Methoprene does not affect juvenile hormone titers in honey bee (Apis mellifera) workers

Abstract

Methoprene, a juvenile hormone (JH) analog, is a widely used insecticide that also accelerates behavioral development in honey bees (Apis mellifera). JH regulates the transition from nursing to foraging in adult worker bees, and treatment with JH or methoprene have both been shown to induce precocious foraging. To determine how methoprene changes honey bee behavior, we compared JH titers of methoprene-treated and untreated bees. Behavioral observations confirmed that methoprene treatment significantly increased the number of precocious foragers in 3 out of 4 colonies. In only 1 out of 4 colonies, however, was there a significant difference in JH titers between the methoprene-treated and control bees. Further, in all 4 colonies, there was no significant differences in JH titers between precocious and normal-aged foragers. These results suggest that methoprene did not directly affect the endogenous JH secreted by corpora allata. Because methoprene caused early foraging without changing workers' JH titers, we conclude that methoprene most likely acts directly on the JH receptors as a substitute for JH.

Roles of Krüppel Homolog 1 and Broad-Complex in the Development of Dendroctonus armandi (Coleoptera: Scolytinae)

“…Solutions of the stock juvenile hormone analog JHA methoprene (Sigma, Saint Louis, United States), were separately diluted to 5, 25 and 100 μg/μL concentrations using acetone ( Huang et al, 2016 ). Next, 0.1 μL of each JHA dilution was injected into D. armandi larvae (mature larvae) and pupae (newly pupated pupae) through the ventral abdomen using Hamilton Microliter syringes (700 series, RN) with 32G sharp-point needles (Hamilton, Switzerland) to a final JHA content of 0.5, 2.5 or 10 μg.…”

Regulation of Juvenile Hormone on Summer Diapause of Geleruca daurica and Its Pathway Analysis

“…The molecular basis of the JH signaling pathway has been recently unveiled [7][8][9][10][11]. Many studies have suggested that exogenous JH analogue (JHA) would mimic the action of JH and likely act directly on the JH receptors as a substitute for JH [12]. JHAs have been effectively used to understand the mechanism of JH action.…”

Effect of a juvenile hormone analogue (methoprene) on ovarian development and survival in the Eastern Carpenter Bee (Xylocopa virginica)

“…The lowest dose, 100 µg, was insu cient to raise ovarian development above levels observed in control bees, but dosages of 500 and 1000 µg were effective. Studies of smaller hymenopterans have used doses below 200 µg, and as low as 30 µg(Bortolotti et al, 2020;Huang et al, 2018;Tibbetts & Sheehan, 2012), whereas a recent study on Bombus impatiens, which are almost as large as carpenter bees, used methoprene dosages similar to our study(Wynants et al, 2023).As bees killed 2 or 4 days after methoprene treatment had similar levels of ovarian development, methoprene effects must have occurred within 2 days. This is consistent with studies in other hymenopterans, in which methoprene induced increases in ovarian development in as little as 3 days(Tibbetts & Sheehan, 2012).…”