Abstract
Individuals of different sex, size or developmental stage can compete differently and hence contribute distinctively to population dynamics. In species with complex life cycles such as insects, competitive ability is often positively correlated with larval developmental stage. Yet, little is known on how the development and survival of early-instars is influenced by interference from late-instar larvae, especially at low densities when exploitative competition is expected to be negligible. Furthermore, the specificity and mechanisms by which interference competition operates are largely unknown. We performed two complementary experiments aiming to quantify the competitive effects of late instar Ochlerotatus caspius on early instar larvae at low densities and under high resource supply rate. The first experiment examined the net effect of interference by 4th on 1st instar O. caspius larvae, relative to the effect of 1st instars on themselves. The second experiment examined the effect of species-specific, non-physical interference competition (i.e., cage larvae) by 4th on 1st instar O. caspius larvae at low or high densities. Specifically, we compared the responses of O. caspius larvae raised in the presence of caged con- or hetero-specific, Culiseta longiareolata, with that of larvae in the empty-cage control group. As expected, interference from late instar larvae had a net negative effect on the development rate of first instars. In contrast, the presence of caged con-specifics (non-physical interference) accelerated the development rate of O. caspius, however, this pattern was only evident at the low density. Notably, no such pattern was detected in the presence of caged hetero-specifics. These results strongly suggest the existence of species-specific growth regulating semiochemicals.
Highlights
Understanding the mechanisms that control population dynamics is essential for predicting ecological, economic, and health impacts of resident and invasive species [1,2,3,4]
Individuals are nested within experimental cups, i.e., experimental cups rather than individuals are considered as the replicates
Variation in competitive abilities among different developmental stages within a population can play an important role in determining population dynamics [21,22,23,24]
Summary
Understanding the mechanisms that control population dynamics is essential for predicting ecological, economic, and health impacts of resident and invasive species [1,2,3,4]. At the heart of these mechanisms are density-dependent competitive effects on survival, development and reproduction [5,6,7,8,9]. Interference competition occurs through physical (e.g., aggression) or non-physical (e.g., chemical) interactions, resulting in direct negative effect on competitors fitness. A growing body of literature illustrates the importance of both exploitative and interference competition in triggering density- and frequencydependent responses that can alter population and community dynamics [11,12,13,14]. Disentangling the negative effects of exploitative and interference competition requires preventing physical contact (e.g., caged competitors) [15], or creating a competitorconditioned environment [16]. We adopted a similar approach to distinguish between physical and non-physical interference competition
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
