Rhyzopertha dominica (lesser grain borer).

Females of R. dominica lay between 200 and 500 eggs in their lifetime. The eggs are laid loose in grain. The lowest temperature at which R. dominica can complete development is 20°C; at this temperature, the development from egg to adult takes 90 days. The fastest rate of development occurs at 34°C; at this temperature the egg takes 2 days, the larvae 17 days, and the pupae 3 days to complete development. R. dominica is unable to complete development between 38 and 40°C. Adults live for 4-8 months. Under optimal conditions of 34°C and 14% grain moisture content, there is a 20-fold increase in the population of R. dominica after 4 weeks. It can successfully infest grain at 9% moisture content, but has higher fecundity, a faster rate of development, and lower mortality on grain of a higher moisture content. Adult males produce an aggregation pheromone in the frass that attracts both male and female adults. Adults are good flyers, and can be trapped in pheromone-baited flight traps placed several kilometres from grain stores. Adults can bore into intact kernels. The larvae of R. dominica are mobile.

Pest potencial of Sitophilus zeamais on Brazil nut under storage conditions

The Brazil nut, fruit of Bertholletia excelsa H.B.K., a native plant of the Amazon region and may be considered one of the main extractivist products of countries like Bolivia, Colombia, Guyana, Venezuela, Peru and Brazil. In Brazil this plant can be found in the states of Acre, Amapá, Amazonas, Mato Grosso, Pará, Rondônia, Roraima and Tocantins. Species of the Coleoptera and Lepidoptera, have been classified as pest potentials of Brazil nut under storage conditions. Sitophilus zeamais (Coleoptera: Curculionidae) is one of the main insect pests attacking grain stores worldwide. This specie may be observed attacking grains in the field and in storage facilities (cross-infestation), presenting a wide variety of hosts. The purpose of this study was to assess the potential of adults of this species feed on Brazil nuts, and also to identify the type of injury as well as the life span of this coleopteran exposed to the meat of the Brazil nut. No feeding injury was observed on the surface of Brazil nuts and the life span of the insects was similar in treatments both with and without this food source in all populations evaluated. Due to the fact that S. zeamais adults do not injure, or feed on the Brazil nut, this beetle is not able to colonize this product and therefore may be considered a non-pest insect for stored Bertholletia excelsa almonds stored.

“That the Price of Bread Be Always in My Hands”: Catherine II and Formation of the Grain Storage System in Russia

Historically, national food supply for population in time of crop failure and famine came within state interests during the reign of Emperor Peter I. Then, national food supply acquired its status of a separate branch of the government. Under Peter I, a whole set of preventive measures was developed to combat crop failure and famine. However, Peter I’s idea of grain stores remained unrealized. Only after accession of Catherine II the question of creating Russian grain stores system as a main mechanism for dealing with crop failures and famine was re-introduced. Over the entire period of her rule, much legislation was issued aimed at preventing hunger in case of crop failure. Crop failure in Russia always led to a rise of bread prices. To combat this, grain stores were introduced throughout Russia. Catherine II personally drafted the Charter on Bread, which, however, was not implemented. What differed the Charter on Bread from subsequently adopted rules for creating, maintaining, and spending grain supplies, was that the state itself was responsible for their replenishment. It had to enter into contractor's agreement or supply contract and to supply the bread to the store. By the end of her reign, consistent policy of Catherine II to led the creation in Russia of a sustainable food supply mechanism, which continued until 1917. Catherine II’s legislature also improved preventive measures and promoted national and international grain trade.

The Persistence of Harvest Shocks in Medieval England

I present evidence that shocks to the Medieval English harvest persisted. Hypothesized mechanisms include varying supplies of seed corn and other complementary harvest inputs. Peasants are modeled as trading off current consumption against grain stores and sow rates so that subsistence-level shocks may persist. For my sample I find that a failed harvest increased the probability of subsequent harvest failure by 20–30 percent. Grain yields are analyzed as a strongly balanced panel by year, manor, and crop. While I reject the hypothesis that harvests were self-contained annual events, I caution against linking harvest persistence directly to runs in grain prices.

Patterns and drivers of genetic diversity and structure in the biological control parasitoid Habrobracon hebetor in Niger

When a promising natural enemy of a key pest exists locally, it is a common practice in biological control (BC) to rear and release it for supplementary control in the targeted agroecosystem even though significant knowledge gaps concerning pre/post release may still exist. Incorporating genetic information into BC research fills some of these gaps. Habrobracon hebetor, a parasitoid of many economically important moths that infest stored and field crops worldwide is commonly used, particularly against the millet head miner (MHM), a key pest of millet in Sahelian countries. To advance our knowledge on how H. hebetor that occurs naturally in open-field cropping systems and grain stores as well as being mass-produced and released for MHM control, performs in millet agroecosystems in Niger we evaluated its population genetics using two mitochondrial and 21 microsatellite markers. The field samples were genetically more diverse and displayed heterozygote excess. Very few field samples had faced significant recent demographic bottlenecks. The mating system (i.e. nonrandom mating with complementary sex determination) of this species may be the major driver of these findings rather than bottlenecks caused by the small number of individuals released and the scarcity of hosts during the longlasting dry season in Niger. H. hebetor population structure was represented by several small patches and genetically distinct individuals. Gene flow occurred at local and regional scales through human-mediated and natural short-distance dispersal. These findings highlight the importance of the mating system in the genetic diversity and structure of H. hebetor populations, and contribute to our understanding of its reported efficacy against MHM in pearl millet fields.

A Study of Strain-Driven Nucleation and Extension of Deformed Grain: Phase Field Crystal and Continuum Modeling

The phase-field-crystal (PFC) method is used to investigate migration of grain boundary dislocation and dynamic of strain-driven nucleation and growth of deformed grain in two dimensions. The simulated results show that the deformed grain nucleates through forming a gap with higher strain energy between the two sub-grain boundaries (SGB) which is split from grain boundary (GB) under applied biaxial strain, and results in the formation of high-density ensembles of cooperative dislocation movement (CDM) that is capable of plastic flow localization (deformed band), which is related to the change of the crystal lattice orientation due to instability of the orientation. The deformed grain stores the strain energy through collective climbing of the dislocation, as well as changing the orientation of the original grain. The deformed grain growth (DGG) is such that the higher strain energy region extends to the lower strain energy region, and its area increase is proportional to the time square. The rule of the time square of the DGG can also be deduced by establishing the dynamic equation of the dislocation of the strain-driven SGB. The copper metal is taken as an example of the calculation, and the obtained result is a good agreement with that of the experiment.

Open for Competition: Domesticates, Parasitic Domesticoids and the Agricultural Niche

This paper explores the relationship of weeds and crop parasites in the domestication of crop-plants within the Old World, drawing predominately on China and the Near East. This relationship is explored using the concept of niche construction in which the act of cultivation sets about chains of feedback in which the ecological worlds of plants and humans became increasingly intertwined resulting in ever increasing spheres of interdependence. Into this domestication entanglement a number of peripheral organisms (termed parasitic domesticoids) were drawn, from the weeds which came to inhabit arable fields, to the insect pests and rodents that came to settle in the grain stores of the first farmers. The evolution and spread of these organisms is then outlined against that of the crop itself.

Adaptations to different habitats in sexual and asexual populations of parasitoid wasps: a meta-analysis

BackgroundCoexistence of sexual and asexual populations remains a key question in evolutionary ecology. We address the question how an asexual and a sexual form of the parasitoidVenturia canescenscan coexist in southern Europe. We test the hypothesis that both forms are adapted to different habitats within their area of distribution. Sexuals inhabit natural environments that are highly unpredictable, and where density of wasps and their hosts is low and patchily distributed. Asexuals instead are common in anthropic environments (e.g., grain stores) where host outbreaks offer periods when egg-load is the main constraint on reproductive output.MethodsWe present a meta-analysis of known adaptations to these habitats. Differences in behavior, physiology and life-history traits between sexual and asexual wasps were standardized in term of effect size (Cohen’sdvalue; Cohen, 1988).ResultsSeeking consilience from the differences between multiple traits, we found that sexuals invest more in longevity at the expense of egg-load, are more mobile, and display higher plasticity in response to thermal variability than asexual counterparts.DiscussionThus, each form has consistent multiple adaptations to the ecological circumstances in the contrasting environments.