Fitness consequences of oviposition site selection by the mosquito species Aedes albopictus (Diptera: Culicidae) Pubblico

Yoshioka, Miho (2011)

Permanent URL: https://etd.library.emory.edu/concern/etds/jw827b99c?locale=it
Published

Abstract

In the naturally heterogeneous environment, mosquito egg-laying or oviposition is intimately related to the search for water habitats where the aquatic immature stages can develop to adulthood. According to the oviposition-preference offspring-performance (P-P) hypothesis for insects, if optimizing offspring performance and fitness ensures high overall reproductive fitness for an individual, the female should accurately assess details of the heterogeneous environment via sensory or perceptive behavior, and then lay her eggs in sites with offspring-suitable conditions. Particularly for a skip-ovipositing female mosquito that disperses her eggs of a single batch in multiple sites, she must select favorable site conditions while "skipping" unfavorable site conditions. In a laboratory setting, we examined the skip oviposition behavior of the mosquito Aedes albopictus by empirically testing the P-P hypothesis and focusing on two habitat conditions: diet and conspecific density (CD) (number of pre-existing larvae of the same species). First, in order to determine which oviposition site conditions were favorable for the aquatic juvenile stages (larvae and pupae), larval development was monitored from the first-instar larval stage through adult emergence over two ascending gradients of diet and CD. Individuals developed significantly faster with each increasing level of diet except from the third (7.2mg) to fourth level (20mg). Regarding, CD, significantly faster development resulted from the first level (zero conspecific larvae) compared to that resulting from the fourth level (80 conspecific larvae). These results are congruent with the hypothesis that higher food and lower conspecific larval density would increase diet availability per capita, thereby reducing density-dependent competition for both food and space. However, the ultimate number of viable adults indicated that even container treatments with suboptimal larval conditions maintained overall high survival and gross mosquito productivity. Upon concluding which diet and CD treatments significantly increased (and decreased) larval performance in the first experiment, these treatments were used to provide the conditions for the single-female oviposition assays. The laboratory assays are currently being conducted under these treatment conditions. The impressive ecological plasticity of Aedes albopictus allows it to thrive in natural and artificial containers commonly found in urban and suburban environments. Therefore, this manipulative study may help us gain a better understanding of the mechanisms underlying the oviposition behavior of Aedes albopictus found in nature.

Table of Contents

Introduction.................................................................................................................... 1-5
Study Species .............................................................................................................. 1-2
Oviposition preference-offspring performance hypothesis.................................... 2-5


Materials and Methods................................................................................................ 6-13
Experiment 1: Larval Development: assessing mosquito performance and fitness
over habitat condition gradients............................................................................. 6-11
Experiment 2: Empirical estimation of oviposition site preference .................. 11-13


Results……………………………………...……………...........................................13-18
Experiment 1: Larval Development……………......………….......................13-18
Experiment 2: Empirical estimation of oviposition site preference……...……18


Discussion………………………………………………..…………………..….…...19-23

References……….............……………………………….....……….....................….24-26

Figures and Tables………………………………………………………………….27-40

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