Population regulation in insect herbivores - top-down or bottom-up?

Recent evidence points to the plant's being a much more limited resource than previously expected. In addition to the restraints on feeding and population growth imposed by such factors as leaf toughness, the physical environment, plant nutrition, etc., recent work points to the role of feeding-induced chemical changes in the leaves in reducing herbivore 'fitness'. This suggests that population regulation in herbivores may indeed sometimes be from the trophic level below that of the herbivore—the plant itself

Food and nutritional security requires adequate protein as well as energy, delivered from whole-year crop production

© 2016 Coles et al.Human food security requires the production of sufficient quantities of both high-quality protein and dietary energy. In a series of case-studies from New Zealand, we show that while production of food ingredients from crops on arable land can meet human dietary energy requirements effectively, requirements for high-quality protein are met more efficiently by animal production from such land. We present a model that can be used to assess dietary energy and quality-corrected protein production from various crop and crop/animal production systems, and demonstrate its utility. We extend our analysis with an accompanying economic analysis of commercially- available, pre-prepared or simply-cooked foods that can be produced from our case-study crop and animal products. We calculate the per-person, per-day cost of both quality-corrected protein and dietary energy as provided in the processed foods. We conclude that mixed dairy/cropping systems provide the greatest quantity of high- quality protein per unit price to the consumer, have the highest food energy production and can support the dietary requirements of the highest number of people, when assessed as all-year-round production systems. Global food and nutritional security will largely be an outcome of national or regional agroeconomies addressing their own food needs. We hope that our model will be used for similar analyses of food production systems in other countries, agroecological zones and economies

The future of farming: the value of ecosystem services in conventional and organic arable land. An experimental approach.

In the current work, a novel, experimental ‘bottom-up’ approach is used to quantify the economic value of ecosystem services (ES) associated with highly modified arable landscapes in Canterbury, New Zealand. First, the role of land management practices in the maintenance and enhancement of ES in agricultural land was investigated by quantifying the economic value of ES at the field level under organic and conventional arable systems. This quantification was based on an experimental approach in contrast with the earlier value transfer methods. Total annual economic value of ES in organic fields ranged from US $1610 to US$19,420 ha⁻¹ yr⁻¹ and that of conventional fields from US $1270 to US$14,570 ha⁻¹ yr⁻¹. The non-market value of ES in organic fields ranged from US $460 to US$5240 ha⁻¹ yr⁻¹. The range of non-market values of ES in conventional fields was US $50 – 1240 ha⁻¹ yr⁻¹. There were significant differences between organic and conventional fields for the economic values of some ES. Next, this economic information was used to extrapolate and to calculate the total and non- market value of ES in Canterbury arable land. The total annual economic and non-market values of ES for the conventional arable area in Canterbury (125,000 ha) were US$332 million and US $71 million, respectively. If half the arable area under conventional farming shifted to organic practices, the total economic value of ES would be US$192 million and US $166 million annually for organic and conventional arable area, respectively. In this case, the non-market value of ES for the organic area was US$65 million and that of conventional area was US $35 million annually. This study demonstrated that arable farming provides a range of ES which can be measured using field experiments based on ecological principles by incorporating a ‘bottom-up’ approach. The work also showed that conventional New Zealand arable farming practices can severely reduce the financial contribution of some of these services in agriculture whereas organic agriculture practices enhance their economic value

Ecosystem Function and the Prediction of Tree Resistance to Defoliators

New Zealand Forest Research InstituteLincoln UniversityProceedings : IUFRO Kanazawa 2003 "Forest Insect Population Dynamics and Host Influences"., Scedule:14－19 September 2003, Vemue: Kanazawa Citymonde Hotel, Kanazawa, Japan, Joint metting of IUFRO working groups : 7.01.02 Tree resistance to Insects | 7.03.06 Integrated management of forset defoloating insects | 7.03.07 Population dynamics of forest insects, Sponsored by: IUFRO-J | Ishikawa Prefecture | Kanazawa City | 21st-COE Program of Kanazawa University, Editors: Kamata, Naoto | Liebhold, Nadrew M. | Quiring, Dan T. | Clancy, Karen M

The effect of seed moisture content and hot water treatment on carrot seed viability and Alternaria radicina control

Hot water treatment of seeds to control seedborne pathogens is an important tool for organic seed production. Reducing seed moisture content may have the potential to increase carrot (Daucus carota L. var. sativus D.C.) seed tolerance to treatment. Two hot water seed treatment experiments were conducted

The effect of seed moisture content and the duration and temperature of hot water treatment on carrot seed viability and the control of Alternaria Radicina

Hot water treatment of seeds to control seedborne pathogens is an important tool for organic seed production. Reducing seed moisture content may have the potential to increase carrot (Daucus carota L. var. sativus D.C.) seed tolerance to treatment. Two hot water seed treatment experiments were conducted. The first studied the effect of seed moisture content (SMC), treatment temperature and treatment duration on germination. Maximum safe treatment temperature and durations were established at 50°C and 30-40 min. Germination decreased slightly from 68% at 5% SMC to 63% at 20% SMC (LSD 1.2) for all durations. The second experiment studied the effect of initial SMC and treatment durations on infestation of seed by Alternaria radicina and seed germination. Treatment at 50°C for 30 min for all SMC compared to the control resulted in a decrease in A. radicina infestation from 69.2 to 1.7%. Reducing SMC from 20 to 5% for all durations resulted in a small decrease in infestation from 25% to 18% (LSD 1.5). Reducing SMC to 5% prior to hot water treatment may be a commercially viable means of minimising reductions in seed viability and decreasing fungal infestation levels

An improved method to produce adults of Costelytra zealandica White (Coleoptera: Melolothinae) from field-collected larvae

Rearing techniques provide a unique opportunity to study aspects of insect ecology, behaviour and physiology. Both the larval and adult stages in Melolonthinae scarabs have important impacts on crop and pasture yields worldwide. Rearing techniques for this group of phytophagous beetles usually results in a low survival rate from larva to adult, varying from 10% to 50%. Here, the current rearing method used for the New Zealand grass grub (Costelytra zealandica) was improved by increasing the pupation weight threshold, as well as by changing the container type used to rear the larvae. This improved method produced an 83% increase in the survival rate from larva to adult, and the technique developed here may help increase the laboratory survival rate of other Melolonthinae species worldwide

Ratios rather than concentrations of nutritionally important elements may shape honey bee preferences for ‘dirty water’

1. Honey bees require minerals for a complete diet. However, minerals from flowers can be inadequate in concentration and composition. Therefore, honey bees may drink ‘dirty water’ from natural sources such as puddles. Some research has attempted to simulate this through honey bee bioassays, but to date, these have tested minerals individually, not as mixtures as would occur in nature. Here, for the first time, we use honey bees in bioassays in which a range of mineral mixtures are presented together in choice experiments. 2. Six minerals (NaCl, KCl, CaCl₂, MgCl₂, NH₄Cl, and KH₂PO₄) were used in mixtures to simulate different mineral stoichiometries, which may occur in ‘dirty water’, such as puddles, from which honey bees often drink. Based on the honey bee mineral tolerance ranges from the literature, these mixtures were offered in aqueous solutions at low, medium, high, and mixed molar concentrations. Deionised water and sucrose were neutral and positive controls, respectively. Petri dishes were set up in containers in a laboratory. Twenty worker honey bees (Apis mellifera L.) were placed into each container and observed for drinking behaviour for 1 h. 3. Honey bees preferred the mixed molar treatment comprising a high Na:K ratio, a medium molarity of NaCl and a low molarity of the other minerals. This novel finding suggests that mixed mineral ‘dirty water’ should be investigated on a larger scale with multiple hives in the field and highlights the importance of stoichiometrically balanced honey bee diets

Understanding the pathways from biodiversity to agro-ecological outcomes: A new, interactive approach

The adoption of agro-ecological practices in agricultural systems worldwide can contribute to increased food production without compromising future food security, especially under the current biodiversity loss and climate change scenarios. Despite the increase in publications on agro-ecological research and practices during the last 35 years, a weak link between that knowledge and changed farmer practices has led to few examples of agro-ecological protocols and effective delivery systems to agriculturalists. In an attempt to reduce this gap, we synthesised the main concepts related to biodiversity and its functions by creating a web-based interactive spiral (www.biodiversityfunction.com). This tool explains and describes a pathway for achieving agro-ecological outcomes, starting from the basic principle of biodiversity and its functions to enhanced biodiversity on farms. Within this pathway, 11 key steps are identified and sequentially presented on a web platform through which key players (farmers, farmer networks, policy makers, scientists and other stakeholders) can navigate and learn. Because in many areas of the world the necessary knowledge needed for achieving the adoption of particular agro-ecological techniques is not available, the spiral approach can provide the necessary conceptual steps needed for obtaining and understanding such knowledge by navigating through the interactive pathway. This novel approach aims to improve our understanding of the sequence from the concept of biodiversity to harnessing its power to improve prospects for ‘sustainable intensification’ of agricultural systems worldwide