Ambrosia beetles bore into trees, excavating galleries where they farm fungi as their sole source of nutrition. These mutualistic fungi typically do not cause significant damage to host trees; however, since their invasion into the U.S., the beetle Xyleborus glabratus has vectored its fungal partner, Harringtonia lauricola, which has acted as a devastating plant pathogen resulting in the deaths of over 500 million trees. Here, we show differences in the mycangial colonization of the indigenous X. affinis ambrosia beetle by H. lauricola, and the native fungal species, H. aguacate and Raffaelea arxii. While X. affinis was a good host for H. lauricola, the related ambrosia beetle, X. ferrugineus, was only marginally colonized by H. lauricola. X. affinis beetles neither fed on, nor were colonized by, the distantly related fungus, Magnaporthe oryzae. Mycangial colonization was affected by the nutritional state of the fungus. A novel method for direct quantification of mycangial contents based on image cell cytometry was developed and validated. The method was used to confirm mycangial colonization and demonstrate alternating fungal partner switching, which showed significant variation and dynamic turnover. X. affinis pre-oral mycangial pouches were visualized using fluorescent and light microscopy, revealing that newly emerged pupae displayed uncolonized mycangia prior to feeding, whereas beetles fed H. lauricola contained single-celled fungi within 6 h post-feeding. Mixed populations of fungal cells were seen in the mycangia of beetles following alternating colonization. Nuclear counter-staining revealed insect cells surrounding the mycangia. These data highlight variation and specificity in ambrosia beetle–fungal pairings and provide a facile method for direct quantification of mycangial contents.

Ambrosia beetles bore into trees, excavating galleries where they farm fungi as their sole source of nutrition. These mutualistic fungi typically do not cause significant damage to host trees; however, since their invasion into the U.S., the beetle Xyleborus glabratus has vectored its fungal partner, Harringtonia lauricola, which has acted as a devastating plant pathogen resulting in the deaths of over 500 million trees. Here, we show differences in mycangial colonization of the indigenous X. affinis ambrosia beetle by H. lauricola, and the native fungal species, H. aguacate and Raffaelea arxii. While X. affinis was a good host for H. lauricola, the related ambrosia beetle, X. ferrugineus, was only marginally colonized by H. lauricola. X. affinis beetles neither fed on, nor were colonized by, the distantly related fungus, Magnaporthe oryzae. Mycangial colonization was affected by the nutritional state of the fungus. A novel method for direct quantification of mycangial contents based on cell cytometry was developed and validated. The method was used to confirm mycangial colonization and to demonstrate alternating fungal partner switching, which showed significant variation and dynamic turnover. X. affinis pre-oral mycangial pouches were visualized using fluorescent and light microscopy, revealing that newly emerged pupae displayed uncolonized mycangia prior to feeding, whereas beetles fed H. lauricola contained single-celled fungi within 6 h post-feeding. Mixed populations of fungal cells were seen in the mycangia of beetles following alternating colonization. Nuclear counter-staining revealed insect cells surrounding the mycangia. These data highlight variation and specificity in ambrosia beetle-fungal pairings and provide a facile method for direct quantification of mycangial contents.

Background/Objectives: Post-coronavirus syndrome (long-COVID) refers to a multi-systemic range of symptoms that follows acute SARS-CoV-3 infection. Long-COVID has been linked with autonomic neuropathy as well as dry-eye disease (DED), an umbrella term that includes a variety of ocular symptoms and signs. Despite these associations, little is known about the co-occurrence of DED and dysautonomia symptoms in individuals with long-COVID. This study aims to examine relationships between dysautonomia and ocular symptoms in a long-COVID patient population. Methods: Cross-sectional study of 162 veterans with long-COVID. The Composite Autonomic Symptom Score-31 (COMPASS-31) assessed dysautonomia symptoms, and the NASA lean test and heart-rate variability metrics captured dysautonomia signs. Dry-eye disease (DED) symptoms were measured with the 5-Item Dry-Eye Questionnaire (DEQ5) and the Ocular Surface Disease Index (OSDI), while ocular pain intensity and neuropathic pain descriptors were evaluated using a Numerical Rating Scale (NRS) and select questions from the Neuropathic Pain Symptom Inventory modified for the Eye (NPSI-Eye), respectively. Results: Most participants (78%) reported DED symptoms (DEQ5 ≥ 6). Nearly all COMPASS-31 domains were associated with DED symptoms, with the strongest correlation observed between the OSDI and pupillomotor scores (r = 0.67, p < 0.001). Among the autonomic signs, the strongest associations were observed between the change in systolic and diastolic blood pressure from baseline to 8 min and ocular pain triggered by temperature (r = −0.44 and r = −0.48, respectively, p < 0.01 for both). On linear regression analyses, pupillomotor and secretomotor symptoms remained positively associated with DED symptoms, while autonomic signs were most closely related to ocular pain metrics, with fluctuating blood pressure changes during orthostasis relating to neuropathic symptoms. Conclusions: DED symptoms, including ocular pain intensity, relate to autonomic symptoms in a long-COVID cohort. While associations with autonomic signs were less consistent, these data suggest that subtle autonomic variability relates to ocular pain in the long-COVID setting.