142Vol. 40, Plant Protect. Sci. & H��� 1983; P������ et al. 1984) in fecundity of the spider mite at higher temperatures. 1983) or decrease (B���� MATERIAL AND METHODSTetranychus urticae was reared on plants of green bean in laboratory conditions at a temperature of 23°C (± 2°C). Development and fecundity of the mite was determined in an air-conditioned box at diverse temperatures (15, 20, 25, 30 and 35°C) and on three host plants (Cucumis sativus L., Capsicum annuum L. and Phaseolus vulgaris L.). The leaf disk method was used; detached leaves were placed on water soaked cotton in a Petri dish (9 cm diameter). The Petri dish was placed onto a plastic cup (9 cm diameter and 5 cm depth) filled with water. Sufficient moisture for the filter paper was supplied by a strip of filter paper (1 cm wide) that was attached to the filter paper at one end while the other reached into the water in the cup via a small hole. For each variant (temperatures, host plants), five Petri dishes were used. To determine the development time of the spider mite, leaves of P. vulgaris with 10-15 freshly hatched eggs were used for each variant. We started with the series at 15°C and finished with the series at 35°C. To observe the fecundity of female mites, 10 young female mites were transferred with a soft brush to each combination following the abovementioned temperature sequence. The results were analysed statistically by the Tukey test. RESULTS AND DISCUSSIONFrom the results of our experiments it follows that temperature has a decisive impact on the time needed for development of T. urticae, whereas the differences between host plants were not significant (Table 1).Development was fastest at 35°C (6.50 d) and 30°C (6.93 d), averaged on the three hosts. P������ R�� et al. (1996) also found that the length of development of the spider mite at 30°C was 6.7-7.9 days. At other temperatures of our experiments, the development time was 9.27 d at 25°C, 12.06 d at 20°C and 16.23 d at 15°C. Thus, the higher the temperature, the faster the development of the spider mite. The differences in development time between temperatures was confirmed with high detectability in the statistical analyses, except for the differences between 30°C and 35°C. P������ et al. (1984) and D����� and M��������� (1986) state that a�er a certain increase in temperature and reaching a maximum of developments. This statement was confirmed in our experiments as well.Tetranychus urticae developed fastest on Phaseolus vulgaris (9.42 d), followed by Cucumis sativus (10.26 d) and Capsicum annuum (10.92 d). The largest differences in development time between hosts were recorded at 15°C, the differences at 20-25°C were small, and at 30-35°C they were almost identical. The largest difference in development time was recorded between P. vulgaris and C. annuum at temperatures of 15, 20 and 25°C; development on P. vulgaris was faster by 1.5 days. The difference was further confirmed by statistical analysis. The differences in the development of the mite on different ho...

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Dependence of individual development stages of cotton bollworm, Helicoverpa armigera, on ambient temperature was studied in laboratory conditions. Temperature-controlled chambers at constant temperatures of 20, 25 and 30°C were used, and the thermal thresholds were established by means of linear regression. The following temperature limits were determined: the lower thermal threshold for the development of H. armigera eggs is 14.8°C, that for larvae is 11.3°C, and that for development of pupae is 8.2°C. The thermal constant for the development of eggs is 64.1 day-degrees, that for larvae is 344.8 day-degrees, and that for the development of pupae is 222.2 day-degrees. The lower thermal threshold for total development of Helicoverpa armigera is 11.5°C and the thermal constant is 625.0 day-degrees.

Malina R., Praslička J. (2008): Effect of temperature on the developmental rate, longevity and parasitism of Aphidius ervi Haliday (Hymenoptera: Aphidiidae). Plant Protect. Sci., 44: 19-24.Temperature-dependent development, longevity and parasitism of the parasitoid Aphidius ervi Haliday was measured at four constant temperatures between 15°C and 30°C using Aphis pomi de Geer as host. The thresholds for egg-mummy and mummy-adult development were 6.8°C and 3.9°C, respectively. Development into mummies required an average of 146.3 degree-days (DD), while development into adults took an average of 85.3 DD. Longevity was increasing linearly in the range from 15°C to 25°C (8-15 days), but was lower at 30°C (11 days). The relationship between parasitism, recorded as percent aphids mummified, and temperature was increasing at the temperatures 15-25°C, but decreasing at higher temperatures; 10.8% of the aphids were parasitised at 15°C, 15.9% at 25°C and 14.6% at 30°C. These results are compared with previously reported data on temperature-dependent development of A. ervi on a different host.Keywords: Aphidius ervi; development time; parasitism; longevity; thermal constants 20 Vol. 44, Plant Protect. Sci. Ohta & Ohtaishi (2003) have reported also the temperature-dependent longevity of Aphidius gifuensis Ashmead. The apple aphid, Aphis pomi de Geer, is a common inhabitant of apple orchards. Dense populations may cause abnormal growth of terminal shoots, reduce the levels of non-structural carbohydrates in shoots, roots and leaves and lower the yield of fruit (Kaakeh et al. 1993).The knowledge of thermal constants and lower development thresholds provides essential information to determine the development rate of a particular species of arthropod (Jarošík et al. 2002). Thermal constants are frequently used to create predictive models of pest development in various environments, including stored products (Subramanyam et al. 1990), greenhouses and orchards (Graf et al. 1996).We studied the effect of temperature on the development, percentage of parasitism and longevity of Aphidius ervi at four constant temperatures to evaluate its potential as a biological agent to control Aphis pomi. MATERiAL AnD METhoDsHost aphid source. Aphis pomi colonies used in this study originated from a single collection of wild aphids from apple trees in the town Banská Bystrica (48°44'N, 19°08'E) in April 2006. The colonies were maintained on fresh apple tree shoots (replaced every 2 days after all aphids had migrated from dry to fresh shots) in a thermostat at 25 ± 1°C, 60 ± 5% RH and a photoperiod of 16:8 (L:D) hours. After a 1-month rearing period, the colonies were used for parasitoid experiments.Parasitoid source. Aphidius ervi were obtained from a single collection of aphid mummies from apple trees in the town Banská Bystrica in May 2006. Mummies were kept individually in small glass vials (5 × 1.5 cm) under the same temperature and humidity conditions as aphids. Mummies were checked daily and parasitoid adults retrieved as they hatc...

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