Temporal Distribution and Abundance of Mosquito Vectors in Dhaka City

Species of Anopheles, Aedes and Culex mosquitoes showed that Anopheles gambiae s.s had the highest number (43.5%) out of the three malaria vectors (viz. Anopheles gambiae, An. arabiensis and An. funestus). For Aedes and Culex species, Aedes aegypti (37.6%) and Culex fatigans (37.1%) had the highest prevalence out of their sibling species. Temperature and rainfall were highly correlated with the abundance of mosquito vectors. It was observed that the rainy season (March to October) recorded the highest number (Total 11 specie) of mosquito vectors collected with the peak (Aedes aegypty, 140) in the months of July (932) and August (976) while the lowest (333) collection was in the dry season (November to February) with lowest (333) in the month of February when there was little or no rains. Asiat. Soc. Bangladesh, Sci. 46(1): 27-35, June 2020

HOST IDENTIFICATION OF ARTHROPOD BLOODMEALS BY AGAR ELECTROPHORESIS*)

A relatively easy and inexpensive method of rapid gel electrophoresis suitable for the host identification of arthropod bloodmeals was investigated. Electrophoretic conditions (preparation of agar and buffer, voltage, temperature, time, etc.) are discussed. The method of preparing and applying the arthropod bloodmeal to the slides is discussed in detail. Two minutes after the start of the electrophoretic run the suitability of the arthropod meal for testing was apparent. When there was visible migration of more than one Hb fraction towards the anode, digestion has proceeded too far for host identification. Bloodmeals of Aedes togoi, Aedes aegypti, Culex fatigans, Anopheles sp., Rhodnius prolixus, Triatoma infestans, Triatoma dimidiata, Cimex lectularius, Pediculus humanus, Ornithodorus moubata, Ornithodorus savignyi and Ornithodorus rudis from man, Cebus and rhesus monkey, dog, cat, rabbit, guinea pig, hamster, rat, mouse, chicken, pigeon, snake, toad and frog were studied and compared with the serum and hemolyzed blood of the host species. It was possible to identify the host from the pattern of the arthropod bloodmeals. A number of details on arthropod digestion processes are given.

Chemical composition and mosquito repellent activity of the essential oil of Plectranthus incanus link

The chemical composition of the essential oil obtained from the leaves of Plectranthus incanus Link, with the yield of 0.6% (w/v), was analyzed by GC and GC/MS. A total of 16 constituents, representing 95.2% of the oil, were identified. The major components of the oil were fenchone (6.0%), piperitone oxide (32.4%), piperitenone (3.0%) and piperitenone oxide (41.5%). The repellent activity of the volatile oil at different concentrations was measured by the protection period against the bites of Anopheles stephensi and Culex fatigans. The tested oil had stronger repellent activity than citronella oil, which was used as a positive control. LC50 (30 min) for P. incanus oil against An. stephensi and C. fatigans were 23.8 and 19.6 ?l/L air, respectively, whereas LC50 of citronella oil were 31.7 and 31.0 ?l/L air. Thus, P. incanus may be regarded as a potential valuable source of chemicals that have strong mosquito repellent activity, and could be used for the preparation of mosquito repellent formulations.