Phytoparasitica最新文献

Liriomyza sativae infestations pose a threat to horticultural crops like melon and tomato, causing economic losses of up to 30%, typically managed through insecticide applications. Despite the inherent risk of resistance development in populations, reported cases are still relatively low that may be associated with the practicality of the existing bioassay methods. To address the resistance phenomenon in a species, a practical and reliable method to generate susceptibility data should be used. This study aimed to refine existing bioassay method(s) for Liriomyza against different modes of action and set up the susceptibility status of field populations to cyantraniliprole and spinetoram in Brazil. Using the leaf disc immersion method, individual larvae on leaf discs were transferred to both bioassay trays and acrylic Petri dishes after treating them, and mortality was assessed 48 and 72 h after exposure. Susceptibility parameters varied with arena type, exposure duration, and insecticide. Bioassay tray arenas showed consistency of response compared to acrylic dishes and improved parameters at 72 h exposure among the modes of action assessed. Thus, survey of populations against cyantraniliprole and spinetoram using Bioassay tray arenas showed to be consistent and data suggested resistance evidence in L. sativae populations. Resistance ratio varied from 1.2- (MSR4) to 4.2- (BRN1) and from 1.6- (MSR5) to 7.9-fold (MSR2) for cyantraniliprole and spinetoram, respectively. Diagnostic concentration (10 mg/L) for both insecticides showed survival up to 10% (spinetoram) and 2% (cyantraniliprole). The bioassay tray method may be an alternative to existing methods for toxicological assessments and detection/documenting resistance to insecticides.

Thrips (Thysanoptera), being eminent pests with significant agricultural implications on a global scale, cause considerable economic harm to an extensive array of ornamental, horticultural, and fruit crops. While morphological identification of thrips is often sufficient, the exploration of molecular methodologies can provide additional accuracy in species identification when needed. In this study, we used sequencing methods targeting the partial mitochondrial cytochrome oxidase subunit I (COI) gene to identify ten thrips species collected from 19 plant species in Brazil. Species-specific primers were developed based on COI and 28S sequences for precise identification of Caliothrips phaseoli and Frankliniella occidentalis. Bayesian phylogenetic analyses showed the absence of species clustering within their respective genus clades, while pairwise analyses demonstrated significant intraspecific variation in F. schultzei.

The complex of phytophagous stink bugs is responsible for considerable reductions in the yield potential of soybean crops. Insecticides are usually used for the management of these pests; however, the egg parasitoid Telenomus podisi Ashmead (Hymenoptera: Scelionidae) has become a promising alternative due to its mass production and commercialization in Brazil. This study evaluated the efficacy of inoculative releases of T. podisi prior to the crop critical period of stink bug attack. The experiments were carried out in the field during the 2019/20 and 2020/21 crop years, using a drone for parasitoid releases. The combined analysis of both crop years showed the potential replacement of chemical control with biological control with T. podisi in the initial applications. This change did not significantly affect crop yield, thousand-seed weight (TSW), and seed physiological quality assessed in germination and tetrazolium tests. In addition, the treatment with the first application performed with the parasitoid release, followed by two applications of synthetic insecticides (applied fortnightly), showed no significant differences in the number of stink bugs captured in a vertical beating cloth when compared to the farmer’s pattern (three insecticide applications). Moreover, abundance of generalist predators was higher in the control (without application) and in the treatment constituted by two T. podisi releases. Thus, inoculative releases of T. podisi prior to the critical crop period constitute a promising management alternative for the stink bug complex in soybean crops, contributing to the stability and sustainability of the production system. 

Phytophagous insects likely select suitable host plants for oviposition based on olfactory and tactile cues. However, details of how insects differentiate among different plant varieties are often unclear. The fall armyworm (Spodoptera frugiperda J. E. Smith) is a highly destructive pest on maize, but little is known about the attraction and oviposition preference of S. frugiperda to different maize varieties, particularly in the context of sub-Saharan Africa, where the insect is a major threat to maize production. We determined the oviposition preference of S. frugiperda females on six different maize plant varieties three of which were hybrid varieties and three were open-pollinated varieties, in multiple-choice and no-choice assays. We also evaluated the attraction preference of S. frugiperda larvae on these maize varieties, using an olfactometer bioassay. We found that S. frugiperda females oviposited significantly less egg masses on the hybrid varieties DEKAIB and 30Y87 than on the other varieties tested and that females oviposited less on the hybrid maize varieties compared to the open-pollinated maize varieties overall. Additionally, we found that S. frugiperda larvae were more attracted to the open-pollinated variety LMFP than to clean air, which was not the case for any of the other maize varieties tested. Taken together, our results show that S. frugiperda responds differentially to the different maize varieties and that hybrid maize varieties seem less attractive. Further investigating the chemistry of hybrid maize varieties like DEKAIB might yield clues on how to breed maize varieties with increased resistance against S. frugiperda infestation.

Astylus atromaculatus Blanchard, 1843 (Coleoptera: Melyridae) is a pollinivorous beetle native to southern South America, which has invaded South Africa more than a century ago. Adults and/or larvae may occasionally damage flowers, seeds, and seedlings of various crops. Severe cattle intoxication has also been reported in Argentina, Uruguay, and South Africa following consumption of alfalfa and forage grasses infested with A. atromaculatus. Despite its economic impact, essential genetic information is lacking for this species. The present paper provides the first DNA barcode reference sequences for A. atromaculatus based on the standard 5’ fragment (658 bp) of the cytochrome c oxidase subunit I gene. The sequences obtained exhibited pairwise distances of ≤ 1.82% among them, and ~ 90% nucleotide identity with the homologous gene fragment in the morphologically similar Astylus variegatus Germar, 1824. The use of this molecular marker to explore the intraspecific variability of A. atromaculatus in central Argentina showed 21 different haplotypes, out of 32 individuals analyzed. A very high haplotype diversity (H_d = 0.962 ± 0.019) and a moderate nucleotide diversity (π = 0.00778 ± 0.00079) were recorded. The haplotype network displayed a diffuse structure due to the abundance of singletons and possible missing haplotypes, with the most common haplotype comprising only 15.6% of the specimens collected. Future research with increased sampling size and geographic coverage will allow for a better understanding of the population genetics of this pest, and consequently, for developing efficient management practices.

This paper documents new country records of five alien armoured scale insect species (Hemiptera: Coccomorpha: Diaspididae), in India, their possible spread and probable threat to crops and ornamental plants grown indoors and outdoors. The insects were mostly collected in open fields, and on indoor plants grown in residential and office areas. The following alien species are recorded from India for the first time: Duplaspidiotus claviger (Cockerell), Lepidosaphes laterochitinosa Green, Kuwanaspis howardi (Cooley), Rutherfordia malloti (Rutherford) and Aulacaspis alisiana Takagi. Each of the five species is diagnosed using a combination of unique field and slide-mounted identification characters. Ecological information on host-plants, distribution, and economic importance is provided.

The insecticide flufenoxuron, one of the insect growth regulators used in pest control, has been presented as a viable alternative against several insects and mites by inhibiting chitin synthesis and leading to changes in the midgut epithelium. The current study aimed to examine whether flufenoxuron interferes with the structural organisation, weight, volume, fecundity and fertility of the male reproductive system of Spodoptera mauritia, a sporadic pest that occasionally inflicts significant losses to rice crops. Median effective dose (ED₅₀) indicates that flufenoxuron is effective against S. mauritia, and the moulting inhibition percentage, when calculated with probit analysis, indicates that ED₅₀ were 0.00068 µg for 144 h. Topical application of two selected doses (ED₂₅ and ED₅₀) was applied to find out the effects of flufenoxuron exposure on male gonadal development. The flufenoxuron treatment significantly impaired the organization and development of the testis follicles and other parameters like weight, volume and gonadosomatic index. Moreover, reductions in fecundity and fertility rate, 27.33 ± 13.86 and 85.36 ± 12 for treated male × untreated female, 47 ± 23.33 and 97.16 ± 22.92 for untreated male × treated female, and 4 ± 4 and zero for both treated pairs, were found in the emerged S. mauritia adult following the larval treatment, suggesting the occurrence of defects in reproductive organs in both male and female moths. These findings highlight the reproductive toxicity of flufenoxuron on the rice swarming caterpillar, offering insights into the male reproductive toxicity associated with chitin synthesis inhibition. The impairment of reproductive organ development suggests the potential use of flufenoxuron for controlling pest populations effectively.

The cotton aphid or melon aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is a rising threat to cotton production. Aphids use needle-like stylets to puncture the plant epidermis, access the sieve tube, and ingest the plant phloem. Aphids release salivary proteins while feeding, allowing them to colonize host plants successfully. Aphid saliva consists of many constituents that facilitate the consumption of phloem sap upon partial digestion and modulate plant defense systems. The salivary proteomes of A. gossypii were studied using liquid chromatography-tandem mass spectrometry (LC–MS/MS), which resulted in the identification of 189 proteins in excised salivary glands and 95 proteins in artificial diet-fed aphid saliva, with 25 proteins commonly noticed in both proteomes. Several proteins, including CAH1711662.1, CAH1735943.1, PFF0380w, XP_027839681.2, CAH1714583.1, CAH1713131.1 and XP_027840117.2 remained unique and uncharacterized. Previously identified salivary proteins of insects, such as glucose dehydrogenase, Mp1, Mp58, peroxidase, heat shock protein (HSP), elongation factor, and aminopeptidases, were also found. The identified proteins were categorized into seven groups, viz., enzymes, cytoskeletal proteins, sheath proteins, calcium-binding proteins, transporter proteins, chromatin-, RNA-, and DNA-binding proteins, and miscellaneous proteins. Twenty-five proteins from diet-fed aphid saliva and 17 proteins in the salivary gland possessed signal peptides. This study's results offer a more detailed understanding of the salivary proteins of A. gossypii and provide the foundation for future functional studies on aphid-cotton interactions to develop new aphid control methods.

The goal of this study is to explore the effects of lemongrass and peppermint essential oils, specifically at their LC50 concentrations, on the demographic parameters of two mite species: Oligonychus mangiferus (Rahman & Sapra) and its predatory mite counterpart, Cydnoseius negevi (Swirskii & Amitai). By evaluating these essential oils, the study aims to contribute to eco-friendly pest management strategies within integrated pest management (IPM) programs. The effects of these oils were assessed in terms of measuring the activity of antioxidant and detoxifying enzymes. GC–MS was used to identify the chemical components of these oils. The main compounds identified by GC–MS in lemongrass and peppermint essential oils were D-Limonene (45.06%), β-Citral (10.30%), α-Citral (9.90%)) and (Menthol (32.03%), Menthone (30.18%), p-Menthan-3-one (11.53%), respectively. The results showed that lemongrass and peppermint were more toxic to O. mangiferus than to C. negevi. Exposure of O. mangiferus to the LC₅₀ of these oils caused a significant increase in peroxidase and catalase enzymes, but it inhibited the detoxifying enzymes, α-esterase, β-esterase, and glutathione s-transferase. Also, these oils had disruptive effects on survival, longevity, and fecundity of O. mangiferus; as they reduced its demographic parameters such as (R₀) (GRR) (r_m), and (λ). However, they did not show any substantial change in the development time and demographic parameters of C. negevi. On the contrary, they improved its enzymes activity. According to these findings, these essential oils can be used in combination with biological control agents in the integrated pest management strategies against the mango spider mite, O. mangiferus.