Fundamentals of Stored-Product Entomology

By David Hagstrum

This reference discusses the fundamentals of stored-product entomology that need to be considered in planning, implementation, and evaluation of a pest management program. It is based on the review of an extensive database of references and many years of research on stored-product insect problems by the expert authors. The information in this book helps answer consumers’ concern about pesticide residues in food by providing helpful IPM and alternative approaches for pest management. It provides the basic information needed to manage pests with and without the use of chemicals.

Managing pests requires a thorough understanding of insect biology, behavior, ecology, sampling, pros and cons of management options, and responses of insects to the various management options. This comprehensive book covers all of these topics, beginning with a discussion of the scope of stored-product entomology. It also provides insight into the diversity of foods and habitats utilized by stored-product insects, the types of economic losses attributable to them, and the ways in which an understanding of their biology can be used to study or manage these insects. Insect mobility, sources of insect infestation, sampling, life history, and population growth are discussed as well, as they play an important role in developing an effective sampling program. In addition, decision aids, the cost of management methods, and the resistance of insects to management methods are covered.

For insight into the thought process of choosing treatment options, eight pest management methods are thoroughly described, including a statement of the basic operating principle and background information. For help choosing various chemical and nonchemical methods for diverse situations, the advantages, disadvantages and implementation options for each method are given. Students, extension educators, consultants, food industry sanitarians and managers, legislators, regulators, and insect pest management professionals are sure to find information that will help them to improve pest management.

• Study questions at the end of each chapter
• Suggested supplemental reading, including books, conference proceeding papers, literature reviews, research papers, government publications, and popular articles
• General overview of the biology for a basic understanding of pest control issues
• Guides the reader through the thought process of designing a pest control program or research study
• Images of the most damaging of stored-product insect pest species for identification of families
• Quick methods for distinguishing closely related stored-product insect species

• Language: English
• Publisher: Elsevier Science
• Release date: Jun 8, 2016
• ISBN: 9780128104286

David Hagstrum

Specialty: Management of stored-product insects Education: BA, Biology-Chemistry, California Western University; PhD, Entomology, University of California, Riverside

Book preview

Fundamentals of Stored-Product Entomology

David W. Hagstrum

Department of Entomology, Kansas State University, Manhattan, Kansas

Bhadriraju Subramanyam

Department of Grain Science and Industry, Kansas State University, Manhattan, Kansas

Table of Contents

Cover image

Title page

Copyright

Dedication

Preface

Part I: Ecology and Decision Aids

Introduction to Part I: Ecology and Decision Aids

Chapter 1: Introduction

Storage habitat

Species associated with stored products

Identification

Economic losses

Regulations

Business practices

Summary

Study questions

Chapter 2: Techniques

Rearing

Insect extraction and detection

Sorting species

Sexing

Mating

Feeding

Age grading

Utilization of entomological techniques

Study Questions

Chapter 3: Mobility

Example 1—Exploitation of food sources by Tribolium castaneum

Example 2—Cadra cautella’s response to calling females and food

Example 3—Insects in stored grain

Environmental factors

Physiological state

Distance moved

Utilization of mobility information

Study questions

Chapter 4: Sources of Infestation

Wild hosts

Field infestation

Residual infestation

Commodities

Locating source populations

Relative importance

Utilization of source population information

Study questions

Chapter 5: Sampling

Sampling plan

Sampling device or method

Time and frequency of sampling

Sampling locations

Size of sample unit

Number of samples

Sampling statistics

Predicting variance of means

Probability of detection (P)

Estimation of insect density

Relationship between probability of detection and variance of estimates

Sequential sampling

Utilizing sampling information

Study questions

Chapter 6: Life History

Developmental time

Survival of immature stages

Egg laying

Adult longevity

Diapause

Handling and processing

Utilization of life history information

Study questions

Chapter 7: Population Growth

Types of models

Predictions

Accuracy

Utilization of insect population growth models

Study questions

Chapter 8: Decision Aids

Monitoring-based insect pest management

Cost-benefit analysis

Area-wide insect pest management

Evaluating the efficacy of insect pest management

Consultants and expert systems

Utilization of decision aids

Study questions

Chapter 9: Economics

Cost comparisons for raw commodities

Cost comparisons for the food processor

Calculating equipment cost

Overall cost

Utilization of economic information

Study questions

Chapter 10: Resistance

Resistance mechanisms

Prevalence

Monitoring

Biological factors

Operational factors

Refuges

Farm storage

Utilization of a resistance-management program

Study questions

Part II: Choosing a Pest Management Method

Introduction to Part II: Choosing a Pest Management Method

Chapter 11: Biological Control

Principles

Advantages

Disadvantages

Implementation options

Integration

Utilization of biological control

Study questions

Chapter 12: Aeration

Principles

Advantages

Disadvantages

Implementation options

Integration

Utilization of aeration

Study questions

Chapter 13: Sanitation and Exclusion

Principles

Advantages

Disadvantages

Implementation options

Integration

Utilization of sanitation and exclusion

Study questions

Chapter 14: Extreme Temperatures

Principles

Advantages

Disadvantages

Implementation options

Integration

Utilization of extreme temperatures

Study questions

Chapter 15: Impact and Removal

Principles

Advantages

Disadvantages

Implementation options

Utilization of impact and removal

Study questions

Chapter 16: Ionizing Radiation

Principles

Advantages

Disadvantages

Implementation options

Integration

Utilization of ionizing radiation

Study questions

Chapter 17: Residual Insecticides

Principles

Advantages

Disadvantages

Implementation options

Integration

Utilization of residual insecticides

Study questions

Chapter 18: Fumigants and Modified Atmospheres

Principles

Advantages

Disadvantages

Implementation options

Integration

Utilization of fumigants and modified atmospheres

Study questions

Chapter 19: Conclusions

Part III: Resources and Exercises

Introduction to Part III: Resources and Exercises

Chapter 20: Books and Reviews

Chapter 21: Conference Proceedings

International Working Conferences

Controlled Atmosphere conferences

Voluntary association of organizations

Chapter 22: Terminology

Augmentation (see Natural enemies)

Belt conveyor (see Elevator)

Bioresmethrin (see Pyrethroids)

Bulk density (see Test weight)

Carbaryl (see Carbamate)

Conservation of natural enemies (see Natural enemies)

DDT (see Chlorinated hydrocarbons)

Deep-bin cup (see Trier)

Deltamethrin (see Pyrethroids)

Drag conveyor (see Elevator)

Fenvalerate (see Pyrethroids)

Inoculative releases (see Natural enemies)

Instar (see Molt)

Inundative releases (see Natural enemies)

Lindane (see Chlorinated hydrocarbons)

Mark-recapture (see Release-recapture)

Methoprene (see Juvenile hormone)

Methoxychlor (see Chlorinated hydrocarbons)

Parasitoids (see Natural enemies)

Pathogens (see Natural enemies)

Permethrin (see Pyrethroids)

Pneumatic conveyor (see Elevator)

Predator (see Natural enemies)

Pirimiphos-methyl (see Organophosphates)

Screw conveyor (see Elevator)

Spouted bed (see Fluidized or spouted bed)

Vacuum probe (see Trier)

Chapter 23: Sampling Exercise

Chapter 24: Insect Population Growth Model

References

Index

Copyright

Cover photographs by Bhadriraju Subramanyam.

Library of Congress Catalog Card Number: 2006920131

ISBN-13: 978-1-891127-50-2

ISBN-10: 1-891127-50-0

©2006 by AACC International

All rights reserved.

No part of this book may be reproduced in any form, including photocopy, microfilm, information storage and retrieval system, computer database or software, or by any means, including electronic or mechanical, without written permission from the publisher.

Reference in this publication to a trademark, proprietary product, or company name is intended for explicit description only and does not imply approval or recommendation of the product to the exclusion of others that may be suitable.

Printed in the United States of America on acid-free paper

AACC International

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St. Paul, Minnesota 55121, U.S.A.

Dedication

The authors dedicate this book to the students of the 2002 and 2004 Stored-Product Insects classes at Kansas State University, whose enthusiasm for the subject encouraged the writing of this book.

Preface

A book entitled Pests of Stored Grain and Grain Products by Richard T. Cotton and one entitled Pests of Stored Products by James W. Munro were last published 40 or more years ago. A wealth of new insights into the fundamentals of stored-product insect biology, ecology, and pest management has been published during the last 40 years. A new stored-product entomology book is needed to cover these advances.

Efforts to improve the quality and safety of our food supply have resulted in the banning of many of the chemicals that were used in the past to manage stored-product insect pests. In the future, a thorough understanding of insect biology, ecology, and behavior will be even more important in developing, implementing, and evaluating pest management programs for stored-product insects. Therefore, this new book provides the fundamental knowledge and training needed to plan, implement, and evaluate a pest management program for stored-product insects. The book also should be useful to readers developing research programs to improve pest management programs for stored-product insects. The objective of our book is to help the readers learn to think about stored-product insect problems in a way that will result in improved pest management programs for stored-product insects. This should enable the readers to apply the information and concepts presented in this book in new situations.

The book has a total of 24 chapters. The first two discuss the scope of stored-product entomology and the techniques useful 1) in choosing live insects to assay the effectiveness of insect pest management methods, 2) in processing and interpreting data from sample units taken to monitor stored-product insect populations, and 3) in understanding the susceptibility and response of stored-product insects to pest management methods. These chapters provide insight into the diversity of foods and habitats utilized by stored-product insects, the types of economic losses attributable to these insects, and the ways in which an understanding of their biology can be used to study or manage them.

Pictures are provided that allow the most damaging of the stored-product insect pest species to be identified to family. The reader is referred to publications with pictures, keys, and descriptions for the identification of these insects to genus and species and for the identification of other stored-product pests and beneficial insect species. Some quick methods of separating closely related stored-product insect species are given in Chapter 2. Study questions provided at the end of many chapters emphasize the main concepts covered in that chapter. Additional reading that exposes readers to a variety of stored-product literature, including books, conference proceeding papers, literature reviews, research papers, government publications, and (in a few cases) even popular articles, is recommended to support and supplement the material discussed in many chapters. A comprehensive reference list at the end of the book gives the sources of studies cited in tables and figure captions.

Chapters 3–7 cover insect mobility, sources of insect infestation, sampling, life history, and population growth. Because stored-product insects are so mobile, managing source populations before these insects can spread to uninfested commodities is very important. Consideration of the frequency, direction, pattern, and speed of insect movement can be important in developing an effective sampling program. A good sampling program can increase the effectiveness and reduce the cost of pest management programs for stored-product insects. Most of the computer simulation models for predicting the growth of stored-product insect populations are based on the effects of temperature and moisture on insect life history. Forecasting insect population growth using computer simulation models can reduce the frequency of sampling and optimize the timing and targeting of insect pest suppression. Insect pests are managed by modifying their life histories (developmental times, mortality, and egg production) and thus their population growth rates. Therefore, understanding the life history and behavior underlying insect population growth can improve insect pest suppression. Preventing reproduction by the first insects that infest a commodity is more effective than killing all their offspring because the damage caused by the developing offspring is prevented. A combination of sampling to estimate insect distribution and abundance and predicting insect population growth using computer simulation models can be a powerful tool for developing and implementing cost-effective insect pest management programs or research programs that will improve pest management programs for stored-product insects.

The next three chapters (8–10), on insect pest management decision aids, the cost of insect pest management methods, and the resistance of insects to insect pest management methods, are pivotal. The readers should be able to assume the role of an insect pest manager or research scientist and to start using the basic understanding of stored-product insect biology acquired from the first seven chapters to plan an insect pest management program that implements, or a research program that improves, the insect pest management methods discussed in the next eight chapters.

These next chapters discuss pest management methods for stored-product insects. Biological (Chapter 11), physical (Chapters 12–16), and chemical (Chapters 17–18) methods have been developed for managing stored-product insect pests. These methods either slow the growth of insect pest populations by delaying or preventing reproduction, or they kill the insect pests. Each of the eight chapters includes a statement of the basic operating principle for that method and some background information. The advantages, disadvantages, and implementation options for each pest management method are given, to take the reader through the thought process involved in choosing the best pest management method or methods for an insect pest management program. Examples of the integration of more than one insect pest management method also are given for most of these chapters. A similar structure is used for each of these chapters to encourage the readers to compare different insect pest management methods. Table 19.1 provides a summary comparison of the advantages and disadvantages across insect pest management methods, and Chapter 19 provides an overview of the ideas discussed in the book. The reader is referred to other publications for more-detailed information on the safe and effective use of these pest management methods for stored-product insects.

The book discusses the solutions to stored-product insect pest problems ranging from those of the subsistence farmer to those encountered at various points in a complex commodity-marketing system. Much of the discussion is as applicable to the subsistence farmer as to other food storage, processing, transportation, and marketing situations. The extensive discussions of field infestation may be of greatest importance for stored-product insect pest management at the subsistence farmer level. The more expensive and high-technology methods may not be appropriate at the subsistence farmer level but could be used at central stores or export facilities in their countries. Expensive equipment will be cost effective only when large quantities of commodities are handled at a facility.

Available evidence suggests that simple technology such as using aeration during the coolest part of the day, could be quite effective in reducing insect damage in tropical climates. Some of the methods such as vegetable oils, botanicals, inert dusts, tumbling beans to prevent insect infestation, and small-scale solar heating have been investigated primarily for use by the subsistence farmer. The only example of a large-scale introduction of natural enemies to suppress stored-product insect pests is the release of Teretrius nigrescens (formerly Teretriosoma nigrescens) against Prostephanus truncates. This biological control was to help subsistence farmers in Africa. Expert systems are discussed for the management of stored-product insect pests in bagged storage of rice in the tropics and in other situations. The criteria used by the maize traders in Africa and those used for the sale of wheat in the United States are discussed.

Many questions about stored-product insects and their management are still unanswered. The mobility of stored-product insects has only rarely been studied in detail under the conditions found in storage, processing, and marketing facilities and transportation vehicles. The majority of quantitative studies on the population dynamics of stored-product insect pests have been done in the laboratory at unrealistically high densities. Crowding is much more important in these laboratory studies than in storage, processing, and marketing facilities, where food is so abundant that insects generally reach high densities only in the food residues, near the surface of bulk commodities, or at locations in the bulk commodities where the moisture is high. Insect pests should be managed before they reach these high densities even in the food residues.

Insect pest management decisions are still often based upon past experience rather than current information about the distribution and abundance of stored-product insect pest populations obtained from a sampling program. Few pest management methods for stored-product insects have been tested on more than a small scale, and generally there has been little follow-up sampling to evaluate their effectiveness. The contributions of diapause, natural enemies, and insect mortality from impact during grain handling to the overall success of pest management programs for stored-product insects have rarely been measured. Studies on integrating more than one insect pest management method have most often been done only on a small scale in the laboratory. Many laboratory studies do not cover the range of environmental conditions under which stored-product insects live in the marketing system. When using information from laboratory or field studies to make insect pest management decisions, careful consideration must be given to whether the environmental conditions in these studies were equivalent to those under which actual insect pest suppression is to be done.

Chapters 20 and 21 provide lists and discussions of many of the published books, reviews, and conference proceedings that are available on stored-product entomology. Roughly every two years, there has been an international meeting of scientists working on stored-product insect problems that occur during storage, processing, transportation, and marketing of stored products. The proceedings of these meetings contain a wide variety of information on stored-product insects. Expanded explanations are provided in Chapter 22 for some of the terms used in the book. These terms are printed in bold type throughout the book. A sampling exercise is provided in Chapter 23 to illustrate how the accuracy of estimating insect density increases with the number of sample units examined. Chapter 24 discusses a computer program that simulates stored-product insect population growth and how it can be modified for different insect species, insect pest management methods, and types of facilities or transportation vehicles.

We have attempted to make the book easy to read and understand. We hope that it will be a useful resource for students, extension educators, consultants, food industry sanitarians and managers, legislators, regulators, and insect pest management professionals. Our book cites a large number of papers, books, and conference proceedings and provides access to a large portion of the available literature on stored-product insects through the references cited in these articles, books, and conference proceedings. For undergraduate college students, the text can be supplemented by lecture material from the suggested readings. For graduate students, the text and suggested readings can be assigned. For advanced classes, the text, suggested readings, references cited in tables and figures, and books and conference proceedings can be utilized.

We thank Drs. Sonny Ramasawamy, Carl Reed, and Rizana Mahroof for reviewing the book and offering constructive criticisms for its improvement. We also thank Drs. Paul Flinn and Jim Throne for their help with Chapter 24. Finally, we thank AACC International for its interest, independent reviews of the book chapters, and publication of this book. We welcome constructive criticism of the book contents from readers.

David W. Hagstrum and Bhadriraju Subramanyam

Part I

Ecology and Decision Aids

Outline

Introduction to Part I: Ecology and Decision Aids

Chapter 1: Introduction

Chapter 2: Techniques

Chapter 3: Mobility

Chapter 4: Sources of Infestation

Chapter 5: Sampling

Chapter 6: Life History

Chapter 7: Population Growth

Chapter 8: Decision Aids

Chapter 9: Economics

Chapter 10: Resistance

Introduction to Part I: Ecology and Decision Aids

Insect pest management is applied insect ecology. Chapters 1 and 2 cover insect habitats, the influences of regulations and business practices, and methods for identifying and working with insects. Chapters 3, 4, and 5 emphasize the spatial aspects and Chapters 6 and 7 the temporal aspects of stored-product insect ecology. Decision aids (Chapter 8) include sampling information, cost-benefit analysis, consultants, expert systems, and the predictions of computer simulation models. The economics of insect pest management (Chapter 9) are important when using cost-benefit analysis. Resistance management (Chapter 10) is necessary because insect populations readily adapt and are likely to eventually become resistant to any pest management method.

Chapter 1

Introduction

Raw and processed commodities must be protected from rodents, birds, insects, mites, and microorganisms throughout the marketing system. The mobility and the ability of many stored-product insects to find and reproduce on many different foods throughout the marketing system make them particularly difficult to manage. This chapter provides an overview of the relative importance of different stored-product insect species and the types of economic losses that can be attributed to these insects. The types of regulations and business practices that can impact pest management programs for stored-product insects and the resources available for identifying stored-product insects also are covered in this chapter.

Storage habitat

Crops are harvested at the end of a growing season, and the harvested grain must be stored with minimal loss of quality until needed for human and animal consumption during the year. Grain reserves also are stored to prevent famine in years when the harvested crop is insufficient. The moisture and temperature at which the grain is stored determine its susceptibility to stored-product insects.

Traditional grain storage structures are still used in some parts of the world (see recommended reading by Reed).¹ Storage structures made of materials available locally are designed to protect grain from weather, insects, mites, fungi, rodents, and birds. Grain may be stored in the field in piles or on vertical poles for varying periods after the harvest. Underground storage in pits is among the most ancient methods still in use today. Grain may be stored in the attic over the kitchen or the living space. It is stored in boxes, baskets, jars, gourds, clay pots, jute bags, and metal drums. Unthreshed grain may be covered with a thatched roof or left uncovered when stored on horizontal poles or platforms. Larger traditional granaries are made of stone, brick, or mud.

The first step toward the development of a marketing system involved production of cash crops by subsistence farmers. As cash-crop production grew and fewer people were needed to grow food crops, a more elaborate marketing system developed. Grain was stored on farms, first in wooden granaries and cribs and later in metal bins. More grain could be produced after mechanical harvesting equipment was invented, and larger storage and marketing facilities were necessary to handle the large quantities of harvested grain. This resulted in increased quantities of grain being stored at grain elevators² rather than on the farm. The first elevators were constructed of wood. Later elevators were made of concrete (see recommended reading by Bailey). Recently, large metal bins or flat storage sheds have been added at elevators because of their lower cost and larger capacities.

Insects are moved through the marketing system along with the grain and grain products. Habitats of stored-product insects include the entire marketing system, from the fields in which a crop is grown to the storage and processing facilities, transportation vehicles, warehouses, and retail stores in which many raw and processed commodities spend some time. For subsistence farmers, only the field and storage environments may be important. Insects have adapted to this diversity of habitats by moving to find essential resources, eating many types of food, and producing lots of offspring. Large numbers of offspring can ensure a new generation even when insect mortality is high. Many stored-product insect species are thought to have been spread by international trade and now have a worldwide distribution (see recommended readings by Buckland and by Howe). The geographical origin of most stored-product insect pests is not known, because they were distributed worldwide by 1800, before the precise identification of insect species was possible. Heated facilities and bulk storage have allowed insects to survive in geographical regions and during seasons in which outside temperatures would otherwise kill them.

Species associated with stored products

Many insect species have adapted to survive and multiply on raw, dry, durable cereal grains, their processed products, and many other stored commodities (Table 1.1). The majority of these species are beetles (order Coleoptera), but several species of moths (order Lepidoptera) also are serious pests. Booklice (order Psocoptera) are often found under warm, humid conditions and can cause economic losses when they reach high numbers. On the other hand, several species of mites (order Acarina), wasps (order Hymenoptera), and bugs (order Hemiptera) often attack insect pest species in stored commodities. Knowing which species of pests and beneficial insects are present is important in developing and implementing the best insect pest management program.

Table 1.1

Species associated with stored commodities

aSome species, most often the natural enemies, do not have common names.

bCloth fabric or carpet (C), drugs (D), dried fruits and nuts (F), cereal grains and products (G), hides (H), legumes (L), peanuts (P), tobacco (T), and wood and dried cassava (W).

cRees 2004 divided stored-product insect pest species into 4 categories with 1 = minor pest, rarely causes much damage; 2 = pest capable of causing damage; 3 = pest capable of significant damage; and 4 = major pest rapidly capable of extensive damage.

dData from Phillips et al 2000. Species of beetles and moths for which pheromones have been identified are marked with a Y if the pheromone is commercially available or N if it is not. Shu et al 1999 identified Callosobruchus subinnotatus pheromone; Rodin et al 1969 identified the Trogoderma inclusum pheromone; Tebayashi et al 1998a,b and Tashiro et al 2004 identified the Gnatocerus cornutus pheromone; Susuki et al 1987 identified the Tribolium freemani pheromone; Persoons et al 1976 identified the Phthorimaea operculella pheromone; and Coffelt et al 1979 identified the Amyelois transitella pheromone.

Figure 1.1, which includes one species from each of the nine families of Coleoptera and one species of Lepidoptera, may allow the species capable of causing significant or extensive damage to stored commodities to be identified to the family level, narrowing the list of possible species. Sixteen of the insect pest species listed in Table 1.1 are capable of rapidly causing extensive damage, and another 16 species are capable of causing significant damage. An additional 51 species of insect pests in Table 1.1 can cause some damage to commodities or are minor pests that rarely cause damage. Although the insect species ranked as minor pests in Table 1.1 may not reproduce on stored commodities, they may be contaminants that reduce the market value of a commodity. Several hundred species of minor insect pests have been reported to infest stored commodities and facilities that store, handle, and process commodities for human and animal food.

Figure 1.1 Insects capable of causing significant or extensive damage to stored products. Insect lengths: L. serricorne, 2–3.5 mm; R. dominica, 2–3 mm; A. obtectus, 2–3.7 mm; S. oryzae, 3–4.6 mm; T. granarium, 1.8–3.8 mm; Cryptolestes ferrugineus, 1.6–2.2 mm; Carpophilus hemipterus, 2–4.1 mm; O. surinamensis, 1.7–3.2 mm; T. castaneum, 2.3–4.4 mm; P. interpunctella, 8 mm. (A and G, reprinted from Beetles associated with stored products in Canada: An identification guide [Bousquet 1990], Figs. 176 and 216, Agriculture and Agri-Food Canada, 1990, reproduced with the permission, of the Minister of Public Works and Government Services Canada, 2005; J from Linsley and Michelbacher 1943; B–F, H, and I used with permission of the Central Science Laboratory of the U.K. Ministry of Agriculture, Fisheries and Food)

Stored-product insect species that belong to the families Bostrichidae, Bruchidae, Curculionidae, and Gelechiidae feed and complete their immature development inside a seed. Larvae of Cryptolestes ferrugineus and Ephestia elutella feed within the germ of wheat kernels. Larvae of Cadra cautella and Plodia interpunctella feed on peanuts inside their shells and between the two halves of the peanut kernels. All of the Hymenoptera are parasitoids, and Acaropsis docta, Blattisocius keegani, B. tarsalis, Cheyletus malaccensis, C. eruditus, Teretrius nigrescens, Xylocoris flavipes, X. sordidus, Lyctocoris campestris, and some psocids are predators. Many of these stored-product insect species have a worldwide distribution. Exceptions include Prostephanus truncatus, Zabrotes subfasciatus, and Cadra calidella, which are pests mainly in countries with tropical climates. Sitophilus granarius, Cynaeus angustus, and some dermestid species are pests mainly in countries with temperate climates. Pheromones have been identified for many of the beetles and moths, and their importance for insect pest reproduction, host finding by natural enemies, and insect pest management programs is discussed in Chapter 3.

Table 1.1 lists the types of commodities infested by each stored-product insect species. Table 1.2 gives a more complete description of the foods infested by three of these species. However, the lists in Table 1.2 use categories that include many different foods, such as grain; dried fruit; drugs; nuts; spices; herbs; herbarium specimens; packaged processed foods from all types of cereals, oil seeds, and pulses; pulses and pulse products; and seeds of trees and other plants. Also, not all of the foods in these lists are equally suitable for insect development, and insect developmental times are longer on the less-suitable foods. When insect developmental times exceed 100 days, survival is often very low.

Table 1.2

Foods infested by three species of stored-product insect pestsa,b

Lasioderma serricorne

Aniseed (Pimpinella anisum, 31.9), areca nuts (betel nuts, Areca catechu), bamboo, beans, beet (65.1), biscuits, cassava (Manihot esculenta), cayenne pepper (71), chickpeas, chilli powder (135), cocoa beans (crushed, 55.2; whole 105.6), coconut meal (31.2), coffee beans, copra, coriander, cottonseed (39.8), cottonseed meal (26.9), cowpeas (crushed, 27.5; whole, 31.6), cumin (42.7), curry powder (122), dates, dried banana, dried cabbage, dried carrots (54.5), dried fish, dried fruit, dried insects, drugs, fish meal, flax tow, ginger (63.7), grain, peanuts (34.4), peas (33.0), herbarium specimens, herbs, horse-bean (36.9), juniper seeds, laboratory diet (35), leather, licorice root, locust beans (crushed, 33.6; whole, 68.5), maize (34.7), nutmeg, papers and books, paprika (70), raisins, residual insecticides containing pyrethrum, rhubarb, rice, seeds of trees and other plants, spices, tobacco, upholstery, wheat feed (26.1), wheat flour (26.5), whole wheat (44.8), yeasts (28.4)

Plodia interpunctella

Acorns, alfalfa hay, almonds (38.6, 45.3), almond hull meal, barley, beans, bilberries, biscuits, bran (28), bread, bread-making ingredient mixtures (47.4), breakfast cereal, cacao, canary grass seed, candied fruit, cantaloupe seed, caraway seeds, chestnuts (cooked and raw), chickasaw plums, chickpeas, chicory roots, chillies, chilli pepper, chocolate, chocolate-covered candies, chocolate-covered almonds, cinnamon bark, clover seeds, corpra, cottonseed meal cake, currants, dandelion root, dead insects, dried fruit (apples, apricots, bananas, cherries, grapes, loganberries, peaches, pears and prunes), dried meat scraps, dried Opuntia, dried roots, dried vegetables (cabbage [43.7], carrots [44.5], green onion [36.2], green paak ts’ oi [42.8], onion [43.7]. and pepper [41.3]), drugs (Archangelica officinalis, Cannabis sativa, Cydonia vulgaris, Datura stramonium, Juniperus communis, Prunus spinosa, Rosa canina, Sambucus nigra, Sarothamus scoparius, Secale cornutum, Tussilago farfara, and Verbascum thapsiforme), figs, flour (123.0), fruit of Zizyphus spinachristi, fur, garlic, hazelnuts, herbarium specimens, herbs, iris rhizomes, jellies, lettuce, lettuce seed, locust beans, lozenges, lupins, macaroni, maize (meal 53.5, whole 65.9), maize germ meal, malt, marzipan, millet, milo (40.6), mixed feed, nougat, nut bars, oats, old books, orange pulp, packaged breakfast cereals, palm seeds, peanuts (47.2), peas, pecans, pepper seed, pineapples, pistachios (38.2), plums, prunes, pollen in bee hives, popcorn, powdered milk, preserves, pulses and pulse products, pumpkin seed, raisins, rice, rice hulls, rolled barley, rolled oats, rye, seeds of Pinus pinea, seeds of salamander, seeds of spruce, sliced beets, soybeans, spices, sultans (38.8), sugar beet pulp, sunflower seed, vetch seed, walnuts (47.2), watermelon seed, wheat (40.7), wheat germ, yeast cake

Tribolium castaneum

Alfalfa seed, almonds, Arhar (43.0), Bajra (20.1), baking powder, barley (20.8), beans, black gram (29.1), cayenne pepper, chocolate, cocoa beans, copra meal, maize, cotton gin trash, cotton seed, cottonseed meal, dried fruits, dried plant roots, English walnuts, flax, flour, food spices, ginger, insect collections, Jowar (23.4), masur (51.7), milk powder, millet, milo, Moong (26.4), moth (28.6), nuts, oilseed cakes and their products, orrisroot, packaged processed foods from all types of cereals, oilseeds and pulses, peanuts, peas (40.4), pulses, rapeseed, red rawan (32.0), rice (30.8), rice bran, rye, sago, snuff, soya bean (45.1), soyflour, soy grits, sunflowers, wheat (23.9), wheat bran, white gram (30.1), white rawan (35.1), yeast

aNumbers in parenthesis are egg-to-adult developmental times in days at a temperature between 25 and 30°C.

bSources: Lasioderma data from Howe 1957, Ali et al 1972, and LeCato 1978; Plodia and Tribolium data from Johnson et al 1992, Locatelli and Biglia 1995, Na and Ryoo 2000, Pant and Dang 1969, Richards and Thomson 1932, Sinha and Watters 1985, and Williams 1964.

Studies identifying the stored-product insect species found at various locations in the marketing system are one way to document the role of commerce in spreading these insects throughout the world (Table 1.3). Alphitobius diaperinus or Alphitobius spp., Lasioderma serricorne, Oryzaephilus surinamensis, Rhyzopertha dominica, and Tribolium castaneum were found in all 12 of these studies. Cadra cautella was found in all of these studies that looked for Lepidoptera, and Plodia interpunctella was found in all except the study on packaged-food warehouses. In total, 76 species of stored-product insects were found in more than one of these studies, and 86 other species were identified in only one study.

Table 1.3

Studies identifying stored-product insect species found at various locations in the marketing system

In these studies, imports into England were from West Africa; those into California and Arizona were from Mexico and South America but mostly Asia; and those into Japan were mostly from Asia but came from all over the world. Empty shipping containers were studied in Australia; food and food-handling areas were studied for ships docking in New Orleans, Louisiana, and in Miami, Florida; bakeries, food stores, restaurants, warehouses, processing plants, a school, and a vending operation were studied in Connecticut; and warehouses were studied in California, Hawaii, Latin America, Africa, and Asia. The study in Hawaii used light traps, food-bait traps, and facility inspections. Insects were found in 93% of the cargos from West Africa and, more recently, in 12.6% of the commodities imported into California. Insects were found in 61% of the Los Angeles, California, port warehouses and all of the 20 packaged-food warehouses in nine countries.

One of the recommended readings for this chapter (by Freeman) is a study of insect infestations in raw commodities imported into Great Britain. This study was not included in Table 1.3 because it does not include a complete list of the stored-product insect species found. The percentage of cargos infested decreased from 52% in 1957 to 34% in 1966 and 23% in 1973. The ranked order by country of the percentage of cargos infested remained fairly constant between 1967 and 1973. The number of cargos received in shipping containers increased from 0.7% in 1968 to 33% in 1973. Cadra cautella and Tribolium castaneum were the predominant species. Interceptions of Trogoderma granarium ranged from 46 to 131 per year (six to 18 per 1,000 inspections); T. granarium was intercepted mostly in rice and peanuts from Burma, India, Nigeria, and Sudan.

Identification

Identification of insects to species is the first step in their management (see Chapter 8). Identification helps in obtaining published information on the biology, ecology, and behavior of an insect species to use in designing a study or a pest management program. In addition, identification is important because the type and amount of damage that insects can cause varies among species. The methods used for monitoring various species and the developmental stage most vulnerable to pest management programs also differ among insect species. For a broad-spectrum chemical pesticide, the susceptibility of insects to the pesticide and the choice of the best application method are likely to vary with species as well.

Important resources available for the identification of stored-product insect species are given in Table 1.4. Some of the stored-product insect species found together appear very similar to the naked eye. Simple methods have been developed for separating some of these species (see Chapter 2). Pictures may be useful for quickly recognizing the major stored-product insect pests (Figure 1.1), but for other species, keys may be necessary to ensure that the identification is correct or that similar-looking species are not present. Only pictures are available for the identification of some species of moth eggs, but both pictures and keys are available for identifying some species of beetle eggs.

Table 1.4

Published pictures and keys for stored-product insect identification

Insects are most easily identified to genus or species in the adult stage because more keys have been developed for this stage. Immature insects generally are reared to the adult stage for identification when keys are not available for the immature stages. A key also is available for identifying insect mandibles to species when insect fragments are separated from commodities. Pictures