In the Mediterranean area the orthopterans Calliptamus barbarus barbarus, Dociostaurus maroccanus and Tettigonia viridissima are considered to be pests of major economic importance crop plants. The aim of the present study was to evaluate the area of leaf of vine, cotton and potato plants consumed by these Orthoptera at two temperatures. Leaf area was determined for each plant species before the leaves were provided to the insects. Virgin male and female adults were allowed to feed on a leaf of each plant species and the area of leaf consumed was determined after 24h at 25 and 30°C. Results showed that temperature had a significant affect on consumption by both males and females of all the species examined, and it was higher at 30°C. The influence of plant species was not significant for C. barbarus barbarus. D. maroccanus and T. viridissima, however, consumed a greater area of potato leaves than of the other species of plants. Females consumed more food than males in all the species tested. The results of the present study provide a first approximation of the area of leaf consumed and the potential loss of foliage these plants might suffer if attacked by the three species of Orthoptera tested., Spyridon A. Antonatos, Nikolaos G. Emmanuel, Argyro A. Fantinou., and Obsahuje seznam literatury
The role of the thermophotoperiod on larval diapause induction and development of Sesamia nonagrioides was investigated under laboratory conditions. The incidences of diapause by TC 12 : 12 thermoperiods under DD, in which the thermophase was 30°C and cryophases varied from 10 to 25°C, were compared to the effects of thermophotoperiods with the same configuration. Higher incidences of diapause were recorded when larvae were exposed to thermophotoperiods with cryophases of 15-25°C, than under thermoperiods under constant darkness. In addition, larvae exhibited significantly lower percentages of diapause when exposed to cryophases < 15°C under either thermo- or thermophotoperiodic condition. Diapausing larvae when exposed to photoperiods 16L : 8D h and different temperatures of 25-30°C proceeded to development in 14-16 days. Moreover time needed for the pupation of diapausing larvae after their transfer to 12L : 12D h, was reduced from approximately 49 to 12 days depending on temperatures of exposures (25-30°C). Diapause termination was also compared under 12L : 12D h and constant temperature of 25°C or a thermoperiod of TC 12:12 (30°: 20°). Days needed for pupation at constant temperature or under the mentioned thermoperiodic regime, were approximately the same when the high temperature of the thermoperiod coincided with the scotophase, while with the co-occurrence of the high temperature of the thermoperiod and the photophase significantly additional time was needed for diapause development. Significantly shorter time was also needed for diapause development after exposure of diapausing larvae to continuous light, than to continuous darkness under 25°C. Thermoperiods of different amplitudes with the same mean temperatures proved that the higher temperature of scotophase led to higher rate of diapause development in spite of the relatively low temperature of the photophase tested. It is suggested that thermoperiod could hasten the time needed for diapause development, but it is not the crucial factor for the termination of diapause.