博士 / 國立臺灣海洋大學 / 海洋生物研究所 / 101 / The resurgence of vector borne diseases and previous history of dengue in Taiwan encouraged me to select the present study which can help to manage vector borne problems. The management of the immature mosquitoes through predators (i.e. fish, tadpoles, copepods, and insects) cannot be assessed and applied properly in the field without understanding the prey-predator behavioral interactions. In the present doctoral thesis, prey-predator behavioral interactions between immature stages of Aedes aegypti (Linnaeus, 1762) and copepods have been studied by using two approaches. Firstly, this study investigated the behavior of the screened and selected predatory copepods for the immature mosquito stages. Predation rate study results revealed that in four collected cyclopoids copepods species, only three of them predated well on mosquito larvae but the Megacyclops formosanus (Harada, 1931) predation rate was the highest among four. Early stages of mosquito larvae were highly vulnerable to predation but later stages were non-susceptible to predatory copepods. Since predation studies unveiled that increased in body size of the prey reduced vulnerability to copepod predation. Thus this study used, Poecilia reticulata Peters, 1859, one of the widely used fish for mosquito biocontrol to understand the pupal antipredator behavior.
The fastcam study was conducted to understand the mechanisms with which an ambush predatory copepod, M. formosanus, captures Ae. aegypti larvae. Predatory mechanisms of the native copepod species revealed two intermediate steps: aiming and stalking during predation. The aiming distance varied between 4-8 body lengths, whereas the attack distance measured was shorter than the aiming distance. Copepods revealed their attack field in the front of the first antenna in cone-shaped area. This study discovered that both the intermediate steps, that is, aiming and stalking, enhanced the predatory success of an ambush predatory copepod by targeting the prey for a sudden attack.
Secondly, this study investigated anti-predator behavioral responses of immature mosquito stages to potential predator. This doctoral study investigated 30-h old mosquito larvae Ae. aegypti behavior through a 2D video recording. In the presence of a predator, larvae adjusted their foraging behavior. Mosquito larvae used mixed foraging tactics by mixing flexing in between filtering and browsing. Aedes larvae identified their most risky behavior, consequently increased their surfacing/air water interfacing significantly to save their life from the predator. Further, 2D videographic observations were conducted to understand and elucidate pupal antipredator behavior. Pupae exhibited more responses and significantly higher escape speeds in the presence of a predator than in the control. Pupal escape responses included shallow, medium, deep diving, surface movement, floating up, and fish-following up movement. Pupae effectively shortened their self-righting time during a fast chase. Pupae achieved complete escape success during diving down. Diving tactics in Culex pipiens quinquefasciatus Say, 1823 pupae that help them escape from aquatic predators lead to increased fitness.
The present doctoral study concludes that prey-predator behavioral interactions study is one of the key factors which can enhance the efficacy and success of biological mosquito control through predation. This study suggests that interactions of the mosquito larvae or pupae with the biological agents must be properly studied before applying in the field to control immature mosquito otherwise we shall not be able to ensure the further expansion of these vector borne diseases through the world’s most abundant taxa on earth.
| Identifer | oai:union.ndltd.org:TW/101NTOU5270002 |
| Date | January 2013 |
| Creators | Amit Kant Awasthi, 哈瓦提 |
| Contributors | Jiang-Shiou Hwang, 黃將修 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | en_US |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 150 |
Page generated in 0.0079 seconds