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Title: Inverse dispersal patterns in a group of ant parasitoids (Hymenoptera: Eucharitidae: Oraseminae) and their ant hosts
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Date Published:
Journal Name:
Systematic Entomology
Page Range / eLocation ID:
p. 1-19
Medium: X
Sponsoring Org:
National Science Foundation
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  2. Abstract

    Parasitic fungi produce proteins that modulate virulence, alter host physiology, and trigger host responses. These proteins, classified as a type of “effector,” often act via protein–protein interactions (PPIs). The fungal parasiteOphiocordyceps camponoti-floridani(zombie ant fungus) manipulatesCamponotus floridanus(carpenter ant) behavior to promote transmission. The most striking aspect of this behavioral change is a summit disease phenotype where infected hosts ascend and attach to an elevated position. Plausibly, interspecific PPIs drive aspects ofOphiocordycepsinfection and host manipulation. Machine learning PPI predictions offer high-throughput methods to produce mechanistic hypotheses on how this behavioral manipulation occurs. Using D-SCRIPT to predict host–parasite PPIs, we found ca. 6000 interactions involving 2083 host proteins and 129 parasite proteins, which are encoded by genes upregulated during manipulated behavior. We identified multiple overrepresentations of functional annotations among these proteins. The strongest signals in the host highlighted neuromodulatory G-protein coupled receptors and oxidation–reduction processes. We also detectedCamponotusstructural and gene-regulatory proteins. In the parasite, we found enrichment ofOphiocordycepsproteases and frequent involvement of novel small secreted proteins with unknown functions. From these results, we provide new hypotheses on potential parasite effectors and host targets underlying zombie ant behavioral manipulation.

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    Ecological impacts associated with ant introductions have received considerable attention, but most studies that report on these impacts contrast species assemblages between invaded and uninvaded sites. Given the low inferential power of this type of space-for-time comparison, alternative approaches are needed to evaluate claims that ant invasions drive native species loss. Here, we use long-term data sets from two different Argentine ant eradication programs on the California Channel Islands to examine how the richness and composition of native ant assemblages change before and after invasion (but prior to the initiation of treatments). At four different sites on two different islands, pre-invasion native ant assemblages closely resembled those at uninvaded (control) sites in terms of species richness, species composition, and the presence of multiple indicator species. Invader arrival coincided with large (> 75%) and rapid (within 1 year) declines in species richness, shifts in species composition, and the loss of indicator species. These impacts will hopefully be reversed by the recolonization of formerly invaded areas by native ant species following Argentine ant treatment, and long-term studies of native ant recovery at these sites are ongoing. Unchecked spread of the Argentine ant on other islands in this archipelago, however, poses a grave threat to native ants, which include a number of endemic taxa. 
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