Insecticidal juvenile hormone analogs stimulate the production of male offspring in the crustacean Daphnia magna.

Abstract

Daphnid culture. Daphnids (Daphnia magna)were cultured in incubators at a density of 40 adults in 1 L of medium at a temperature and photoperiod of 20°C and 16 hr light. Algae (Selenastrum capricornutum), cultured in Bold's basal medium, was used as a food source for daphnids during culturing and

Pyriproxyfen, a juvenoid hormone analog, does not induce male production in parthenogenetic lineages of Eucypris virens (Crustacea: Ostracoda)

“…Adults were sorted out and batches of 10 individuals were transferred to 50 ml jars filled with mineral water and varying concentrations of pyriproxyfen: 0 nM, 0.003 nM, 0.03 nM, 0.3 nM, 3 nM and 30 nM. This range covers the concentrations that are known to induce male production in Daphnia (Olmstead & LeBlanc 2003;Rider et al 2005) and includes the doses applied to rice fields (Hopkins 1994). The medium was renewed every four days.…”

“…Ethanol concentrations did not differ between control jars (0 nM pyriproxyfen; 0.5% v/v ethanol) and treatment jars (0.003-30 nM pyriproxyfen; 0.5% v/v ethanol). A 0.5% v/v ethanol solution does not affect sex ratios of D. magna offspring (Olmstead & LeBlanc 2003). There were three replicate jars per treatment.…”

“…In particular, pyriproxyfen proved to be very powerful. Exposure of gravid Daphnia to a pyriproxyfen concentration of 0.3 nM resulted in the production of 80% males, whereas a similar proportion of male neonates was only observed for Daphnia reproducing in an 800 nM methylfarnesoate solution (Olmstead & LeBlanc 2003). Pyriproxyfen is widely used in agriculture as a pesticide.…”

“…The hormone induced male production in lineages that were considered as non-male producers (Rider et al 2005), and even in species for which males were not known (Kim et al 2006). Several synthetic analogs of methylfarnesoate, namely pyriproxyfen, methoprene and fenoxycarb, were found to have similar sex determining effects (Olmstead & LeBlanc 2003;Rider et al 2005). In particular, pyriproxyfen proved to be very powerful.…”

“…Pyriproxyfen is widely used in agriculture as a pesticide. It is mainly applied to terrestrial environments, for example to control white fly on cotton and scale insects on trees (Center of Integrated Pest Management 2002, in Olmstead & LeBlanc 2003, after which it may leach into aquatic systems. The pesticide is also applied directly to aquatic environments against mosquitos in rice fields (Hopkins 1994).…”