Please login first

List of accepted submissions

Show results per page
Find papers
  • Open access
  • 76 Reads
Molecular Identification of Mealybug Species (Hemiptera: Pseudococcidae) Affecting Theobroma cacao for Improved Pest Management

Theobroma cacao is affected by viruses on every continent where the crop is cultivated (North America, South America, Asia, and Africa), with the most well-known ones belonging to the Badnavirus genus. Badnaviruses are transmitted by several species of Pseudococcidae, a large, taxonomically diverse group of insects collectively known as mealybugs. Effective management of mealybugs depends on accurate identification of species present, as even closely related species have distinct life cycles and are vulnerable to chemical control at different times. To develop a molecular identification strategy, mealybugs were collected from four randomly selected T. cacao trees in a greenhouse in Florida, and DNA was extracted from individual specimens. This study compares the usefulness of the COI, ITS2, and 28S markers using the primer pairs (MFCO1/MRCO1, ITS2-M-F/ITS2-M-R, D10F/D10R, and D2F/D2R) to identify mealybugs associated with cacao plants in North America. All markers were equally informative for Pseudococcus comstocki (n=4) and Maconelicoccus hirsutus (n=8), but only CO1 provided unambiguous identification for Pseudococcus jackbeardsleyi (n=11). However, primer pair D2F/D2R is not recommended for mealybug identification. In addition to poor amplification, many of the sequences obtained were Anagyrus sp., wasp-like parasites frequently used for biocontrol. This study describes molecular diagnostic protocols for identifying cacao-infecting mealybugs and estimating the prevalence of certain parasitoids. This information is essential for selecting the most effective interventions as part of an integrated pest management program.

  • Open access
  • 135 Reads
Systematics of Tephritid Fruit Flies: A Machine Learning Based Pest Identification System

Tephritid fruit flies (Diptera: Tephritidae) are the major economically important agricultural pests around the world. Numerous control measures are undergoing to reduce their abundance. An efficient pest identification system is a prerequisite for such tasks. Typically, the classification/identification of different insect species is done based on either external body features or DNA barcoding. However, those approaches are time-consuming by nature, requiring expert knowledge in relevant fields. Several machine learning (ML) models have been successfully deployed in the field of systematics, but there is a lack of ML models for fruit fly species. This study aims to curate and validate a comprehensive tephritid image database and build ML models to automatically identify Tephritids from non-Tephritid dipteran flies and classify four major genera of notorious Tephritid flies, namely, Anastrepha, Ceratitis, Rhagoletis, and Bactrocera. The images of our experiment were collected from the iNaturalist database. The dataset was cleaned by removing uninformative images using a deep learning model (Inception-V3) and unsupervised k-mean clustering. Several state-of-the-art ML models were tested on the dataset, resulted in the highest accuracy of 95.44% with the EfficientNet-B0 model to identify tephritid flies from non-tephritids. Moreover, the EfficientNet-B2 model achieved 88.68% accuracy for classifying representatives of the major tephritid genus and showed the potential to enhance the identification accuracy. Overall, this work of the systematics of harmful fruit flies can be transformed into a practical and effective detection tool and can be implemented easily with existing agricultural pest control systems.

  • Open access
  • 75 Reads

Better Effect of a Lower Dose of Plant Substances in Deterring Storage Pests

The aim of the study was to compare the effect of two concentrations (0.1 and 1%) of different plant substances on dettering Rhyzopertha dominica F. and Sitophilus granarius L. Both species were treated with the essential oils of Foeniculum vulgare Mill. and Carum carvi L. as well as L-carvone, anethole and thymoquinone. In addition, the repellent effect of yachycline oil and dialyl disulphide was tested on R. dominica. The tests were carried in laboratory. The deterrence of insects were noted after 1, 2, 3, 4, 5, 24 and 48 h. It turned out that the essential oils and chemical compounds used in the experiments do not show the normal relationship described in the previous literature on storage pests, in which the repellency gets higher with the increase in the concentration of the tested plant material. It was found that a lower dose of the tested substances causes a greater deterrence of these species of beetles. In the case of R. dominica, the highest repellant effect was exerted by the concentration of 0.1%: carvone, diallyl disulphide and yachlane oil. Differences between the concentration of 0.1% and 1% were found among all tested substances in each time interval in the deterrent of R. dominica. This difference ranged from 4.17% to 52.92%. All substances used in the tests had a large deterrent effect on S. granarius (from 48 to 100%). Differences in the deterrence of S. granarius were found between 0.1% and 1% concentration in most of the tested substances in each time interval. The difference ranged from 1% to 15.42%.

  • Open access
  • 42 Reads
Invasive Pests of Robinia pseudoacacia Foliage in Plantings of the Lower Volga region, Russia

Plants of generic complex Robinia L., 1753 are characteristic of the dendroflora of the Lower Volga region. They are not native to the arid zone, their natural range is confind to North America. The beginning of the introduction of plants of this generic complex in Russia falls on the late 18th – early 19th centuries. They began to be used most massively in planting from the middle of the 20th century. Robinia species have been resistant to pests for many years. For the last decade, damage to the foliage of the robinia (whiteacacia) marginal gall midge Obolodiplosis robinia (Haldeman, 1847) (Diptera: Cecidomyiidae) and Nematus tibialis (Newman, 1837) (Hymenoptera, Tenthredinidae) has been recorded annually in the crowns of Robinia pseudoacacia L. On the territory of the Russian Federation, gall midge was first recorded in 2006 and by 2010, it reaches the Volgograd region. Here, Obolodiplosis robiniae successfully masters the assimilation apparatus of Robinia of different ages in plantations of various types and ecological categories. The density of galls in plantings on average is 1.9 pcs. / leaf, the maximum is 7.0 pcs. / leaf. Since 2017, on the territory of the Lower Volga region, Nematus tibialis has been recorded in plantations with the participation of woody plants of the genus Robinia. This pest prefers the foliage of trees of intra-quarter plantings and squares located near buildings or adjacent to them. On average, the density of larvae in the crown of a tree is 2.12 pcs. / leaf.

  • Open access
  • 69 Reads
Improving the Monitoring System Towards Early Detection and Prediction of the Siberian Moth Outbreaks in Eastern Siberia

The Siberian moth, Dendrolimus sibiricus Tschetverikov (Lepidoptera: Lasiocampidae) is a dangerous pest of the taiga forest in Siberia. The present research is aimed to improve the monitoring system towards early detection and prediction of the Siberian moth outbreaks in dark-coniferous taiga in the mountainous region of Krasnoyarsk Krai (Eastern Siberia). The study determined the habitats preferred by the Siberian moth considering the relief, the type of forest and forest inventory characteristics. For that, we analyzed data obtained with the remote sensing and those collected in nature in 2018-2019 through surveying the plots damaged by the pest.

  • Open access
  • 38 Reads
Mediterranean Wild Herbs As Grain Protectants

In this study we explored the pesticide properties of several essential oils (EOs) yielded from aromatic plants of the Mediterranean Basin. For this purpose, the insecticidal effect of the EOs from Citrus limon (Sapindales: Rutaceae), Juniperus phoenicea (Pinales: Cupressaceae), Laurus nobilis (Laurales: Lauraceae), Echinophora tenuifollia ssp. sibthropiana (Apiales: Apiaceae), Origanum majorana and O. vulgare ssp. hirtum (Lamiales: Lamiaceae) was evaluated in laboratory bioassays on two target insect pests, the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae). The EOs were formulated to micro emulsions, with food grade emulsifier and were applied as wheat coating. Subsequently, the treated grain was infested by larvae of T. castaneum or adults of T. granarium. Mortality data obtained from the dose-response trials were subjected to probit analysis and LD50 values were estimated. The LD50 values for T. castaneum larvae were 416.1, 424.1, 454.5, 490.5, 539.4 and 649.4 ppm for the C. limon, E. tenuifollia ssp. sibthropiana, O. majorana, O. vulgare ssp. hirtum, L. nobilis and J. phoenicea EOs, respectively. Regarding T. granarium adults, the LD50 values were 440.6, 501.3, 506.9, 530.7, 619.1, and 745.3 ppm for the O. majorana J. phoenicea, L. nobilis, O. vulgare ssp. hirtum, E. tenuifollia ssp. sibthropiana and C. limon EOs, respectively. The generated results could be useful for the management of the target stored-product insect pests by using reduced-risk plant protection products.

  • Open access
  • 54 Reads
Development of formulation based on essential oils of rosemary to manage pests of stored cereal foodstuffs

The aim of this work is to evaluate the insecticidal activity of the encapsulatedrosemary (Rosmarinus officinalis L.) essential oil coated intochitosan matrix. The effectiveness of crude and encapsulated oils has been studied during different storage periods (30, 45 and 60 days). Results revealed that the chitosan-essential oil formulation exhibited high insecticidal activity against adults of Tribolium castaneum as compared to crude essential oil during the different storage periods.

  • Open access
  • 55 Reads
Orchard floor weed cover does not influence infestation of peach trees by the peachtree borer, Synanthedon exitiosa

The peachtree borer, Synanthedon exitiosa, is an economically important wood boring pest of peach and other stone fruit trees throughout much of the United States. Infestation and damage by larvae of this species is generally confined to the trunk and roots near the soil line. A two-year field experiment was conducted in a commercial peach orchard to study the effect of orchard floor weed cover on incidence of peachtree borer infestation in peach blocks under two different pest management regimes; mating disruption and conventional insecticides. During the study, weed cover did not significantly affect the mean percentage of peach trees infested by peach tree borer, regardless of management regime. A weak to small, negative Pearson correlation coefficient existed between weed cover ratings and the percentage of infested trees. Our hypothesis that weed free (bare soil) areas around the trunks of peach trees would favor peachtree borer infestation was not supported by our data.

  • Open access
  • 56 Reads
Double Strand RNA Absorption in Citrus Trees for Delivery to Asian Citrus Psyllids, Diaphorina citri (Hemiptera: Liviidae).

RNA interference, RNAi, continues to be a leading tool in functional genomics studies and in crop plants, for the management of viral pathogens, insect pests, and improving plant traits. However, there are still questions concerning consistent delivery into plants when using topically applied RNAi. RNAi products have the potential to reduce psyllid vector populations by disrupting nymph survival, which may provide an effective strategy in the disruption of Candidatus Liberibacter asiaticus transmission throughout citrus trees. This study examined factors that may affect dsRNA absorption and systemic movement in citrus trees and the subsequent delivery into the hemipteran, Diaphorina citri, the Asian citrus psyllid.

  • Open access
  • 97 Reads

The efficacy of Datura ferox (Fierce Thorn apple) leaf extracts against Yellow Sugarcane Aphid (Sipha flava) in the Zimbabwe Sugar Industry

The study was carried out to test the efficacy of Datura ferox (fierce thorn apple) leaf extracts against Yellow Sugarcane Aphid (Sipha flava) in the laboratory. Sequential exhaustive extraction was performed using three solvents of varied polarities and these included ethanol, hexane and ethylacetate. This was done to obtain crude extracts with components of a wide range of polarity. The most polar solvent yielded the highest followed by an intermediate polar and then non polar. This showed an increase trend in yield with solvent polarity. The laboratory experiment had three treatments which were extracts from different solvents. Different concentrations were prepared using the N1V1= N2V2 method. Acetamprid (Allice) was used as the standard/ positive control and pure solvents were also used as negative controls. To test for the toxicity of the extracts, the filter paper method was adopted and petri dishes were used to confine the aphids. Aphid numbers between 50 and 70 were chosen. Mortality was recorded after 3, 24 and 36 hours. LD50 and LD90 were calculated in excel. Ethanol extracts showed the highest efficacy against the aphids. Alkaloids which are the main active ingredients in Datura ferox are polar and they tend to be extracted by more polar solvents which explains why ethanol extracts showed the highest efficacy against the aphids.The extracts that showed the highest insecticidal activity were taken for phytochemical screening. Alkaloids were phytochemicals of interest in this survey. However, screening was also done for flavonoids, tannins, phenols, coumarins, saponins anthraquinones and terpenoids. Alkaloids and flavonoids were also confirmed using Thin Layer Chromatography.