Primary Pest Research Articles

Preharvest insect pests of peanuts and associated aflatoxin contaminants in Georgia, USA.

On-farm losses of peanuts (Arachis hypogaea L.,Fabales: Fabaceae) pose a persistent threat to the sustainable production and value of peanuts in the United States. This study presents empirical data on the spatial distribution of subterranean insect pests and various quality aspects of peanuts. Surveys were conducted in 20 randomly selected peanut fields in 10 counties in Northeast, Southeast, and Southwest Georgia. The primary insect pests found in Georgia's peanut production counties were Pangaeus bilineatus (Say), Elasmopalpus lignosellus (Zeller), and Diabrotica undecimpunctata Howardi. In the northeast counties, a high prevalence of P. bilineatus led to a significant increase in insect-damaged pods (%IDP), insect-damaged kernels (%IDK), discolored kernels (%DK), pod weight loss (%PWL), and kernel weight loss (%KWL). Similarly, southeast counties had a high %DK, cracked pods (%CP), and E. lignosellus infestation. In southwest counties, predominantly high D. undecimpunctata infestations resulted in the highest %IDP. Moisture content (%MC) was excessively high in all the counties (22.19%-23.17%). Preharvest aflatoxin contamination in peanuts was prevalent across all studied locations, particularly in counties with a high incidence of P. bilineatus and may cause increased risk in aflatoxin levels along the supply chain. Nevertheless, the diverse regional abundance of insect pests and the widespread presence of aflatoxins in Georgia's peanut fields offer valuable insights for developing integrated pest management strategies targeting subterranean insect pests. This is especially crucial in addressing the impact of P. bilineatus, E. lignosellus, and D. undecimpunctata on aflatoxins content of peanuts and determining the pathway for mitigation of aflatoxin contaminations in peanuts at harvest.

Prediction of Thrips Damage Distribution in Mango Orchards Using a Novel Maximum Likelihood Classifier

Thrips constitute the primary pest responsible for reducing mango yield and quality every year in Asia. Therefore, the efficient monitoring of thrips damage across mango orchards on a large scale to aid farmers in devising rational pesticide application strategies poses a significant challenge within the current mango industry. This study designs a mango thrips damage inversion prediction method based on the maximum likelihood classifier (MLC). Initially, drone multispectral remote sensing technology is utilized to acquire multispectral data from mango orchards, which are then combined with ground hyperspectral information to identify sensitive bands indicative of mango leaf damage caused by thrips. Subsequently, correlation analysis is conducted on various vegetation indices, leading to the selection of the Greenness Normalized Difference Vegetation Index (GNDVI), which exhibits a strong correlation coefficient of 0.82, as the spectral characteristic parameter for the inversion prediction model. The construction of a remote sensing prediction model for thrips damage distribution in mango orchards is then undertaken based on the MLC. Acknowledging the bias-variance trade-off inherent in the MLC when processing spectral data and its potential limitations in feature extraction and robustness, this study proposes a modification wherein neighboring pixels are weighted differently to enhance the model’s feature extraction capabilities. Experimental results show that the novel MLC maintains stable estimation levels across various numbers of domain pixels, achieving an inversion accuracy of 91.23%. Through the reconstruction of the pixel matrix, the damage distribution of thrips in mango orchards can be swiftly and comprehensively visualized over extensive areas.

Integrated Omics Analysis Reveals Key Pathways in Cotton Defense against Mirid Bug (Adelphocoris suturalis Jakovlev) Feeding.

The recent dominance of Adelphocoris suturalis Jakovlev as the primary cotton field pest in Bt-cotton-cultivated areas has generated significant interest in cotton pest control research. This study addresses the limited understanding of cotton defense mechanisms triggered by A. suturalis feeding. Utilizing LC-QTOF-MS, we analyzed cotton metabolomic changes induced by A. suturalis, and identified 496 differential positive ions (374 upregulated, 122 downregulated) across 11 categories, such as terpenoids, alkaloids, phenylpropanoids, flavonoids, isoflavones, etc. Subsequent iTRAQ-LC-MS/MS analysis of the cotton proteome revealed 1569 differential proteins enriched in 35 metabolic pathways. Integrated metabolome and proteome analysis highlighted significant upregulation of 17 (89%) proteases in the α-linolenic acid (ALA) metabolism pathway, concomitant with a significant increase in 14 (88%) associated metabolites. Conversely, 19 (73%) proteases in the fructose and mannose biosynthesis pathway were downregulated, with 7 (27%) upregulated proteases corresponding to the downregulation of 8 pathway-associated metabolites. Expression analysis of key regulators in the ALA pathway, including allene oxidase synthase (AOS), phospholipase A (PLA), allene oxidative cyclase (AOC), and 12-oxophytodienoate reductase3 (OPR3), demonstrated significant responses to A. suturalis feeding. Finally, this study pioneers the exploration of molecular mechanisms in the plant-insect relationship, thereby offering insights into potential novel control strategies against this cotton pest.

First record of Zaprionus tuberculatus (Diptera: Drosophilidae) in mainland France

AbstractAs most drosophilid species are not considered as primary pest, studies of their communities in natura, with standardized surveys, are relatively sparse. However, Drosophila suzukii and its rapid expansion through the world led to the implementation of many monitoring programs. As part of a research project on D. suzukii, we set up in 2022 an annual fly monitoring in 16 fruits plantations in France to understand population's dynamics of D. suzukii and to broadly survey drosophilid communities. The captures led to the first observation of Zaprionus tuberculatus in mainland France. Over the whole monitoring, we trapped a total of 111 specimens in a fig orchard located in southern France (Salses‐le‐Château), both in fig trees and nearby hedgerow. The first detection of Zaprionus tuberculatus occurred in July 2022 in the hedgerow, and captures continued until January 2023 with an interruption in November and December. In addition, in this orchard we collected overripe figs in September 2023 from which over 20 Z. tuberculatus have emerged in the following 2 weeks, confirming the establishment of a permanent population. The pest status of Z. tuberculatus and its potential risk for agriculture is not yet clear, but the pest behavior of the close‐relative species Zaprionus indianus, especially on figs, should be a warning point for the entry of Z. tuberculatus into the EU and France, as they may have similar polyphagous habit. The pest status and range expansion of Z. tuberculatus should be assessed to estimate risk to fruit's production.

Cassia tora (L.) Seeds, An Alternative Host to Callosobruchus subinnotatus (Pic.) Infestation: A Preliminary Research Note

An investigation was carried out in the laboratory of the Department of Microbiology, Federal University Dutsin-Ma to identify and evaluate the effect of an insect pest attack on the proximate composition of Cassia tora L. in Dutsin-Ma, Katsina State, Nigeria. A laboratory culture of naturally infested seeds of C. tora was kept at 20-25°C ± 2°C and 70 % relative humidity in a plastic cup measuring 8.80 cm (outside lid diameter) cut at the centre (5.80 cm inner diameter) to complete metamorphosis. The emerged adult was taken to Insect Museum, Institute for Agricultural Research, Ahmadu Bello University, Zaria for identification at the. The result of the identification revealed it as Callosobruchus subinnotatus Pic. [Coleoptera: Bruchidae]. The insect is widely known to be a primary pest of Bambara nut, Vigna subterranean (L.) Verdcourt. The insect is reported in this research as an alternative host in periods when Bambara nut is not available. Therefore, farmers in the area should observe adequate farm sanitation by keeping their farms devoid of Cassia tora weeds to eliminate likely hibernation sites.

Biopesticidal Potential of Indigenous Plant Extracts against Rice Weevil in Stored Wheat

Stored products are significantly affected by certain well-known stored grain pests, with Sitophilus oryzae L. (Coleoptera: Curculionidae) being one of the most destructive pests of stored products. It is a primary pest that causes substantial quantitative and qualitative losses. The present study was conducted to investigate the insecticidal efficacy of different plant extracts from four commonly grown plants in Pakistan: ginger (Zingiber officinale), neem (Azadirachta indica), clove (Syzygium aromaticum), and tobacco (Nicotiana tabacum) against S. oryzae infesting stored wheat. Crude extracts from these plants were applied to stored wheat at various dose rates (20, 40, 60, 80 mg). Adults of S. oryzae were introduced to the treated wheat and observed for mortality, repellency, and grain damage. The results of the study indicated that the maximum mortality of S. oryzae (99.17%) was recorded due to the application of crude extract of Z. officinale, while the minimum mortality of S. oryzae (67.50%) was recorded due to the crude extract of N. tabacum at an 80 mg dose rate after a 10-day exposure interval. The maximum grain damage due to S. oryzae (0.19%) was observed in N. tabacum treated crude extract at an 80 mg dose rate, while the minimum grain damage due to S. oryzae (0.04%) was observed in Z. officinale treated crude extract at an 80 mg dose rate. Z. officinale also exhibited the maximum repellent effect on S. oryzae (95.77%). This study concluded that Z. officinale emerged as a potent, readily available biopesticide against S. oryzae, surpassing current alternatives with near-eradication efficacy, minimal grain damage, and a proactive repellent effect, paving the way for sustainable and eco-friendly pest management. Further research is needed to optimize extraction methods, dosage recommendations, and assess long-term effects on grain quality and storage stability.

Phototactic response of angoumois grain moth Sitotroga cerealella (olivier) to visible spectrum: Attraction analysis and modelling using machine learning

The Angoumois grain moth Sitotroga cerealella (Olivier), a primary pest of food grain storage, poses serious problems in India and many other countries. The insect's stronger phototaxis behaviour has been studied using monochromatic wavelengths in the visible spectrum. Among the different wavelengths (250, 330, 410, 480, 530, 580, and 680 nm) assessed for attraction under laboratory conditions, the highest attraction was observed for the blue wavelength (480 nm). Subsequently, the impact of luminance intensities (60, 80, and 100 lux) at each wavelength was also determined. At 60 lux, the 480 and 250 nm wavelengths attracted significantly more adults, i.e., 91.67% and 85%, respectively. The 680 nm wavelength exhibited the lowest attraction rate of only 15% at 100 lux. A gender-based analysis of S. cerealella adults demonstrated that female moths showed a significantly lower attraction (1:3.5) than male moths. This attraction behaviour was also predicted using machine learning. Among the different machine learning algorithms used for modelling insect behaviour, artificial neural network produced the highest prediction with an R2 value of 0.96. In conclusion, the results suggest that using the 480 nm wavelength may be an effective option for mass trapping and monitoring of S. cerealella.

Genetically engineered eucalyptus expressing pesticidal proteins from Bacillus thuringiensis for insect resistance: a risk assessment evaluation perspective.

Eucalyptus covers approximately 7.5million hectares in Brazil and serves as the primary woody species cultivated for commercial purposes. However, native insects and invasive pests pose a significant threat to eucalyptus trees, resulting in substantial economic losses and reduced forest productivity. One of the primary lepidopteran pests affecting eucalyptus is Thyrinteina arnobia (Stoll, 1782) (Lepidoptera: Geometridae), commonly referred to as the brown looper caterpillar. To address this issue, FuturaGene, the biotech division of Suzano S.A., has developed an insect-resistant (IR) eucalyptus variety, which expresses Cry pesticidal proteins (Cry1Ab, Cry1Bb, and Cry2Aa), derived from Bacillus thuringiensis (Bt). Following extensive safety assessments, including field trials across various biomes in Brazil, the Brazilian National Technical Commission of Biosafety (CTNBio) recently approved the commercialization of IR eucalyptus. The biosafety assessments involved the analysis of molecular genomics, digestibility, thermostability, non-target organism exposure, degradability in the field, and effects on soil microbial communities and arthropod communities. In addition, in silico studies were conducted to evaluate allergenicity and toxicity. Results from both laboratory and field studies indicated that Bt eucalyptus is as safe as the conventional eucalyptus clone for humans, animals, and the environment, ensuring the secure use of this insect-resistant trait in wood production.

A Comprehensive Review of Insect Pest Management in Muga Silkworm (Antheraea assamensis Helfer): Current Scenario and Future Prospects

Muga silkworm (Antheraea assamensis Helfer), renowned for its natural production of prized golden silk, is native to Assam and adjacent regions in North-Eastern India. However, outdoor rearing of Muga silkworms exposes them to environmental fluctuations year-round, resulting in significant crop losses due to insect pests. Notably, pre-seed crops (Aherua and Jarua) and seed crops (Chotua and Bhodia) experience significantly higher losses compare to commercial crops (Jethua and Kotia). This paper presents a thorough analysis of insect pests impacting Muga silkworm rearing, classified according to activity periods and intensity of attacks. Primary insect pests include Exorista sorbillans (Uzi fly), Apanteles glomeratus (Brachonid fly), ants and wasps. Uzi fly inflicts damage during winter (November to February), primarily affecting 4th and 5th instar Muga larvae, leading to substantial losses during cocoon harvest in March-April, jeopardizing seed production for subsequent Jethua (April-May) commercial crops. Apanteles glomeratus and ants pose threats during summer. Vespa orientalis (wasp) causes damage to late instars from April to September. Chemical control methods are discouraged due to their adverse effects on silkworms. Therefore, urgent research into environmentally sustainable pest management strategies tailored to Muga rearing's specific needs and limitations are warranted. This review synthesizes detailed descriptions of identified pests, challenges in insect pest management, and discusses various mitigation strategies, offering insights into the biology of major insect pests affecting Muga silkworms and evaluating the effectiveness of different pest management approaches.

Investigation of Agricultural Diseases and Pests in the Republic of Kiribati and the Republic of Fiji

The Republic of Kiribati (Kiribati) and the Republic of Fiji (Fiji) are two island countries in the Middle and Eastern Pacific Ocean, respectively. Coconut (Cocos nucifera L.), banana (Musa spp.), sugarcane (Saccharum officinarum L.), and breadfruit (Artocarpus incisa (Thunb.) L.) are the primary economic crops. To date, there have been few reports on the status of agricultural diseases and pests in these countries. From June 6 to June 16, 2023, our team investigated agricultural diseases and pests in Kiribati and Fiji. Thirty-six diseases, five pests and one parasitic plant from twenty-eight species of plants were identified in Kiribati. Among the deleterious organisms, coconut gray spot (Pestalotiopsis palmarum (Cooke) Steyaert), banana Cordana leaf spot (Cordana musae (Zimm) Hhon), hala (pandanus) leaf blight (Unidentified pathogen), breadfruit anthracnose (Colletotrichum spp.), frangipani rust (Coleosporium plumierae Pat.) and noni anthracnose (Colletotrichum spp.) were predominant. A total of twenty-seven diseases and one parasitic plant were identified on twenty-one species of plants in Fiji. Mango bacterial black spot (Xanthomonas campestris pv. mangiferaeindicae), banana black leaf streak (Pseudocercospora musae (Zimm.) Deighton), pumpkin virus disease (Unidentified), and frangipani rust (Coleosporium plumierae Pat.) were prevalent. The results of our survey could provide the governments of Kiribati and Fiji with basic data to control the primary agricultural diseases and pests in their countries.

A novel insecticide, isocycloseram, shows promise as an alternative to chlorpyrifos against a direct pest of peanut, Diabrotica undecimpunctata howardi (Coleoptera: Chrysomelidae).

Larvae of the southern corn rootworm (SCR) Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae) are primary pests of peanut in the Virginia-Carolina region of the United States, and are relatively sporadic pests in southern states such as Georgia, Alabama, and Florida. Peanuts have strict quality standards which, when they are not met, can diminish crop value by more than 65%. Management of direct pests like SCR is therefore crucial to maintaining the economic viability of the crop. The soil-dwelling nature of SCR larvae complicates management due to difficulties associated with monitoring and predicting infestations. Nonchemical management options are limited in this system; preventative insecticide applications are the most reliable management strategy for at-risk fields. Chlorpyrifos was the standard product for larval SCR management in peanut until its registration was revoked in 2022, leaving no effective chemical management option for larvae. We tested a novel insecticide, isocycloseram, for its ability to reduce pod scarring, pod penetration, and non-SCR pod damage in field studies conducted in Suffolk, Virginia in 2020-2022. Overall injury was low in 2020 and 2022, and in 2022 there was not a significant effect of treatment. In 2021, 2 simulated chemigation applications of isocycloseram in July significantly reduced pod scarring and overall pod injury relative to chlorpyrifos and the untreated control. Our results suggest that isocycloseram may become an effective option for managing SCR in peanut, although more work is needed to understand the mechanisms by which it is effective as a soil-applied insecticide.

Trehalose 6-phosphate synthase gene rdtps1 contributes to thermal acclimation in Rhyzopertha dominica

BackgroundThe lesser grain borer (Rhyzopertha dominica), a worldwide primary pest of stored grain, causes serious economic losses and threatens stored food safety. R. dominica can respond to changes in temperature, especially the adaptability to heat. In this study, transcriptome analysis of R. dominica exposed to different temperatures was performed to elucidate differences in gene expression and the underling molecular mechanism.ResultsIsoform-sequencing generated 17,721,200 raw reads and yielded 20,416 full-length transcripts. A total of 18,880 (92.48%) transcripts were annotated. We extracted RNA from R. dominica reared at 5 °C (cold stress), 15 °C (cold stress), 27 °C (ambient temperature) and 40 °C (heat stress) for RNA-seq. Compared to those of control insects reared at 27 °C, 119, 342, and 875 differentially expressed genes (DEGs) were identified at 5 °C, 15 °C, and 40 °C, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that pathways associated with “fatty acid metabolism”, “fatty acid biosynthesis”, “AMPK signaling pathway”, “neuroactive ligand receptor interaction”, and “longevity regulating pathway-multiple species” were significantly enriched. The functional annotation revealed that the genes encoding heat shock proteins (HSPs), fatty acid synthase (FAS), phospholipases (PLA), trehalose transporter (TPST), trehalose 6-phosphate synthase (TPS), and vitellogenin (Vg) were most likely involved in temperature regulation, which was also validated by RT-qPCR. Seven candidate genes (rdhsp1, rdfas1, rdpla1, rdtpst1, rdtps1, rdvg1, and rdP450) were silenced in the RNA interference (RNAi) assay. RNAi of each candidate gene suggested that inhibiting rdtps1 expression significantly decreased the trehalose level and survival rate of R. dominica at 40 °C.ConclusionsThese results indicated that trehalose contributes to the high temperature resistance of R. dominica. Our study elucidates the molecular mechanisms underlying heat tolerance and provides a potential target for the pest management in R. dominica.

Seeds of nonhost species as sources of toxic compounds for the cowpea weevil Callosobruchus maculatus (F.)

Cowpea weevil, Callosobruchus maculatus, is the primary pest of stored cowpea seeds. The management of this infestation currently relies on insecticides, resulting in environmental pollution and selection of insecticide-resistant pests. Consequently, research efforts are being devoted to identify natural insecticides as sustainable and environment friendly alternatives for the control of C. maculatus. In this study, we explore the toxic effects of the nonhost seeds Parkia multijuga, Copaifera langsdorffii, Ormosia arborea, Amburana cearensis, Lonchocarpus guilleminianus, Sapindus saponaria, and Myroxylon peruiferum, on the cowpea weevil C. maculatus. Notably, all nonhost seeds led to reductions between 60 and 100% in oviposition by C. maculatus females. Additionally, the larvae were unable to penetrate the nonhost seeds. Artificial seeds containing 0.05% to 10% of cotyledon flour were toxic to C. maculatus larvae. Approximately 40% of larvae that consumed seeds containing 0.05% of O. arborea failed to develop, in contrast to control larvae. Proteomic analysis of A. cearensis and O. arborea seeds identify revealed a total of 371 proteins. From those, 237 are present in both seeds, 91 were exclusive to O. arborea seeds, and 43 were specific to A. cearensis seeds. Some of these proteins are related to defense, such as proteins containing the cupin domain and 11S seed storage protein. The in silico docking of cupin domain-containing proteins and 11S storage protein with N-acetylglucosamine (NAG)4 showed negative values of affinity energy, indicating spontaneous binding. These results showed that nonhost seeds have natural insecticide compounds with potential to control C. maculatus infestation.

Emerging Insect Pests of Vegetable Crops under Changing Climate Scenario

Crop losses in vegetables vary greatly depending on plant variety, cropping season, geographical location, and pest damage potential. Vegetable crops are heavily impacted by insect pests and diseases due to their softness, fragility and short duration in comparison to other crops. An emerging insect pest is one that has been observed in a specific crop-infested area and has progressively increased in population over time. Emerging insect pests have the potential to cause economic harm. In other words, an emerging insect pest is a pest insect whose position has shifted from minor to major or secondary to primary pest. The number of existing minor pests is increasing, as is the arrival of new ones, such as mealybugs, fruit flies, stem borers, diamondback moths among phytophagous insects and red spider mites among acarine. Recent infestations, such as South American tomato pinworm and chili black flower thrips, have caused serious damage to tomato and chili harvests. This review envisages on the variables that contribute to the establishment of new invasive pests, the persistence of main pests, general pest management practices, and integrated pest management to achieve sustainable vegetable production.

WITHDRAWN: Rice Pests and Diseases Around the World: Who, Where and What Damage Do They Cause?

Rice stands as one of the most important staple crops for nearly half of the world’s population. Its productivity is pivotal in ensuring global food security, yet pests and diseases are one of the most important constraints. Despite its paramount significance, a comprehensive overview of the primary pests and diseases affecting rice worldwide has not been previously undertaken. This systematic review, following PRISMA guidelines and drawing upon three online databases (PubMed, WOS, and CAB Abstract), enabled the identification of distribution patterns of these pests and diseases across the globe. From an initial pool of 13.983 articles, exclusion criteria were applied, resulting in 838 final articles. Given that rice cultivation primarily occurs in Asia and Africa, it's unsurprising that the majority of documented pests and diseases are found on these continents. In Africa, the genera Diopsis, Maliarpha and Chilo are the most important pests affecting rice productivity, while in Asia the most important are Nilaparvata, Scirpophaga, Sogatella, Chilo, Cnaphalocrocis, Sesamia, and Nephotettix genera, demonstrating different pests under a continent overview. Regarding diseases, in Africa, the fungi Pyricularia, the bacteria Xanthomonas and the virus Sobemovirus are the most significant. In Asia, the fungal genera Fusarium, Pyricularia, Rhizoctonia, Bipolaris, Curvularia, Ustilaginoidea, Alternaria, and Sarocladium, and bacteria Xanthomonas, Pantoea, Pseudomonas, and Burkholderia are the most frequently reported. These findings reveal distinct geographic patterns in the distribution of rice pests and diseases, implying the development of specific regional management guidelines. In terms of yield loss, the most severe fungi are Pyricularia and Bipolaris, responsible for blast and brown spot diseases, respectively. Both occur in Africa and Asia and affect different parts of the plant, with Bipolaris being more evident on the leaves. A big concern restricted to Africa is the Sobemovirus (causing rice yellow mottle virus), which can lead to yield losses of up to 100%, primarily affecting the leaves. This study significantly contributes to identifying global rice pests and diseases, assessing their current distribution patterns and evaluating their effects on future rice productivity. Furthermore, it highlights the overlooked reporting of studies in Africa, despite the region’s significance in rice cultivation and production.

Temperature-dependent development and life tables of Palpita unionalis (Lepidoptera: Pyralidae)

Abstract Palpita unionalis Hubner (Lepidoptera: Pyralidae) is one of the primary pests in olive orchards, damaging buds and fruits of the olive tree. The present study investigated the biology of P. unionalis across a temperature gradient and elaborated on the corresponding life tables for a better understanding of its population dynamics in the environment. The biology of the pest was studied at six temperatures (17, 20, 22, 25, 27, and 30 °C). The duration and survival of immature stages, sex ratio, and survival of emerged adults were evaluated. The female fecundity and longevity (pre-oviposition, oviposition, and post-oviposition periods) were calculated. The life tables were elaborated from these parameters. The life cycle of P. unionalis was significantly longer at 17 °C and shorter at 30 °C. Larval survival was significantly reduced at 30 °C, however, adult survival was at a maximum, yet their sex ratio was not affected by temperature. The lower temperature, 20 °C, was optimal for fecundity (586.3 eggs), which was reflected in the highest net reproductive rate (105.7 offspring per individual). The thermal constant (K) and the lower thermal threshold (t 0) for egg to adult period were 582.9° days and 7.1 °C, respectively. Based on the current study, it is concluded from the parameters of biology and life tables that temperature has a significant role in the population growth of P. unionalis. This should be considered throughout the monitoring and management of P. unionalis at different agro-ecologies in the context of global warming.

Metarhizium spp. isolates effective against Queensland fruit fly juvenile life stages in soil.

Queensland fruit fly, Bactrocera tryoni, Froggatt (Diptera: Tephritidae) is Australia's primary fruit fly pest species. Integrated Pest Management (IPM) has been adopted to sustainably manage this polyphagous species with a reduced reliance on chemical pesticides. At present, control measures are aimed at the adult stages of the fly, with no IPM tools available to target larvae once they exit the fruit and pupate in the soil. The use of entomopathogenic fungi may provide a biologically-based control method for these soil-dwelling life stages. The effectiveness of fungal isolates of Metarhizium and Beauveria species were screened under laboratory conditions against Queensland fruit fly. In bioassays, 16 isolates were screened for pathogenicity following exposure of third-instar larvae to inoculum-treated vermiculite used as a pupation substrate. The best performing Metarhizium sp. isolate achieved an average percentage mortality of 93%, whereas the best performing Beauveria isolate was less efficient, with an average mortality of 36%. Susceptibility to infection during different development stages was investigated using selected fungal isolates, with the aim of assessing all soil-dwelling life stages from third-instar larvae to final pupal stages and emerging adults. Overall, the third larval instar was the most susceptible stage, with average mortalities between 51-98% depending on the isolate tested. Moreover, adult mortality was significantly higher when exposed to inoculum during pupal eclosion, with mortalities between 56-76% observed within the first nine days post-emergence. The effect of temperature and inoculum concentration on insect mortality were assessed independently with candidate isolates to determine the optimum temperature range for fungal biological control activity and the rate required for application in field conditions. Metarhizium spp. are highly efficacious at killing Queensland fruit fly and have potential for use as biopesticides to target soil-dwelling and other life stages of B. tryoni.

Biological Characteristics and Thermal Requirements of Telenomus podisi and Trissolcus basalis (Hymenoptera: Scelionidae) in Fresh and Cryopreserved Eggs of Euschistus heros and Nezara viridula (Hemiptera: Pentatomidae)

Brazil is one of the largest producers of pulses globally, and soybean ranks highly in terms of production. However, pests increase crop production costs and affect oilseed production and quality. Pests are primarily controlled by chemicals, leading to changes in insect pest populations. For example, secondary pests can become primary pests because of the selection of resistant insects and the elimination of natural enemies. Farmers have widely accepted biological control because of its high control efficacy and low environmental contamination risk. Two successful biological control programs in soybean used Telenomus podisi Ashmead (Hymenoptera: Platygastridae) to manage the Neotropical brown stink bug, Euschistus heros (Fabricius) (Hemiptera: Pentatomidae), and Trissolcus basalis (Wollaston, 1858) (Hymenoptera: Scelionidae) to manage the southern green stink bug, Nezara viridula (Linnaeus) (Hemiptera: Pentatomidae), when these pests were the most abundant in soybean-producing regions. To release parasitoids, rearing protocols must be developed in order to optimize production. This study evaluated the effect of temperature on the biological characteristics of T. podisi and T. basalis when fresh or frozen E. heros eggs were provided. Fifty fresh or previously frozen eggs were placed with parasitoids for 24 h in a climate chamber (25 ± 1 °C, 70 ± 10% RH, and 14-h photophase). At the end of this period, the eggs were transferred to other chambers and maintained at different temperatures (19, 22, 25, 28, 31, and 34 ± 1 °C, 70 ± 10% RH, with a 14-h photoperiod). The number of emerging adults from eggs parasitized by T. basalis was lower than that from eggs parasitized by T. podisi. Differences in T. basalis and T. podisi parasitism were observed depending on whether the E. heros eggs were frozen or fresh, but neither development nor emergence were affected. The duration of egg–adult development and the longevity of the two parasitoids were inversely proportional to the temperature increase. The sex ratio of T. basalis and T. podisi progeny was not affected by different temperatures or by the use of frozen or fresh eggs. The estimated number of both parasitoids’ generations corresponded with temperature, reaching 14–15 generations/cycle of soybean for Rio Verde, GO, and 12–14 generations/cycle for Barreiras, BA. Given these characteristics, we conclude that a biological control program using T. podisi can benefit large areas of soybean production by controlling the eggs of phytophagous bugs in soybean crops.

Potential of Solid Gel Formulation of Kaffir Lime Peel Extract Against Postharvest Pest Sitophilus Zeamais on Stored Rice

Maize weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) is a primary pest on maize, rice, wheat, sorghum, and other cereal grains. The purpose of this study was to determine the effectiveness of using kaffir lime peel extract in solid gel formulation as a plant-based insecticide. This study used five treatments, untreated (control), 0.5%, 1%, 1.5%, and 2%. The results of this study are the treatments tested had effects on adult mortality and repellency. The 2% concentration showed the highest adult mortality and repellency. The major volatile organic compounds contained in kaffir lime peel were α-fernesene, α-sinensal, D-citronellol, and citronellal.

Some essential oils as potential control agents for varroa mite (Varroa destructor) in infected honey bees (Apis mellifera).

Ecto-parasite, varroa mite, (Varroa destructor), is the primary pest affecting the apiculture sector globally in various regions. This study examined the toxicity of nine essential oils to Apis mellifera L. and the acaricidal impact of those oils against V. destructor. The acaricidal effects of nine essential oils, extracted from plant materials were used. In the screening experiment, 10 mg of the active ingredients of the plant material extracts were prepared in an alcohol solution with concentrations of 5%, 10%, and 15%. For each type of plant extract, five female V. destructor were transferred to a Petri dish with five worker bees incubated at 70% humidity and 33°-34° for 2 days, for each treatment four replicates were used compared to the control. Forty-eight hours following treatment, the number of dead and live mites was counted to determine the mortality rate. In the second assay experiment, the best five essential oils of the previous experiment were selected to re-assess their effectiveness on varroa mites and honeybee workers by using a concentration of 15%. Five females of V. destructor were transferred to a Petri dish with 10 adult bees and treated with the solution of the selected oils. Five replicates and control treatments were taken for each sample simultaneously. Dead and live bees were counted for each replicate at 48 hours after treatment. There were no significant differences between the concentrations used of each oil on the rate of death of mites, and its effectiveness ranged between 70.0% and 53.3% compared to the control groups. In addition, the best oil used was bitter melon, with a death rate of 80% at a concentration of 15%, while peppermint oil showed the lowest death rate of 45% at a concentration of (5%). However, all these treatments were statistically highly significant compared with the natural death rate in control (2%). In the second test, the results of the statistical analysis indicated that there were highly significant differences (P0.05 <0.0001) in the average numbers of dead varroa mites compared to the control when using a 15% concentration of five selected oils. On the other hand, there was no statistically significant difference in the honey bee workers' mortality rate between the treatment and control groups (P0.05 <0.3390), and it was relatively low for all treatments except the basil oil, where the bee mortality rate was 16% compared to the control (10%). It is clear from this experiment that bitter melon oil can be used to control varroa mites and it can be considered safe for honey bees as well as for the environment.