Food limitation in Chironomus tepperi: Effects on survival, sex ratios and development across two generations

Species from the Dipteran family Chironomidae are widely used in laboratory and field studies to identify toxicity in freshwater environments. However, toxicity assessments can be influenced by food availability, which can alter endpoints in assays including viability, sex ratios and development time. The aim of this study was to determine if food limitation affected the endpoints used in toxicity tests with the Australian model organism, Chironomus tepperi, including responses in offspring. First instar larvae were subjected to food treatments with larval density controlled and offspring were either raised under the same food conditions as their parents or under standard conditions. In lower food density treatments adults in the F0 generation experienced delayed emergence and females produced fewer egg masses. F0 diet affected the performance of F1 to continued exposure and there was evidence that the quality of the offspring was compromised. Although sex ratios were not skewed, males and females responded differently to food limitation, especially in the F1 generation where female development was more delayed. These results demonstrate that endpoints used in toxicity evaluation in C. tepperi also respond to food availability, highlighting the need to control for food in both laboratory and field toxicity studies. Multiple generations should ideally be exposed to stressors under laboratory conditions to elucidate likely long term effects in the field.

► The sublethal effects of food limitation in Chironomus tepperi were examined.
► Effects were investigated across two generations.
► Food limitation does not affect sex ratios in either generation.
► Food limitation delayed larval development to adulthood.
► Developmental delays were more pronounced in the second generation and the sexes responded differently.