Development of the present concept of cause of death

Mortality Dynamics and Life Tables of Megachile rotundata (Hymenoptera: Megachilidae), a Pollinator Managed for Alfalfa Seed Production

The alfalfa leafcutting bee, Megachile rotundata (F.), contributes to the pollination of more than two-thirds of alfalfa used in seed production in North America. However, losses in managed populations of more than 50% are common in the United States. Thus, understanding the causes of mortality of M. rotundata is critical to find ways to maintain and increase bee populations. Over 2 yr, we identified and quantified six mortality classes of M. rotundata, as well as estimated mortality risk using the demographic life-table model, M-DEC. Research was conducted on an alfalfa field in Toston, Montana and offspring mortality was assessed in the fall of each year. Nest shelters were manipulated for a main temperature treatment (low vs high), and nest boxes inside the shelters were manipulated for a parasitism sub-treatment (parasitism-resistant vs parasitism-enabled). Total mortality was approximately 15% for both years, but the proportion for each mortality class differed substantially. Mortality increased with increasing internal nest-tunnel temperature, and nest boxes with parasitism-enabled entry had nearly double the mortality than those with parasitism-resistant entry. Based on demographic multiple decrement life table analyses, mortality from each class was highly irreplaceable. Identifying and quantifying irreplaceable mortality classes and strategies to mitigate those causes may help producers decrease total population loss of M. rotundata before the adult stage.

Mortality risk in insects

Understanding how and why insect numbers fluctuate through time and space has been a central theme in ecological research for more than a century. Life tables have been used to understand temporal and spatial patterns in insect numbers. In this study, we estimated cause-of-death probabilities for phytophagous insects using multiple decrement life tables and the irreplaceable mortality analytic technique. Multiple decrement life tables were created from 73 insect life tables published from 1954 to 2004. Irreplaceable mortality (the portion of mortality that cannot be replaced by another cause) from pathogens, predators, and parasitoids was 8.6 +/- 7.2, 7.8 +/- 4.9, and 6.2 +/- 1.6%, respectively. In contrast, the mean irreplaceable mortality from all non-natural enemy mortality factors (mortality from factors other than natural enemies) was 35.1 +/- 4.4%. Irreplaceable mortality from natural enemies was significantly lower compared with non-natural enemy factors. Our results may partially explain cases of unsuccessful efficacy in classical biological control, after successful establishment, by showing low irreplaceable mortality for natural enemies, including 5.2 +/- 1.6% for introduced natural enemies. We suggest that the environment (i.e., the degree of environmental stability) influences the magnitude of the irreplaceable mortality from natural enemies. Our results lead to several testable hypotheses and emphasize that it is not possible to estimate the effect of any mortality factor without considering its interaction with competing mortality factors, which has far-reaching consequences for population biology and applied ecology.

The WHO principles for registering causes of death: suggestions for improvement

In the ongoing 10th revision of the International Classification of Diseases, the WHO's rules for registering causes of death are revised. Previous studies have shown that deficiencies in the WHO's rules and basic concepts for registering causes of death impair the quality of cause-of-death statistics. The purpose of the present paper is to elucidate some of these shortcomings and to make suggestions for improvement. Also, the purpose of the WHO's definition of 'the underlying cause of death' is discussed, and a modification suggested. Suggestions are also made for new definitions of the four basic WHO concepts, 'causes of death', 'the underlying cause of death', 'direct cause' and 'contributory conditions'. At the end an account is given of the proposals made within the WHO for changes in the rules for registering causes of death.

The multiple decrement life table: a unifying framework for cause-of-death analysis in ecology

The multiple decrement life table is used widely in the human actuarial literature and provides statistical expressions for mortality in three different forms: i) the life table from all causes-of-death combined; ii) the life table disaggregated into selected cause-of-death categories; and iii) the life table with particular causes and combinations of causes eliminated. The purpose of this paper is to introduce the multiple decrement life table to the ecological literature by applying the methods to published death-by-cause information on Rhagoletis pomonella. Interrelations between the current approach and conventional tools used in basic and applied ecology are discussed including the conventional life table, Key Factor Analysis and Abbott's Correction used in toxicological bioassay.

Medico-legal aspects of medical certification of cause of death

This paper deals with the medico-legal aspects of death certification, the inadequate attention accorded to these aspects in most of the present death certificate forms, and the consequences resulting from this circumstance. A description is also given of the revision of the national system of medical certification of causes of death in Finland. This revision seeks to avoid the drawbacks mentioned by means of an improved form of death certificate introduced in 1960. Certain recommendations are also made on the basis of the experience acquired so far.