Developmental thresholds and day-degree requirements of Paratanytarsus grimmii and Corynoneura scutellata (Diptera: Chironomidae), two midges associated with potable water

Studies on the development and mortality of Paratanytarsus grimmii (Schneider) and Corynoneura scutellata (Winnertz), which can infest potable water distribution networks, were carried out at eight constant temperatures between 10 degreesC and 27 degreesC. Using weighted linear regression, the developmental thresholds were calculated as 7.9 and 8.7degreesC for P. grimmii and C. scutellata, respectively. Corynoneura scutellata had a day-degree requirement of 172.4 per generation and developed significantly faster (P <0.001) than P. grimmii with a day-degree requirement of 294.1. Both species were identified as multivoltine with a maximum theoretical number of five generations per year for P. grimmii and seven for C. scutellata. These results are discussed in the context of the management of chironomid infestations within water-treatment works.