In animals, skewed sex ratios can affect individual fitness via sexual (e.g., intersexual conflict or intrasexual mate competition) or nonsexual (e.g., sex-specific resource competition) interactions. Because most analyses of sex ratio focus on sexual interactions, the relative importance of sexual versus nonsexual mechanisms remains unclear. We tested both mechanisms in the flour beetle Tribolium castaneum, where male-biased sex ratios increase female fitness relative to unbiased or female-biased groups. Although flour beetles show both sexual and nonsexual (resource) competition, we found that sexual interactions did not explain female fitness. Instead, female fecundity was dramatically reduced even after a brief exposure to flour conditioned by other females. Earlier studies suggested that secreted toxins might mediate density-dependent population growth in flour beetles. We identified ethyl benzoquinone and methyl benzoquinone (quinones) as components of adult stink glands that regulate female fecundity. In female-biased groups (i.e., at high female density), females upregulated quinones and suppressed each other's reproduction. In male-biased groups, low female density and associated low quinone levels maximized fecundity. Thus, females appear to use quinones as weapons for female-specific, density-dependent interference competition. Our results underscore the importance of nonsexual interference competition that may often underlie the fitness consequences of skewed sex ratios.

Objectives:To identify system-based factors contributing to Emergency Department (ED) admissions of children with diabetic ketoacidosis (DKA) and related complications with emphasis on parental and physician awareness and prereferral management.Materials and Methods:A prospective observational root cause analysis study of all consecutive admissions of children with DKA to pediatric ED of a tertiary care referral hospital in northern India over a period of 1 year (July 2010–June 2011). Prehospital, health-care system, referral, follow-up, and continuum of care related details were obtained through direct interview of parents and physicians and/or field observations for all enrolled children.Results:Of the 30 children enrolled, 26 (86.6%) were referrals; 16 (61.5%) from first, 7 (26.9%) from second, and 3 (11.5%) from third health-care facility. More than half (n [%], 18 [60%]) had new onset diabetes and belonged to lower socioeconomic strata. Twenty-two (73.3%) were complicated DKA; shock (n [%], 19 [63%]), hypokalemia (n [%], 11 [36%]), and CE (n [%], 3 [10%]) were the most common complications. Most parents were ignorant of diabetes, its symptoms or complicating DKA. Nearly, half of the cases remained undiagnosed (n = 11) at first contact health-care facility; more so for new onset as compared to known diabetes (9/18 vs. 2/8; P = 0.022). The referring hospitals had limited facilities for rapid blood glucose estimation (n [%], 12 [40%]), blood gas analysis (n [%], 6 [20%]) and insulin infusion. On univariate analysis, patients with missed/delayed diagnosis more often had severe and complicated DKA.Conclusion:Parental ignorance, lower socioeconomic status, lack of clinical experience, and limited primary health-care facilities were root causes for severe and complicated DKA.

Myrmecochory is the ant-mediated secondary dispersal of seeds that depends on the presence of a lipid-rich seed appendage known as "elaiosome." Attractive cues of elaiosomes that drive such an interaction and benefits to the plant are not clearly understood. Here, using Ricinus communis, we establish reward compositions and determine the benefits of myrmecochory to the plant. We also compare elaiosome compositions across ecotypes. Our results show that the elaiosome is essential for seed displacement and olfactory cues are important attractive cues. Nonanal and 2-decenal were found to be the major attractive volatiles in the castor elaiosome. Different ant species showed different behaviors toward elaiosome-bearing seeds. Among them, Pheidole grayi was efficient in dispersal but did not disperse all seed ecotypes tested. Major differences in fatty acid levels were observed between ecotypes. To determine the benefits of myrmecochory, germination rates before and after removal of elaiosome were studied. Seed germination improved upon elaiosome removal and aqueous elaiosome extract inhibited germination indicating water-soluble inhibitory factors. Further, ant nest sites were richer in nitrogen than control sites, revealing a clear benefit of seed displacement. In summary, we demonstrate the ecological significance of the seed elaiosomes in the absence of nutritive rewards for seed dispersers.