Journal of Mosquito Research, 2024, Vol.14, No.5, 237-246 http://emtoscipublisher.com/index.php/jmr 242 6 Case Study 6.1 Overview of the selected case study region The selected case study region is southwest Ethiopia, an area characterized by its temporary wetlands and ponds, which serve as natural habitats for both Anopheles mosquito larvae and their potential invertebrate predators. This region is particularly significant due to the high prevalence of malaria, a disease transmitted by Anopheles mosquitoes, which poses a substantial public health threat. The local environment provides a unique opportunity to explore biological control methods as an alternative to traditional insecticides, which are increasingly facing resistance issues (Eba et al., 2021). 6.2 Implementation of biological control agents in the region In southwest Ethiopia, a study was conducted to evaluate the effectiveness of various invertebrate predators in controlling Anopheles mosquito larvae. The predators, including backswimmers (Notonectidae) and dragonflies (Libellulidae), were collected from the natural habitats within the region. Laboratory experiments were designed to determine the optimal conditions for predation, such as the appropriate larval instar, water volume, and predator density. The backswimmer emerged as the most effective predator, with a daily mean predation rate of 71.5 larvae (Table 1) (Eba et al., 2021). This implementation highlights the potential of using native aquatic predators as a biological control strategy in integrated malaria vector control programs. Table 1 The optimal conditions for larval predation in terms of larval instar, water volume and number of predators and the number of larvae consumed (95% confidence interval) at that optimal level for the 7 different predators (Adopted from Eba et al., 2021) Predator Family Mosquito Instar Water Volume # of Predators # of Larvae Consumed Aeshinidae 4 2 15 109 (98;121) Belostomatidae 2 2 15 90 (80;101) Corixidae 2 2 15 20 (16;26) Dytiscidae 4 3 15 168 (154;184) Gomphidae 3 3 15 33 (27;40) Libellulidae 4 2 15 29 (24;36) Notonectidae 1 1 15 140 (127;154) Note: # = number 6.3 Measured outcomes and impact on mosquito populations The study's outcomes demonstrated that the selected invertebrate predators could significantly reduce the population of Anopheles mosquito larvae under controlled conditions. The backswimmer, in particular, showed a high predation rate, suggesting its potential effectiveness in natural settings. However, the study also noted that the effectiveness of these predators could vary based on environmental factors such as water volume and the developmental stage of the larvae. While the laboratory results are promising, further field trials are necessary to confirm these findings and assess the long-term impact on mosquito populations and malaria transmission rates in the region (Eba et al., 2021). 6.4 Lessons learned and recommendations for future applications Several key lessons were learned from the implementation of biological control agents in southwest Ethiopia. Firstly, the selection of effective predators is crucial, as different species exhibit varying predation rates and preferences for larval instars. Secondly, environmental factors such as water volume and habitat type significantly influence the success of biological control methods. Therefore, it is essential to tailor the approach to the specific conditions of the target area. Future applications should focus on conducting extensive field trials to validate laboratory findings and ensure that the introduction of predators does not disrupt local ecosystems. Additionally, integrating biological control methods with other vector control strategies could enhance overall effectiveness and sustainability (Dambach, 2020; Eba et al., 2021).
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