Role of Modified Atmosphere in Pest Control and Mechanism of Its Effect on Insects

Hermetic SuperGrain bags for controlling storage losses caused by Callosobruchus maculatus Fabricius (Coleoptera: Bruchinae) in stored mung bean (Vigna radiata)

Mung bean is highly susceptible to insect attack during storage. Hermetic storage is an effective technique to control insect damage. This study investigated the potential of the hermetic SuperGrain bag (SGB) for controlling bruchids during storage. The dry samples were packed in SGB infested with adult bruchids (SGB-I), SGB natural field infested (SGB-N), woven polypropylene bags (WPP-I and WPP-N) and kept at room temperature for 180 days. Oxygen (O₂) and carbon dioxide (CO₂) concentrations were measured at 15 days intervals. Moisture content, infestation level, seed damage and weight loss were determined at 60 days intervals. Seed colour, hardness, crude protein and fat contents were analysed before and after storage. The O₂ level decreased to 10.09%, whereas the CO₂ level increased to 8.87% in both SGB-I and SGB-N treatments. The moisture content of mung bean was maintained as onset storage in both SGB-N and SGB-I treatments, whereas reduced in WPP-N (9.26% db) and WPP-I (9.21% db). In SGB treatments, no significant bruchids were detected, but they increased drastically in WPP-N (52 ± 9) and WPP-I (377 ± 14). Seed damage (2-3%) and weight loss (0.8-1.0%) were recorded in both SGB-N and SGB-I. Conversely, seed damage reached 26.67 and 54.17%, corresponding to weight losses of 12.33 and 20.82% in WPP-N and WPP-I, respectively. Seed colour, hardness, crude protein and fat contents in SGBs showed no significant changes than in the WPP bags. The study illustrated that the SGB is an efficient hermetic device in protecting mung beans against bruchids attacks compared to the WPP bags.

Sustainable Strategies to Counteract Mycotoxins Contamination and Cowpea Weevil in Chickpea Seeds during Post-Harvest

Mycotoxins contamination and pest infestation of foods and feeds represent a pivotal threat for food safety and security worldwide, with crucial implications for human and animal health. Controlled atmosphere could be a sustainable strategy to reduce mycotoxins content and counteract the vitality of deleterious organisms in foodstuff. Ozone treatment (O3, 500 ppb for 30, 60 or 90 min) and high nitrogen concentration (N2, 99% for 21 consecutive days) were tested in the post-harvest management of four batches of Cicer arietinum grains to control the presence of mycotoxigenic fungi and their secondary metabolites, as well as pest (i.e., Callosobruchus maculatus) infestation. At the end of the treatment, O3 significantly decreased the incidence of Penicillium spp. (by an average of -50%, independently to the time of exposure) and reduced the patulin and aflatoxins content after 30 min (-85 and -100%, respectively). High N2 concentrations remarkably reduced mycotoxins contamination (by an average of -94%) and induced pest mortality (at 100% after 5 days of exposure). These results confirm the promising potential of O3 and N2 in post-harvest conservation strategies, leading to further investigations to evaluate the effects on the qualitative characteristics of grains.

Performance of a hermetic device and neem (Azadirachta indica) in storing wheat seed: Evidence from participatory household trials in central Bangladesh

Smallholder farmers in Bangladesh often use low-density polyethylene (LDPE) bags contained within woven polypropylene bags to store wheat seed during the summer monsoon that precedes winter season planting. High humidity and temperature during this period can encourage increased seed moisture and pests, thereby lowering seed quality. Following a farm household survey conducted to inform trial design, eighty farmers were engaged in an action research process in which they participated in designing and conducting trials comparing traditional and alternative seed storage methods over 30 weeks. Factorial treatments included comparison of hermetic SuperGrainbags® (Premium RZ) against LDPE bags, both with and without the addition of dried neem tree leaves (Azadirachta indica). SuperGrainbags® were more effective in maintaining seed moisture at acceptable levels close to pre-storage conditions than LDPE bags. Both seed germination and seedling coleoptile length were significantly greater in hermetic than LDPE bags. Neem had no effect on seed moisture, germination, or coleoptile length. SuperGrainbags® were also more effective in abating seed damage during storage, although inclusion of neem within LDPE bags also had significant damage. Quantification of seed predating insects and diseases suggested that SuperGrainbags® also suppressed Coleopteran pests and blackspot, the latter indicative of Fusarium graminearum. Conversely, where farmers used LDPE bags, neem also had an additional though limited pest suppressive effect. Post-storage treatment scoring by farmers revealed a strong preference for SuperGrainbags® and no preference differences for or against neem. This study demonstrates a process by which farmers can be involved in the participatory co-design and testing of alternative wheat storage options, and stresses the need to develop SuperGrainbag® supply chains so hermetic storage can be made widely available.

A Scientometric Review of Grain Storage Technology in the Past 15 Years (2007-2022) Based on Knowledge Graph and Visualization

Food storage helps to ensure the food consumption needs of non-agricultural populations and to respond to major natural disasters or other emergencies, and the application of food storage technology can reduce post-harvest food losses. However, there are still obvious shortcomings in coping with large grain losses. Therefore, quantitative analysis of the research hotspots and evolutionary trends of grain storage technology is important to help the development of grain storage technology. This article uses the Web of Science database from 2007 to 2022 as a data sample with the help of CiteSpace software to analyze the basic situation, research hotspots, and evolutionary trends to draw a series of relevant knowledge maps. Visual analysis revealed that the number of publications had grown rapidly since 2015. First, the Journal of Stored Products Research, Journal of Economic Entomology, and Journal of Agricultural and Food Chemistry, with citation frequencies of 929, 536, and 453, should be focused on in order to keep up with the latest research developments in this field. The United States, China, and Brazil occupy dominant positions in relation to grain storage technology studies in general. Purdue University, Kansas State University, and Agricultural Research Institute ranked the top three in terms of the number and centrality of publications. In terms of research hotspots, the centrality of temperature, insects, carbon dioxide, and quality were 0.16, 0.09, 0.08, and 0.08. It shows that the field of grain storage technology in recent years has focused on grain storage temperature, pest control, and grain storage quality research. From the perspective of the evolution trend, the life cycle of emergent words lasts for several years, after which the strength of emergent words slowly decreases and is replaced by new emergent words. Mortality was the first keyword to appear and remained from 2007 to 2011, indicating that research on fumigants and their toxicity, as well as pest mortality under air fumigation and chemical fumigation conditions, became more popular during this period. In recent years, new terms have emerged that had never been used before, such as "grain quality" (2019-2022) and "stability" (2020-2022). We can find that people pursue food quality more with the improvement of people's living standards. In this context, future research should seek more efficient, safe, economical, and environmentally friendly methods of grain storage and continuously improve the level of scientific grain storage.

Effects of Long-Term Low Oxygen Storage Treatment on Survival of Rice Weevil (Sitophilus oryzae) and Confused Flour Beetle (Tribolium confusum)

There is a need for alternative treatments for postharvest pests on stored products. In this study, 45-d long-term controlled atmosphere (CA) treatments with 3, 5, 6.5, and 8% O2 were studied to determine effects on survival and development of rice weevil (Sitophilus oryzae) and confused flour beetle (Tribolium confusum) eggs and susceptibility of different life stages to a 14-d 5% O2 treatment. Low oxygen treatments were effective against S. oryzae and T. confusum. The 45-d CA treatments with 6.5, 5, and 3% O2 resulted in 0.26, 0.004, and 0% survival rates from egg to adult respectively for S. oryzae and 6.51, 0.14, and 0% survival rates from egg to later stages respectively for T. confusum. For both species, eggs were more susceptible to low oxygen treatment than larvae or pupae. A 14-d CA treatment with 5% O2 resulted in 4.9 and 3.3% survival of eggs of S. oryzae and T. confusum, respectively, as compared with over 50% survival of larvae and pupae for both species. S. oryzae adults, however, were very susceptible to low oxygen treatment and 14-d exposure to 5% O2 atmosphere resulted in zero survival. In contrast, the 14-d exposure to 5% O2 atmosphere resulted in over 94% survival for T. confusum adults. This study suggested there were considerable differences between stored product insects in susceptibility to low oxygen treatment and that long-term CA storage treatments with a low oxygen level of ≤6.5 and ≤5% have potential in controlling S. oryzae and T. confusum, respectively.

Effects of High-Pressure Carbon Dioxide on the Sensory and Chemical Properties of Dried Dates and Its Toxicity against Galleria mellonella (L.) and Plodia interpunctella (Hübner)

ABSTRACT

The use of chemical pesticides can have many detrimental side effects, including environmental pollution, and be a threat to human health. Carbon dioxide (CO2) treatment, a relatively new method for storage pest management, can replace harmful chemicals. Dates, an important food worldwide, contains many minerals, fiber, and a variety of vitamins and are an important dried fruit export from Iran annually. Thus, control of the pests of dried dates by using eco-friendly agents that do not affect quality features are critical. In this study, larval mortality of the Indian meal moth (Plodia interpunctella (Hübner)) and the greater wax moth (Galleria mellonella (L.)), two key pests of stored products, especially dried dates, was studied after exposure to different CO2 pressures within 24 h. Mortality percentages of the third-instar larvae of both pests were increased with an increase in CO2 pressure. Sensory tests on the qualitative characteristics of the dates revealed that CO2 pressures did not affect their aroma, color, sweetness, sourness, crispness, firmness, and overall acceptance. The highest tested pressure (33.4 mol%) of CO2 also had no significant effects on the chemical properties of the date samples, including moisture content, pH, acidity, Brix value, reducing sugar, and total sugar. We conclude that atmospheric CO2 gas can provide a cost-effective and environmentally friendly method for controlling the insect pests of dried dates in addition to preserving their sensory and quality properties.

HIGHLIGHTS

Green grain warehousing: bibliometric analysis and systematic literature review

Grain warehousing contributes persistent environmental effects in the food supply chain because of its long-term storage feature and distribution requirements. Thus, it has attracted a number of interdisciplinary researchers to the investigations of green grain warehousing (GGW) over the past decades. This paper presents a valuable comprehensive literature review on the existing publications on this topic via bibliometric analysis and systematic review based on 37 papers obtained from three common international academic databases, namely Web of Science, Scopus, and EBSCOhost. We concluded a framework of existing literature with proposing three macro-themes (energy-saving in transporting, environmental harmony, and green deinsectization) as well as a classification of commonly used methods. The results revealed that (1) the increase in research interests over years was found; (2) there are differences in the attention of GGW among countries. Most of the scholars from developing countries focused more on the green operational technologies or strategies, while most of the scholars from developed countries placed their research focuses on keeping grain quality and developing environment-friendly deinsectization approaches with low emission or chemical alternatives; (3) grain quality started to become the most popular hotspot in recent years; (4) the researchers tended to use more comprehensive methodologies or combined methods to conduct their works. Accordingly, we proposed potential research directions. The contribution of this work is to extend current literature and to offer reference to scholars and practitioners for future research and operation in GGW.

Insulin-Like ILP2 Regulates Trehalose Metabolism to Tolerate Hypoxia/Hypercapnia in Tribolium castaneum

RNAi was used to downregulate the expression of insulin-like peptides (ILP2), with air-modulation, and high-concentration CO₂ stress, in the larvae of Tribolium castaneum. We assessed the changes in carbohydrate-related content, trehalase activity, and the expression levels of trehalose pathway genes. And pupation, adult emergence, pupation rate, and mortality were assessed. There was a significant change in the expression of ILPs in T. castaneum, at a certain concentration of CO₂. ILP2 RNAi did not alter the trehalose content significantly, however, the glycogen and glucose content increased significantly. High-concentration CO₂ stress altered the trehalose content and reduced the glycogen and glucose content. The expression levels of TPS and TRE2 were up-regulated by hypoxia/hypercapnia and dsILP2 combination, with the increase of CO₂ concentration, other trehalase genes begin to respond successively. ILP2 knockout raised the mortality and reduced the pupation rate and eclosion rate in CO₂. Understanding the insulin pathway responses to hypoxic stress induced by a high concentration of CO₂ would further elucidate the mechanisms underlying trehalose metabolism in insects.

Pest categorisation of Bagrada hilaris

The EFSA Panel on Plant Health performed a pest categorisation of Bagrada hilaris (Hemiptera: Pentatomidae) for the EU territory. B. hilaris, known as the bagrada bug or painted bug, is a polyphagous pest feeding on at least 25 plant families including several economically important brassica crops such as broccoli, cabbage and cauliflower. Other economically important hosts suffering impacts include beans (Fabaceae), wheat and maize (Poaceae). Young plants are particularly vulnerable to adults and nymphs feeding on tender leaves and growing points, which can cause yield losses. B. hilaris occurs in Africa and Asia and has spread to North America (USA and Mexico) and South America (Chile) where there are multiple generations per year. It is not widely distributed in the EU but has been established in Malta and on the Italian island of Pantelleria, south west of Sicily, since the 1970s where it is an economically important pest of capers. The reasons why it has not spread further within southern Europe are unknown. B. hilaris is not a regulated pest in the EU. It could further enter and spread within the EU via the import and movement of host plants or as a hitchhiking species forming aggregations in conveyances and amongst non‐plant traded goods. Host availability and climate suitability suggest that, in addition to Malta and Pantelleria, southern areas of the EU around the Mediterranean would also be suitable for B. hilaris establishment. The introduction of B. hilaris to other Mediterranean areas of the EU would likely cause impacts in a range of crops, particularly brassicas. Measures to prevent entry and spread are available. B. hilaris satisfies all of the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest.

Synthetic and Natural Insecticides: Gas, Liquid, Gel and Solid Formulations for Stored-Product and Food-Industry Pest Control

The selective application of insecticides is one of the cornerstones of integrated pest management (IPM) and management strategies for pest resistance to insecticides. The present work provides a comprehensive overview of the traditional and new methods for the application of gas, liquid, gel, and solid physical insecticide formulations to control stored-product and food industry urban pests from the taxa Acarina, Blattodea, Coleoptera, Diptera, Hymenoptera, Lepidoptera, Psocoptera, and Zygentoma. Various definitions and concepts historically and currently used for various pesticide application formulations and methods are also described. This review demonstrates that new technological advances have sparked renewed research interest in the optimization of conventional methods such as insecticide aerosols, sprays, fumigants, and inert gases. Insect growth regulators/disruptors (IGRs/IGDs) are increasingly employed in baits, aerosols, residual treatments, and as spray-residual protectants for long-term stored-grain protection. Insecticide-impregnated hypoxic multilayer bags have been proven to be one of the most promising low-cost and safe methods for hermetic grain storage in developing countries. Insecticide-impregnated netting and food baits were originally developed for the control of urban/medical pests and have been recognized as an innovative technology for the protection of stored commodities. New biodegradable acaricide gel coatings and nets have been suggested for the protection of ham meat. Tablets and satchels represent a new approach for the application of botanicals. Many emerging technologies can be found in the form of impregnated protective packaging (insect growth regulators/disruptors (IGRs/IGDs), natural repellents), pheromone-based attracticides, electrostatic dust or sprays, nanoparticles, edible artificial sweeteners, hydrogels, inert baits with synthetic attractants, biodegradable encapsulations of active ingredients, and cyanogenic protective grain coatings. Smart pest control technologies based on RNA-based gene silencing compounds incorporated into food baits stand at the forefront of current strategic research. Inert gases and dust (diatomaceous earth) are positive examples of alternatives to synthetic pesticide products, for which methods of application and their integration with other methods have been proposed and implemented in practice. Although many promising laboratory studies have been conducted on the biological activity of natural botanical insecticides, published studies demonstrating their effective industrial field usage in grain stores and food production facilities are scarce. This review shows that the current problems associated with the application of some natural botanical insecticides (e.g., sorption, stability, field efficacy, and smell) to some extent echo problems that were frequently encountered and addressed almost 100 years ago during the transition from ancient to modern classical chemical pest control methods.

High-Pressure Carbon Dioxide Use to Control Dried Apricot Pests, Tribolium castaneum and Rhyzopertha dominica, and Assessing the Qualitative Traits of Dried Pieces of Treated Apricot

One of the new ways of warehouse pest control is the carbon dioxide treatment, which had no residues on the target products. In the present research, at first, CO₂ gas was applied to control two important pest species infesting dried apricots. Dry apricots infested with adults of Tribolium castaneum (Herbst) or Rhyzopertha dominica (F.) were exposed to CO₂ gas pressures correspond to 9.1, 16.7, 23.1, 28.6, and 33.4 mol% for 24 h. The results showed higher mortality rates with increasing the gas pressures in all the experiments. The minimum and maximum losses of the pests were determined at concentrations of 9.1 and 33.4 mol%, respectively. Evaluation of CO₂ gas effects on the quality characteristics of dried apricots showed no impacts on the color, brittleness, hardness, sweetness, sourness, and general acceptance of products. CO₂ gas treatments at the concentration of 33.4 mol% showed no significant influences on the chemical features of dried apricots, including pH, acidity, Brix, humidity percentage, reducing sugar, and total sugar. It was concluded that CO₂ gas had the potential to control T. castaneum and R. dominica in warehouses of dried apricots, without any significant impacts on product qualities.

Combination of Modified Atmosphere and Irradiation for the Phytosanitary Disinfestation of Trogoderma granarium Everts (Coleoptera: Dermestidae)

Simple Summary

The khapra beetle is defined as one of the most important quarantine pests globally, and fumigating by methyl bromide, one of the ozone-depleting substances under the Montreal Protocol, is a routine measure used for phytosanitary treatment. To protect the Ozone layer, an environmentally friendly measure is needed to be developed. The middle- to late-stage larvae and adults were treated with irradiation, modified atmosphere (MA) alone, and their combinations at room temperature of 24–26 ℃. As a result, late-stage larvae are determined as the most tolerant stage. Ionizing radiation was used to enhance the effects of 1% and 2% O₂ MA treatments that the obvious synergistic effects are presented in all combinations, resulted in saving as high as 60% of the estimated exposure times comparing with MA treatment alone. A total of 111,366 late-stage larvae were exposed to a 1% O₂ atmosphere for 14 or 15 days after a 200 Gy irradiation, resulted in no survivor in the validating tests. Therefore, the MA-irradiation combination treatment can provide quarantine security at a very high level, it may be combined with international transportation (train or sea container) to disinfest the commodities infested by khapra beetle and other stored products insect pests.

Abstract

The khapra beetle, Trogoderma granarium Everts, is defined as one of the most important quarantine pests globally, and fumigation with methyl bromide, an ozone-depleting substance, is a common phytosanitary measure currently used. The modified atmosphere (MA), irradiation, and their combination treatments of T. granarium larvae and adults were performed at room temperature (24–26 ℃) to develop an ecofriendly phytosanitary disinfestation measure and to shorten the exposure time and overcome treatment disadvantages of irradiation. Late-stage larvae are determined as the most tolerant stage resulted in large LT_99.9968 values of 32.6 (29.2–37.5) and 38.0 (35.1–41.7) days treated under 1% and 2% O₂ (with N₂ balance) atmosphere, respectively. Ionizing radiation was used to enhance the effect of MA and the mortality was highly significantly affected by all the interaction effects, indicating that the synergistic effects present in all the combined treatments. The synergistic ratios, which is defined as the estimated lethal time for MA treatment (LD₉₀, LD₉₉, and LD_99.9968), divided by that of combined treatment, were between 1.47 and 2.47. In the confirmatory tests, no individuals recovered from a sum of 111,366 late-stage larvae treated under 1% O₂ atmosphere for 14- or 15-d after 200 Gy irradiation, which resulted in validating the probit estimations and achieving an efficacy of 99.9973% mortality at 95% confidence level. Therefore, these treatment schedules are recommended to disinfest T. granarium infecting commodities for phytosanitary purposes under the warehouse, MA packaging, or in combination with international transportation by train or sea container.

Mediterranean Fruit Fly Ceratitis capitata (Diptera: Tephritidae) Eggs and Larvae Responses to a Low-Oxygen/High-Nitrogen Atmosphere

Simple Summary

Many chemicals have been removed from registration for the postharvest treatment of insect pests due to consumer/environmental safety and phytotoxicity. There is very limited operation for international trade purposes, particularly for management of Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae) on harvested fruit. Therefore, the non-chemical method is being considered for postharvest treatment of fruit. This study explored and evaluated Medfly response to low-oxygen and high-nitrogen treatment. The results will guide the development of a novel postharvest strategy and the approach to controlling this destructive fruit fly and other pests.

Abstract

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), is one of the most damaging horticultural insect pests. This study used a low-oxygen/high-nitrogen bioassay to control C. capitata. Two low-oxygen treatments were applied (0.5% O₂ + 99.5 N₂ and 5% O₂ + 95% N₂) to C. capitata eggs and 1st, 2nd and 3rd instar larvae from 0 to nine days on a carrot diet at 25 °C; 70—75% RH. The pupariation, adult emergence, and sex ratios of survived flies were examined. The results demonstrate that increased mortality of all tested life stages correlated with increased exposure times at both levels of low-oxygen treatments. Complete control of eggs was achieved after eight days and nine days for larvae using 0.5% O₂ at 25 °C; 70–75% RH. The 3rd instar was the most tolerant stage, while the egg was the most susceptible stage to the low-oxygen environment. There were no significant differences in sex ratios between emerged adults after low-oxygen and control treatments. The present work demonstrates and confirms the mortalities of C. capitata caused by low-oxygen treatment, which may help develop new postharvest strategies to control this destructive fruit fly pest.

Modified Atmosphere Does Not Reduce the Efficacy of Phytosanitary Irradiation Doses Recommended for Tephritid Fruit Flies

Phytosanitary irradiation (PI) has been successfully used to disinfest fresh commodities and facilitate international agricultural trade. Critical aspects that may reduce PI efficacy must be considered to ensure the consistency and effectiveness of approved treatment schedules. One factor that can potentially reduce PI efficacy is irradiation under low oxygen conditions. This factor is particularly important because storage and packaging of horticultural commodities under low oxygen levels constitute practices widely used to preserve their quality and extend their shelf life. Hence, international organizations and regulatory agencies have considered the uncertainties regarding the efficacy of PI doses for insects infesting fresh commodities stored under low oxygen levels as a rationale for restricting PI application under modified atmosphere. Our research examines the extent to which low oxygen treatments can reduce the efficacy of phytosanitary irradiation for tephritids naturally infesting fruits. The effects of normoxia (21% O₂), hypoxia (~5% O₂), and severe hypoxia (< 0.5% O₂) on radiation sensitivity of third instars of Anastrepha fraterculus (sensu lato), A. ludens (Loew), Bactrocera dorsalis (Hendel), and Ceratitis capitata (Wiedemann) were evaluated and compared at several gamma radiation doses. Our findings suggest that, compared to normoxia, hypoxic and severe-hypoxic conditioning before and during irradiation can increase adult emergence and contribute to advancement of larval development of tephritid fruit flies only at low radiation doses that are not used as phytosanitary treatments. With phytosanitary irradiation doses approved internationally for several tephritids, low oxygen treatments applied before and during irradiation did not increase the emergence rates of any fruit fly species evaluated, and all treated insects died as coarctate larvae. Thus, the findings of our research support a re-evaluation of restrictions related to phytosanitary irradiation application under modified atmospheres targeting tephritid fruit flies.