Contrasting predation services of predator and omnivore diversity mediated by invasive ants in a tropical agroecosystem

Abstract

Invasive natural enemies are known to either strengthen or weaken the suppression of herbivorous arthropods. However, the impact of invasive species on the predation service provided by natural enemy diversity remains largely unexplored. Here, we tease apart the roles of invasive ants as providers of a predation service and a potential disservice, i.e. reducing the diversity of natural enemies. In mango orchards on Reunion Island, we evaluated the predation service in 20 open fields by simultaneously monitoring the predation on bait eggs and arthropod communities in two strata: the ground surface and the mango tree canopy. Our results show that the predation on bait eggs was limited to the ground surface. This stratum is dominated by three invasive omnivorous ants: Pheidole megacephala and Solenopsis geminata strongly increased the predation rate of bait eggs, whereas Brachymyrmex cordemoyi was responsible for only a small decrease in predation rate. Predation rate was positively related to predator species richness, and was negatively related to omnivore species richness. The negative relationship between the predation rate and omnivore species richness is caused by the most dominant invasive ant, P. megacephala, which reduces omnivore richness and seems to strongly prey on eggs. This study demonstrates, for the first time, the distinct influence of the diversity of two trophic groups on the predation service and how these effects can be mediated by invasive ant species. (Résumé d'auteur

Contrasting beta diversity of spiders, carabids, and ants at local and regional scales in a black soil region, northeast China

“…Accordingly, it is wise to think that soil variables are more important drivers at local scales, and climate and spatial variables are more relevant when considering regional scales for soil arthropod species distribution. Spiders, carabids, and ants are successful natural enemies for pest control in agroecosystems (Eyre et al, 2016;Jacquot et al, 2017;Benhadi-Marín et al, 2020). They are sensitive agroecosystem bioindicators that have been used to monitor anthropogenic impact and agroecosystem health (Widhiono et al, 2017;Avgın et al, 2010;Borchard et al, 2014).…”

Six new non‐native ants (Formicidae) in the Canary Islands and their possible impacts

“…Subsequently, risk assessment for these new exotic ants is necessary to minimize potential damage. Brachymyrmex cordemoyi is known to cause damage to native fauna in other regions (Jacquot et al, 2017). Moreover, species belonging to genera that include highly invasive species such as Pheidole should be considered as potential invasive species.…”

“…In its introduced range, it has been collected both indoors (Husemann & Ortiz-Sepulveda, 2019) and outdoors, nesting in soil (Sharaf, Salman, Aldhafer, Yousef, & Aldawood, 2016). There is not much information about its effects as an invasive species, but it seems they are mild (Jacquot et al, 2017). However, other species of this genus can act as urban pests, such as B. obscurior or B. patagonicus (Klotz, Mangold, Vail, Davis, & Patterson, 1995;MacGown, Hill, & Deyrup, 2007).…”

Proceedings of the 5th International Symposium on Biological Control of Arthropods, Langkawi, Malaysia, September 11-15, 2017

“…This has led, over the years, to the increasing use of pesticides, in particular insecticides and herbicides. This agrochemical protection has its limitations: reduced insecticide efficacy on pests, weed resistance to herbicides, negative effects on the environment (soil, water) and on biodiversity (animals and plants) on an island internationally recognised as a biodiversity hotspot (Myers, 2003). There are also health risks for producers and consumers and ecological imbalances.…”