Biological aspects and life tables of the predacious mites,Typhlodromips swirskii (Athias-Henriot) and Euseius scutalis (Athias-Henriot) feeding on two scale insect species and plant pollen

Biological aspects and life table parameters of the predacious mites, Typhlodromips swirskii (Athias-Henriot) and Euseius scutalis (Athias-Henriot) (Acari: Phytoseiidae) consuming eggs of the Maskell scale insect, Insulaspis pallidula (Green) and the red date scale insect, Phoenicococcus marlatti Cockerell (Homoptera: Diaspididae, Phoenicococcidae) as well as pollen grains of date palm, Phoenyx dactylifera L. were determined under laboratory conditions. The life cycle and pre-oviposition period of T. swirskii were the shortest, while the oviposition period and female longevity were the longest as well as the egg production was the highest when fed on pollen compared with eggs of I. pallidula and P. marlatti. On the other hand, the life cycle, pre-oviposition and oviposition periods as well as the female longevity of E. scutalis were the best when devoured P. marlatti followed by pollen and I. pallidula. However, the total and daily fecundity of E. scutalis were the highest after consuming pollen compared with eggs of P. marlatti and I. pallidula. The sex ratio of females to total in the progeny of T. swirskii and E. scutalis was the highest when consumed I. pallidula followed by pollen and P. marlatti. Life table parameters were the most favourable for T. swirskii and E. scutalis feeding on date palm pollen compared with eggs of I. pallidula and P. marlatti.     

Meat,dairy, and more: Analysis of material,energy, and greenhouse gas flows of the meat and dairy supply chains in the EU28 for 2016

To decarbonize the European Union, protein consumption must transition to diets low in meat and dairy which will drastically change the material and energy flows in current meat and dairy supply chains. To understand the impacts on current flows, a baseline is required. Although recent studies have improved the scope of reported greenhouse gas (GHG) emissions, no quantitative overview exists including intermediate and final product flows. To address this knowledge gap, we structured the meat and dairy supply chains into a connected set of transformation nodes and distribution nodes. The former are processes transforming inputs into outputs, whereas the latter distribute the outputs to other processes using them as inputs. Currently, livestock play a central role in agriculture and other industries through the consumption of 271 Mt fodder crops, 108 Mt grain, 85 Mt grazed biomass, 49 Mt oil meal, and 16 Mt feed by‐products. This feed is transformed into 64 Mt dairy and 35 Mt meat which ensures that the EU28 is a net exporter of meat and dairy while providing 25 Mt of by‐products. This production also leads to 435 Mt CO₂‐eq. with the main contribution from beef cattle (35%), dairy cattle (32%), and swine (20%). Thus, the lower GHG intensities of dairy products compared to meat do not imply a low contribution to the total emissions. By mapping the material, energy, and GHG emission flows, we have created a baseline suitable for identifying potential supply chain changes and their related GHG increase or decrease resulting from the protein transition.     

Critical periods in the life cycle and the effects of a severe spate vary markedly between four species of elmid beetles in a small stream

1. The chief objectives were: (i) to describe quantitatively the life cycles of four species of Elmidae, Elmis aenea, Esolus parallelepipedus, Oulimnius tuberculatus and Limnius volkmari; (ii) to use life tables to identify critical periods for survival in the life cycle of each species; (iii) to evaluate the immediate and longer‐term effects of a severe spate on densities of the four species. Monthly samples were taken over 63 months at two contrasting sites in a small stream: one in a deep section with macrophytes abundant, and the other in a shallow stony section. 2. There were five larval instars for O. tuberculatus, seven for L. volkmari and six for the other two species. The life cycle of each species took 1 year from egg hatching (chiefly in June for E. aenea and O. tuberculatus, and July for the other species) to pupation in the stream bank and a further year before the adults in the stream matured and laid their eggs. Mature adults were present in most months, but were rare or absent in January and February and attained maximum densities in April for O. tuberculatus and May for the other species. 3. Laboratory experiments provided data on egg hatching and pupation periods and the number of eggs laid per female. Life tables compared maximum numbers per square metre for key life‐stages. Within each species, mortality rates between adjacent life‐stages were fairly constant among six cohorts and between sites, in spite of large differences in numbers. The only exception for all species was the high adult, but not larval, mortality during a severe spate. 4. Standardised life tables, starting with 1000 eggs, identified key life‐stages with the highest mortality, namely the early life‐stages for E. aenea (36% mortality), start of the overwintering period to pupation for O. tuberculatus (41%) and L. volkmari (51%), start of pupation to the maximum number of immature adults for E. parallelepipedus (41%) and between the maximum numbers of immature and mature adults for O. tuberculatus (41%). Therefore, critical periods for survival in the life cycle differed between species, presumably because of their different ecological requirements. Similarly, the effects of the spate on adult mortality, and hence egg production, varied between species, being most severe and long‐term for E. aenea and O. tuberculatus, less severe for E. parallelepipedus and least severe with a rapid recovery for L. volkmari. Possible reasons for these discrepancies are discussed, but more data are required on the food and microhabitat requirements of the elmids before satisfactory explanations can be found.     

Apple pollen as a supplemental food for the western flower thrips, Frankliniella occidentalis: response of individuals and populations

Experiments were performed to investigate the influence of apple pollen, plant diet, and relative humidity on the individual life‐history traits and on the population growth of the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). In experiments with individual thrips, availability of bean pods plus a mixture of apple pollen and lycopodium shortened larval development time, and hence time from egg to adult, compared to bean pods alone. Similarly, the total number of eggs laid and the mean number of eggs laid per female per day were greater in the presence of pollen plus bean pods than on bean pods alone. Diet did not affect survival or length of the pre‐oviposition and oviposition periods. A diet including bean pods plus pollen shortened the generation time and population‐doubling time, and increased the net reproductive rate and the intrinsic rate of increase, compared to bean pods alone. In experiments on populations, growth was measured with different amounts of pollen on bean pods under two relative humidities, ca. 38% and 66%, and separately on two bean substrates, pods or leaves, at ca. 45% r.h. The presence or amount of pollen had no effect on population growth regardless of the other variables. Greater population growth occurred under the higher relative humidity regardless of substrate. Population growth was greater on bean pods than on bean leaves. Despite reports on the nutritional benefit of pollen for F. occidentalis, this benefit may be affected by pollen type, host plant, and other factors. In situations in which pollen has little influence on the growth of F. occidentalis populations, pollen that benefits a thrips predator could be used in an integrated management plan for controlling thrips.     

Partial ecological life table of immature Helicoverpa zea (Lepidoptera: Noctuidae) in an irrigated cotton cropping system in the Trans-Pecos region of Texas, USA

During the summers of 1996 and 1997 cotton bollworm, Helicoverpa zea (Boddie), life stages were sampled in insecticide-free, irrigated cotton, Gossypium hirsutum L., in the Trans-Pecos region of Texas. Partial ecological life tables were constructed for one generation of H. zea in each of the two growing seasons. Partial generation mortality (egg to fifth-instar) surpassed 97% in both years. The egg stage exhibited the greatest amount of real (r_x) and apparent (q_x) mortality followed by the third-instar. One hundred percent of the collected life stages consisted of H. zea. Egg parasitism ranged from 4.1 to 6% and egg predation by Orius tristicolor (White) was 4.1% in 1996 and 13.2% in 1997. Unexplained factors made the greatest contribution to H. zea mortality regardless of the life stage sampled. Each cotton bollworm generation monitored in 1996 and 1997 exhibited a Type III survivorship curve. As a result of the extensive early life stage mortality, rescue management tactics associated with contemporary H. zea control in the region appears to be generally unnecessary for cotton grown under irrigation in the Trans-Pecos region.     

Demography of three populations of American mink Mustela vison in Europe

• 1 Demographic data on an invasive species of management concern, the American mink, are presented. Data were obtained on three feral mink populations in Europe distinguished by differences in the time elapsed since population establishment.
• 2 Demographic data are presented in the form of life tables, age–sex distributions and sex ratios. Mink lived a maximum of 6 years, and mortality of 1‐year‐olds and adults differed substantially between populations.
• 3 The data support the hypothesis that mink populations subject to culling have a higher proportion of young (less than 1 year old) to adults compared with non‐culled populations.

     

The Exact Evaluation of 2-way Cross-classifications: The Combinatory Distribution

A practical methodology is presented for the exact combinatory evaluation of 2-way cross-classifications. The combinatory distribution is based on a test-statistic relating to the information content of an observed table. Several examples of exact evaluation accompany this presentation.     

A unifying framework for assessing changes in life expectancy associated with changes in mortality: the case of violent deaths

For over forty years, demographers have worked intensely to develop methods that assess a gain in life expectancy from a reduction in mortality, either hypothetical or observed. This considerable body of research was motivated by assessing the gains in life expectancy when mortality declined in a particular manner and determining the contribution of a cause of death in observed changes in life expectancy over time. As yet, there has been no framework unifying this important demographic work. In this paper, we provide a unifying framework for assessing the change in life expectancy given a change in age- and cause-specific mortality. We consider both conceptualizations of mortality change—counterfactual assessment of a hypothetical change and a retrospective assessment of an observed change. We apply our methodology to violent deaths, the leading cause of death among young adults, and show that realistic targeted reductions could have important impacts on life expectancy.