Caterpillars and fungal pathogens: two co-occurring parasites of an ant-plant mutualism

In mutualisms, each interacting species obtains resources from its partner that it would obtain less efficiently if alone, and so derives a net fitness benefit. In exchange for shelter (domatia) and food, mutualistic plant-ants protect their host myrmecophytes from herbivores, encroaching vines and fungal pathogens. Although selective filters enable myrmecophytes to host those ant species most favorable to their fitness, some insects can by-pass these filters, exploiting the rewards supplied whilst providing nothing in return. This is the case in French Guiana for Cecropia obtusa (Cecropiaceae) as Pseudocabima guianalis caterpillars (Lepidoptera, Pyralidae) can colonize saplings before the installation of their mutualistic Azteca ants. The caterpillars shelter in the domatia and feed on food bodies (FBs) whose production increases as a result. They delay colonization by ants by weaving a silk shield above the youngest trichilium, where the FBs are produced, blocking access to them. This probable temporal priority effect also allows female moths to lay new eggs on trees that already shelter caterpillars, and so to occupy the niche longer and exploit Cecropia resources before colonization by ants. However, once incipient ant colonies are able to develop, they prevent further colonization by the caterpillars. Although no higher herbivory rates were noted, these caterpillars are ineffective in protecting their host trees from a pathogenic fungus, Fusarium moniliforme (Deuteromycetes), that develops on the trichilium in the absence of mutualistic ants. Therefore, the Cecropia treelets can be parasitized by two often overlooked species: the caterpillars that shelter in the domatia and feed on FBs, delaying colonization by mutualistic ants, and the fungal pathogen that develops on old trichilia. The cost of greater FB production plus the presence of the pathogenic fungus likely affect tree growth

Low rates of serious complications but high rates of hardware removal after high tibial osteotomy with Tomofix locking plate

© 2020, European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA). Purpose: The purpose of this study was to analyse adverse events encountered in medial opening wedge high tibial osteotomy (MOWHTO) utilizing contemporary surgical techniques with the Tomofix locking plate (DePuy Synthes, Raynham, MA, USA) and categorize them by their severity and need for further medical/surgical management. It was hypothesized that there would be low rates of serious complications after medial opening wedge high tibial osteotomy utilizing an internal locking plate fixator. Methods: This study included 169 consecutive patients (200 knees) who underwent MOWHTO with a Tomofix locking plate at a single center, completing a minimum 2-year follow-up. Types of intra- and post-operative adverse events were retrospectively identified by an independent observer and categorized by their severity and further need of management. Additional surgery due to elective hardware removal was not included in the adverse event classification. Results: There were in total 58 (29%) adverse events, the majority (13.5%) of which required no additional treatment (class 1). Class 1 events included lateral cortex hinge fractures that were observed in 8.5% (17 knees) and delayed wound healing 2% (4/200). Adverse events requiring additional or extended nonoperative management (class 2) were 9%. These included post-operative stiffness in 1% (2/200), low grade infection in 1.5% (3/200), delayed union in 5.4% (11/200), deep vein thrombosis 0.5% (1/200). One hundred and four knees (52%) underwent elective hardware removal. Serious adverse events requiring unplanned additional or revision surgery and/or long-term medical care (class 3) were the least reported (6.5%). Aseptic non-union was reported in 2.5%, deep infection requiring revision in 2% and limited hardware failure 1%. Conclusion: A low rate of serious complications (6.5%) requiring unplanned additional surgery (class 3) was found. The overall rate of complications following MOWHTO with Tomofix locking plate was 29% and the majority (13.5%) required no additional treatment (class 1). Lateral hinge fractures were the most common complication (8.5%) and these were associated with corrections over 12 mm. However, 52% knees required a further operation for elective hardware removal. Level of evidence: Level IV, prospective study without control group