The capacity for increase at a low temperature of some Australian populations of the granary weevil,Sitophilus granarius (L.)

The capacity for increase (r_c) of one laboratory and seven field populations of young adult S. granarius from different sites in Australia was determined over thirty-two weeks at 15°C in wheat of 14% moisture content. The mean value of r_c was 0.0704 ±0.0016 and the populations differed significantly with respect to this parameter. Variation in the net reproductive rate (R₀), which averaged 25.4± 1.29, had a greater effect on the value of I_c than did variation in the cohort generation time (T_c), which averaged 45.7±0.37 weeks. The populations did not differ significantly in terms of adult survivorship and 94% of females were still alive at thirty-two weeks. The maximum rate of oviposition, about ten eggs per female per week, was achieved in the eighteen-twenty week age-interval. About 41% of the immature stages survived to adulthood. Estimates of r_c over a twenty-four week period were only slightly lower than those over thirty-two weeks. The capacity for increase at 15°C of a given population was shown to be correlated with its fertility at 29°C, an optimal temperature, and with its body weight rather than with its cold tolerance, as indicated by its chill-coma temperature, or its previous temperature-history. The temperature experienced by the immature stages had a marked influence on r_c in that weevils reared at 15°C and 27°C had respective values of 0.0654 and 0.0786 when subsequently held at 15°C. The differences in the survivorship and fertility of S. granarius and S. oryzae (L.) when both species were reared at 15°C are considered.     

A comparison of the capacity for increase at a low temperature of foreign and Australian populations of Sitophilus oryzae (L.) and S. granarius (L.)

The capacity for increase (r_c) of three populations of S. oryzae and three populations of S. granarius from Great Britain and Canada was determined over 15 and 24 weeks respectively at 15°C in wheat of 14% moisture content. The fertility of these populations at 27°C, their body weight and chill-coma threshold was also measured. With both S. oryzae and S. granarius, values of r_c for the foreign populations fell within the range previously observed when several Australian populations were reared under the same conditions. The cohort generation times (T_c) of the foreign S. oryzae populations were significantly shorter than those of the Australian populations because of the shorter immature development periods (D) of the former. Two of the foreign S. granarius populations had lower values for D than all but one of their Australian counterparts but their values of T_c were within the range previously observed for Australian weevils. When the Australian and foreign populations were considered together, the value of r_c was more strongly correlated with fertility at 27°, an optimal temperature, than with body weight in both S. oryzae and S. granarius. With S. oryzae, r_c was correlated with the chill-coma threshold of cold-acclimated weevils only. There were no correlations between r_c and chill-coma thresholds in S. granarius. It was concluded that the observed differences in r_c were related to differences in the vigour of the populations rather than to physiological differences in cold-tolerance. The likelihood of grain weevils becoming cold-tolerant as a result of grain aeration is discussed and the practical significance of differences in r_c considered.     

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).     

Life tables and intrinsic rate of natural increase ofPediobius furvus [Hym.: Eulophidae] onChilo partellus [Lep.: Pyralidae]

In the present studies, life table data and intrinsic rate of natural increase (r_m) of the eulophid pupal parasitoid,P. furvus (Gahan) were obtained fromChilo partellus (Swinhoe) at a constant temperature of 26.7±0.6°C, 52.3±2.7% RH in the laboratory. Development of immature stages took 19.1±0.3 days; adult females lived for 7.9±3.3 (range, 2–13) days and produced a mean of 91.9±22.4 progeny per female, with a sex ratio of 1:2.9 (♂:♀). The intrinsic rate of natural increase (rm) was 0.2558/female/day; the net reproductive rate (R₀), 237.25; the capacity for increase (r_c) of 0.252; and the finite rate of increase (λ) of 1.29/female/day; thus, each female contributed 231.42 individuals to the population in a mean generation time of 21.38 days.      

Low‐temperature physiology of climatically distinct south African populations of the biological control agent Neochetina eichhorniae

1. Neochetina eichhorniae is the most widely established biocontrol agent on water hyacinth populations around South Africa. However, some N. eichhorniae populations have failed to adequately control their host population, specifically those exposed to cold conditions.
2. The aim of this study was to determine whether two climatically distinct populations of N. eichhorniae in South Africa differ in their low‐temperature physiology, which tests whether local‐climate adaptation has occurred.
3. We estimated weevil CT_min, LLT₅₀, SCP, and SCP mortality using standard approaches. Contrary to expectation based on climatic thermal profiles at the two sites, weevils from the warm locality ((mean ± SE) CT_min = 5.0 °C ± 0.2, LLT₅₀ = ?11.3 °C ± 0.03, SCP = ?15.8 °C ± 0.6) were able to maintain activity and tolerate colder temperatures than the weevils from the colder site (CT_min = 6.0 °C ± 0.5, LLT₅₀ = ?10.1 °C ± 0.1, SCP = ?12.9 °C ± 0.8).
4. These contradictory outcomes are likely explained by the poor nutrient quality of the plants at the cold site, driving low‐temperature performance variation that overrode any macroclimate variation among sites. The cold site weevils may also have adapted to survive wide‐temperature variability, rather than perform well under very cold conditions. In contrast, the mass‐reared population of insects from the warm site has likely adapted to the consistent conditions that they experience over many years in confinement.

     

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.     

Longevity and development of the egg-parasitoid,Cheiloneurus pyrillae [Hymenoptera: Encyrtidae] at different combinations of temperature and relative humidity

Out of the 2 important physical factors like temperature and relative humidity, the former plays significant role in affecting the survival of adults and development of immature stages ofCheiloneurus pyrillae Mani which is an important egg parasitoid of the sugarcane leaf hopper (Pyrilla perpusilla Walker) in India. Average longevity of males and females of this parasitoid decreased from 2.47 to 0.81 days and from 4.95 to 0.84 days, respectively when the test temperature was increased from 15 to 35±1.5°C. Similarly, its mean developmental period was found to reduce from a maximum of 45.87 to a minimum of 10.12 days when the rearing temperature was increased from 15 to 30±1.5°C. The parasitoid could not be reared at or above 32.5±1.5°C because its immature stages failed to withstand this temperature. These informations will be helpful in maintaining the mass culture ofC. pyrillae in the laboratory.     

Fecundity and life table parameters of Campoletis sonorensis (Hymenoptera: Ichneumonidae), an endoparasitoid of the Cabbage Looper Trichoplusia ni Hübner (Lepidoptera: Noctuidae), under laboratory conditions

The fecundity and life table parameters of Campoletis sonorensis females were measured using thirty 4-day-old Trichoplusia ni larvae daily at 24°C, 60% RH and a photoperiod of 12 h L:12 h D. The mean longevity was 34.5±2.8 days, the mean oviposition period was 22.7±1.9 days, and the mean constant oviposition period and the mean post-oviposition period were 15.9±1.3 and 11.9±2.2 days, respectively. The mean realised fecundity and the mean fertility differed significantly at 66.9±7.8 and 60.4±7.8 parasitoids per female, respectively. The mean sex ratio for the mean oviposition period (23 days) was 0.13±0.07, indicating a highly female biased ratio. The life table parameters were: intrinsic rate of natural increase (r _m), 0.135 female/day; gross reproductive rate (GRR), 50.30; net reproductive rate (R _o), 49.96; finite capacity for increase (λ), 1.14 female/day; mean generation time (T), 28.97 days; doubling time (DT), 5.13; capacity for increase (r _c), 0.33; and cohort generation time (T _c), 11.69. Campoletis sonorensis may be a suitable candidate for a biocontrol program of T. ni populations mostly because the primary selection criterion, r_m , obtained for this parasitoid can be similar to or larger than the rate obtained for T. ni.     

Life tables and development of <Emphasis Type="Italic">Amblyseius swirskii</Emphasis> (Acari: Phytoseiidae) at different temperatures

Development time, reproduction, survival and sex ratio were determined for the omnivorous mite Amblyseius swirskii at nine constant temperatures (13, 15, 18, 20, 25, 30, 32, 34 and 36°C) on pepper leaf disks with cattail, Typha latifolia, pollen for food. These data were used to derive life table parameters at these constant temperatures. No development was observed at 13°C. The lower development threshold, based on the fit to the linear portion of the development curve, was 11.3°C. The upper development threshold was 37.4 ± 1.12°C, and the optimum temperature was calculated to be 31.5°C. Average lifetime fecundity ranged from a low of 1.3 ± 0.24 eggs/female at 15°C to a high of 16.1 ± 0.34 eggs/female at 25°C, and r _m was greatest at 32°C. Non-linear regression of the relationship between temperature and r _m produced an estimate of 15.49 ± 0.905°C for the lower threshold for population growth and 36.99 ± 0.816°C for the upper threshold for population growth, and an optimum temperature of 30.1°C. These values suggest that A. swiskii populations should grow quickly in response to food availability (pollen or prey) between 20 and 32°C, but that, especially below 20°C, population growth could be slow and impacts on prey populations should be monitored carefully.     

Some aspects of acclimation to low temperatures in the grain weevils Sitophilus oryzae (L.) and S. granarius (L.)

The ability of Sitophilus oryzae (L.) and S. granarius (L.) to acclimate when transferred from 27°C, a near optimal temperature, to 15° C, a marginal temperature, was examined in terms of chill-coma temperature, dispersal, oxygen consumption and rate of oviposition. The chill-coma temperature of S. oryzae was higher and the increment of acclimation less than that of S. granarius. Acclimation, although well advanced after 2 weeks after transfer, took more than 4 weeks to complete. Re-acclimation after the reciprocal transfer took only 2 weeks. The dispersal of S. oryzae held at 15 and 27° C prior to testing differed when the weevils were released in wheat at 27°C but not when released at 15°C. Cold-acclimated S. granarius dispersed less than warm-acclimated weevils when released in wheat at both 15 and 27°C. The activity oxygen consumption of cold-acclimated weevils was less than that of warm-acclimated weevils. Inverse-shifts of acutely determined R-T relationships appeared more significant than changes in temperature sensitivity. Acclimation to 15° C took 8–10 days and re-acclimation to 27°C about 6–8 days. S. oryzae consumed less oxygen per unit of weight than S. granarius but was more temperature sensitive. Resting oxygen consumption, which was less temperature sensitive than activity consumption, also exhibited inverse acclimation in both species. S. granarius showed evidence of inverse acclimation of oviposition rate after acclimation at 15°C.     

Fertility life table parameters of different strains of Trichogramma spp. collected from eggs of the carob moth Ectomyelois ceratoniae

Fertility life table parameters were assessed for five populations (strains) of two Trichogramma species, T. embryophagum Hartig and T. principium Sugonyaev & Sorokina, collected from eggs of the carob moth Ectomyelois ceratoniae (Zeller) in Iranian pomegranate orchards. Four combinations of two constant temperatures (25°C, 30°C) and two relative humidity levels (50% RH, 70% RH) were used. The overall intrinsic rate of natural increase (r_m) was significantly decreased with decreased relative humidity but was uninfluenced by temperature. The highest and lowest r_m values were observed in T. embryophagum from Qum (0.34 ± 0.004) and T. embryophagum from Varamin (0.13 ± 0.01), respectively. Two‐way interaction analyses revealed that the strains had significantly different responses in their r_m values at different temperatures and relative humidities. In general, r_m values were significantly higher at 25°C and 70% RH than at 30°C and 50% RH. The Qum strain of T. embryophagum was the most promising candidate to be considered as a biocontrol agent against E. ceratoniae due to its high reproductive rate (0.27 ± 0.01) at conditions (30°C and 50% RH) similar to the actual climatic conditions in Iranian pomegranate orchards during the major part of the growing season.     

Further studies on acclimatization to low temperatures in the grain weevils Sitophilus oryzae (L.) and Sitophilus granarius (L.)

The effect of thermal acclimatization on the resting metabolism of adult grain weevils was examined by closely restraining the weevils during respirometry. Sitophilus oryzae (L.) acclimatized to 15°C consumed less oxygen over 11–23°C than 27°C-acclimatized weevils but like amounts over 25–35°C. Similar results were observed with S. granarius (L.). Respiration R–T curves of unrestrained S. oryzae and S. granarius showed no evidence of rotation at temperatures close to their chill-coma thresholds but warm- and cold-acclimatized weevils consumed similar amounts of oxygen when both categories of weevils were in chillcoma. Acclimatizing S. oryzae from 27 to 13.5°C through four, weekly 4.5°C step-transfers lowered the median chill-coma thresholds of the weevils from 8.9 to 6.2°C, increased their life span at 9°C, an unfavourable temperature for this species, from 2 to 8 weeks and lowered their oxygen uptake at 9°C by 19%.     

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.     

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.     

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.     

Effect of temperature on life table parameters of Plutella xylostella (Lepidoptera: Plutellidae) on two brassicaceous host plants

Life table parameters of diamondback moth, Plutella xylostella (L.), were studied at seven constant temperatures (10, 15, 20, 25, 28, 30, and 35 °C) on two brassicaceous host plants, cauliflower (Brassica oleracea var. botrytis) and cabbage (Brassica oleracea var. capitata). Survival, longevity and reproduction were examined and used to construct a life table. The survival at immature stages varied from 53.0 to 84.1% on cauliflower and from 58.3 to 86.2% on cabbage at 10–30 °C. P. xylostella did not survive at 35 °C. The female adult longevity ranged from 12.9 days at 30 °C to 30.4 days at 10 °C on cauliflower and 9.7 days at 30 °C to 40.0 days at 15 °C on cabbage. The net reproductive rate (R₀) increased with increasing temperature, while generation time (T) decreased. This caused the intrinsic rate of increase (r_m) to increase from 0.038 to 0.340 on cauliflower and 0.033 to 0.315 on cabbage from 10 to 28 °C. The significant decrease in R₀ caused a decrease in r_m at 30 °C. The r_m values on cauliflower were significantly higher than cabbage at 15, 20, 28 and 30 °C.     

Life tables of the predatory mite Phytoseiulus longipes feeding on Tetranychus evansi at four temperatures (Acari: Phytoseiidae, Tetranychidae)

The tomato red spider mite, Tetranychus evansi, is reported as a severe pest of tomato and other solanaceous crops from Africa, from Atlantic and Mediterranean Islands, and more recently from the south of Europe (Portugal, Spain and France). A population of the predaceous mite Phytoseiulus longipes has been recently found in Brazil in association with T. evansi. The objective of this paper was to assess the development and reproduction abilities of this strain on T. evansi under laboratory conditions at four temperatures: 15, 20, 25 and 30°C. The duration of the immature phase ranged from 3.1 to 15.4 days, at 30 and 15°C, respectively. Global immature lower thermal threshold was 12.0°C. Immature survival was high at all temperatures tested (minimum of 88% at 30°C). The intrinsic rate of increase (r _m) of P. longipes ranged from 0.091 to 0.416 female/female/day, at 15 and 30°C, respectively. P. longipes would be able to develop at a wide range of temperatures feeding on T. evansi and has the potential to control T. evansi populations.     

Photosynthetic and respiratory responses of <Emphasis Type="Italic">Gracilaria salicornia</Emphasis> (C. Ag.) Dawson (Gracilariales,Rhodophyta) from Thailand and Japan

The photosynthetic and respiratory responses of Gracilaria salicornia in the subtropical waters of Japan (in Okinawa) and in the tropical waters of Thailand (in Rayong and Phuket Provinces), were studied under various conditions of irradiance, salinity and temperature. This alga showed adaptability in its photosynthetic and respiratory responses to oceanic salinity as well as to subtropical to tropical temperature. Significant differences in the photosynthetic and respiratory rates among the G. salicornia populations collected from the above sites were observed. The Phuket population showed adaptability to high irradiance and temperature, characteristic of its natural sun-exposed environment, as it exhibited the highest I _k and I _c, and lowest α and higher P _max at 30–35°C. On the other hand, the Okinawa population demonstrated adaptability to low submarine irradiance as it had a lower I _k and I _c than either population from Thailand. Its P _max at 20–25°C was also higher than that of the Phuket population. The Rayong population, however, showed the highest P _max, R_d, α, I _k and I _c, suggesting its adaptability to both sun and shade light conditions in its natural environment. Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines     

Reproductive performance of seven strains of the tomato red spider mite <Emphasis Type="Italic">Tetranychus evansi</Emphasis> (Acari: Tetranychidae) at five temperatures

The tomato red spider mite Tetranychus evansi Baker et Pritchard occurs on solanaceous plants, and causes serious damage to a variety of crops in Africa and Europe. In 2001 this species was also found in Japan, on nightshade (Solanum nigrum L.), and its invasion to solanaceous of agricultural importance is feasible. To evaluate its potential severity as a pest, the present study assessed the life-history parameters, such as the rate of development and the intrinsic rate of natural increase (r _m), on S. nigrum for T. evansi collected on seven sites worldwide. Increasing temperatures between 15 and 32.5°C significantly increased the developmental rate of the seven strains while immature developmental duration was about the same at 32.5–40°C. The rate of egg-to-adult development [(% hatch) × (% survival)] exceeded 88% at temperatures between 15 and 37.5°C. The lower thermal thresholds (LT) were 11.9–12.5°C for both egg-to-adult and egg-to-egg development. The optimum developmental temperatures ranged from 36.7 to 43.8°C and the upper developmental threshold (UT) ranged from 45.2 to 59.4°C. The r _m-values became higher with temperature increasing from 15 to 35°C. The r _m-values at 25°C ranged from 0.265 to 0.277 which are relatively high for species of the genus Tetranychus. These results indicate that T. evansi after invasion into Japan has the potential to become a serious pest on solanaceous crops, just the same as in Africa and Europe.