Field and laboratory life cycle studies of Malenka depressa (Banks, 1898) (Plecoptera: Nemouridae)

Abstract

During 1982–1985, laboratory and field studies of 125 eggs, 8055 nymphs and 1426 adults indicated a univoltine slow life cycle for Malenka depressa (Banks, 1898) in a first-order perennial stream in the Mediterranean climate of the San Francisco Bay area. Nymphal growth and adult emergence were continuous throughout the year, further enhanced by a thick, protective tree canopy shading of the canyon that provided an insulated stabilised thermal tube of cool air, ground and stream water temperatures. Leaf senescence of the overhead California bay trees was a perennial source of allochthonous food for the immature stages. Maximum assimilation efficiency for middle to late-nymphal growth stages fed on bay leaves was 42% at 10 °C.

Keywords:

• Malenka
• life history
• Plecoptera
• Nemouridae
• voltinism

Acknowledgements

I thank Drs John Brittain, University of Oslo, Norway, Bill Stark, Mississippi College, Mississippi, and George Schultz, for critical reviews of the current manuscript. I am grateful to Dr Vincent Resh and kindly remember the late Drs Richard Garcia and Ken Hagen, University of California, Berkeley for earlier reviews and support. I thank Dr Richard W. Baumann, Brigham Young University, Utah for species identification confirmation.

Disclosure statement

No potential conflict of interest was reported by the author.