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The role of temperature in egg development of three aquatic insects Lestagella penicillata (Ephemeroptera), Aphanicercella scutata (Plecoptera), Chimarra ambulans (Trichoptera) from South Africa

Ross-Gillespie, Vere, Picker, Mike D., Dallas, Helen F., Day, Jenny A.
Journal of thermal biology 2018 v.71 pp. 158-170
Ephemeroptera, Philopotamidae, Plecoptera, aquatic insects, eggs, guidelines, hatching, rain, streams, sublethal effects, water temperature, winter, South Africa
1.The sub-lethal effects of water temperature on egg development was investigated in three syntopic mountain stream insects, viz. Lestagella penicillata (Ephemeroptera: Teloganodidae), Aphanicercella scutata (Plecoptera: Notonemouridae) and Chimarra ambulans (Trichoptera: Philopotamidae) from the winter rainfall Western Cape Province, South Africa.2.Eggs of each species were incubated after fertilisation at six temperature treatments across the range of 5–30°C. Total development time required for 50% hatch, total hatch success, duration of the hatching period, upper and lower thermal limits for development, as well as thermal reaction norms were calculated for each species.3.Successful egg development and hatching occurred between 10 and 20°C for L. penicillata, with highest percentage hatch (90%) at 10, 15 and 20°C treatments. For A. scutata successful hatching also occurred between 10 and 20°C but hatching success was reduced (~ 30%) at 20°C compared to ~ 80% hatching success at 10 and 15°C treatments. For C. ambulans, successful development and hatching occurred over a wider range of temperatures (10–25°C) but with lower (5–20%) and more variable hatching success at all temperatures.4.Thermal reaction norms in conjunction with egg hatch parameters showed that L. penicillata and particularly C. ambulans were warm adapted, while the A. scutata was cold adapted. These observed differences in egg development characteristics similarly relate to the different life-histories and their relation to developmental season.5.Lethal thermal limits for egg development along with the sub-lethal effects of temperature on hatch success provide valuable information for setting environmental water temperature guidelines for species conservation as well as environmental flow studies.