Bark beetles oxidize the defensive monoterpenes of their host trees both to detoxify them and to convert them into components of their pheromone system. This oxidation is catalysed by cytochrome P450 (CYP) enzymes and occurs in different stages of the insect. We identified two new CYP4 genes in the Chinese white pine beetle (Dendroctonus armandi), and carried out bioinformatic analysis one the full-length nucleic acid sequences and deduced amino acid sequences. Differential expression of the CYP4 genes was observed between sexes, and within these significant differences amongst development stages, fed on phloem of Pinus armandi and exposed to stimuli((±)- α-pinene, (R)-(+)- α-pinene, (S)-(-)-α-pinene, (S)-(-)-β-pinene and (+)-3-carene) at 8 and 24 h, and their interactions were found upon exposure to host monoterpenes. Increased expression of CYP4 genes suggested that they play a role in the detoxification of monoterpenes released by the host trees. The differential transcript accumulation patterns of these bark beetle CYP4 genes provides insight into the ecological interactions of D. armandi with its host pine.

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In 1999, Barry Bolton postulated the presence of a basimandibular gland in the mandibles in all species of the ant genus Strumigenys, solely based on scanning microscopy observations. We now confirm the presence of this putative gland in the proximal outer part of the mandibles of 22 investigated species by histological and ultrastructural examination, including 10 short- and 12 long-mandibulate species. All species have a basimandibular gland, that is formed by 15–25 µm thick epithelial cells and belongs to class-1 following the standard classification of insect exocrine glands. We consider it a novel gland because of its peculiar bowl-shape and special arrangement of the microvilli that are confined to large vacuolar spaces instead of reaching the cuticle. The gland is most pronounced in S. mutica, particularly in the queen. In addition to this gland, we also found scattered class-3 intramandibular gland cells in the mandibles. Queens of S. mutica are peculiar in having a cluster of these cells in the distal tip of their mandibles. As this species is a social parasite, further research is required to determine whether the development of these mandibular glands is related to its parasitic lifestyle.

This paper describes the morphology and ultrastructure of the infrabuccal pocket in workers of the carnivorous ant Ectomomyrmex javanus, using SEM and TEM. The infrabuccal pocket is a flexible bag with a diameter of 330 ± 30 μm. In its anterior part, the pocket wall reaches a thickness of 24.45 ± 3.45 μm, which is thicker than the wall lining the rest of the infrabuccal pocket, where it measures 6.87 ± 1.12 μm. The epidermal cells of the wall form a thickened epithelium with a thickness of 10.18 ± 2.50 μm. There are different kinds of hairs inside the pocket, that help in filtering solid pellets. Literature data on the infrabuccal pocket are limited and the function of the thicker epithelium is not yet known. It may provide mechanical strength as the pocket undergoes daily size changes because of the filling up and spitting out of pellets.