Morphological characteristics and distribution of sensilla on ovipositor and tarsal of Ostrinia furnacalis (Guenée) (Lepidoptera: Crambidae)

The distribution of sensilla located on the ovipositor and tarsal organs of Asian corn borer Ostrinia furnacalis (Guenée) (Lepidoptera: cambridae) are described based on observations using scanning electron microscopy and selective staining with silver nitrate. This was done to provide a structural base for further physiological work and to explain behavioural studies that had been observed previously. Results showed that abundant sensilla chaetica are distributed on the ovipositor and tarsi. The ovipositor is made up of three sensilla that may have mechanoreceptive functions and two types of chemoreceptive sensilla. On the tarsi, the sensillum consists of one type of multiporous sensilla trichodea, spine-like sensilla trichodea, and spines that serves as mechanoreceptors and three types of sensilla chaetica mainly on the ventral side of the fifth tarsomere that have chemoreceptive role. There is a sexual dimorphism in the number and size of sensilla on these organs. These results are discussed in relation to the possible function of the sensilla types in the oviposition behavior of O. furnacalis, the sensilla on both the ovipositor and tarsi could be used as specialized structure for mechano-reception and chemo-reception.

Keywords:  sensilla, Asian corn borer, oviposition, sexual dimorphism, SEM, silver staining.