Biological control of mosquito larvae

Objective: To evaluate the toxicity of Annona squamosa (A. squamosa) aqueous (physiological
saline) seed soluble extract and its control of mosquito population.
Methods: Ovicidal, larvicidal and pupicidal activity of A. squamosa crude soluble seed
kernel extract was determined according to World Health Organization. The mortality of each
mosquito stage was recorded after 24 h exposured to plant material. Toxicity assay was used
to assess the non-target organisms with different concentrations according to Organisation for
Economic Co-operation and Development.
Results: The aqueous solubilized extracts of A. squamosa elicit the toxicity against all stages
of Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus, and the LC50 values against
stages of egg, 1st-4th larvae were (1.45 and 1.26–2.5 mg/mL), (1.12 and 1.19–2.81 mg/
mL) and (1.80 and 2.12–3.41 mg/mL) respectively. The pupicidal activity also brought forth
amended activity against all three mosquitoes species, and the LC50 values were consider to
be 3.19, 2.42 and 4.47 mg/mL. Ultimately there was no mortality observed from non-target
organism of Chironomus costatus.
Conclusions: Based on the findings of the study, it suggests that the use of A. squamosa plant
extract can act as an alternate insecticidal agents for controlling target mosquitoes without
affecting the non-target aquatic insect. Further investigation to identify the active compounds
and their mechanisms of action is recommended.

The predatory potential of B. geminata and C. coromandelianum larvae on Aedes aegypti larvae was investigated under laboratory condition with a view to screening these predators for use in the control of Ae. aegypti breeding in dengue prone areas. The feeding rate of 8 th instar B. geminata on Ae. aegypti showed maximum predation on 1 st instar larvae (86%), followed by 2 nd , 3 rd and 4 th instars (72%, 66% and 48%), respectively. In the first hour, the consumption rate was maximal for all instars and a low intake (about 5%) was observed in subsequent hours. In 12 th instar B. geminata larvae maximum predation was observed for the 1 st and 2 nd instar larvae (98%) of Ae. aegypti, followed by 3 rd and 4 th instars (92% and 78%), respectively. The feeding rate of 12 th instar C. coromandelianum larvae on Ae. aegypti larvae showed that the maximum predation was of the 1 st instar larvae (82%), followed by 2 nd , 3 rd and 4 th instars (51%, 35% and 24%) respectively. The first hour consumption rate was maximum for all instars and no significant intake was seen in the following hours. The predation of Aedes larvae by the 2 spp. of odonate larvae was compared for the 4 mosquito larval instars by using one way ANOVA. No significant difference was found between them for 1 st instar larvae of Ae. aegypti but there was a significant difference (P<0.05) in predation on the other 3 instars, with B. geminata consuming more mosquito larvae. A single anisopteran larva is sufficient for eliminating the huge mass of larval mosquitoes breeding in a cement tank or a cement cistern. Therefore, this biological control agent could be released to control Aedes larval production in areas of dengue epidemics.

Sungai Besar Village is one of the endemic villages of Dengue Hemorrhagic Fever (DHF) in Banjarbaru city. Containers have an important role in the spread of dengue fever as a breeding ground for mosquitoes. The purpose of this research is to know the correlation of container condition with larva. Benefits to provide information that can be used to reduce the number of larvae. The design of this study used an analytical survey with cross-sectional approach on 673 containers from 107 houses in Sungai Besar village in December 2007. The data were analyzed using chi square test with 95% confidence degree. The results showed there was a correlation between container type (p = 0,002), container placement (p = 0.000), container color (p = 0,002), container surface (p = 0,002) and container cover (p = 0,000) with larva. The existing larvae density distribution is high is House Index (HI) = 63,55% and container index 30,76%. Communities that collect water should use a water reservoir that is easily depleted and has the smallest risk to become a breeding ground and more concerned about proper water reservoirs.