Methoprene, a juvenile hormone analogue, modifies maturation and emergence in overwintering Osmia rufa L. adults

Abstract

The development of methods aimed at activation of imagos at any point of wintering provides a compelling potential avenue to utilize bees for pollination of greenhouse crops during autumn, winter, and early spring. In this study, we tested methoprene, a juvenile hormone (JH) analogue as a chemical stimulant to end a diapause of Osmia rufa L. and enable bee activation and emergence under experimental conditions. The application of methoprene significantly reduced the emergence time of adult bees in winter months as compared to vehicle (acetone) and negative controls. Bees treated with methoprene started to emerge 3–6 days earlier than bees from acetone and control groups and finished emergence 2–6 days earlier too. Statistically significant differences were observed between methoprene and controls groups of male and female in all tested incubation periods. It was also observed that the effects of methoprene were significantly more effective in female specimens during the first 2 months of winter. Moreover, in females, methoprene improved reproductive traits such as an increase in the size of terminal oocytes. Similarly, in males, methoprene treatment resulted in a significant increase in a seminal vesicle size and dynamic elevation of spermatozoa number. Taken together, our results indicate that methoprene may play an important role in the termination of diapause, bee activation, and emergence.

Use of Osmia bicornis L. for Pollination of Cyclamen persicum Mill. Cultivated in Greenhouse Environment During Winter Period

“…Our previous studies had confirmed the positive impact of methoprene on reproductive traits in O. bicornis (Giejdasz et al 2021). Although the evaluation of male and female vitality was not the aim of our work, it can be concluded indirectly on the basis of pollination effectiveness that the administration of methoprene did not have any negative effects on the activity of both sexes.…”

“…This process proceeds slowly, which makes flights and blooming difficult to synchronize. Therefore, apart from the temperature application of a juvenile hormone analogue, methoprene was successfully used to accelerate the end of diapause (Wasielewski et al, 2011;Giejdasz et al, 2021). This enabled us to reduce the Osmia overwintering period, which provided evidence that it can become a very effective pollinator in greenhouse environments even during the winter.…”

Juvenile hormone and temperature effects in the postzygotic parental investment of male waterbug Abedus ovatus (Belostomatidae)

“…Different studies show that topical application or ingestion of methoprene can simulate the effects of the juvenile hormone synthesized by the corpora allata (Bachmann et al., 2017; Ma et al., 2021; Trumbo, 2018; Zhu et al., 2017). Furthermore, unlike juvenile hormone, methoprene is not photosensitive (Bachmann et al., 2017) and appears to remain in the body longer due to a low degradation rate (Giejdasz et al., 2021), which makes it suitable for single‐application experiments.…”

“…In waterbugs of the genus Abedus, the females oviposit their eggs on the dorsum of the males and secrete a mucous substance with which it glues the eggs (Smith, 1997). Males protect the eggs from oviposition to hatching and carry out two different parental care behaviors that maintain adequate oxygenation and humidity conditions for the development of the eggs (Goforth & Smith, 2011). The most frequent behavior is oxygenation through flexions called brood pumping, in which males perform a series of abrupt push-up movements and repeatedly flexing their hind legs.…”

Methoprene, a Juvenile Hormone Analog, Causes Winter Diapause Elimination in Univoltine Bee Species Osmia bicornis L.

“…The most sensitive developmental stage to methoprene application was the 3- The experimental cocooned females were treated topically on the cocoon surface once a day for five consecutive days with 200 µg of methoprene dissolved in 5 µL acetone (Sigma, Sosnowiec, Poland) and cocooned males with 120 µg of methoprene dissolved in 3 µL acetone [24][25][26]. Appropriate volume and concentration of methoprene were prepared according to our previous experience and experiments and based on authors who performed their experiments on Apis mellifera, a honeybee who belongs, similar to Osmia, to the Apoidea superfamily and has similar body weight [18,27,28]. The vehicle control was treated with 5 µL of acetone (female) or 3 µL (male) and the negative control was not treated.…”