Psocids as Global Pests of Stored Products

By Shiqian Feng, Farman Ullah, Zhihong Li and 10 more

Psocids have become widespread pests of stored products during the last two decades, yet little was known about their biology and management until this change in their pest status. The aim of this book is to synthesize current information on biology and management of these stored-product insect pests. The book covers their identification, biology and ecology, monitoring, chemical and non-chemical control, resistance to insecticides, molecular biology, and the future of stored-product psocid research.

This is the first-ever comprehensive book on Psocids infesting stored products and is written by a carefully selected list of experts on these pests. It is essential reading for all those involved in the control of pests in stored products and postharvest systems, students and researchers in applied entomology and pest management practitioners in general.

• Language: English
• Publisher: CAB International
• Release date: Jan 30, 2023
• ISBN: 9781789245547

Book preview

Preface

To address the continuous demand for supply of food for a growing global population, currently, the universal focus is rapidly shifting from producing more food to protecting what we produce. Although there have been enormous advancements in storage technology and on commodity protection fronts with the turn of the century, postharvest losses of durable food commodities such as grain continue to be a major concern. A major contributing factor for postharvest losses is destruction and spoilage by insects, particularly in warm and tropical regions. Of the 32 taxonomic orders of insects, species belonging to only three orders, Coleoptera (beetles), Lepidoptera (moths), and Psocoptera (psocids), are considered pests of stored commodities.

In the recent past, several books and chapters have been written on the classification, identification, and general biology and management of major beetle and moth pest species that are relevant to stored commodity protection. However, although psocids have emerged as a new threat to postharvest commodities across the globe over the last two decades, there have been no special books or chapters dedicated to them. It is clearly established now through several researches that they are quite different from the other pest groups and that established control strategies for beetles and moths are not suitable for managing psocids. Moreover, even though psocids do not cause significant physical damage to the stored commodities, their mere presence is unacceptable in view of the increasing consumer demand for high-quality food products. Although an article was published some years ago, titled Biology and management of psocids infesting stored-products [Nayak et al. (2014) Annual Review of Entomology 59, 279–297], it mostly focused on critical analysis and synthesis of literature in the areas of biology and management. Due to their continuing global importance as emerging pests in stored commodities, it is imperative that comprehensive information on psocids—particularly their identification, biology, and ecology—and monitoring and control strategies involving both chemical and non-chemical methods are available not only to storage operators, but to students and academics who are interested in stored commodity protection as well.

The fact that stored-product protection, especially in durable commodities, is a keystone in the fight against hunger and the global food crisis, has highlighted the importance of stored-product psocids as emerging pests. Traditionally, while psocids were always considered pests, they were definitely less important than other categories of pests of stored products, such as beetles and moths. In a recent bibliometric review [Stopar, K., Trdan, S., Bartol, T., Arthur, F.H. and Athanassiou, C.G. (2022) Research on stored products: A bibliometric analysis of the leading journal of the field for the years 1965–2020. Journal of Stored Products Research 98, 101980]—which consists of a global scientific forum in stored-product protection—it is underlined that articles that have been published in this journal with the term psocid are less than 1% of the total number of articles, while the respective figure for beetles (Coleoptera) corresponds to more than 40% of the total. Nevertheless, it is now evident that psocids are at least equally important and may cause serious degradations in a wide range of products. Apart from the direct infestation, certain psocid species are also important for public health and have also been classified as frequent sources of allergenic reactions. All the above, along with the difficulties in the detection and estimation of their presence, are expected to increase the research interest on stored-product psocids in the near future. This is one of the main reasons for preparing this book: to gather as much information as possible on this subject, given that there are disproportionally lesser data on psocids, as compared with most other pest groups that occur at the postharvest stages of agricultural commodities. In this context, this book covers a wide range of topics that are related to stored-product psocids, ranging from effective monitoring and detection protocols to management methods and molecular diagnostics.

Our effort to bring this book forward with updated information in the key aspects as discussed in the preceding paragraph would not have been successful without the willingness of the dedicated experts in their respective areas to write up the allocated chapters in a timely manner. Our sincere thanks to all the authors not only for their valuable time and effort in delivering the chapters, but also for their continuous support in several other aspects throughout the preparation of this book. Finally, we extend our sincere gratitude to our families for their continuous support and encouragement toward achieving our goal.

Manoj K. Nayak, Brisbane, Queensland, Australia

Christos G. Athanassiou, Nea Ionia, Magnesia, Greece

1The Order Psocoptera and Its Importance for Stored Products

CHRISTOS G. ATHANASSIOU

¹* AND MANOJ K. NAYAK²

¹University of Thessaly, Greece

²Queensland Department of Agriculture and Fisheries, Australia

*Corresponding author: [e-mail]

©CAB International 2023. Psocids as Global Pests of Stored Products (eds C.G. Athanassiou and M.K. Nayak)

DOI: 10.1079/9781789245547.0001

1.1 Introduction

Although the biology and ecology of psocids are provided in detail in Chapters 2–4, this chapter will touch on some biological aspects that are related to the menace posed by these species for stored products and discuss their impact on public health. In contrast with stored-product mites, which are generally considered a short-lived species, stored-product psocids live longer and have life spans that are comparable with those of most stored-product beetle species (Nayak et al., 2014). Psocids, especially the species of the genus Liposcelis (Psocoptera: Liposcelididae), have a tremendous capacity to increase their population in a very short period of time (Athanassiou et al., 2010, 2014; Aminatou et al., 2011; Opit et al., 2018). Indicatively, in 10 g of wheat or sorghum, 5 parental individuals of Liposcelis entomophila (Enderlein) produced approximately 182 and 245 individuals after 35 days (Athanassiou et al., 2010). Although in comparison with other large-bodied stored-product insect species (beetles and moths), psocids cause less damage to grains and related commodities (Kučerová, 2002; Gautam et al., 2013), their population can explode quickly. The damage is definitely higher in the case of germinating kernels (Gautam et al., 2013).

1.2 Importance for Control Programs

Most stored-product psocids generally have a higher developmental threshold than most common stored-product insect species. In fact, some of them complete their development at 35°C or an even higher temperature (Opit and Throne, 2009; Gautam et al., 2010, 2016). At these temperatures most common species are not able to reproduce at all or their progeny production is limited, psocids can outcompete most of these species if the conditions prevailing are suitable. Some Liposcelis species can have an extremely high population at temperatures that exceed 40°C (Opit et al., 2018), which might be problematic in heat treatment applications, although psocids are generally considered susceptible to heat (Nayak et al., 2014).

At the same time, psocids are also highly tolerant to subzero temperatures (Athanassiou et al., 2018, 2021), which enables a rapid population rebound after cold treatments. In most stored-product insects, eggs are considered the most cold-tolerant life stage, and psocid eggs have been found tolerant to a temperature of −15°C or even −18°C. Psocid adults are also extremely tolerant to subzero temperatures (Athanassiou et al., 2018), which allows for a rapid population increase at higher temperatures; psocid eggs, despite their tolerance, have a certain expiration date and may not contribute much to this rapid population rebound. The fact that some psocids can easily develop when available food is scarce is also an important parameter in their success at rapid development and colonization (Athanassiou et al., 2014; Nayak et al., 2014). Also, psocids can be considered the most resistant stored-product insect species against a wide range of chemical control measures, for reasons that are illustrated in Chapter 6.

1.3 Importance for Public Health

As in the case of other insects in stored products that are found in areas with elevated relative humidity levels, psocids are associated with fungi that are present in commodities (Nayak et al., 2014). Mills et al. (1992) reported that psocids can feed on a wide variety of fungal species that occur in storage facilities and fungal species found in the field. Among these fungi, some species produce toxins that may endanger human health. In a recent work, Yoshinami et al. (2020) reported that Liposcelis bostrychophila Badonnel can feed vigorously on several fungi species, and hence, apart from an indicator of poor hygienic conditions, this species can greatly contribute to fungal dispersal. Not surprisingly, some of these fungal species produce toxins, and we can suggest that psocids can actively increase the frequency of toxins in the commodity; nevertheless, some aflatoxigenic fungi may have a low feeding attraction to psocids (Mills et al., 1992). Morphological characteristics and odors are responsible for fungal preferences as food by psocids, and grains that are infested by fungi are more readily infested (Ahmedani et al., 2010; Yoshinami et al., 2020).

As in the case of stored-product mites, stored-product psocids are associated with allergenic reactions as well as asthma development (Perotin et al., 2011; Hubert et al., 2018). In stores in the Czech Republic, Stejskal and Hubert (2008) found the major group of arthropods related to allergens to be mites, but there was also a considerable proportion of psocids in a number of samples. Recently, Babaei and Vadas (2020) reported an important case of human anaphylaxis to oatmeal infested by psocids, while, traditionally, these species are considered allergens and are present in houses and other structures (Turner et al., 1996; Patil et al., 2001; Turner, 2005; Perotin et al., 2011; Nayak et al., 2014). Indicatively, Patil et al. (2001) reported that among 75 house dust samples collected in Mumbai, 25% of them were found to contain psocids, and a strong sensitivity to psocids was detected in 20% of the patients examined. Moreover, sensitization to psocids among the public in Japan has been reported to be specific to psocids only and not related to insect panallergy, a phenomenon in which other insects present in the environment contribute to allergic sensitization. The occurrence of specific IgE to psocids can be further utilized to quantify the importance of these species as allergens in different types of indoor environments (houses, hospitals, etc.) (Perotin et al., 2011; Fukutomi et al., 2012) as well as in the development of occupational asthma (Marco et al., 2016) and specific infections (Lin et al., 2004). In this context, psocids may be responsible for allergenic reactions that are falsely attributed to mites. Additional studies quantifying this phenomenon should be considered a priority, especially in the case of food that is contaminated with psocids.

1.4 Synanthropic Aspect

In this chapter, we have illustrated the menace of psocids, which goes beyond direct infestation. In our opinion, the contribution of stored-product psocids to allergy development and other major disorders, such as asthma, is largely underestimated and can be further examined, because of the extremely large and varied food preferences of these species and the fact that they remain undetected even if they are present in high density. This is particularly important because Liposcelis spp. infest commodities that are critical for human nutrition, such as wheat and its products (flour, bran, etc.), along with other commercial food products, including yeast and germ (Diaz-Montano et al., 2015). There are clear indications that psocids are extremely frequent colonizers of houses, hospitals, and other buildings (Fukutomi et al., 2012; Hubert et al., 2018; Babaei and Vadas, 2020). Some directions for research are given in Chapter 8.

References

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Aminatou, B., Gautam, S., Opit, G., Talley, J. and Shakya, K. (2011) Population growth and development of Liposcelis pearmani (Psocoptera: Liposcelididae) at constant temperatures and relative humidities. Environmental Entomology 40(4), 788–796. DOI: 10.1603/EN11066.

Athanassiou, C.G., Opit, G.P. and Throne, J.E. (2010) Influence of commodity type, percentage of cracked kernels, and wheat class on population growth of stored-product psocids (Psocoptera: Liposcelidae). Journal of Economic Entomology 103(3), 985–990. DOI: 10.1603/ec09280.

Athanassiou, C.G., Kavallieratos, N.G., Throne, J.E. and Nakas, C.T. (2014) Competition among species of stored-product psocids (Psocoptera). PloS ONE 9(8), e102867. DOI: 10.1371/journal.pone.0102867.

Athanassiou, C.G., Arthur, F.H. and Hartzer, K.L. (2018) The efficacy of low temperatures for the control of all life stages of Plodia interpunctella and Liposcelis bostrychophila. Journal of Pest Science 91(4), 1363–1369. DOI: 10.1007/s10340-018-0982-0.

Athanassiou, C.G., Arthur, F.H., Kavallieratos, N.G. and Hartzer, K.L. (2021) Influence of the presence of flour on the efficacy of low temperatures against stored product insects. Crop Protection 144, 105514. DOI: 10.1016/j.cropro.2020.105514.

Babaei, D. and Vadas, P. (2020) Anaphylaxis to oatmeal and psocid crisps. Iranian Journal of Allergy, Asthma, and Immunology 19(2), 200–202. DOI: 10.18502/ijaai.v19i2.2773.

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Gautam, S.G., Opit, G.P. and Giles, K.L. (2010) Population growth and development of the psocid Liposcelis rufa (Psocoptera: Liposcelididae) at constant temperatures and relative humidities. Journal of Economic Entomology 103(5), 1920–1928. DOI: 10.1603/ec10127.

Gautam, S.G., Opit, G.P., Giles, K.L. and Adam, B. (2013) Weight loss and germination failure caused by psocids in different wheat varieties. Journal of Economic Entomology 106(1), 491–498. DOI: 10.1603/ec12253.

Gautam, S.G., Opit, G.P. and Shakya, K. (2016) Population growth and development of the psocid Liposcelis fusciceps (Psocoptera: Liposcelididae) at constant temperatures and relative humidities. Environmental Entomology 45(1), 237–244. DOI: 10.1093/ee/nvv148.

Hubert, J., Stejskal, V., Athanassiou, C.G. and Throne, J.E. (2018) Health hazards associated with arthropod infestation of stored products. Annual Review of Entomology 63, 553–573. DOI: 10.1146/annurev-ento-020117-043218.

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Mills, J.T., Sinha, R.N. and Demianyk, C.J.I. (1992) Feeding and multiplication of a psocid, Liposcelis bostrychophilus Badonnel (Psocoptera: Liposcelidae), on wheat, grain screenings, and fungi. Journal of Economic Entomology 85(4), 1453–1462. DOI: 10.1093/jee/85.4.1453.

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Yoshinami, M., Machida, R., Kobayashi, N., Sugita-Konishi, Y. and Furuhata, K. (2020) Multifaceted fungal characteristics determining the fungal feeding preferences of the psocid, Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelidae). Journal of Stored Products Research 88, 101659. DOI: 10.1016/j.jspr.2020.101659.

2Molecular Identification of Stored-Product Psocids

SHIQIAN FENG, FARMAN ULLAH AND ZHIHONG LI*

China Agricultural University, People’s Republic of China

*Corresponding author: [e-mail]

©CAB International 2023. Psocids as Global Pests of Stored Products (eds C.G. Athanassiou and M.K. Nayak)

DOI: 10.1079/9781789245547.0002

2.1 Introduction

Psocids (Psocoptera) are tiny insects with a body length of about 1 mm, which makes it difficult to identify them with traditional morphological methods (Barrett and Hebert, 2005; Jinbo et al., 2011). Most taxonomic keys are used for identifying insects of stored products at the adult stage; therefore, we cannot identify insects at immature stages or damaged samples using traditional taxonomy traits (Barrett and Hebert, 2005). Nonetheless, morphological identification methods are not always effective in identifying cryptic species due to phenotypic plasticity (Murugan et al., 2016). Only well-trained researchers can correctly use taxonomic keys (Ball and Armstrong, 2006), especially with regard to Psocoptera. With the rapid development of sequencing technologies, the utilization of molecular data for identifying psocids has become extremely popular over the past ten years. Representative molecular methods and techniques for identifying stored-product psocids were developed and applied systematically based on an international collaboration involving China, the Czech Republic, and the United States. A large number of research articles, theses, and dissertations on the molecular identification of stored-product psocids were written in the period from 2008 to 2019. Here, we list the main molecular identification techniques ready for practical application: DNA barcoding (Li et al., 2011; Yang et al., 2012, 2013b; Cui, 2013; Yang, 2014; Cui et al., 2020), restriction fragment length polymorphism (RFLP) (Qin et al., 2008; Qin, 2009), species-specific polymerase chain reaction (SS-PCR) (Arif et al., 2012; Yang et al., 2013a; Zhao et al., 2016), real-time PCR (Pang, 2017), and gene chip (Fig. 2.1; Liu et al., 2017).

2.2 DNA Barcoding

The DNA barcoding method has been widely used for the molecular identification of common stored-product