The Red Queen in a potato field: integrated pest management versus chemical dependency in Colorado potato beetle control

Originally designed to reconcile insecticide applications with biological control, the concept of integrated pest management (IPM) developed into the systems‐based judicious and coordinated use of multiple control techniques aimed at reducing pest damage to economically tolerable levels. Chemical control, with scheduled treatments, was the starting point for most management systems in the 1950s. Although chemical control is philosophically compatible with IPM practices as a whole, reduction in pesticide use has been historically one of the main goals of IPM practitioners. In the absence of IPM, excessive reliance on pesticides has led to repeated control failures due to the evolution of resistance by pest populations. This creates the need for constant replacement of failed chemicals with new compounds, known as the ‘insecticide treadmill’. In evolutionary biology, a similar phenomenon is known as the Red Queen principle – continuing change is needed for a population to persevere because its competitors undergo constant evolutionary adaptation. The Colorado potato beetle, Leptinotarsa decemlineata (Say), is an insect defoliator of potatoes that is notorious for its ability to develop insecticide resistance. In the present article, a review is given of four case studies from across the United States to demonstrate the importance of using IPM for sustainable management of a highly adaptable insect pest. Excessive reliance on often indiscriminate insecticide applications and inadequate use of alternative control methods, such as crop rotation, appear to expedite evolution of insecticide resistance in its populations. Resistance to IPM would involve synchronized adaptations to multiple unfavorable factors, requiring statistically unlikely genetic changes. Therefore, integrating different techniques is likely to reduce the need for constant replacement of failed chemicals with new ones. © 2014 Society of Chemical Industry     

In Memoriam: Dr. John M. Laflen

The soil erosion research and soil and water conservation global community lost a treasured member on November 20, 2020, when Dr. John Matthew Laflen (Fig. 1) died. Always one with a friendly welcoming smile, John had hundreds of friends, both personally and professionally throughout the world. This article includes many of his professional and scientific contributions, and impacts from his research and outreach activities.     

Spatial dynamics of coastal forest bird assemblages: the influence of landscape context,forest type,and structural connectivity

Context

Complex structural connectivity patterns can influence the distribution of animals in coastal landscapes, particularly those with relatively large home ranges, such as birds. To understand the nuanced nature of coastal forest avifauna, where there may be considerable overlap in assemblages of adjacent forest types, the concerted influence of regional landscape context and vegetative structural connectivity at multiple spatial scales warrants investigation.

Objectives

This study determined whether species compositions of coastal forest bird assemblages differ with regional landscape context or with forest type, and if this is influenced by structural connectivity patterns measured at multiple spatial scales.

Methods

Three replicate bird surveys were conducted in four coastal forest types at ten survey locations across two regional landscape contexts in northeast Australia. Structural connectivity patterns of 11 vegetation types were quantified at 3, 6, and 12 km spatial scales surrounding each survey location, and differences in bird species composition were evaluated using multivariate ordination analysis.

Results

Bird assemblages differed between regional landscape contexts and most coastal forest types, although Melaleuca woodland bird assemblages were similar to those of eucalypt woodlands and rainforests. Structural connectivity was primarily correlated with differences in bird species composition between regional landscape contexts, and correlation depended on vegetation type and spatial scale.

Conclusions

Spatial scale, landscape context, and structural connectivity have a combined influence on bird species composition. This suggests that effective management of coastal landscapes requires a holistic strategy that considers the size, shape, and configuration of all vegetative components at multiple spatial scales.

     

THE OUTPUT OF SWARDS ON COMMERCIAL FARMS IN RELATION TO FERTILIZER AND OTHER MANAGEMENT FACTORS

Survey data collected during a grassland-recording investigation showed a strong positive correlation between nitrogen input and the output of utilized starch equivalent per acre. At the levels of output covered, sward type was not very important in relation to total yield. Herbage species were important for other reasons and the choice of seeds mixtures should be determined by factors such as earliness and lateness of growth and resistance to disease and drought. The survey showed that well-managed ley and permanent pasture are both capable of producing at a high level. A disturbing feature of the results was the low production of most spring resowings, primarily as a result of poor management. Although the records were obtained from an above-average group of farms, the results have general application. Potential responses to fertilizers may be even greater on less intensive farms, especially with regard to phosphate and potash. However, the level of production of a field will always depend finally on the level of management exercised by the farmer himself.     

A COMPARISON OF COCKSFOOT- AND TALL FESCUE-DOMINANT SWARDS FOR OUT-OF-SEASON PRODUCTION

Swards based on a mixture of SI 70 tall fescue and S215 meadow fescue were very early in spring, gave high yields for conservation in mid-season and, rested from mid-August, gave good grazing in November-December. Under this treatment, the tall fescue assumed dominance, and the swards were persistent and remained productive. The digestibility of the tall fescue swards was always higher than that of swards based on cocksfoot with which they were compared. During spring and autumn the former sward was better grazed by stock, but the position was reversed in mid-summer. Cattle grazing tall-fescue-dominant swards made better liveweight gains than those grazing cocksfoot swards during November-December.     

THE INFLUENCE OF TWO LEVELS OF NITROGENOUS FERTILIZING ON THE LONG-TERM PRODUCTIVITY OF LEYS

Two levels of nitrogen application (70 and 180 lb per acre per annum) were compared on 6 long-duration leys. The treatments were repeated for periods of up to 4 years on tiie same swards. The higher N dressing produced 2230 lb more dry matter per acre than the low rate, an increase of 28%, and the yield was also more evenly spread throughout the season. There was virtually no clover on the high-N swards. The proportion of clover varied under low N but tended to increase as the season progressed. The sown grasses remained the dominant sward constituents throughout the experiment, and there was no sign of loss of vigour on the high-N swards. Utilized-starch-equivalent outputs were calculated from 3 different swards for 1956–8 and there was a significant positive correlation between the dry-matter yields and utilized-starch-equivalent output of swards.     

Aquatic food security: insights into challenges and solutions from an analysis of interactions between fisheries,aquaculture, food safety,human health,fish and human welfare,economy and environment

Fisheries and aquaculture production, imports, exports and equitability of distribution determine the supply of aquatic food to people. Aquatic food security is achieved when a food supply is sufficient, safe, sustainable, shockproof and sound: sufficient, to meet needs and preferences of people; safe, to provide nutritional benefit while posing minimal health risks; sustainable, to provide food now and for future generations; shock‐proof, to provide resilience to shocks in production systems and supply chains; and sound, to meet legal and ethical standards for welfare of animals, people and environment. Here, we present an integrated assessment of these elements of the aquatic food system in the United Kingdom, a system linked to dynamic global networks of producers, processors and markets. Our assessment addresses sufficiency of supply from aquaculture, fisheries and trade; safety of supply given biological, chemical and radiation hazards; social, economic and environmental sustainability of production systems and supply chains; system resilience to social, economic and environmental shocks; welfare of fish, people and environment; and the authenticity of food. Conventionally, these aspects of the food system are not assessed collectively, so information supporting our assessment is widely dispersed. Our assessment reveals trade‐offs and challenges in the food system that are easily overlooked in sectoral analyses of fisheries, aquaculture, health, medicine, human and fish welfare, safety and environment. We highlight potential benefits of an integrated, systematic and ongoing process to assess security of the aquatic food system and to predict impacts of social, economic and environmental change on food supply and demand.     

One-Seed Juniper Sapling Use by Goats in Relation to Stocking Density and Mixed Grazing With Sheep

Suppression of one-seed juniper (Juniper monosperma [Englem.] Sarg.) reinvasion with goats requires achieving levels of defoliation of newly established saplings that eventually kill or suppress plant growth. We tested the effects of stocking density and mixed grazing with sheep on the level of use of one-seed juniper saplings by goats. In summer and spring, groups of 10 does (goats alone, GA) or 5 does and 4 ewes (mixed grazing, MG), grazed 20 × 30 m cells infested with saplings (500–533 · ha^?1; mean: 0.8 m tall), either continuously for 6 d (low stocking density, LD) or with daily rotation through 10 × 10 m cells during the 6-d period (high stocking density, HD) in a block design. Feeding activity; juniper in feces; utilization of herbaceous vegetation; frequency of saplings with light, moderate, and heavy foliage and bark use; and branch utilization were determined. Goats in HD spent more time feeding on saplings, less time feeding on herbaceous forages, and tended to consume more juniper than goats in LD. Utilization of herbaceous vegetation ranged from 52% to 73% and was higher for MG than GA and for LD than HD. The MG–HD treatment resulted in the highest frequency of short saplings (< 0.5 m) with heavy defoliation in summer and spring, and lowest frequency of saplings with light debarking in spring. Heavy defoliation was more frequent in short saplings, whereas heavy debarking was more frequent in tall (> 1 m) saplings. Sapling mortality was not affected by treatments (P > 0.05) and averaged 5% across treatments. Branch debarking was greater in spring (P = 0.02) and explained approximately 80% of branch mortality and 62% and 52% of the reduction in sapling live crown height and volume. Branch utilization (percent length) was not affected by grazing treatments (range: 45–48%), but was influenced by the length and diameter of branches. This study suggests that high stocking density and mixed grazing stimulate feeding behaviors that increase utilization of juniper saplings by goats. Susceptibility of saplings to defoliation and debarking varies with sapling size, branch structure, and season. Targeted grazing in spring appears to have a greater impact on sapling suppression and branch mortality due to higher debarking frequency.     

Validation of plantation transpiration in south-eastern Australia estimated using the 3PG+ forest growth model

Forest plantations for wood production are an increasingly important land use in southern Australia, and there are potentially important hydrologic consequences of what is mostly a change in land use from agriculture to silviculture. An ability to predict, with some degree of accuracy, the impact of plantation expansion on surface water and groundwater resources is essential. A validated process-based modelling approach, integrating the many interacting environmental and management factors which may influence plantation growth and transpiration, can be used for this purpose. The 3PG forest growth model has been evaluated for a number of species from widely differing climate and site conditions. While growth predictions have been validated, little attention has been given to testing the accuracy of the transpiration predictions or the model's representation of the water balance. We enhanced the 3PG forest growth model (known as 3PG+) and then integrated it into the Catchment Analysis Tool (CAT), so that it now interfaces with a more detailed multi-layered, daily time step representation of the soil water balance. Simulated transpiration using 3PG+ in CAT was compared with field measurements in 30 plots (across 15 sites) representing 5 common plantation species (Eucalyptus globulus, E. nitens, E. grandis, E. regnans and Pinus radiata) across ages 2–31 years. Mean daily plot transpiration during the measurement periods ranged between 0.4 and 4.2 mm day⁻¹ (average 2.0 mm day⁻¹). Simulated mean daily plot transpiration using 3PG+ in CAT for Eucalyptus was good (coefficient of efficiency = 0.80; R² = 0.81). While the model tended to slightly under-predict transpiration at higher measured rates (>3.5 mm day⁻¹), predictions at monthly timescales had acceptable accuracy. The integration of 3PG+ into CAT resulted in an improvement in accuracy and applicability of CAT, and provides for the spatial application of 3PG+ across diverse and mixed land use catchments for investigation into carbon and water movement in forest systems.