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Species-specific non-physical interference competition among mosquito larvae.

Silberbush A, Tsurim I, Rosen R, Margalith Y, Ovadia O - PLoS ONE (2014)

Bottom Line: The first experiment examined the net effect of interference by 4(th) on 1(st) instar O. caspius larvae, relative to the effect of 1(st) instars on themselves.As expected, interference from late instar larvae had a net negative effect on the development rate of first instars.These results strongly suggest the existence of species-specific growth regulating semiochemicals.

View Article: PubMed Central - PubMed

Affiliation: Center for Biological Control (CBC), Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.

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 4(th) on 1(st) instar O. caspius larvae, relative to the effect of 1(st) instars on themselves. The second experiment examined the effect of species-specific, non-physical interference competition (i.e., cage larvae) by 4(th) on 1(st) 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.

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A Kaplan-Meier fit for the relationship between the time since hatching and the proportion of larvae not yet pupated (out of the final emerging population).In the lower initial density, both males and females pupated sooner in the Caged-conspecific treatment (caged O. caspius 4th instar larvae); relative to the Empty-cage control treatment. This pattern was not evident in the higher initial larval density. Moreover, caged-heterospecifc treatment (caged C. longiareolata 4th instar larvae) did not affect larval pupation rate, relative to control.
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pone-0088650-g002: A Kaplan-Meier fit for the relationship between the time since hatching and the proportion of larvae not yet pupated (out of the final emerging population).In the lower initial density, both males and females pupated sooner in the Caged-conspecific treatment (caged O. caspius 4th instar larvae); relative to the Empty-cage control treatment. This pattern was not evident in the higher initial larval density. Moreover, caged-heterospecifc treatment (caged C. longiareolata 4th instar larvae) did not affect larval pupation rate, relative to control.

Mentions: The presence of caged con-specifics brought about a ∼3.7 fold increase in female pupation rate, relative to the empty-cage control (P = 0.006, Table 2). However, this pattern was only evident at the low density (Caged con-specifics×Density interaction, P = 0.004; Table 2; Fig. 2). We could not detect similar patterns in the caged hetero-specifics treatment (Caged hetero-specifics: P = 0.510; Caged hetero-specifics×Density interaction: Z = 0.077, P = 0.940; Fig. 2). Similarly, the presence of caged con-specifics caused a ∼2.5 fold increase in male pupation rate, relative to the empty-cage control (P = 0.043; Table 2; Fig. 2). Here too, this pattern was only evident at the low density (Caged con-specifics×Density interaction, P = 0.043; Table 2; Fig. 2). Again, we could not detect similar patterns in the caged hetero-specifics treatment (Caged hetero-specifics: P = 0.160; Caged hetero-specifics×Density interaction: Z = −0.693, P = 0.490; Fig. 2).


Species-specific non-physical interference competition among mosquito larvae.

Silberbush A, Tsurim I, Rosen R, Margalith Y, Ovadia O - PLoS ONE (2014)

A Kaplan-Meier fit for the relationship between the time since hatching and the proportion of larvae not yet pupated (out of the final emerging population).In the lower initial density, both males and females pupated sooner in the Caged-conspecific treatment (caged O. caspius 4th instar larvae); relative to the Empty-cage control treatment. This pattern was not evident in the higher initial larval density. Moreover, caged-heterospecifc treatment (caged C. longiareolata 4th instar larvae) did not affect larval pupation rate, relative to control.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928246&req=5

pone-0088650-g002: A Kaplan-Meier fit for the relationship between the time since hatching and the proportion of larvae not yet pupated (out of the final emerging population).In the lower initial density, both males and females pupated sooner in the Caged-conspecific treatment (caged O. caspius 4th instar larvae); relative to the Empty-cage control treatment. This pattern was not evident in the higher initial larval density. Moreover, caged-heterospecifc treatment (caged C. longiareolata 4th instar larvae) did not affect larval pupation rate, relative to control.
Mentions: The presence of caged con-specifics brought about a ∼3.7 fold increase in female pupation rate, relative to the empty-cage control (P = 0.006, Table 2). However, this pattern was only evident at the low density (Caged con-specifics×Density interaction, P = 0.004; Table 2; Fig. 2). We could not detect similar patterns in the caged hetero-specifics treatment (Caged hetero-specifics: P = 0.510; Caged hetero-specifics×Density interaction: Z = 0.077, P = 0.940; Fig. 2). Similarly, the presence of caged con-specifics caused a ∼2.5 fold increase in male pupation rate, relative to the empty-cage control (P = 0.043; Table 2; Fig. 2). Here too, this pattern was only evident at the low density (Caged con-specifics×Density interaction, P = 0.043; Table 2; Fig. 2). Again, we could not detect similar patterns in the caged hetero-specifics treatment (Caged hetero-specifics: P = 0.160; Caged hetero-specifics×Density interaction: Z = −0.693, P = 0.490; Fig. 2).

Bottom Line: The first experiment examined the net effect of interference by 4(th) on 1(st) instar O. caspius larvae, relative to the effect of 1(st) instars on themselves.As expected, interference from late instar larvae had a net negative effect on the development rate of first instars.These results strongly suggest the existence of species-specific growth regulating semiochemicals.

View Article: PubMed Central - PubMed

Affiliation: Center for Biological Control (CBC), Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.

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 4(th) on 1(st) instar O. caspius larvae, relative to the effect of 1(st) instars on themselves. The second experiment examined the effect of species-specific, non-physical interference competition (i.e., cage larvae) by 4(th) on 1(st) 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.

Show MeSH