Plastic Peril: How do Phthalates Impact Growth, Development, and Reproduction in Insects

Plasticizers, such as phthalate esters (PAEs), make plastics more flexible and durable, but they have infiltrated ecosystems and food chains worldwide. Di(2-ethylhexyl) phthalate (DEHP) is the most commonly used PAE, and it impairs reproduction by disrupting the regulation of sex steroid hormones in vertebrates. In insects, steroid hormones—particularly ecdysteroids—play a central role in regulating both development and reproduction. Furthermore, differential regulation of ecdysteroids is associated with distinct life-history strategies in some species, such as wing-dimorphic crickets, where hormone levels differ between flight-capable and flightless individuals. Here, we investigated the effects of DEHP exposure in the diet (0, 2, or 20 mg/kg DEHP added to food) during development in the native variable field cricket (Gryllus lineaticeps) to address three hypotheses. First, DEHP impairs reproduction similar to its effects in vertebrates. Second, DEHP is costly to development given its putative interference with the regulation of ecdysteroids that govern development in insects. Third, DEHP promotes flight capacity because DEHP is expected to interfere with ecdysteroid binding more in flightless Gryllus because they exhibit higher circulating levels of ecdysteroids. Our results will provide new insight into the effects of plastic pollution on growth, development, and reproduction in insects, which play key roles in a diversity of terrestrial ecosystems.