Gary J. Brewer

Within-field distribution of the sunflower midge (Diptera: Cecidomyiidae)

Abstract The sunflower midge, Contarinia schulzi Gagné (Diptera: Cecidomyiidae), is a pest of cultivated sunflower (Helianthus annuus L.). Larval feeding can cause damage and yield loss to the sunflower head. Adult emergence is extended and larvae are well protected in the sunflower receptacle, making chemical control methods difficult and expensive. Sunflower midge enter sunflower fields at the edges but fieldwide distributions occur, although the dynamics are not fully understood. Two commercial fields in 1999 and one field in 2000 were systematically sampled by dividing each field into fixed sample points. Mean egg and larval densities from each sample point were used to describe sunflower midge populations. The sunflower heads at each sample point were also assessed for damage. Maps of sunflower midge population density, cumulative density, and sunflower head damage ratings were estimated with kriging interpolation. Maps were estimated several times during first generation sunflower midge infestation. Field edges that were initially populated continued to be areas of infestation throughout the sampling period. Damage ratings were related to population densities when infestations were high. In 2000, we tested the larval hatching rate from different-sized egg masses with regression to determine an estimation technique for combining numbers of eggs and larvae.

Sunflower Beetle (Coleoptera: Chrysomelidae): Pattern of Larval Distribution and Parasitism in Cultivated Sunflower Fields

Abstract The sunflower beetle, Zygogramma exclamationis (Fabricius), is a major pest of commercial sunflower, Helianthus annuus L. (Asteraceae), in the Plains area of central North America. Although an economic injury level for the sunflower beetle has been determined, in-field distributions of the larvae and their natural enemies have not been described. Over a three year period, fields were sampled for sunflower beetle larvae and for larvae of the endoparasitoid, Myiopharus macellus (Reinhard). Sunflower beetle larvae were generally found to have aggregated distributions. Knowledge of the distribution pattern will allow the development of more efficient sunflower beetle sampling protocols. Parasitism rates of M. macellus throughout fields were equivalent, indicating effective host searching. Although the data supports aggregated distributions for M. macellus, it is less clear than that for the sunflower beetle.

Mechanisms of resistance to the red sunflower seed weevil in sunflower accessions

In the northern Great Plains of North America, internal seed feeding by larvae of the red sunflower seed weevil, Smicronyx fulvus LeConte, causes economic damage to sunflower, Helianthus annuus L. Our purpose was to identify sunflower germplasm with resistance to the red sunflower seed weevil and to determine mechanisms of resistance. In 1986, 300 sunflower accessions were evaluated for the percentage of seed damaged by red sunflower seed weevil larvae. In 1987, six accessions selected on the basis of the 1986 results were evaluated for resistance to the red sunflower seed weevil. The selected accessions had flowering dates comparable to the susceptible check. The percentage of seeds with exit holes (emerged and successfully developed larvae), with larvae (unemerged larvae remaining in the seed), with inclusive damage (total percentage of seeds with exit holes or larvae), and with adult feeding or oviposition scars was used to test for larval antibiosis and adult preference. Larval antibiosis was detected in accessions 251465, 175730, 170407 and 170408 which had significantly higher percentages of seeds with larvae than did the susceptible check. The percentages of seeds with larvae and with inclusive damage were positively correlated with adult feeding or oviposition scars. Therefore, in the accessions tested, larval infestations appeared to be at least partially determined by adult red sunflower seed weevil preference.

Determining Optimum Soil Type and Salinity for Rearing the Federally Endangered Salt Creek Tiger Beetle, Cicindela (Ellipsoptera) nevadica lincolniana Casey (Coleoptera: Carabidae: Cicindelinae)

Abstract Effective rearing methods are needed to recover the federally endangered Salt Creek tiger beetle, Cicindela (Ellipsoptera) nevadica lincolniana Casey, a subspecies that occurs exclusively in saline wetlands and seeps along Little Salt Creek in Lancaster County, Nebraska. Experiments were initiated to determine soil type and salinity concentrations appropriate for stimulating female oviposition in laboratory settings to produce larvae and/or adults for reintroduction to native habitats. In 2013, there were highly significant differences between native soil and a sand/loess soil mixture, but no differences between two salinity levels, 0.354 M and 0.5 M. In 2014, using only a sand/loess soil mixture, there were again no differences between the test salinity levels. A sand/loess soil mixture of either 0.354 M or 0.5 M salinity was determined to be optimum for egg production.

Using banded sunflower moth (Lepidoptera: Tortricidae) egg density to estimate damage and economic distance in oilseed sunflower.

Abstract The banded sunflower moth, Cochylis hospes Walsingham (Lepidoptera: Tortricidae), is an important economic pest of sunflower in the Upper Great Plains of North America. Economic losses due to reductions in seed number, weight, and quality can be significant. Previously, the potential for economic losses were estimated by sampling for adult moths. However, sampling for moths can be difficult and inaccurate. An alternative is to sample for banded sunflower moth eggs, which can be accurately counted in the field by using a binocular 3.5 headband magnifier. The egg counts are used to calculate the economic injury level (EIL) (EIL = C/VWPK), where C is the cost of treatment per unit area, V is the crop market value per unit of weight, W is the slope of the regression between banded sunflower moth egg densities and weight loss per plant, P is a term for plant population per unit area, and K is the control treatment efficacy. Estimates of populations of banded sunflower moth eggs are taken from the center of 400-m spans along all field sides. From these samples and the calculated EIL, a map of the extent of the economically damaging banded sunflower moth population throughout the field is made using economic distance; ED = e(((EIL/E) − 1.458)/−0.262). Economic distance estimates the distance an economic population extends into the field interior along a transect from the sampling site. By using egg samples to calculate the EIL and mapping the distribution of economic populations throughout a field, producers can then make more effective pest management decisions.

Spatial distribution and sequential sampling plans for the banded sunflower moth eggs in sunflower

The banded sunflower moth, Cochylis hospes Walsingham (Lepidoptera: Cochylidae), is distributed in most parts of North America (Beregovoy et al., 1989) and in the northern Great Plains, and is a major pest of cultivated sunflower, Helianthus annuus L. (Charlet et al., 1987). This moth is univoltine with adult emergence beginning in early July (Charlet & Gross, 1990). Beregovoy & Riemann (1987) found that the R3 sunflower stage (a plant with an immature bud more than 2.0 cm above the nearest leaf, Schneiter & Miller, 1981) is the most attractive for oviposition by the banded sunflower moth. Females oviposit on the outer surface of the bracts and on the back of sunflower heads (Beregovoy & Riemann, 1987; Charlet & Gross, 1990). Early instars feed on the inner surface of the bracts or florets which may reduce the total number of mature sunflower seeds (Charlet & Busacca, 1986). Later instars feed on developing kernels, damaging an average of 6-7 seeds per larva (Charlet & Gross, 1990), which may be largely or entirely consumed (Peng & Brewer, 1995). Management strategies for the chemical control of banded sunflower moth are to target either adult moths or the early stage of larvae. Because adult moths aggregate at field margins, in weedy areas, or in adjacent crops before their diurnal movement into sunflower, they are difficult to control (McBride et al., 1984). Charlet & Busacca (1986) reported that insecticidal control of larvae was effective, but the economic threshold has not been determined. One moth per two plants is recommended by McBride & Charlet (1991) as a treatment threshold. However estimating adult moth density in fields is difficult because moths rest on the undersides of the lower leaves of sunflower plants during the day, are small, and difficult to see, especially in fields where the plants are dense and tall. Attempts to use pheromone catches as a treatment threshold failed to correlate between larval infestations and moth catches (Wilde et al., 1994; Blodgett et al., 1994). Evidently, moth counts are not reliable for making control decisions. We propose using counts of the eggs per head to make control decisions. The objective of this study was to determine spatial distribution of banded sunflower moth eggs which would allow the development of sequential sampling plans to estimate banded sunflower moth egg populations.

Integrated Pest Management in the Global Arena

INTEGRATED PEST MANAGEMENT in the Global Arena is a large book with 39 chapters and 500 pages of text. Despite the wide range of topics and numerous contributing authors, the book is consistently well written and worth reading in its entirety or by selectively choosing particular topics. The book should be a welcome reference for researchers and extension personnel across disciplines as well as for policy makers in government agencies and nongovernmental organizations working to promote integrated pest management (IPM) and sustainable agriculture. The reader can select any chapter and Þnd a relevant discussion of IPM. As someone who teaches an IPM class, I found several new ideas and novel presentations of concepts that I will include in my class. The book has four parts. Part 1 includes eight chapters discussing a wide range of emerging issues in IPM. Part 2, the largest section of the book with 20 chapters, details individual country experiences. These chapters are grouped into large geographic regions for convenience and some similarity of climate and sociopolitical factors. Part 3 describes IPM experiences of different international agencies working to promote and develop IPM. Part 4 brings the diverse topics set out in parts 1-3 to a conclusion and has recommendations for promoting global success of IPM. As might be expected given the number of programs and agencies discussed, a lot of jargon and acronyms are used throughout the book. Fortunately, the editors include in the front of the book a nearly complete glossary of acronyms and abbreviations. Part 1 deals with issues in IPM and is not designed to be a stand-alone text on the topic. However, it does give a good overview of issues ranging from biological control to biotechnology and introduces the importance of policy change and sustainable development to the success of IPM. A major contribution in this part is the attention paid to social, political, and gender issues. The point is made that IPM technologies, no matter what their level of effectiveness, often fail unless they have relevance to the accompanying social structures of the end users and consumers. These topics are not generally covered in other IPM books. The country experiences in part 2 are extremely varied. Most of the chapters provide an overview of the political and environmental conditions before adopting IPM. In general, the countries reached a pest management crisis that resulted in policy change from promoting pesticide use to a more balanced policy favoring an integrated approach to pest management. Although difÞcult pest management was a common factor leading to the adoption of IPM policy and programs, it was often not the sole or even major motivation. For example, in Indonesia, pest issues in rice production threatened rice self-sufÞciency. In the Philippines, farm proÞtability was a goal and in several West African nations reducing the cost of off-farm purchased inputs for agricultural production motivated a move to IPM. Although the situation in each country was unique and each countryÕs motivation for adapting IPM was speciÞc, there was a common need for policy change and attention to social structure. In most locations, IPM adoption relied on some variation of farmer Þeld schools to build support for the new technologies. On reading part 3, I was struck by bureaucracy of many of the international programs dealing with IPM. Nevertheless, international organizations have made real gains in promoting and building IPM capacity around the world. Several of the agencies are not interested in IPM as a stand-alone program but see IPM as critical to their mission of promoting sustainable agricultural and social systems in their host countries. Part 4 summarizes and highlights the commonalities of the book and very brießy concludes by introducing trends and challenges that need to be addressed before IPM is globally adopted.