Life table and predation of Neoseiulus longispinosus (Acari: Phytoseiidae) on Oligonychus coffeae (Acari: Tetranychidae) infesting tea

Life table and predation of the predatory mite Neoseiulus longispinosus (Evans) on the red spider mite (RSM), Oligonychus coffeae (Nietner), a major pest of tea in India, were studied in the laboratory. Developmental time from egg to adult varied from 4 to 14 days at 30 to 15 °C, respectively; at 35 °C no larva survived. Survival of immature stages was more than 94 % at all temperatures. Threshold temperature for development of immature stages of females and males was 10 and 9.9 °C, respectively, and thermal constant was 84.03 degree-days for females and 80 for males. Sex ratio was female biased and temperature (20–30 °C) had no clear effect on sex determination. Egg hatchability was 73 % at 35 °C and >97 % at lower temperatures. Average number of eggs laid per female/day was higher at 30 °C than at 20 or 25 °C. The highest net reproductive rate (R ₀) was 40.7, at 20 °C. Mean generation time (T) decreased from 28 to 13 days with temperature increasing from 20 to 30 °C. Weekly multiplication (6.5) and intrinsic rate of natural increase (r _m ) (0.268) were highest at 30 °C. Males lived longer than females at every temperature tested. Longevity was highest at 20 °C (50 days for females and 55 for males). Survival and longevity were adversely affected by temperature above 30 °C. Daily consumption of prey increased with the advancement of predator’s life stages; adult females consumed the highest numbers of prey items, preferably larvae and nymphs.     

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

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

Cross-mating experiments with geographically different populations of <Emphasis Type="Italic">Amblyomma cajennense</Emphasis> (Acari: Ixodidae)

The effect of temperature on the development and fecundity of Sancassania polyphyllae fed on tissues of Polyphylla fullo larvae was studied at 15, 20, 25, 30, and 35 ± 1°C and 65 ± 10% RH in a dark incubator. Mean developmental period of immature stages decreased significantly with increasing temperatures from 15 to 30°C. Developmental periods at 30–35°C were not significantly different. The estimated lower developmental thresholds of the various immature stages ranged between 10.1 and 11.5°C. The thermal constant for the egg-to-female adult was 93.5 degree-days. The pre-oviposition, oviposition, and post-oviposition periods and female longevity were significantly longer at 15°C than at higher temperatures. Mean total and daily fecundity were the highest at 25°C, which were significantly different from those obtained at 15, 20 and 30°C. The net reproductive rate (R ₀) was the highest at 25°C (588.3 ♀/♀). The longest mean generation time (T ₀) occurred at 15°C (36 days) and the shortest occurred at 30°C (9.2 days). The highest intrinsic rate of increase (r _m) for S. polyphyllae was observed at 25 (0.61 ♀/♀/day) and 30°C (0.62 ♀/♀/day).     

Functional response of Neoseiulus californicus (Acari: Phytoseiidae) to Tetranychus urticae (Acari: Tetranychidae) on strawberry leaves

Neoseiulus californicus (McGregor) is a predatory mite employed for biological control of the agricultural pest Tetranychus urticae (Koch). We explored whether environmental differences, in this case the trichome densities of abaxial leaf surfaces of strawberry cultivars (‘Maehyang’ and ‘Sulhyang’ varieties) affect the functional response of adult female N. californicus preying on immature stages (egg, larva and nymph) of T. urticae. We also evaluated the functional response of N. californicus to eggs of T. urticae at different temperatures (15, 20, 25, 30 and 35°C). We conducted a logistic regression of the proportion of prey consumed as a function of initial prey density to identify functional response types, and used nonlinear least‐squares regression and the random predator equation to estimate attack rates and handling times. The functional response of adult female N. californicus to T. urticae was not influenced by non‐glandular trichomes on abaxial leaves but was affected by temperature. Overall, adult female N. californicus exhibited a type 2 functional response to T. urticae. The handling time of N. californicus was highest (1.9970 h) against T. urticae nymphs. The attack rate did not change much at 15–30°C, but was significantly higher at 35°C. The handling time decreased significantly with increasing temperature at 15–35°C. At 35°C, the attack rate was highest (0.2087) and the handling time was lowest (0.9511 h).     

Temperature-dependent development and reproductive traits of <Emphasis Type="Italic">Tetranychus macfarlanei</Emphasis> (Acari: Tetranychidae)

Development and reproductive traits of Tetranychus macfarlanei Baker & Pritchard (Acari: Tetranychidae) were investigated on kidney bean, Phaseolus vulgaris L., at eleven constant temperatures. Tetranychus macfarlanei was able to develop and complete its life cycle at temperatures ranging from 17.5 to 37.5°C. At 15 and 40°C, a few eggs (2–4%) hatched but further development was arrested. Development from egg to adult was slowest at 17.5°C and fastest at 35°C for both females and males. Using Ikemoto and Takai’s linear model, the estimated lower developmental thresholds for egg-to-female adult, egg-to-male adult and egg-to-egg development were 12.9–13.0°C. The thermal constants for the respective stages were 110.85, 115.99 and 125.32 degree-days (DD). The intrinsic optimum temperatures (T _Φ) calculated by non-linear SSI model were determined as 24.4, 24.4 and 24.2°C for egg-to-female adult, egg-to-male adult and egg-to-egg development, respectively. The net reproductive rate (R ₀) was highest at 25°C (167.4 females per female) and lowest at 17.5°C (42.6 females per female). The intrinsic rate of natural increase, r _m, increased linearly with the rising of temperature from 0.102 at 17.5°C to 0.441 day⁻¹ at 35°C. These values suggested that T. macfarlanei could be growing quickly in response to increasing temperatures from 17.5 to 35°C and provide a basis for predicting its potential geographical range.     

Life tables of the predatory mite Neoseiulus cucumeris (Acari: Phytoseiidae) on two pest mites as prey,Aculops lycopersici and Tetranychus urticae

Abstract

Studies on the life history and life table parameters of Neoseiulus cucumeris Oudemans (Acari: Phytoseiidae) were carried out under laboratory conditions of 25?±?1?°C and 65?±?5% RH; 30?±?1?°C and 60?±?5% RH; 35?±?1?°C and 55?±?5% RH. As prey, immature stages of tetranychid spider mite T. urticae Koch (Acari: Tetranychidae) and the moving stages of the Tomato Russet Mite A. lycopersici (Massee) (Acari: Eriophyideae) were selected. The predatory phytoseiid mite, Neoseiulus cucumeris (Oudemans) was able to develop successfully from egg to adult stage through the entire life history on both preys. The higher of different temperatures and relative humidities shortened the development and increased reproduction and prey consumption and vice versa. The maximum reproduction (3.91, and 3.09 eggs/♀/day) was recorded at 35?°C and 65% RH, while the minimum (2.12, and 1.90 eggs/♀/day) was at 25?±?1?°C and 55?±?5% RH. when N. cucumeris fed on A. lycopersici and T. urticae, respectively. The reproductive rate on eriophyid was significantly higher than previously recorded on tetranychid. Life table parameters indicated that feeding of phytoseiid mite N. cucumeris on tomato russet mite A. lycopersici led to the highest reproduction rate (rm?=?0.268, 0.232 and 0.211 females/female/day), while feeding on T.urticae gave the lowest reproduction rate (rm?=?0.159, 0.143 and 0.131) at 35?°C and 55% RH, 30?°C and 60% RH and 25?°C and 65% RH, respectively. The population of N. cucumeris multiplied (36.81, 28.71 and 20.47) and (24.60, 19.58 and 14.62 times) in a generation time of (20.10, 23.20 and 25.14) and (22.35, 25.36 and 27.79 days) when a predator fed on A. lycopersici and T. urticae at the same temperature above mentioned, respectively. These results suggest that the two mites, particularly A. lycopersici, proved to be suitable prey for N.cucumeris, as a facultative predator.     

Effect of temperature on development and reproduction of Proprioseiopsis asetus (Acari: Phytoseiidae) fed on asparagus thrips,Thrips tabaci

Thrips tabaci Lindeman (Thysanoptera: Thripidae) is one of the most important pests of asparagus in China. In this study the effects of five constant temperatures (15, 20, 25, 30 and 35 °C) on the growth, survivorship and reproduction of Proprioseiopsis asetus (Chant) (Acari: Phytoseiidae) fed on T. tabaci was examined under laboratory conditions. Development time of immatures decreased with increasing temperature. The lower egg-to-adult developmental threshold (T ₀) and thermal constant (K) of P. asetus were estimated at 15.2 °C and 75.8 degree days by means of a linear model. Fertilized females fed on T. tabaci produced offspring of both sexes, whereas the offspring sex ratio [♀/(♀ + ♂)] of P. asetus at 20–35 °C was female-biased (0.68–0.78) and not significantly influenced by temperature. Survivorship during immature development was significantly influenced by temperature, and was especially low at 15 °C. Pre- and post-oviposition periods of fertilized females shortened with the increase in temperature. The longest oviposition period was 20.4 days, at 25 °C, whereas at 15 °C the mites did not reproduce. Maximum average life time fecundity and mean daily fecundity was recorded at 25 and 35 °C, respectively; the intrinsic rate of increase ranged from 0.05 (20 °C) to 0.17 (35 °C). The results indicate the capability of P. asetus to develop and reproduce at a broad range of temperatures, especially above 25 °C, which can be used for better management of T. tabaci in asparagus.     

Temperature‐dependent development of Neoseiulus barkeri (Acari: Phytoseiidae) on Tetranychus urticae (Acari: Tetranychidae) at seven constant temperatures

Abstract The effect of seven constant temperatures of 15, 20, 25, 27, 30, 35 and 37°C on developmental time of Neoseiulus barkeri Hughes were determined in laboratory conditions under 65%± 5% RH and a photoperiod of 12 : 12 (L : D) h on nymphal stages of Tetranychus urticae Koch. Total developmental time of females (from egg to adult emergence) at the above‐mentioned temperatures was 26.59, 14.43, 6.32, 5.64, 4.59, 3.98 and 4.67 days, respectively. Developmental rate of the N. barkeri increased as temperature increased from 15 to 35°C, but declined at 37°C. A linear and two nonlinear models were fitted to developmental rate of immature stages of N. barkeri to predict the developmental rate as a function of temperature, as well as to estimate the thermal constant (K) and critical temperatures (i.e., T_min, T_opt and T_max). The estimated values of the T_min and K for total developmental time using the linear model were 12.07°C and 86.20 degree‐days (DD), respectively. The T_min and T_max estimated by the Sharpe‐Schoolfield‐Ikemoto (SSI) model were 11.90°C and 37.41°C, respectively. The estimated T_opt for overall immature stage development of N. barkeri by the Lactin and SSI models were 33.89°C and 24.51°C, respectively. Based on the biological criteria of model evaluation, the linear and SSI models were found to be the best models for describing the developmental rate of overall immature stages of N. barkeri and estimating the temperature thresholds.     

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

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

Effects of temperature on development,survival, longevity,and fecundity of Serangium japonicum (Coleoptera: Coccinellidae), a predator of Bemisia tabaci Gennadius (Homoptera: Aleyrodidae)

In this study, we evaluated the effect of temperature on the development and reproductive biology of Serangium japonicum (Coleoptera: Coccinellidae) at seven constant temperature regimes (17, 20, 23, 26, 29, 32 and 35°C) for its effect as a predator of Bemisia tabaci (Homoptera: Aleyrodidae). Results indicated that the duration of the egg, larval and pupal stages were significantly affected by temperature. The developmental time gradually declined with the increase of temperature from 17 to 29°C, however an extension in the developmental periods was observed in the temperature range of 32 to 35°C. The survival rates of different insect stages were stable at temperatures between 20 and 32°C; however at extreme temperatures of 35°C, a sharp decrease was evident. The highest fecundity of the female (387.2 eggs per female) was recorded at 20°C. Based on these results, life tables of S. japonicum were constructed for temperatures in the range 20–35°C. The maximum reproductive rate (R ₀=279.9) occurred at 26°C. The maximum values for innate capacity for increase (r _m=0.1131) and the finite rate of increase (λ=1.1197) occurred at 29°C. The mean generation time (T) decreased with increased temperature, the longest of which was 76.0 days (at 20°C) and the shortest was 36.6 days (at 32°C). These results offer valuable insight on the importation and establishment of S. japonicum into new environments with diverse temperature regimes.     

Effects of temperature on the life-history traits of Sancassania (Caloglyphus) berlesei (Acari: Astigmatina: Acaridae) feeding on root-knot nematodes,Meloidogyne spp. (Nematoda: Meloidogynidae)

Sancassania (Caloglyphus) berlesei (Michael) is a cosmopolitan and free-living mite that inhabits soil as well as laboratory colonies of insects and fungi and may have a role as a biocontrol agent of nematodes. In this study, we investigated the effects of temperature on the development, reproduction, and food consumption of S. berlesei fed egg masses of root-knot nematodes, Meloidogyne spp., an important group of agricultural pests. Mites were reared at 20, 25 or 30 °C in the dark. The mites could feed on the nematode egg masses, and their developmental time decreased at higher temperatures. Time from the egg to adult was similar in females and males reared at the same temperature. Adult females lived longer than males at 25 °C, but not at 20 or 30 °C. Generally, females showed a higher rate of food consumption than males. Females laid the largest number of eggs at 20 and 25 °C (199.7 and 189.8 eggs/female, respectively), but the intrinsic rate of natural increase was highest at 30 °C (r _m = 0.29). In comparing our data with previous reports, we noted that S. berlesei that fed on egg masses of root-knot nematodes showed a longer developmental time and a lower reproductive rate than Sancassania mites that fed on other diets. Nonetheless, the relatively high value of r _m (e.g., at 25 and 30 °C) suggests that this mite may have certain advantages as a biocontrol agent of root-knot nematodes.     

Antimicrobial activity in the egg wax of the African cattle tick Amblyomma hebraeum (Acari: Ixodidae)

Eggs of the tick Amblyomma hebraeum Koch (Acari: Ixodidae) inhibited the growth of Escherichia coli and Serratia marcescens (Gram-negative bacteria) in solid culture, but not the growth of Staphylococcus epidermidis, and only marginally the growth of Bacillus subtilis (Gram-positive bacteria). When egg wax was extracted with chloroform/methanol (2:1), the extract contained antibacterial activity, but the denuded eggs did not. When assayed against bacteria in liquid culture, the aqueous phase inhibited the growth of S. epidermidis. However, the activity against E. coli was lost during extraction. The antimicrobial component of the aqueous phase was heat stable (100°C for 10 min), resistant to proteinase K (15 min at 55°C) and to pronase (30 min at 37°C). The antibacterial activity in the aqueous phase increased the permeability of the cell membrane of susceptible bacterial cells within 30 min. However, lysis of the cells was detected by optical density measurements (OD_{600 nm}) only after 1.5 h. The most evident cytological changes observed by transmission electron microscopy were a thickening of the cell wall and the appearance of numerous electron lucent areas within the cytoplasm of treated bacteria. Gené’s organ, the egg-waxing organ in ticks, grew enormously during the first 16 days post-engorgement, and gained antimicrobial activity by day 10 (when oviposition began). This suggests that Gené’s organ is the major source of the antibacterial substance in the egg wax. The vitellogenic hormone in A. hebraeum, 20-hydroxyecdysone, when injected into recently engorged females, did not stimulate growth of Gené’s organ or precocious secretion of antimicrobial activity.     

Thermal requirements and biological life table parameters of the predatory mite Amblyseiella denmarki (Zaher and El-Borolossy) (Acari: Phytoseiidae)

The biological aspects, thermal requirements and life table parameters of the phytoseiid predatory mite Amblyseiella denmarki fed on Aceria dioscoridis was determined at four temperatures, i.e. 15, 20, 28 and 35°C. The total developmental durations for both females and males were correlated negatively with increasing temperature. The minimum developmental thresholds (T ₀) of egg, larva, protonymph, deutonymph stages and life cycle of A. denmarki females averaged 13.15, 4.56, 11.22, 12.72 and 11.80, respectively, while those of males were 12.40, 3.01, 9.82, 10.88 and 10.04. On the other hand, females and males required 89.28 and 93.45 degree days (DD), respectively, to reach adulthood. The male life span averaged 63.32, 49.25, 25.39 and 18.26 days while that of female was 90.51, 64.44, 29.51 and 19.99 days when the predator was reared at 15, 20, 28 and 35°C, respectively. The mean generation time (T) averaged 38.84, 24.87, 9.24 and 8.56 days, and the net reproductive rate (R ₀) values were 3.79, 10.042, 26.488 and 7.172 when the predator was kept at 15, 20, 28 and 35°C, respectively. The net rate of natural increase (r _m) was 0.032, 0.092, 0.354 and 0.230, whereas the finite rate of increase (e ^rm) averaged 1.032, 1.097, 1.425 and 1.258 at 15, 20, 28 and 35°C, respectively.     

Effects of contrasting diets and temperatures on reproduction and prey consumption by <Emphasis Type="Italic">Proprioseiopsis asetus</Emphasis> (Acari: Phytoseiidae)

Proprioseiopsis asetus (Chant) (Acari: Phytoseiidae) is a relatively unknown predacious mite with potential as a biological control agent of Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) and Tetranychus urticae Koch (Acari: Tetranychidae). In this study, the developmental rate and other biological parameters of P. asetus were investigated. Development of P. asetus was temperature dependent from 10 to 40°C. Nonlinear models were fitted to development rate (1/time) data from egg to adult and by sex to estimate development times. The model of Sharpe and De Michele (1977) best fits the developmental data. The shortest development time on cattail (Typha latifolia (L.)) pollen occurred at 35°C for all stages except for the egg stage, for which it was longer. The optimum development time at 35°C is above the temperature optimum of most phytoseiid mites. Fecundity increased when P. asetus mated more than once. Males were needed at all times for maximum oviposition, although their consumption was negligible. Oviposition, prey killed (Franklinella occidentalis or T. urticae) and longevity of P. asetus females were recorded in the presence of males. Egg production increased with number of prey killed and P. asetus has the characteristics of successful predators of thrips.     

A comparative study of development and demographic parameters of <Emphasis Type="Italic">Tetranychus merganser</Emphasis> and <Emphasis Type="Italic">Tetranychus kanzawai</Emphasis> (Acari: Tetranychidae) at different temperatures

We investigated the effect of temperature on development and demographic parameters such as the intrinsic rate of natural increase (r _m) of the two spider mite species Tetranychus merganser Boudreaux and T. kanzawai Kishida at eleven constant temperatures ranging from 15 to 40°C at intervals of 2.5°C. Both male and female T. merganser and T. kanzawai completed development from egg to adult at temperatures ranging from 15 to 37.5°C. The longest developmental duration of immature stages was found at 15°C and the shortest developmental duration was found at 35°C for both species. Using linear and non-linear developmental rate models, the lower thermal thresholds for egg-to-adult (female and male) and egg-to-egg development were estimated as 12.2–12.3°C for T. merganser and as 10.8°C for T. kanzawai. The highest developmental rates were observed at around 35°C, whereas the upper developmental thresholds were around 40°C for both species. In fact, at 40°C, a few eggs of either species hatched, but no larvae reached the next stage. The r _m-values of T. merganser ranged from 0.072 (15°C) to 0.411 day⁻¹ (35°C), whereas those of T. kanzawai ranged from 0.104 (15°C) to 0.399 (30°C). The r _m-values were higher for T. kanzawai than for T. merganser at temperatures from 15 to 30°C, but not at 35°C (0.348 day⁻¹). Total fecundity of T. merganser was also higher than that of T. kanzawai at 35°C. These results indicate that higher temperatures favor T. merganser more than T. kanzawai.     

Fumigant activity of essential oils and their components from Eucalyptus codonocarpa and E. dives against Tetranychus urticae (Acari: Tetranychidae) at three temperatures

Essential oils derived from eighteen species of the Myrtaceae family native to Australia, and major constituents of two oils selected from these oils were tested for their fumigant activity against adult females and eggs of Tetranychus urticae Koch (Acari: Tetranychidae) at 5, 15 and 25°C. Essential oils of Eucalyptus codonocarpa and Eucalyptus dives showed the highest fumigant activity against female adults at 10 μl/l at 15 and 25°C. Among major constituents of the two essential oils, piperitone was the most effective against female adults, followed by terpinene‐4‐ol at 10 μl/l at all three temperatures. The two essential oils and these two constituents lowered egg hatchability at 10 μl/l at 25°C. Our results suggest that piperitone should be further investigated as a potential fumigant against T. urticae.     

Functional response of Telenomus busseolae (Hym.: Scelionidae) an egg parasitoid of the sugarcane stem borer,Sesamia nonagrioides (Lep.: Noctuidae) at different temperatures

Telenomus busseolae Gahan is the most important egg parasitoid of sugarcane stem borers in Iran. Laboratory experiments were conducted to evaluate the functional response of T. busseolae to egg densities of Sesamia nonagrioides (Lefebvre) under four different temperatures (20, 25, 30 and 35°C). Results of logistic regression revealed a type III functional response for all temperatures tested and type of functional response was not affected by temperature. Roger's random parasite equation was fitted to observed data at 35°C. In the other data sets (collected data under 20, 25 and 30 °C) Roger's equation could not provide meaningful parameters, therefore Holling's disk equation was used to fit the data. The attack rate for T. busseolae varying from 0.001784 to 0.10704, 0.0026 to 0.152, 0.0024 to 0.144 and 0.000866 to 0.05196 per h and estimated handling times were 0.59, 0.50, 0.53 and 0.29 h at 20, 25, 30 and 35°C, respectively. Based on asymptotic 95% confidence intervals, functional response parameters did not differ significantly from 20 to 30°C, which indicates that handling time and attack rate are least affected by the temperature changes. The results suggest a similar performance of T. busseolae against S. nonagrioides eggs at temperatures of 20–30°C. These results show that T. busseolae is well adapted to temperature changes during the sugarcane growing season.     

Life history parameters for Nesidiocoris tenuis (Reuter) (Het., Miridae) under different temperature regimes

The development time for eggs and nymphs and female fertility were determined for Nesidiocoris tenuis Reuter (Het., Miridae: Dicyphini) at 15, 20, 25, 30, 35 and 40 ± 1°C, using tomato, Solanum esculentum (Miller), as substrate and eggs of Ephestia kuehniella Zeller as substitute prey. At 40°C, N. tenuis was unable to develop and barely reproduced. Egg development ranged from 30.8 days at 15°C to 6.3 days at 35°C. The cumulative thermal requirements for the eggs were 148.6 degree days (°d) and the lower thermal threshold, 10.3°C. The duration of the nymphal instar decreased from 55.9 days at 15°C to 8.6 days at 35°C. The thermal constant for the nymphs was 182.3 °d and the lower thermal threshold 11.7°C. No nymphs survived at 40°C, and the highest mortalities were at extreme temperatures (15 and 35°C). Female and male weights were influenced significantly by temperature. The fertility of N. tenuis females was reduced greatly at 15 and 40°C. The highest fertility during an observation period of 18 days following female emergence (79.5–60.0 nymphs per female) was within the temperature range of 20 to 35°C. Fertility was related directly to female weight and temperature (r² = 0.932). Based on development, reproduction data and thermal requirements, the optimum temperature range for N. tenuis was established as being between 20 and 30°C. Overall, N. tenuis is the most thermophilous of all dicyphines from vegetable crops in the Mediterranean area studied so far.     

Temperature-dependent development and life table parameters of <Emphasis Type="Italic">Typhlodromus bagdasarjani</Emphasis> (Phytoseiidae) fed on two-spotted spider mite

The predatory mite Typhlodromus bagdasarjani Wainstein and Arutunjan (Acari: Phytoseiidae) is an indigenous and widespread species of the Middle East fauna. In this paper we assess the effect of temperature on developmental rate and reproduction potential of T. bagdasarjani under laboratory conditions. The development of this species was determined at 15, 20, 25, 30, 35 and 37.5 ± 1°C, 60 ± 10% RH and L16:D8 h photoperiod. The total developmental time averaged 28.2, 15.0, 8.9, 7.6, 7.2 and 7.4 days at 15–37.5°C, respectively, when feeding on immature stages of two-spotted spider mite, Tetranychus urticae Koch. The lower developmental threshold (T ₀ ) and thermal constant (K) for the development of this predator were estimated 9.2°C and 162 degree-days by the Ikemoto linear model. The life table parameters were estimated at 15–35°C. The shortest life span of females at 35°C was 45.0 days, followed by 50.7, 50.9, 103.3 and 136.8 days at 30, 25, 20 and 15°C, respectively. Mated females laid on average 19.9, 26.3, 41.1, 39.6 and 31.3 eggs per female at 15–35°C, respectively. The intrinsic rate of increase (r _m ) and finite rate of increase (λ) increased significantly with increasing temperature. The r _m values ranged from 0.021 (15°C) to 0.186 (35°C) days⁻¹. The highest value of net reproductive rate (R ₀) was 13.6 females progeny/female/generation at 25°C. The results demonstrated that T. bagdasarjani is well adapted to high temperatures. However, the efficiency to control spider mites may be affected by behavioral characteristics of the predator and its prey under real conditions.     

Influence of Temperature on Virulence of Fungal Isolates of <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> and <Emphasis Type="Italic">Beauveria bassiana</Emphasis> to the Two-Spotted Spider Mite <Emphasis Type="Italic">Tetranychus urticae</Emphasis>

Twenty-three isolates of Metarhizium anisopliae (Metschnikoff) Sokorin and three isolates of Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales: Clavicipitaceae) were assessed for their virulence against the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Based on the screening results, nine isolates of M. anisopliae and two isolates of B. bassiana were tested for their virulence against young adult (1- to 2-day-old) female T. urticae at constant temperatures of 20, 25, 30 and 35°C. At all temperatures tested, all the fungal isolates were pathogenic to T. urticae but mortality varied with isolates and temperatures. Fungal isolates were more virulent at 25, 30 and 35°C than at 20°C. The lethal time to 50% mortality (LT₅₀) and lethal time to 90% mortality (LT₉₀) values decreased with increased temperature. There were no significant differences in virulence between fungal isolates at 30 and 35°C; however, significant differences were observed at 20 and 25°C.