MIR S. MULLA,1
USAVADEE THAVARA,2
APIWAT TAWATSIN 2
J. CHOMPOOSRl 2
Affiliations :
1 Department of Entomology, University
of California, Riverside, California 92521, USA
2 National Institute of Health,
Department of Medical Sciences, Ministry of Public Health
88/7 Tiwanon Rd., Nonthaburi 11000, Thailand
Source:
Journal of the American Mosquito
Control Association, 20(1):64 - 73, 2004
Language :
English
Abstract :
In
Thailand, water-storage jars, barrels, drums, pails, and tanks constitute vast
developmental sites for Aedes aegypti in urban, semiurban, and
rural areas. Earthen water jars, cement jars, and concrete tanks constitute
the greatest proportion of artificial containers where Ae. aegypti breed.
This species is a major vector of the causal agents of dengue and dengue hemorrhagic
fever, and vector control by larviciding is one of the main approaches to disease
control. At present, temephos sand granules (SG) (1%) are used in large-scale
community-based larviciding programs. Because of the use of this larvicide over
the past 30 years, the likelihood exists that Ae. aegypti already
has become resistant to this larvicide. To develop more options for control
and make them available for use, we evaluated VectoBac tablets (Bacillus
thuringiensis var. israelensis [Bti ] 5%)
and a new formulation of zeolite granules (ZG) of temephos (1%) and compared
these formulations for efficacy with temephos SG (1%) in water-storage jars.
In these tests, we used 48 identical glazed earthen water-storage jars (200-liter
capacity) and developed quantitative sampling procedures for larvae, pupae,
and pupal skins. Pupal skins were the easiest to count and this technique was
used for the Ist time for assessing emergence of adults in water-storage containers.
Three water regimens were used: full jars, half-full jars, and full jars emptied
half way and refilled weekly. The 3 formulations with 3 regimens of water were
assessed over a period of 6 months. VectoBac tablets at the dosage of I tablet
or 0.37 g per 50 liters of water provided excellent control for about 112 days
in full water jars. In the other 2 water regimens, VectoBac gave excellent control
for 90 days. The 2 temephos formulations at the operational rate of 5 g per
50 liters of water were equal in efficacy, yielding almost 100% control for
more than 6 months. Unlike temephos SG, the temephos ZG had no objec-tionable
odor. Both the temephos ZG and Bti tablets increased clarity of
the water, a feature desired by the users. Lack of odor and depression of turbidity
are important attributes of Bti tablets and temephos ZG.
KEY WORDS Aedes aegypti , control, Bacillus thuringiensis
var. israelensis tablets, temephos formulations, water-storage
containers