Surface morphology and morphometric analysis of sensilla of Asian tiger mosquito, Aedes albopictus (Skuse): an SEM investigation

Background & objectives: The sensilla and sensory mechanism play a significant role in hostseeking and oviposition behaviour of mosquitoes, which enable them to transmit various diseases to humans. Aedes albopictus (Skuse) has emerged as a major vector of Chikungunya virus in the recent epidemics in most parts of southern India. Studies on the sensory structures of dengue vector, Aedes aegypti (Linn) are comprehensive; whereas information on the sensillary systems of Asian tiger mosquito, Ae. albopictus is inadequate. Therefore, the present study has been carried out to observe various types of sensilla located on the antenna, maxillary palp, labial palp, tarsi and ovipositor of Ae. albopictus using scanning electron microscopy. Methods: The antennae, maxillary palpi, labellum, tarsi and ovipositor of 10 different female mosquito of Ae. albopictus were fixed individually in 2.5% glutaraldehyde solution, washed twice and dehydrated with ascending grades of ethanol. Samples were cleared with xylene, air-dried, mounted on stubs, gold coated in an ion-sputtering unit and the sensilla were viewed between 5 and 10 KV using FEI Quanta 400 EDAX scanning electron microscope. ANOVA revealed significant differences in the morphometric features of various sensilla. Results: In the antenna Sensilla trichoidea are numerously distributed in all flagellar segments revealed four distinct subtypes. Two types of grooved peg sensilla were observed. Sensilla coeloconica was observed in the terminal flagellum of antenna and tarsomeres with large variation in diameter. Sensilla chaetica are distributed throughout the body and revealed greater variation in morphology and morphometric parameters. Interpretation & conclusion: The significant difference among various types of sensilla would possibly reveal their functions. The porous sensilla are olfactory and contact chemoreceptors while the aporous sensilla would play the role of mechanoreception. Sensilla coeloconica on the antenna, tarsus showed major differences with Ae. aegypti. The ovipositor sensilla revealed three types of chaetica arranged in rows but has not been reported earlier with other mosquito species

Edge Based Fiber Bragg Grating Interrogator

Fiber Bragg Grating (FBG) interrogation system based on spectral edge characteristics of Chirped Fiber Bragg Grating (CFBG) is reported to measure temperature of hot water bath. We use in-house fabricated FBG and CFBG as an edge filter in developing FBG interrogator. The CFBG transmission profile at rising and falling edge varies linearly with wavelength. The Bragg wavelength of FBG as a function of temperature forms the basis of temperature measurement. The ratio of optical intensity of Bragg wavelength due to edge slope of CFBG and intensity of the Bragg wavelength vs. temperature of water bath observed is linear. Using the slope of linear curve, the temperature measurement resolution of 0.30C with temperature range of 300C was achieved