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Stage-dependent responses to emergent habitat heterogeneity: consequences for a predatory insect population in a coffee agroecosystem.

Liere H, Perfecto I, Vandermeer J - Ecol Evol (2014)

Bottom Line: Interactions among members of biological communities can create spatial patterns that effectively generate habitat heterogeneity for other members in the community, and this heterogeneity might be crucial for their persistence.The abundance of adult beetles located around trees with ants increased with the size of the ant nest clusters but the relationship is not significant for larvae.We suggest that this dependency arises due to the different responses that the predator's life stages have to this emergent spatial pattern.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of the South 735 University Ave, Sewanee, Tennessee, 37383.

ABSTRACT
Interactions among members of biological communities can create spatial patterns that effectively generate habitat heterogeneity for other members in the community, and this heterogeneity might be crucial for their persistence. For example, stage-dependent vulnerability of a predatory lady beetle to aggression of the ant, Azteca instabilis, creates two habitat types that are utilized differently by the immature and adult life stages of the beetle. Due to a mutualistic association between A. instabilis and the hemipteran Coccus viridis - which is A. orbigera main prey in the area - only plants around ant nests have high C. viridis populations. Here, we report on a series of surveys at three different scales aimed at detecting how the presence and clustered distribution of ant nests affect the distribution of the different life stages of this predatory lady beetle in a coffee farm in Chiapas, Mexico. Both beetle adults and larvae were more abundant in areas with ant nests, but adults were restricted to the peripheries of highest ant activity and outside the reach of coffee bushes containing the highest densities of lady beetle larvae. The abundance of adult beetles located around trees with ants increased with the size of the ant nest clusters but the relationship is not significant for larvae. Thus, we suggest that A. orbigera undergoes an ontogenetic niche shift, not through shifting prey species, but through stage-specific vulnerability differences against a competitor that renders areas of abundant prey populations inaccessible for adults but not for larvae. Together with evidence presented elsewhere, this study shows how an important predator is not only dependent on the existence of two qualitatively distinct habitat types, but also on the spatial distribution of these habitats. We suggest that this dependency arises due to the different responses that the predator's life stages have to this emergent spatial pattern.

No MeSH data available.


Related in: MedlinePlus

Map of 50 × 50 m quadrant in a coffee farm in Mexico showing Azya orbigera abundance distribution in relation to Azteca instabilis nests during the rainy season (June 2008). Red dots represent A. instabilis nests and black/gray-scaled squares represent beetle adult (left panel) and larvae (right panel) abundance in coffee bushes within a 5 m radius of the sampled tree (all shade trees in the quadrant were sampled). White squares represent zeroes, light gray squares represent low abundances, and dark gray squares represent high abundances.
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fig03: Map of 50 × 50 m quadrant in a coffee farm in Mexico showing Azya orbigera abundance distribution in relation to Azteca instabilis nests during the rainy season (June 2008). Red dots represent A. instabilis nests and black/gray-scaled squares represent beetle adult (left panel) and larvae (right panel) abundance in coffee bushes within a 5 m radius of the sampled tree (all shade trees in the quadrant were sampled). White squares represent zeroes, light gray squares represent low abundances, and dark gray squares represent high abundances.

Mentions: Figure 3 shows the beetle distribution map in the quadrant in relation to the ant nest cluster. There were significant differences in the mean rank of beetles among sites with and without ants (adults: H = 18.61, df = 1; P = 1.6 × 10−05; larvae: H = 11.44, df = 1, P = 0.0007). The mean adult abundance per site was 19.1 (±6.68 SE, n = 8) in sites with ants and 1 (±0.28 SE, n = 70) in sites without ants. The mean larva abundance per site was 12.00 (±6.6 SE, n = 8) in sites with ants and 0.94 (±0.29 SE, n = 70) in sites without ants. There was a significant negative relationship between beetle abundance in trees without ants and the mean distance to all ant nests in the quadrant (adults pseudo-R2 = 0.10; larvae pseudo-R2 = 0.09; Table 2).


Stage-dependent responses to emergent habitat heterogeneity: consequences for a predatory insect population in a coffee agroecosystem.

Liere H, Perfecto I, Vandermeer J - Ecol Evol (2014)

Map of 50 × 50 m quadrant in a coffee farm in Mexico showing Azya orbigera abundance distribution in relation to Azteca instabilis nests during the rainy season (June 2008). Red dots represent A. instabilis nests and black/gray-scaled squares represent beetle adult (left panel) and larvae (right panel) abundance in coffee bushes within a 5 m radius of the sampled tree (all shade trees in the quadrant were sampled). White squares represent zeroes, light gray squares represent low abundances, and dark gray squares represent high abundances.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4222207&req=5

fig03: Map of 50 × 50 m quadrant in a coffee farm in Mexico showing Azya orbigera abundance distribution in relation to Azteca instabilis nests during the rainy season (June 2008). Red dots represent A. instabilis nests and black/gray-scaled squares represent beetle adult (left panel) and larvae (right panel) abundance in coffee bushes within a 5 m radius of the sampled tree (all shade trees in the quadrant were sampled). White squares represent zeroes, light gray squares represent low abundances, and dark gray squares represent high abundances.
Mentions: Figure 3 shows the beetle distribution map in the quadrant in relation to the ant nest cluster. There were significant differences in the mean rank of beetles among sites with and without ants (adults: H = 18.61, df = 1; P = 1.6 × 10−05; larvae: H = 11.44, df = 1, P = 0.0007). The mean adult abundance per site was 19.1 (±6.68 SE, n = 8) in sites with ants and 1 (±0.28 SE, n = 70) in sites without ants. The mean larva abundance per site was 12.00 (±6.6 SE, n = 8) in sites with ants and 0.94 (±0.29 SE, n = 70) in sites without ants. There was a significant negative relationship between beetle abundance in trees without ants and the mean distance to all ant nests in the quadrant (adults pseudo-R2 = 0.10; larvae pseudo-R2 = 0.09; Table 2).

Bottom Line: Interactions among members of biological communities can create spatial patterns that effectively generate habitat heterogeneity for other members in the community, and this heterogeneity might be crucial for their persistence.The abundance of adult beetles located around trees with ants increased with the size of the ant nest clusters but the relationship is not significant for larvae.We suggest that this dependency arises due to the different responses that the predator's life stages have to this emergent spatial pattern.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of the South 735 University Ave, Sewanee, Tennessee, 37383.

ABSTRACT
Interactions among members of biological communities can create spatial patterns that effectively generate habitat heterogeneity for other members in the community, and this heterogeneity might be crucial for their persistence. For example, stage-dependent vulnerability of a predatory lady beetle to aggression of the ant, Azteca instabilis, creates two habitat types that are utilized differently by the immature and adult life stages of the beetle. Due to a mutualistic association between A. instabilis and the hemipteran Coccus viridis - which is A. orbigera main prey in the area - only plants around ant nests have high C. viridis populations. Here, we report on a series of surveys at three different scales aimed at detecting how the presence and clustered distribution of ant nests affect the distribution of the different life stages of this predatory lady beetle in a coffee farm in Chiapas, Mexico. Both beetle adults and larvae were more abundant in areas with ant nests, but adults were restricted to the peripheries of highest ant activity and outside the reach of coffee bushes containing the highest densities of lady beetle larvae. The abundance of adult beetles located around trees with ants increased with the size of the ant nest clusters but the relationship is not significant for larvae. Thus, we suggest that A. orbigera undergoes an ontogenetic niche shift, not through shifting prey species, but through stage-specific vulnerability differences against a competitor that renders areas of abundant prey populations inaccessible for adults but not for larvae. Together with evidence presented elsewhere, this study shows how an important predator is not only dependent on the existence of two qualitatively distinct habitat types, but also on the spatial distribution of these habitats. We suggest that this dependency arises due to the different responses that the predator's life stages have to this emergent spatial pattern.

No MeSH data available.


Related in: MedlinePlus