Chironomus riparius midge larvae are ubiquitous in freshwater ecosystems throughout the Northern Hemisphere. Recently, freshwater in temperate regions has experienced a threat from salinization due to the use of road de-icers. As ambient temperatures fluctuate, snow and ice melt carry the de-icers into nearby freshwater and significantly raise salt levels. Recently, organic de-icers including brine beet juice de-icer (BBJD) have been implemented as an "ecofriendly" alternative to traditional road salt. Not much is known about the effects of BBJD on freshwater invertebrates. Aquatic insects respond to salinity by adjusting the ion transport functions of osmoregulatory organs. A key component in insect osmoregulation is the presence of water channel proteins known as aquaporins (AQPs) that allow movement of water along an osmotic gradient. To date, there is limited knowledge on the effects of salinity on AQP function in aquatic insects. In this study, we characterized a water-specific AQP known as CrAQP2 (a PRIP homolog) in the osmoregulatory organs of C. riparius larvae. CrAQP2 was immunolocalized in osmoregulatory organs with greatest transcript abundance in the Malpighian tubules. NaCl caused differential Craqp2 transcript expression in some of the organs, whereas BBJD had little effect on Craqp2 transcript levels. Craqp2 knockdown decreased total body water regardless of treatment and reduced survival of larvae in BBJD and NaCl. Therefore, CrAQP2 appears to be important in maintaining total body water levels stable and likely plays a role in the ability of midge larvae to respond to salinity.

In insects, juvenile hormone (JH) is essential for orchestrating reproductive events. For example, in the male moth Agrotis ipsilon, the behavioral response to female sex pheromone is linked to neuronal sensitivity in the primary olfactory centers (antennal lobes, ALs), and the maturation of accessory sex glands (ASGs) are known to be age- and JH-dependent. The molecular basis of this regulatory action of JH is not fully deciphered, and we show here that the heterodimerizing partner of Methoprene-tolerant called Taiman (Tai) is essential for the sexual maturation of male A. ipsilon. Tai expression in ALs and ASGs is elevated from the third day of adult life and is responsible for the acquisition of behavioral responsiveness to the sex pheromone and ASG maturation. Tai-deficient old males exhibited altered sexual behavior and delayed ASG maturation. Moreover, the expression levels of Tai and Krüppel homolog 1 (Kr-h1), an early JH-induced transcription factor, were reduced in ALs and ASGs of JH-deprived and Tai-deficient old males, respectively. Exogenous JH injection into young males resulted in precocious sexual maturation and this JH induction was suppressed by Tai silencing. Our results demonstrate that Tai is an actor of the JH signaling pathway that operates in ALs and ASGs to promote pheromone information processing and consequently the display of sexual behavior in synchrony with ASG maturation, ultimately optimizing male reproductive success. Thus, this study provides additional insights into the molecular mechanisms underlying hormonal regulation of sexual maturation in insects.

Per-/polyfluoroalkyl substances (PFAS) have been commonly used over several decades for a variety of products and are very persistent in the environment. However, not much is known about their direct effects on aquatic invertebrates and their ecosystems. We examined the survival, behavior, development, and predation susceptibility of mosquito larvae Culex quinquefasciatus exposed to concentrations of perfluorooctanesulfonic acid (PFOS) ranging from 0.02 to 453.7 µg/L. PFOS exposure resulted in reduced larval survival, with a 48 hour LC50 (concentration with 50 % mortality) of 255.99 µg/L. PFOS exposure also resulted in reduced developmental success and slower maturation to adulthood (and thus slower emergence from the water) compared to control larvae. PFOS also resulted in delays in reaction to prodding stimuli, which were meant to simulate a predator attack, and longer reactions to prodding. Larvae exposed to PFOS also spent more time at the bottom of the water column, rather than at the surface where respiration takes place. Effects of larval mosquito PFOS exposure on predation by unexposed damselfly naiads (genus Ischnura) were not detected. Overall, this research suggests that PFOS impacts mosquito larvae survival, behavior, development, and adult emergence, which could have important implications for food webs or public health given the role of mosquitos as disease vectors.

Optimisation of life history and organismal performance underlies success in insect mass-rearing. Rearing schedules, resource use and production yield depend on many aspects of insect fitness and performance within and across generations, such as growth, development, longevity, and fecundity, which are all temperature dependent. Despite this general understanding, we often lack species-specific information needed to make informed decisions about manipulating rearing temperatures to optimise insect growth and development. Here, we characterise the effects of rearing temperature on nymph to adult development and lifespan (20 - 38 °C), and reproductive output (30 - 38 °C) in a farmed cricket (Gryllodes sigillatus). Crickets grew larger and reached adulthood sooner at higher developmental temperatures at the expense of longevity. Reproductive output was similar across a range of temperatures but decreased at 38 °C. Therefore, while temperature control is necessary to maximise production rates, temperature is unlikely to affect production yield in a fixed harvest cycle provided it is maintained within the narrow range enabling both fast growth and stable reproduction (32 - 36 °C). Our study provides a fundamental basis for further optimisation of insect rearing operations and a deeper understanding of the thermal biology of this commonly farmed species.