The morphology and ultrastructure of the olfactory sensilla on the antennae and maxillary palps were investigated through scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and their responses to five volatile compounds were measured using electroantenogram (EAG) and electropalpogram (EPG) techniques in the pumpkin fruit fly, Bactrocera depressa (Shiraki; Diptera: Tephritidae). Male and female B. depressa displayed distinct morphological types of olfactory sensilla in the antennae and maxillary palps, with predominant populations of trichoid, basiconic, and coeloconic sensilla. Basiconic sensilla, the most abundant type of olfactory sensilla in the antennae, could be further classified into two different types. In contrast, the maxillary palps exhibited predominant populations of a single type of curved basiconic sensilla. High‐resolution SEM observation revealed the presence of multiple nanoscale wall‐pores on the cuticular surface of trichoid and basiconic sensilla, indicating that their primary function is olfactory. In contrast, coeloconic sensilla displayed several longitudinal grooves around the sensillum peg. The TEM observation of individual antennal olfactory sensilla indicates that the basiconic sensilla are thin‐walled, while the trichoid sensilla are thick‐walled. The profile of EAG responses of male B. depressa was different from their EPG response profile, indicating that the olfactory function of maxillary palps is different from that of antennae in this species. The structural and functional variation in the olfactory sensilla between antennae and maxillary palps suggests that each plays an independent role in the perception of olfactory signals in B. depressa.

Many plant species possess compounds with juvenile hormone disruptor (JHD) activity. In some plant species, such activity has been attributed to diterpene secondary metabolites. Plant JHD diterpenes disrupt insect development by interfering with the juvenile hormone (JH)-mediated formation of JH receptor complexes. Here, we demonstrate that a plant extract and a diterpene from Lindera erythrocarpa (methyl lucidone) interfere with the formation of both methoprene-tolerant (Met)/Taiman and Germ cell-expressed (GCE)/Taiman heterodimer complexes in yeast two-hybrid assays in vitro. In addition to the in vitro JHD activity, the diterpene and the plant extract from L. erythrocarpa also disrupt the development of larvae and pupae in Drosophila melanogaster. Comparing the transcriptomes of juvenile hormone analog (JHA, methoprene)- and JHD (methyl lucidone)-fed wandering third-instar larvae revealed a large number of genes that were coregulated by JHA and JHD. Moreover, most (83%) of the genes that were repressed by methyl lucidone were significantly activated by methoprene, indicating that JHDs and JHAs have opposing effects on the transcriptional regulation of many JH-dependent genes. Gene ontology analysis also suggested that some of the genes activated-by-JHA/repressed-by-JHD play roles in spermatogenesis. Affymetrix microarray-based analysis indicated that the expression of genes activated-by-JHA/repressed-by-JHD was testis-specific. Together, these results suggest that JH is involved in testis-specific gene expression and that plant JHD diterpenes function as JH antagonists in such JHA-mediated gene regulation.

Superhydrophobic and transparent surfaces on cotton fabrics have been developed using silica nanomaterials. Initially, trichlorododecylsilane was treated on the silica nanoparticles to lower the surface energy of the fabric. By simply spraying alcohol suspensions containing hydrophobized silica nanoparticles, extremely water repellent coatings were formed on the textile fabrics. The effect of three types of alcohol solvent on the hydrophobicity of the coated cotton fabrics was examined by measuring the surface wettability. The treated cotton textiles in methanol exhibited contact angles higher than 160°, contact angle hysteresis lower than 10°, and good water repellency. It proved to be essential to form hierarchical morphology in achieving superhydrophobicity.

Here, we report that the olfactory attraction of the striped fruit fly, Bactrocera scutellata (Hendel; Diptera: Tephritidae), a serious pest of pumpkin and other cucurbitaceae plants, to cue lure and raspberry ketone is mediated by the maxillary palps. The antennae, bearing three morphological types (basiconic, trichoid, and coeloconic) of olfactory sensilla, in male and female B. scutellata exhibited significant electroantennogram (EAG) responses to a plant volatile compound, 3-octanone, and methyl eugenol, whereas cue lure, raspberry ketone, and zingerone that are known to attract several other species of Bactrocera fruit flies elicited no significant EAG responses from both sexes. In contrast, maxillary palps, housing one morphological type of basiconic sensilla, displayed the largest electropalpogram (EPG) responses to cue lure followed by raspberry ketone among the five compounds tested in male and female B. scutellata, with only minor EPG responses to 3-octanone, which indicates that the maxillary palps are responsible for detecting cue lure and raspberry ketone in this species. In field trapping experiments, significant number of male B. scutellata were captured in the traps baited with cue lure or raspberry ketone, in which the attractiveness of cue lure was significantly higher than that of raspberry ketone. Methyl eugenol and zingerone were not behaviorally attractive to B. scutellata although they elicited significant EPG responses.Our study indicates that the behavioral attraction of B.Arch. Insect Biochem. Physiol. 2018;99:e21510. wileyonlinelibrary.com/journal/arch