual reproduction by stem replacement at the optimum time, although accidents can, to some extent, determine when the stem actually dies.     

Physiological constraints on the life cycle and distribution of the Antarctic fairy shrimp <Emphasis Type="Italic">Branchinecta gaini</Emphasis>

Maturation to adulthood and successful reproduction in the Antarctic fairy shrimp, Branchinecta gaini, must be completed within a physiologically challenging temporal window of ca. 2.5 months in the southern Antarctic Peninsula. Although adults show considerable metabolic opportunism at positive temperatures, little is known of their tolerance of two physiological insults potentially typical to pool life in the maritime Antarctic: sub-zero temperatures and salinity. B. gaini are freeze-avoiding crustaceans with temperatures of crystallisation (T _cs) of −5°C. No antifreeze proteins were detected in the haemolymph. Adults osmoregulate in relation to temperature, but rapid mortality in saline solutions of even low concentration, indicate they cannot osmoregulate in relation to salinity. Survival of ice encasement at temperatures above their T _c was found to be pressure but not time dependent: at severe inoculative ice pressures, there was little immediate survival and none survived after 48 h below −2°C; at mild inoculative ice pressures, immediate survival was ca. 100% at −3°C, but <20% after 48 h. There was no significant difference in survival after 1 and 6 h encasement at −3°C. Observations of ventilation suggest that it is not low temperature per se, but ice that represents the primary cryo-stress, with ventilatory appendages physically handcuffed below the freezing point of pool water. Both sub-zero temperatures and salinity represent real physiological constraints on adult fairy shrimp.     

Development and reproduction of Stratiolaelaps scimitus (Acari: Laelapidae) with fungus gnat larvae (Diptera: Sciaridae), potworms (Oligochaeta: Enchytraeidae) or Sancassania aff. sphaerogaster (Acari: Acaridae) as the sole food source

Stratiolaelaps ( = Hypoaspis) miles (Berlese) (Acari: Mesostigmata: Laelapidae) is a polyphagous soil-dwelling predatory mite that is widely marketed for use in greenhouse production systems to manage populations of dark-winged fungus gnats, Bradysia spp. (Diptera: Sciaridae) and for supplemental control of thrips. The suggestion by Walter and Campbell (2003, Biol. Control 26: 253–269) that North American commercial cultures of S. miles may actually be S. scimitus was confirmed. The development and reproduction at 21–23 °C of S. scimitus provided ad libidum with one of three different prey – the fungus gnat Bradysia aff. coprophila (Lintner), potworms (Enchytraeidae), or Sancassania aff. sphaerogaster (Zachvatkin, 1937) (Acari: Astigmata: Acaridae) – were compared. Developmental duration of the egg and non-feeding larval stages were 2.47 and 1.11 days, respectively; mortalities were 8.3 and 5.5%. Stratiolaelaps scimitus failed to develop beyond the protonymphal stage when provided with S. aff. sphaerogaster alone, although some feeding was observed. Development and reproduction of S. scimitus was successful on both fungus gnat larvae and enchytraeids, with no influence of prey on protonymphal duration (4.70 days) and mortality (8.3%), or on deutonymphal duration (4.61 days) and mortality (6.1%). Adult female S. scimitus feeding on potworms, compared to those feeding on fungus gnat larvae, had a significantly shorter pre-oviposition period (2.69 vs. 4.59 days). However, diet did not influence other adult female developmental or reproductive characteristics (oviposition period, 18.6 days; post-oviposition period, 6.2 days; total adult longevity, 27.3 days; total number of eggs, 26.5). S. scimitus reared on potworms tended (p = 0.06) to have a higher intrinsic rate of increase, a higher finite rate of increase and a shorter doubling time (r _m = 0.142 day⁻¹, λ = 1.153, Dt = 4.85 days) than those reared on fungus gnat larvae (r _m = 0.105 day⁻¹, λ = 1.110, Dt = 6.58 days), but differences in net reproductive rate (R ₀) and generation time (G) were not significant.     

Individual- and population-level effects of antibiotics on the rotifers, <Emphasis Type="Italic">Brachionus calyciflorus</Emphasis> and <Emphasis Type="Italic">B. plicatilis</Emphasis>

The toxicity of three common antibiotics (streptomycin sulfate, tetracycline hydrochloride, and tylosin tartrate) to the freshwater rotifer Brachionus calyciflorus and brackish-water rotifer B. plicatilis was investigated using full-lifespan exposure durations. Effects of each antibiotic on lifespan, lifetime reproduction, and Malthusian parameter were assessed at seven nominal concentrations (ranging from 5.6 mg l⁻¹ to 2,000 mg l⁻¹) and a negative control. Lowest Observed Effect Concentrations (LOECs) were determined for reproduction and lifespan, while 1%, 10%, 25%, and 50% Inhibitory Concentrations (IC₁, IC₁₀, IC₂₅, IC₅₀) and 95% confidence intervals were estimated for all three endpoints. LOECs ranged from 5.6 mg l⁻¹ to 90 mg l⁻¹, with all LOECs less than 90 mg l⁻¹ occurring in B. calyciflorus. The lowest IC1 concentrations were 3.91 mg l⁻¹ for the effect of tetracycline on lifetime reproduction in B. calyciflorus and 4.06 mg l⁻¹ for the effect of tylosin on lifetime reproduction in B. plicatilis. Overall, lifetime reproduction was the most sensitive endpoint and the Malthusian parameter was the least sensitive. IC₁ values for lifetime reproduction were roughly one to two orders of magnitude lower than the corresponding IC₅₀ values. Guest editors: S. S. S. Sarma, R. D. Gulati, R. L. Wallace, S. Nandini, H. J. Dumont and R. Rico-Martínez Advances in Rotifer Research     

Life history ofAphis gossypii on cucumber: influence of temperature, host plant and parasitism

Life table data forAphis gossypii Glover (Homoptera: Aphididae), an important pest in glasshouse cucumber crops, were studied at 20, 25 and 30°C on two cucumber cultivars (Cucumis sativus L.) in controlled climate cabinets. The development time on the cucumber cv. ‘Sporu’ ranged from 4.8 days at 20°C to 3.2 days at 30°C. Immature mortality was approximately 20% and did not differ between temperatures. Most mortality occurred during the first instar. Reproduction periods did not differ among temperatures, but at 25 and 30°C more nymphs were produced (65.9 and 69.8 nymphs/♀, respectively) than at 20°C (59,9 nymphs/♀) because of a higher daily reproduction. Intrinsic rate of increase was greatest at 25°C (r _m =0.556 day⁻¹). At 20 and 30°C the intrinsic rate of increase was 0.426 and 0.510, respectively. On cv. ‘Aramon’, the development time ofA. gossypii was approximately 20% longer at all temperatures. Immature mortality did not differ between the two cultivars. The intrinsic rate of increase on cv. ‘Aramon’ was 15% smaller than on cv. ‘Sporu’. The use of cucumber cultivars partially resistant to aphids is discussed in relation to biological control of cotton aphid in glasshouses. Development time and immature mortality on leaves of the middle and upper leaf layer of glasshouse grown cucumber plants (cv. ‘Aramon’) were comparable to development in the controlled climate cabinets. On the lower leaves immature mortality was much higher (approximately 82%) than on leaves of the middle (24.0%) and upper leaf layer (24.5%). Reproduction was less on the lower leaf layer (45.9, 70.5 and 70.1 nymphs/♀ on leaves of the lower, middle and upper leaf layer, respectively). Aphids, successfully parasitized byAphidius colemani Viereck (Hymenoptera: Braconidae) only reproduced when they were parasitized after the third instar. Fecundity was 0.1 to 0.9 and 10.5 to 13.3 nymphs/♀ for aphids parasitized in the fourth instar or as adults, respectively. Reproduction of aphids that were stung but survived the attack was lower than for aphids not stung. Average longevity of these aphids was equal to the longevity of aphids not stung byA. colemani.     

Life tables ofProctolaelaps deleoni Nawar,Childers and Abou-Setta (Gamasida: Ascidae) at different temperatures

Life tables were constructed for the predatory mite,Proctolaelaps deleoni, fed on the free-living nematodeRhabditis scanica at 20, 25, 28, 30 and 32°C. The intrinsic rate of increase (r _m ) and the net reproduction rate (R _o ) reach maximum values at 28°C. Mean generation time (t _g ) decreases with increasing temperature reaching its lowest value at 32°C.     

Life history elasticity and the population-level effect of p-nonylphenol on Daphnia galeata

In order to evaluate population-level effects of p-nonylphenol on a cladoceran zooplankton (Daphnia galeata), the chronic effects on survival and reproduction were estimated with partial life table tests, which examined responses in life history characters until 3 weeks after birth. The observed responses in survival and reproduction were converted to reductions of the intrinsic rate of natural increase r. The population level EC₅₀, which is defined as the exposure concentration that reduces r by 50%, was estimated as 16.1 g l^–1. In order to examine the extent to which the population-level effect in terms of r is influenced by extra mortality in nature, which is induced by predation, starvation, etc., sensitivity (elasticity) measures of the intrinsic rate of natural increase to reductions in age-specific survival and reproduction were calculated under hypothetical predation schemes. The sensitivities of the intrinsic rate to changes in survival and reproduction invariably decline rapidly after the onset of reproduction irrespective of predation schemes. This implies that partial life cycle tests until 21 days after birth can provide reliable estimates of the population-level effects.     

Effect of African nightshade species (Solanaceae) on developmental time and life table parameters of <Emphasis Type="Italic">Tetranychus evansi</Emphasis> (Acari: Tetranychidae)

The effect of five African nightshade (Solanum sp.) species on the biological and demographic parameters of the tomato spider mite, Tetranychus evansi Baker and Pritchard, was examined in the laboratory at 25 ± 1°C, 70–80% RH and 12L:12D photoperiod. Duration of each development stage, reproduction rate, longevity, intrinsic rate of natural increase (r _m), and doubling time (DT) of the tomato spider mite on the five nightshade species were calculated. The results indicated that S. villosum, S. scabrum, S. tarderemotum and S. americanum are more suitable for T. evansi due to a shorter developmental period, longer adult longevity, higher reproduction and intrinsic rate of natural increase ranging between 0.180 and 0.196 females/female/day compared with S. sarrachoides which cannot support T. evansi populations as the r _m (−0.063 females/female/day) and DT were negative on this host. Differences in developmental time and life table parameters among the other host plants were not significant.