Chlorination Is Ineffective at Eliminating Insects from Wastewater: A Case Study Using Ceratitis capitata

Eradicating insects from small bodies of water without resorting to environmentally harmful methods is a challenge worldwide. Among the practices used to treat the water waste of arthropod containment facilities, chlorination is still used, despite the known impacts of chlorine byproducts on the environment and limited scientific literature documenting its potency against arthropods. Here, we evaluated the efficacy of chlorination as a means to kill insects in water by immersing eggs of the Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae) in 10 solutions containing different concentrations of chlorine ranging from 0 to 65,000 ppm for a duration of 4, 24, and 48 h, and measuring egg survivorship. Results showed that egg survivorship was negatively correlated with chlorine concentration and immersion duration. The rate of decrease in egg survivorship due to chlorine was steeper as immersion duration increased. However, egg mortality never reached 100% even with the highest chlorine concentration, and concentrations < 2000 ppm had little effect on eggs. Our results demonstrate clearly that chlorination is not an effective treatment method to ensure insect eradication from wastewater. More effective alternative methods, such as heat treatment, are preferable.