Ant assemblage composition explains high predation pressure on artificial caterpillars during early night

Abstract

1. Predator-prey interactions, especially those involving herbivorous insects, are of great importance in maintaining biodiversity. Predation pressure varies temporally in response to prey availability and activity. However, little is known about the patterns and drivers of fluctuations in predation pressure at fine temporal scales.2. Artificial caterpillars (placed on plant leaves at breast height) were used to assess changes in predation pressure across four time intervals of the day in a monsoonal tropical rainforest in south-west China. The study examined how assemblage composition of arboreal ants, the dominant predators, changed across the same time intervals. The potential linkages between biotic (arboreal ants) and abiotic (temperature and light intensity) factors with predation rate were evaluated.3. Predation rate on caterpillars during the early part of the night (19.00-01.00 hours) was significantly higher than in the morning, afternoon, or late night. Ant assemblage composition, rather than species richness or total abundance, best explained the variations in predation rate on artificial caterpillars. 4. The results help to strengthen understanding of trophic interactions by demonstrating that predation pressure fluctuates at finer timescales than previously tested, and that a particular set of ant species may play major roles in predation on caterpillars and possibly other organisms.

The Influence of Tree Diversity on Natural Enemies—a Review of the “Enemies” Hypothesis in Forests

“…For further research, it may be important that evidence is accumulating which shows that predator functional diversity might be more relevant for herbivore reduction than predator species richness [123]. Moreover, observational studies in forests have started to relate diversity measures beyond species richness to predation (e.g., [124]). As research on functional and phylogenetic diversity is just beginning to thrive [14•], future experimental work will likely clarify whether functional and phylogenetic diversity of trees and predators can consolidate tests of the "enemies" hypothesis.…”

“…Testing Predation and Herbivore Control Predator abundance or diversity is not necessarily the most suitable surrogate of the "enemies" hypothesis, as it is often unclear whether they translate into higher herbivore control, which would require direct measurements of predation pressure [142]. In recent years, indirect means for assessing predation have become popular, especially by scoring attack marks on artificial caterpillars made from plasticine [82,83,87,124,143]. However, whether or not this method allows inference on true predation pressure is questionable.…”

Assessing temporal dynamics of predation and effectiveness of caterpillar visual defense using sawfly larval color and resting posture as a model

“…In fact parasitoid wasps show preferences toward certain colors (Michaud & Mackauer, 1994, 1995; Lobdell et al ., 2005; Langley et al ., 2006) and shapes of their prey (Pérez et al ., 2012) but the preference depends on wasp species. Although such preferences in ants have not been reported, ant species composition affects predation pressure on dummy caterpillars (Liu et al ., 2019), suggesting that the effectiveness of caterpillar visual traits may vary depending on the assemblage composition of ant species. Although many arthropod predators generally rely on chemical cues for foraging, our results showed that all arthropod predator groups were more or less affected by caterpillar visual traits and that the attack rates on certain visual traits varied seasonally.…”

Vertebrates but not ants protect rainforest trees from herbivorous insects along an elevational gradient in Papua New Guinea

“…Plant damage in the absence of ants was reported to increase between 0 and 250% on average, with the duration of the ant exclosure (Sam, et al 2022), and productivity of the study site (Rosumek, et al 2009, Sam, et al 2022) having signficant impacts. Ant exclosures are difficult to conduct (Hood, et al 2022, Rosumek, et al 2009) thus bait removal is often considered as a proxy of predation (e.g., Liu, et al 2020, Roslin, et al 2017, Burger, et al 2021). Unfortunately, this method may not accurately measure the realized top-down control and trophic cascade to plants from ants.…”