Potential Pest Research Articles

Disentangling a Neotropical pest species complex: genetic diversity and population structure of the native rice stink bug Oebalus poecilus and the invasive O. ypsilongriseus.

A first step in any pest management initiative is recognizing the existing problem - identifying the pest species and its abundance and dispersal capacities. This is not simple and even more challenging when insidious (invasive) species are involved constituting a pest complex. Understanding a species' population diversity and structure can provide a better understanding of its adaptation and relative pest potential. Such is the need for the native rice stink bug Oebalus poecilus and the invasive O. ypsilongriseus in low and high flatlands of South America. The genetic structure differed between both rice stink bug species (FST =0.157, P=0.001), where 84% of the overall genetic variability takes place within species and three genetic groups were recognized through Bayesian approach (K=3). Oebalus poecilus exhibited slightly higher genetic diversity (HE =0.253) and structuring (FST =0.050, P=0.001) than the invasive O. ypsilongriseus (HE =0.211; FST =0.038, P=0.013). Nonetheless, only the former exhibited significant correlation between genetic and geographic distances (r=0.48, P=0.013). Despite the pointed peculiarities, the obtained results indicate overlap in both species' occurrence and similar genetic structure allowing for a compound problem to be dealt with as the complex requires managing without, as yet, a prevailing species or a niche specialization. © 2022 Society of Chemical Industry.

Modelling potential natural pest control ecosystem services provided by arthropods in agricultural landscapes

Natural pest control has the potential to reduce pesticide use. Therefore, it has an essential role to play in the transition towards a more sustainable agriculture. For the prediction of natural pest control, it is essential to understand the distribution of the species providing this ecosystem service. The presence of pests and natural enemies depends on a combination of abiotic and biotic factors, each playing a determining role at different spatial scales. We developed a hierarchical model composed of environmental predictors including bioclimatic and land use variables at the European scale, as well as landscape complexity and biotic interactions at the landscape scale. This paper presents the predicted distribution of 111 species from seven different arthropod families (two pest aphid species and their natural enemy species) in an agricultural region in northern Germany. The hierarchical framework allows determining the capacity of landscapes to support pest control ecosystem services provided by arthropods at the local scale and informs on vulnerable areas or potential mismatches between natural pest control demand and supply. Thereby it can support the design of local scale measures for habitat improvement, biodiversity conservation and the increase of ecosystem services supply. The hierarchical approach can be adapted to other agroecosystems and leaves potential for further adaptations to improve the prediction of pests and their natural enemy distribution, dynamics and factors influencing their spatial distribution.

Pest categorisation of Neomaskellia andropogonis.

The EFSA Panelon Plant Health performed a pest categorisation of Neomaskellia andropogonis (Hemiptera: Aleyrodidae), the sugarcane whitefly, for the EU territory. N. andropogonis is a tropical and subtropical species that originates in south central Asia and has recently established in Iran and Iraq. N. andropogonis is not listed in Commission Implementing Regulation (EU) 2019/2072. It is oligophagous on Poaceae and most frequently reported on sugarcane (Saccharum officinarum), on which it has become an important emerging pest in western Iran. The larvae feed on the foliage and stalks and can cause a reduction of photosynthesis rate and growth. In heavy infestations, the sugar purity and content are greatly decreased. Honeydew egested by feeding N. andropogonis larvae can promote the growth of black sooty mould over the host. No evidence was found indicating economic damage to other grasses. The ornamental grass hosts Andropogon sp. and Imperata cylindrica are ornamental grasses in the subfamily Panicoideae and are exempt from a general prohibition on Poaceae entering the EU and together with fresh sugarcane, provide potential pathways for entry. An estimated threshold for development from egg to adult of 7.2°C with approximately 500 degree days required for a generation suggests that climatic conditions, together with the availability of grass hosts in the southern EU, would support establishment. Adults disperse naturally by flying and all stages can be moved over long distances by the trade of infested plant material. The pest has the potential to impact sugarcane production in Portugal and Spain. N. andropogonis 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. However, this conclusion has high uncertainties regarding the likelihood of entry and the magnitude of potential impact within the EU as the insect is only recorded as an economically important pest in Iran, and its host range is poorly known and understood.

Pest categorisation of Penthimiola bella.

The EFSA Panelon Plant Health performed a pest categorisation of Penthimiola bella (Hemiptera: Cicadellidae), the citrus leafhopper, for the European Union (EU). P. bella is native to the Afrotropical region; it has spread to Israel (first reported in 1974), Lebanon, and was reported from Morocco in 2018. Within the EU, P. bella is established in Portugal (Algarve) where it was first found on sweet oranges in 2012, and then in Spain in 2020, also on sweet oranges. P. bella is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. It is a polyphagous species reported, among cultivated hosts, on sweet orange, grapefruit and avocado. It is also described as being found on unspecified trees and bushes in savannahs, mountain forests and rain forests in Africa. Climatic conditions in some parts of southern EU countries are favourable and host plants are available in those areas to support establishment and spread. Despite being present in Portugal for over 10 years, there is a lack of evidence of impacts; hence, the magnitude of impact following introduction is uncertain. Nevertheless, in South Africa, P. bella was reported as being an economically important pest of citrus and to cause damage to avocado fruit during the early stages of development. Phytosanitary measures are available to reduce the likelihood of entry and further spread. Except for having uncertain economic or environmental impacts as a result of its introduction, P. bella satisfies all the other criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest.

Pest categorisation of Dendrolimus spectabilis.

The EFSA Panelon Plant Health performed a pest categorisation of Dendrolimus spectabilis (Lepidoptera: Lasiocampidae), a moth, also known as the Japanese pine caterpillar, for the European Union (EU). D. spectabilis is native to China, Japan and Korea. Its larvae primarily feed on the needles of Pinus densiflora and P. thunbergii and can also feed on P. strobus, P. rigida, P. taeda and P. tabuliformis. The pest can have one or two generations per year; winter is mostly spent as fifth instar larvae in the soil. Adults emerge in July and August and females lay egg masses of 200-300 eggs on coniferous host needles. Natural enemies are described as significant factors of population density changes in Japan and the Republic of Korea. The pest can be detected visually, and there are morphological keys as well as molecular markers allowing identification. D. spectabilis could enter the EU, either as eggs, larvae or pupae in the foliage of plants for planting or cut branches, as larvae on wood with bark or as overwintering larvae in the litter of potted plants. However, Annex VI of Regulation 2019/2072 prohibits the introduction of D. spectabilis hosts from countries and areas where the pest occurs. D. spectabilis occurs in climatic zones that are found in the EU, and the fact that it attacks the North American P.strobus, P. taeda and P. rigida in its Asian native area suggests a potential to shift to local conifer species in the EU territory. There is uncertainty regarding the magnitude of economic and environmental impact of D. spectabilis on conifer species commonly occurring in the EU. Notwithstanding this uncertainty, D. spectabilis satisfies all the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest.

Pest categorisation of Stenocarpella maydis.

The EFSA Plant Health Panelperformed a pest categorisation of Stenocarpella maydis, a clearly defined fungus causing seedling blight, stalk and ear rot in maize, its only confirmed main host. The pathogen occurs in many countries of North, Central and South America, Africa, Asia and Oceania where maize is grown commercially. It is present in the EU with restricted distribution (Czech Republic and Spain). Stenocarpella maydis is not included in Commission Implementing Regulation (EU) 2019/2072. Plants for planting (maize seeds) is the main pathway of entry and spread in the EU. Host availability and climate are favourable for the establishment of the pathogen in maize-growing areas of the EU. The pathogen has a direct impact on yield and quality of maize production. Phytosanitary measures are available to mitigate further introduction and spread of the pathogen into the EU. The Panelconcludes that S. maydis satisfies all the criteria to be regarded as a potential Union quarantine pest.

Pest categorisation of chickpea chlorotic dwarf virus.

The EFSA Panelon Plant Health conducted a pest categorisation of chickpea chlorotic dwarf virus (CpCDV) for the EU territory. The identity of CpCDV, a member of the genus Mastrevirus (family Geminiviridae) is established. Reliable detection and identification methods are available. The pathogen is not included in the EU Commission Implementing Regulation 2019/2072. CpCDV has been reported in Africa, Asia and Oceania. It has not been reported in the EU. CpCDV infects plant species in the family Fabaceae and several species of other families (Amaranthaceae, Brassicaceae, Caricaceae, Cucurbitaceae, Malvaceae and Solanaceae), including weeds. It may induce symptoms on its hosts, causing severe yield reduction. The virus is transmitted in a persistent, circulative and non-propagative manner by the leafhopper species Orosius orientalis and O. albicinctus, which are not regulated. O. orientalis is known to be present in some EU member states. Plants for planting (other than seeds), parts of plants and cut flowers of CpCDV hosts and viruliferous leafhoppers were identified as the most relevant pathways for the entry of CpCDV into the EU. Cultivated and wild hosts of CpCDV are distributed across the EU. Would the pest enter and establish in the EU territory, impact on the production of cultivated hosts is expected. Phytosanitary measures are available to prevent entry and spread of the virus in the EU. CpCDV fulfils the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest.

Pest categorisation of Matsucoccus massonianae.

The EFSA Panelon Plant Health performed a pest categorisation of Matsucoccus massonianae (Hemiptera: Matsucoccidae), the Massonian pine bast scale, for the EU territory. M. massonianae occurs in western China and has been reported as a pest of Pinus massoniana (Chinese red pine) and P. thunbergii (Japanese black pine). These hosts occur in the EU as ornamental/amenity trees. Other scales in the Matsucoccus genus feed on a variety of Pinus species and the host range of M.massonianae could be wider than is currently recorded. There is one generation per year. All stages occur on the branches and stems of hosts with developing nymphs and adult females feeding under the bark on the phloem vessels of the host. Symptoms include the yellowing/browning of host needles, early needle drop, desiccation of shoots and bark necrosis. The most serious infestations occur in hosts aged 8-25 years old and there can be some host mortality. In principle, host plants for planting and plant products such as cut branches and wood with bark could provide entry pathways into the EU. However, prohibitions on the import of Pinus from non-European third countries close these pathways. In China, M. massonianae occurs in regions with temperate humid conditions and hot summers. These conditions are also found in parts of southern EU. Were M. massonianae to establish in the EU, it is conceivable that it could expand its host range; however, this remains uncertain. M. massonianae satisfies all the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest. Some uncertainty exists over the magnitude of potential impacts.

Identification and Management of Plant Parasitic Nematodes Associated with Walnut (Juglans Regia L.) in Abbottabad

Purpose: Phytonematodes known as the hidden enemies of plants and crops are potential pest of walnut trees in Abbottabad, KP Pakistan. Methods: Soil samples from walnut trees were collected from different localities were processed by using Bearmann funnel techniques. Several nematode species were identified including Meloidogyne incognita, Helicotylenchus dihystera, Psilenchus hilarulus, Tylenchus sp. and Helicotylenchus vulgaris. Findings & Practical implication: Management of plant parasitic nematodes by using castor oil cakes (8kg/tree), cow dung (8 kg/tree) and duck manure (8kg/tree) showed that population was declined after application. Plant growth and yield was also improved. Data plotted in histogram graphs and t-test showed that p values were found significant. Conclusion: The mean and S.D values of initial population, 3 month, 6 month and 12 month for castor oil cakes are 116 ± 1.2, 84 ± 1.0, 60 ± 1.0, 42 ± 0.6, for cow dung 127 ± 5.7, 110 ± 2.4, 87 ± 2.4, 73 ± 1.3 and for duck manure 108 ± 2.4, 92 ± 1.0, 69 ± 0.5, 45 ± 1.0. Keywords: Phytonematodes, walnut, castor oil, cow dung, duck manure.

Role of Intercropping in Sustainable Insect-Pest Management: A Review

Reduced soil fertility and rising pest and disease pressures are contributing to the already serious problem of global food insecurity. Monoculture is the most labour and resource-intensive form of crop production around the globe. Unfortunately, monocultures are more vulnerable to pests, diseases, and weeds, so the expansion of this system is accompanied by a host of biological issues. Negative effects on the environment, human health, and ecosystem stability are all associated with monocropping because it relies so heavily on the use of chemical plant protection products of all generations of pesticides. Although crop production strategies are important for overall enhancement in production, the intercropping can help farmers in attaining raised economic returns by taking multiple crops in a single season. Intercropping is an alternative strategy for improved resource use efficiency, environmental safety, and sustainable pest management without the use of chemical pesticides that can help mitigate these risks. Intercropping (two or more crop species coexisting) is a cultural practice in pest management that reduces insect pests by increasing ecosystem diversity. Intercropping and planting crops that kill or repel pests, attract natural enemies, or have antibacterial effects can reduce disease and pest damage and pesticide use. Intercropping, where crops grow between main crops, reduces the likelihood of pest infestation. Intercropping is a potential pest management practice because it diversifies crops in an agro-ecosystem to reduce insect populations and attacks. Intercropping relies on a deep understanding of insect ecology and crop traits. Intercropping can be used alone or in combination with host-plant resistance and biological control. Intercropping ensures crop yield stability, protects against crop failure, improves soil fertility, increases soil conservation, and reduces pesticide use, minimizing agriculture's environmental impact. The aim is to define the role and importance of intercropping as a strategy in crop pest management and as a boost for crop production vis-à-vis soil fertility.

Identification of the neuropeptide gene family and feeding regulation by neuropeptide Y in Mythimna separata (Lepidoptera: Noctuidae)

Mythimna separata is a crucial agricultural pest with polyphagous characteristic. Neuropeptide signaling, especially neuropeptide Y (NPY) involved in feeding regulation, is considered as a potential pest control target. In this study, we identified 50 neuropeptides including NPY of M. separata using transcriptome sequencing. Bioinformatics analysis showed that NPY had a conserved carboxyterminal motif of RGRYamide and shared very high homology across lepidopteran insects. Spatio-temporal expression profile articulated that NPY was mainly expressed in the larval stage, and with the highest expression in larval midgut and adult alimentary canal. RNAi knockdown by the injection of dsNPY into larvae significantly inhibited food uptake and body weight, delayed developmental duration, and also caused increase of trehalose and decrease of glycogen and total lipid compared to dsGFP. This study identified nearly the entire neuropeptide gene family of M. separata and further indicated that NPY signaling pathway might played a vital role in the feeding regulation and related to energy metabolism. Our results not only laid a preliminary foundation for functional studies on neuropeptide of M. separata, but also provided a potential molecular target for future pesticide development.

Involvement of Methoprene-tolerant and Krüppel homolog 1 in juvenile hormone-mediated vitellogenesis of female Liposcelis entomophila (End.) (Psocoptera: Liposcelididae).

Methoprene-tolerant (Met) as an intracellular receptor of juvenile hormone (JH) and the Krüppel-homolog 1 (Kr-h1) as a JH-inducible transcription factor had been proved to contribute to insect reproduction. Their functions vary in different insect orders, however, they are not clear in Psocoptera. In this study, LeMet and LeKr-h1 were identified and their roles in vitellogenesis and ovarian development were investigated in Liposcelis entomophila (Enderlein). Treatment with exogenous JH III significantly induced the expression of LeKr-h1, LeVg, and LeVgR. Furthermore, silencing LeMet and LeKr-h1 remarkably reduced the transcription of LeVg and LeVgR, disrupted the production of Vg in fat body and the uptake of Vg by oocytes, and ultimately led to a decline in fecundity. The results indicated that the JH signaling pathway was essential to the reproductive process of this species. Interestingly, knockdown of LeMet or LeKr-h1 also resulted in fluctuations in the expression of FoxO, indicating the complex regulatory interactions between different hormone factors. Besides, knockdown of both LeMet and LeKr-h1 significantly increased L. entomophila mortality. Our study provides initial insight into the roles of JH signaling in the female reproduction of psocids and provided evidence that RNAi-mediated knockdown of Met or Kr-h1 is a potential pest control strategy.

Integrating morphology and DNA barcodes for identification of Delia sanctijacobi Bigot 1885 (Diptera: Anthomyiidae): new host and new records in South America

Delia sanctijacobi is critically assessed and given a revised description using data from scanning electronic microscopy (SEM) and DNA barcode analysis. This species is recorded for the first time in Brazil and Peru. We provide a morphological identification key (with figures) for Delia species from Brazil, a molecular identification based on COI (cytochrome C oxidase subunit I) barcode sequences and an updated distributional map. We also report the first occurrence of D. sanctijacobi feeding on Brassica species in Brazil. This potential pest was observed in broccoli roots (Brassica oleracea var. italica; Brassicaceae) in União da Vitória, Paraná, southern Brazil, in August and September of 2017. The infested plants displayed reduced growth due to damage to the stem base or death if severely attacked.

Earwigs as potential pests of groundnut

Earwigs as potential pests of groundnut

Diversity and Role of Entomological Fauna Associated With Annona senegalensis (Magnoliales: Annonaceae) in Burkina Faso, West Africa.

Annona senegalensis Pers. is a shrub of tropical countries that, during the fruiting period, harbor many insects. All parts of the plant are used and exploited in traditional medicine, food, and firewood. Our study aimed at evaluating the diversity of insects associated with the different phenological stages of A. senegalensis fruits in two phytogeographic zones of Burkina Faso. Sampling was carried out on flowers, green fruits, ripe fruits, and decayed fruits of A. senegalensis. For the first time, a total of 48 insects species belonging to 6 orders and 23 families were identified. These orders were Orthoptera, Hemiptera, Hymenoptera, Coleoptera, Lepidoptera, and Diptera. Our data indicated that the diversity of insect species varies according to the stages of development of the fruit (P = 0.017) and according to the site (P = 2.2e-16). Among these insects, Curculionidae (Endaeus spp.) predominate on flowers, are known to be pollinators, and Formicidae (Messor galla Mayr, [Hymenoptera: Formicidae], Trichomyrmex abyssinicus Forel, [Hymenoptera: Formicidae], and Crematogaster sp.) and Tettigometridae (Hilda undata Walker, [Hemiptera: Tettigometridae]) are suspected to have mutualistic relationships on green fruits. Potential pests belonging to the Scarabaeidae (Pachnoda spp., Polybaphes spp., and Xeloma Maura Boheman, [Coleoptera: Scarabaeidae]), Drosophilidae (Zaprionus indianus Gupta, [Diptera: Drosophilidae]), and Nitidulidae (Carpophilus nepos Murray, [Coleoptera: Nitidulidae]) are associated with ripe and decayed fruits. The data in this study highlight the diversity in terms of pollinators that ensure the fruit production and Formicidae known to protect A. senegalensis against potential pests. These data provide valuable information in terms of valuation of this plant.

Improving artemisinin and essential oil production from Artemisia plant through in vivo elicitation with gamma irradiation nano-selenium and chitosan coupled with bio-organic fertilizers

Artemisia plants process potential bioactive secondary metabolites such as artemisinin and essential oil. They are useful in controlling potential pests and microbes and have a therapeutic effect. The commercial production of artemisinin and essential oil is limited to regarding the worldwide demand. Urgent attempts must be undertaken to improve the production of bioactive secondary metabolites. The objectives of this experiment were to increase the production and improve the quality of bioactive secondary metabolites in order to limit the use of agrochemicals. Therefore, a field experiment was conducted during the 2018 and 2019 seasons. Treatments included three elicitations (gamma irradiation, nano-selenium, and chitosan) and three kinds of fertilizers (NPK, Moringa leaf extract, and humic acid). The experiment was conducted as a factorial with a completely randomized block. The designs and treatments were arranged in a split–split plot with three replicates. A single application of elicitors showed that chitosan > nano-selenium, chitosan > gamma irradiation, and Moringa > humic acid > NPK in plants’ artemisinin and essential oil content, while the interaction showed a significant synergistic relationship between elicitors and the fertilizers in enhancing the quantity and quality of artemisinin and essential oil of Artemisia plants. Without using any pesticides, there was no infection that appeared in Artemisia plants, this could be due to the enhancement of bioactive secondary metabolite production.

Fitness of the Papaya Mealybug, Paracoccus marginatus (Hemiptera: Pseudococcidae), after Transferring from Solanum tuberosum to Carica papaya, Ipomoea batatas, and Alternanthera philoxeroides.

Simple SummaryThe papaya mealybug, Paracoccus marginatus, is a polyphagous invasive pest that causes severe damage in China. To improve our understanding of the expansion and prevalence of P. marginatus individuals on host plants, it is important to explore the fitness changes of insects after host plant shifting. In this study, we measured the development, fecundity, and population parameters in P. marginatus individuals over a span of three consecutive generations after being transferred from potato (Solanum tuberosum) to papaya (Carica papaya), sweet potato (Ipomoea batatas), and alligator weed (Alternanthera philoxeroides). Further, the population growth rates of insects on C. papaya, I. batatas, and S. tuberosum in the F2 generation were projected. We found that P. marginatus individuals transferred to C. papaya had higher fitness. When transferred to I. batatas, the fitness of P. marginatus initially decreased in F0 and then rebounded in F1 and F2. Paracoccus marginatus individuals could rapidly expand their populations on the above host plants. However, P. marginatus individuals were unable to complete their development on A. philoxeroides. Our findings provide new insights into the host plant fitness, prevalence, and potential pest control of P. marginatus.The papaya mealybug, Paracoccus marginatus Williams and Granara de Willink (Hemiptera: Pseudococcidae), is a polyphagous invasive pest in China. The effect that the shifting of the host plant has on the fitness of a polyphagous pest is critical to its prevalence and potential pest control. In order to assess the fitness changes of P. marginatus after transferal from potato (Solanum tuberosum (Tubiflorae: Solanaceae)) to papaya (Carica papaya (Parietales: Caricacea)), sweet potato (Ipomoea batatas (Tubiflorae: Convolvulaceae)), and alligator weed (Alternanthera philoxeroides (Centrospermae: Amaranthaceae)), the life table data of three consecutive generations were collected and analyzed using the age-stage, two-sex life table method. The results showed that when P. marginatus was transferred from S. tuberosum to papaya, a higher intrinsic rate of increase (r) and finite rate of increase (λ) were observed. Paracoccus marginatus individuals transferred to I. batatas had the significantly lower population parameters than those on C. papaya; however, the fitness recovered for those on I. batatas after two generations. Paracoccus marginatus individuals were unable to complete development on A. philoxeroides. Our results conclusively demonstrate that P. marginatus individuals can readily adapt to C. papaya and I. batatas even after host plant shifting, and are capable of causing severe damage to these hosts.

Family dinner: Transcriptional plasticity of five Noctuidae (Lepidoptera) feeding on three host plant species.

Polyphagous insects often show specialization in feeding on different host plants in terms of survival and growth and, therefore, can be considered minor or major pests of particular hosts. Whether polyphagous insects employ a common transcriptional response to cope with defenses from diverse host plants is under‐studied. We focused on patterns of transcriptional plasticity in polyphagous moths (Noctuidae), of which many species are notorious pests, in relation to herbivore performance on different host plants. We compared the transcriptional plasticity of five polyphagous moth species feeding and developing on three different host plant species. Using a comparative phylogenetic framework, we evaluated if successful herbivory, as measured by larval performance, is determined by a shared or lineage‐specific transcriptional response. The upregulated transcriptional activity, or gene expression pattern, of larvae feeding on the different host plants and artificial control diet was highly plastic and moth species‐specific. Specialization, defined as high herbivore success for specific host plants, was not generally linked to a lower number of induced genes. Moths that were more distantly related and showing high herbivore success for certain host plants showed shared expression of multiple homologous genes, indicating convergence. We further observed specific transcriptional responses within phylogenetic lineages. These expression patterns for specific host plant species are likely caused by shared evolutionary histories, for example, symplesiomorphic patterns, and could therefore not be associated with herbivore success alone. Multiple gene families, with roles in plant digestion and detoxification, were widely expressed in response to host plant feeding but again showed highly moth species‐specific. Consequently, high herbivore success for specific host plants is also driven by species‐specific transcriptional plasticity. Thus, potential pest moths display a complex and species‐specific transcriptional plasticity.

Evaluation of the Effect of Four Bioactive Compounds in Combination with Chemical Product against Two Spider Mites Tetranychus urticae and Eutetranychus orientalis(Acari: Tetranychidae).

Currently, pests control using chemical acaricides constitutes worries for ecologists and health care people as these chemical products create damage to the ecosystem as well as the development of spider mites resistance. Such concerns request deep and rapid feedback by looking for new alternative and eco-friendly methods. In recent years, a new field is evolving in the use of essential oils in pest management practices. Essential oils have been considered as potential pest management agents, because they demonstrate to have a broad range of bioactivity, possess contact, and fumigant toxicity. In addition, the major advantages of many plant-based acaricides lie in their low toxicity to agroecosystems. Botanical acaricides composed of essential oils may prove to be a good choice for the more persistent synthetic acaricides. In this study, the acaricidal effect of four plant-derived essential oils against adults of the two important crop pests, Tetranychus urticae (Koch) 1836 and Eutetranychus orientalis (Klein) 1936 are studied. The fumigant toxicity revealed that all the essential oils tested Mentha pulegium L., Lavandula stoechas L., Rosmarinus officinalis L., and Origanum compactum Benth (Lamiaceae family) displayed an acaricidal effect. At the highest dose (625 µl/ml), mortalities recorded were found between 91 and 98% and 92 and 99% at 24 and 48 h, respectively, for T. urticae, and between 90 and 98% and 94 and 99% at 24 and 48 h, respectively, for E. orientalis. The M. pulegium L. essential oil represents the highest activity against E. orientalis and T. urticae. For the binary combination between the EOs (essential oils) and the acaricide based on the active ingredient acequinocyl, the results showed that the mixture of O. compactum EO (essential oil) + acequinocyl exhibited an important acaricidal effect on T. urticae and E. orientalis with 99% at 24 h and 100% at 48 h of mortality, followed by M. pulegium EO + acequinocyl with 92% at 24 h and 95% at 48 h for T. urticae as well as 99% at 24 h and 100% at 48 h for E. orientalis of mortality. Whereas, the mixture of L. stoechas EO + acequinocyl presented the lowest activity against T. urticae and E. orientalis with 82–87% at 24 h and 86–90% at 48 h, respectively. The mixtures (M. pulegium EO + acequinocyl, R. officinalis EO + acequinocyl, and O. compactum EO + acequinocyl) exerted a high acaricidal effect against E. orientalis. These promising results could help to develop botanical pesticides that could be used in integrated pest management.

Gradually Increasing the Temperature Reduces the Diapause Termination Time of Trichogramma dendrolimi While Increasing Parasitoid Performance.

Simple SummaryTrichogramma dendrolimi is one of the most widely used biological control agents around the world, and diapause is a vital way to preserve Trichogramma products during mass production. However, diapause is a time-consuming process. In this study, we evaluated the effect of gradually increasing temperature on the diapause termination and the quality of Trichogramma products. The diapause termination rate reached the 95% required by practical applications when the induction period was high or in the treatments involving at least two-step variable temperatures (preceded by an induction period of 55, 60, and 70 days). Moreover, treatments consisting of at least two different temperatures led to higher parasitism and emergence rates while keeping the other parameters constant. In addition, the treatment with the highest temperature variation preceded by only 55 days of induction period had the highest population trend index. Our results demonstrate that gradually increasing temperature allows T. dendrolimi to complete diapause earlier than at present while increasing its potential pest control capacity and providing additional flexibility in mass production of T. dendrolimi.Trichogramma dendrolimi Matsumura is widely used as a biological control agent of many lepidopteran pests. Diapause has been used as an effective method to preserve the Trichogramma products during mass rearing production. However, it currently takes at least 70 days to break diapause, and we tested whether gradually increasing the temperature instead of using constant temperature could reduce the time of diapause termination and offer a higher flexibility to Trichogramma producers. The diapause termination rates of individuals kept at different conditions were measured, and five groups for which diapause termination rate reached the 95% were selected to test five biological parameters, including the number of eggs parasitized, the parasitism and emergence rates, the female sex ratio, the wing deformation rate, and the parasitoid longevity. Compared to the currently used procedure (70 days at 3 °C), treatments with at least two different temperatures resulted in higher parasitism and emergence rates while keeping the other parameters constant. The treatment that consisted of at least two different temperatures preceded by only 55 days of induction period had the highest population trend index, meaning that the population under these conditions grows more rapidly. Our results demonstrate that gradually increasing temperature allows T. dendrolimi to complete diapause earlier than at present while increasing its potential pest control capacity and providing additional flexibility in mass production of T. dendrolimi.