How mites affect honey bee colonies
Fluorescence of bee fat body and mites match (1 mm scale).
The parasitic mite Varroa destructor is a major driver of honey bee colony losses worldwide. The mites are thought to feed exclusively on a blood-like fluid called hemolymph. In contrast to this view, Samuel Ramsey et al. (pp. 1792–1801) found that Varroa mites damage and exploit host bees primarily by consuming a liver-like tissue called fat body. The authors fed bees two fluorescent stains to mark the hemolymph and fat body and imaged both of these tissues as well as the gut contents of mites that fed on the bees. The fluorescence profile of the mites matched the fat body signal, but not the signal detected in the hemolymph. Moreover, mites that were exclusively fed hemolymph survived only 1.8 days on average, with 5% producing eggs, similar to starved mites. By contrast, mites that consumed only fat body survived 3.5 days on average, with 40% producing eggs. Taken together, the results suggest that the primary source of sustenance for Varroa is the fat body, which is essential for honey bees’ immune function, pesticide tolerance, and overwinter survival. According to the authors, the findings could lead to the development of ways to curb the destructive impact of Varroa on honey bee health. — J.W.
Institutionalization and cognitive development
Children who spend their early lives in institutions characterized by low caregiver consistency and little opportunity for social or cognitive stimulation are subject to psychosocial neglect. Childhood trauma and adversity are associated with negative outcomes in memory and executive function in young children. However, the trajectories of improvement among institutionalized children, particularly the benefits associated with a move to foster care, were previously unexplored. Mark Wade et al. (pp. 1808–1813) analyzed data from the Bucharest Early Intervention Project, a randomized controlled trial in which the development of previously institutionalized children placed in foster care was tracked. The authors compared the development of 136 participants in the project with 72 never-institutionalized children. Growth in memory and executive function occurred in institutionalized, foster care, and never-institutionalized children between ages 8 and 16. However, some cognitive deficiencies persisted in institutionalized children, regardless of foster care placement; gaps in some cognitive deficiencies between institutionalized and never-institutionalized children widened; and difficulties with visual-spatial memory improved in children placed in foster care. According to the authors, institutionalization can produce persistent long-term cognitive effects, although opportunities for cognitive improvements exist before adolescence. — P.G.