Oxygen Consumption by Grain Storage Pests in Relation to Hermetic Storage Systems and an Evaluation of Postharvest Management Practices by Smallholder Farmers in Haiti

Food security is a serious issue throughout the world. An estimated 700 million people in developing countries currently lack the food necessary for an active and healthy lifestyle (World Bank, 1999). Competition with insect pests for food has always been a challenge. An estimated 20-30% of the grain can be lost postharvest due to insect pests alone (Tefera et al., 2011). To reduce postharvest losses and improve food security, alternative storage solutions are needed to replace the traditional, and often-ineffective storage methods employed by smallholder farmers. Hermetic grain storage is an airtight technology that provides a cost effective and insecticide free pest control option. With the more recent focus on reducing postharvest losses via hermetic technology, there is a need to investigate the postharvest management practices of smallholder farmers in new regions where the technology has yet to be introduced, such as in the Americas and the Caribbean countries. There is also a need to increase our understanding of hermetic environments and factors that affect their efficacy including insect oxygen consumption, insect population density and varying temperatures. In Chapter 1, I report the results from a study investigating the oxygen requirements of Callosobruchus maculatus Fabricius and Plodia interpunctella Hubner under normal atmospheric conditions. In chapter 2, I report the results from trials on the effect of high and low temperatures and variable insect population densities on the survival of C. maculatus during hermetic storage. In chapter 3, I report the results of a survey on assessing postharvest management practices of smallholder farmers in Haiti

Potential repellency of cedarwood oil from a novel extraction method to stored product insects

Producers lose 10-30% of crops during storage, processing, and marketing after harvest each year to stored product insects (1,2). Globally, there has been a rise in insecticide resistance to phosphine, the most common fumigant for these pests (3). As a result, producers need to diversify post-harvest IPM methods to preserve existing tools. One alternative strategy is push-pull, whereby a repellent is used to “push” an insect away from the commodity of interest, while also simultaneously “pulling” the insects to an alternate location away from the commodity using an attractant (4)(Fig. 1). This system notably requires a long-distance repellent. One potential repellent includes cedarwood oil, which has shown repellency to termites and ants (5,6). A novel extraction process for this compound has been developed, which leaves many of its main constituents intact (7). However, to date, this compound has never been assessed for repellency to post-harvest insects

Oxygen Consumption by Grain Storage Pests in Relation to Hermetic Storage Systems and an Evaluation of Postharvest Management Practices by Smallholder Farmers in Haiti

Food security is a serious issue throughout the world. An estimated 700 million people in developing countries currently lack the food necessary for an active and healthy lifestyle (World Bank, 1999). Competition with insect pests for food has always been a challenge. An estimated 20-30% of the grain can be lost postharvest due to insect pests alone (Tefera et al., 2011). To reduce postharvest losses and improve food security, alternative storage solutions are needed to replace the traditional, and often-ineffective storage methods employed by smallholder farmers. Hermetic grain storage is an airtight technology that provides a cost effective and insecticide free pest control option. With the more recent focus on reducing postharvest losses via hermetic technology, there is a need to investigate the postharvest management practices of smallholder farmers in new regions where the technology has yet to be introduced, such as in the Americas and the Caribbean countries. There is also a need to increase our understanding of hermetic environments and factors that affect their efficacy including insect oxygen consumption, insect population density and varying temperatures. In Chapter 1, I report the results from a study investigating the oxygen requirements of Callosobruchus maculatus Fabricius and Plodia interpunctella Hubner under normal atmospheric conditions. In chapter 2, I report the results from trials on the effect of high and low temperatures and variable insect population densities on the survival of C. maculatus during hermetic storage. In chapter 3, I report the results of a survey on assessing postharvest management practices of smallholder farmers in Haiti

Improving management of the larger grain borer, Prostephanus truncatus, and the maize weevil, Sitophilus zeamais

Doctor of PhilosophyDepartment of EntomologyMajor Professor Not ListedKun Yan ZhuThe invasive larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) is a devastating stored product pest of maize and cassava, originating from Meso-America. Many outstanding areas of basic behavior and ecology remain to be assessed for P. truncatus, and its main cosmopolitan competitor, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae). This includes enhancing knowledge of P. truncatus and S. zeamais management through chemical control, improving understanding of interspecific competition in grain columns, and elucidating how these species potentially vector microbes. To enhance management through chemical control, I investigated the efficacy of a novel insecticide formulation (S-methoprene + deltamethrin + piperonyl butoxide; Gravista®) compared to an existing commercial standard formulation without synergist (Diacon IGR+®), and water-treated controls. We found significant multiple-fold mortality induction and movement reduction when applied as a grain protectant or surface treatment on concrete for 4–168 h compared to the control. In a more realistic test, we evaluated the recovery and horizontal dispersal capacity of P. truncatus and S. zeamais to food patches after 48 h in a dispersal apparatus with 15 g of maize. We found the percentage of P. truncatus and S. zeamais dispersing was significantly reduced by 90–97% or 5–25% after exposure to Gravista or Diacon IGR+ compared to the control. Further, we evaluated two other grain protectants (deltamethrin and pirimiphos-methyl) as surface treatments for maize to manage both species. Mortality of adults was nearly 100% for all treatments for both insecticides with P. truncatus, while progeny production was low. Mortality for S. zeamais remained low for deltamethrin but they were easily controlled by pirimiphos-methyl. These insects also co-occur in many regions of the world. Thus, I evaluated the outcome of interspecific competition between P. truncatus and S. zeamais between 25–35°C and found that coexistence may be possible at a range of 25–30°C, but mixed colonies experienced a direct competitive cost. Prostephanus truncatus than S. zeamais performed better at warmer temperatures. Even less information is available on the spatial dispersion of these species in grain columns, therefore we evaluated competition under three different densities (10–300 insects/kg) in monolayers of maize after 1 and 7 d in pure or mixed colonies. Both species generally aggregated together and were correlated to the same location as heterospecifics. When alone, P. truncatus created a clear path of destruction to the bottom of the monolayer, but when S. zeamais was present, damage was lessened and shifted upwards. Finally, the ability of both species to vector microbes when given the opportunity to forage on agar dishes (e.g., a novel food patch) after a 0, 24, or 72 h dispersal period was assessed. Both species readily vectored several plant pathogenic microbes, including 21 taxa from 11 genera, notably Aspergillus, Penicillium, and Fusarium spp. Increasing dispersal period resulted in a third less microbial growth by S. zeamais after 72 h. Colonization by S. zeamais resulted in 6.6-fold more microbial growth than P. truncatus. This highlights the importance of behavioral ecology in IPM and suggests new tactics for these economically important species

Postharvest Management of Grains in Haiti and Gender Roles

Food security is a continuing challenge in Haiti. The demand for food far exceeds local supply. As a result, Haiti imports nearly 50% of its national food needs. Postharvest management is an often neglected link in the grain value chain that has potential to improve food availability. We interviewed 214 farmers in three departments in July–August 2017 to assess postharvest handling and storage of grains and gender roles in Haiti. Results showed that among the respondents: 64% were male; 55% were over the age of 40 years; and about half had attended secondary school. Maize and beans were the most grown and stored crops. The average production for maize and beans was 288 kg and 88 kg, respectively. About 75% of the respondents stored less than 100 kg of either crop. Rodents and insects were the main causes of loss during storage. Farmers who produced more grain, stored longer, and experienced losses during drying and seed storage were more likely to use insecticides on stored products. Postharvest management practices were gendered at the lower end of the value chain; where women played a key role in marketing the grain. Addressing postharvest management challenges, through targeted interventions, to increase food availability while investing in maize and bean production can improve food security in Haiti

Extrarenale Entgiftung des Blutfiltrats durch Elektrooxidation und oxidative Adsorption MSO 514 Abschlussbericht

TIB Hannover: FR 1535 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman