Juvenile hormone (JH) plays important roles in almost every aspect of insect development and reproduction. JHs are a group of acyclic sesquiterpenoids, and their farnesol backbone has been chemically modified to generate a homologous series of hormones in some insect lineages. JH III (epoxidised methyl farnesoate) is the most common JH in insects, but Lepidoptera (butterflies and moths) and 'higher' Diptera (suborder: Brachycera; flies) have developed their own unique JH. Although JH was first proposed in the hemipteran suborder Heteroptera (true bugs), the chemical identity of the heteropteran JH was only recently determined. Furthermore, recent studies revealed the presence of a novel JH, JH III skipped bisepoxide (JHSB₃), in some heteropterans, but its taxonomic distribution remains largely unknown. In the present study, we investigated JHSB₃ production in 31 heteropteran species, covering almost all heteropteran lineages, through ultra-performance liquid chromatography coupled with tandem mass spectrometry. We found that all of the focal species produced JHSB₃, indicating that JHSB₃ is wide-spread in heteropteran bugs and the evolutionary occurrence of JHSB₃ ascends to the common ancestor of Heteroptera.

For further explanation and references, see the main text of our article (Matsumoto et al., 2021. Royal Society Open Science).

Insects were collected from the field in Osaka, Nara, Kyoto, and Okayama prefectures in Japan or obtained from colonies in our and other laboratories (see, Table S1 and Figure S1). Only adults were used. Due to the limited number of individuals collected from the field, results from 14 species are based on a single specimen. Insects were individually anaesthetized on ice and immobilized by clay. The CA attached with the corpora cardiaca was removed from these individuals according to the methods outlined in a previous study [25]. In brief, the CA was incubated in 30–50 µL of the modified minimal essential medium at 30 °C for 5 h. The JHs were extracted with hexane, dried under the stream of argon gas, and dissolved again in 30-1200 µL of methanol (Table S1).

The UPLC-MS/MS (ACQUITY UPLC H-Class, Xevo TQ-S micro, Waters, Milford, MA, USA) with a chiral column (CHIRALPAK IA-U, 3.0 mm x 100 mm, 1.6 µm particle size, Daicel, Tokyo, Japan) was used to compare the retention times of JHSB3 [18,19]. Authentic JHSB3 and 10S-JHSB3 were synthesised as described previously [15]. The MS/MS analysis of the authentic JHSB3 showed the [M+H]+ ion at m/z 283.2 and the [M+Na]+ at m/z 305.3. The product ions were detected at m/z 42.9 and m/z 233.2 when ions at m/z 283.2 were used as a precursor, whereas no fragmentation was detected when ions at m/z 305.3 were used. In the present study, ions at m/z 283.2 and their product ions at m/z 233.2 were used as monitor ions for detecting JHSB3 and 10S-JHSB3. The lowest detection limit of JHSB3 in our methodology is 0.25 pg [19]. Ten µL of the CA product in methanol was used.

The figures show charts of chiral ultra-performance liquid chromatography coupled with tandem mass spectrometry of the corpus allatum products from various heteropteran species. The vertical axis indicates the signal intensity of the product ion at m/z 233.2 produced from the precursor ion at m/z 283.2.