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Effect of environmental conditions on progeny production by the oriental cockroach Blatta orientalis
- Patourel, G.
- Entomologia experimentalis et applicata 1995 v.74 no.1 pp. 1-6
- Blatta orientalis, cold, cold stress, cold tolerance, egg masses, eggs, embryogenesis, environmental factors, exposure duration, females, fungi, hatching, insects, nymphs, progeny, temperature, viability
- Oothecal production by both mated and unmated female oriental cockroaches Blatta orientalis L. (Dictyoptera: Blattidae) was measured at temperatures between 10° and 28 °C. Production was inhibited at 15 °C and below, and only partially recovered when cooled insects were returned to 28 °C. Mean incubation times for oothecae varied from 41.4 to 43.9 days at 28 °C, 60.5 to 60.8 days at 24 °C and 86.8 to 91.7 days at 20 °C depending on RH. No nymphs emerged from oothecae kept continously at 15 °C, 75% RH over a 6 month period, although hatch at both 10° and 15 °C was observed in a few cases when oothecae containing eggs close to hatching (28-35 days from deposition, maintained at 28 °C) were transferred to these lower temperatures. The mean number of nymphs emerging from oothecae (non-hatching oothecae included) increased with temperature over the range 20-28 °C and with RH over the range 43-95% RH. At 28 °C there was a decline in oothecal viability in the range 95-100% RH attributable to fungal attack, and few nymphs emerged from oothecae kept at 0% RH. The viability of oothecae subjected to periods of cold exposure and then returned to 28 °C decreased with decreasing exposure temperature (10° to −5 °C), increasing exposure period (2 h to 30 days) and stage of embryogenesis when exposed (oothecae incubated for 0 to 7 days at 28 °C prior to cold exposure less cold-tolerant than oothecae incubated for 28 to 35 days).