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
About this Honors Thesis
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