Polyphagous Pest Research Articles

Discovery of Three Bemisia tabaci Effectors and Their Effect on Gene Expression in Planta.

Bemisia tabaci (whitefly) is a polyphagous agroeconomic pest species complex. Two members of this species complex, Mediterranean (MED) and Middle-East-Asia Minor 1 (MEAM1), have a worldwide distribution and have been shown to manipulate plant defenses through effectors. In this study, we used three different strategies to identify three MEAM1 proteins that can act as effectors. Effector B1 was identified using a bioinformatics-driven effector-mining strategy, whereas effectors S1 and P1 were identified in the saliva of whiteflies collected from artificial diet and in phloem exudate of tomato on which nymphs were feeding, respectively. These three effectors were B. tabaci specific and able to increase whitefly fecundity when transiently expressed in tobacco plants (Nicotiana tabacum). Moreover, they reduced growth of Pseudomonas syringae pv. tabaci in Nicotiana benthamiana. All three effectors changed gene expression in planta, and B1 and S1 also changed phytohormone levels. Gene ontology and KEGG pathway enrichment analysis pinpointed plant-pathogen interaction and photosynthesis as the main enriched pathways for all three effectors. Our data thus show the discovery and validation of three new B. tabaci MEAM1 effectors that increase whitefly fecundity and modulate plant immunity. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Investigation on the Biology of Helicoverpa armigera (Hubner) on Chickpea under Laboratory Condition

The Helicoverpa armigera (Hubner) is a polyphagous pest that is found throughout the world. Due to its damaging nature, it causes quantitative as well as qualitative loss and finally overalleconomic loss in agricultural crop production. So, the present investigation was done by rearing of H. armigera on chickpeas under laboratory conditions. The study revealed that this pest has four distinct stages i.e., egg, larva, pupa, and adult for completing its life cycle. The total life cycle of males and females were completed in 49-50 days and 52.30-53.00 days, respectively. The wholelife period was divided asthe incubation period takes 4-5 days, larval stage was completed in 20.00-20.50 days by passing through six instars under laboratory conditions at a temperature of 27±10C with 70±5 % relative humidity in 12 hours of light. The last larval instar did not molt and it contracted into a grub-like pre-pupal stage which lasted for 2-3 days and a pupal period of 13-14 days. The adult period of male and female insects was completed in 8.50-9.00 and 12.00-12.50 days, respectively. The female moths had a pre-oviposition period of 3-4 days that included a sexual maturity period. The oviposition and post-oviposition periodsrecorded were 5-6 days and 2 days, respectively. A single female produced on average 992.50-1085 eggs throughout her entire life span. The average hatching percentage of eggs recorded on 63.00-67.50 percent.

Cellulose nanocrystal filled synthetic rubber: Sustainable production, environmental assessment and end-of-life biodegradation by polyphagous pests

Plastic and rubber productions have reached staggering levels, leading to environmental concerns and accumulation of microplastics (MPs) rising in ecosystems. Rubber tires, a major source of MPs, pose further challenges due to excessive use of carbon black (CB) nanofillers in their manufacturing process, stresses on adding the element of sustainability to these products. This study emphasizes on the production of bio-based cellulose nanocrystals (CNC) filled synthetic rubber with sustainability assessment through life cycle assessment (LCA). It investigates the end-of-life (EOL) biodegradation potentials of rubber waste using a polyphagous pest, fall armyworm (FAW) (Spodoptera frugiperda). The results revealed that the production of CNC filled rubber demonstrate enhanced modulus compared to CB nanofillers, while requires substantial resource consumption, impacting abiotic resource depletion–fossil fuels (ADPf), freshwater ecotoxicity (CTUe), global warming potential (GWP), particulate matter (PM) and other impact categories. Emissions associated with CNC filled rubber during EOL phase are comparatively lower than CB, rendering CNC based rubbers a potentially viable choice from an environmental sustainability perspective. EOL pest biodegradation of CNC filled rubber showed negligible to no discernible physiological effects, potentially attributed to the presence of a diverse gut microbiota community in FAW (S. frugiperda). These findings highlight the relationship between physiochemical properties and CNC biodegradability in synthetic rubbers, aiding the development of sustainable EOL strategies for rubber waste management.

Phytometabolites from coral jasmine flower extracts: Toxic effects on Spodoptera litura and enzyme inhibition in nontarget earthworm Eisenia fetida as an alternative approach

Green pesticides, derived from natural sources, have gained wider attention as an alternative to synthetic pesticides for managing polyphagous pests, such as Spodoptera litura. In this study, the methanolic flower extract of Nyctanthes arbor-tristis (Mx-Na-t) was subjected to chemical screening, and 3-hydroxy-1,2-dimethyl-4(1H)-pyridone (3H-dp) and tyrosol (Ty-ol) were identified as the major derivatives. The toxic effects of Mx-Na-t (500 ppm) were highest in third-instar S. litura larvae (96.4%), while those of 3H-dp and Ty-ol (5 ppm) were highest in second-instar larvae (76.5% and 81.4%, respectively). The growth and development of S. litura larvae and pupae were significantly reduced by all three treatments. Fecundity rates were also reduced by all treatments [from 1020 eggs (control) to 540 eggs by Mx-Na-t treatment, 741 eggs by 3H-dp treatment, and 721 eggs by Ty-ol treatment]. The extract and its active constituents decreased adult emergence and slowed total larval development in a dose-dependent manner. A decrease was noted in the major gut enzymes of young S. litura larvae exposed to Mx-Na-t, 3H-dp, and Ty-ol. Moreover, midgut tissues of fourth-instar larvae were severely damaged by Mx-Na-t (250 ppm), 3H-dp (2.5 ppm), and Ty-ol (2.5 ppm); the treatments induced structural damage to the epithelial cells and gut lumen. The earthworm Eisenia fetida was used to assess nontarget toxicity. Compared with cypermethrin, the phytochemicals exhibited minimal effects on the earthworm's detoxifying enzymes superoxide dismutase and catalase after 14 days of treatment. Moreover, in silico predictions using BeeTox and ProTox-II indicated little or no toxicity of 3H-dp and Ty-ol toward honey bees and other nontarget species.

Morphometric Studies of Tobacco Caterpillar, [Spodoptera litura (Fabricius)] on Different Host Plants

Tobacco caterpillar, Spodoptera litura (Fabricius) is an economically important polyphagous pest inflicting significant economic damage to numerous field and horticultural crops. Research was conducted at the Department of Entomology, Bihar Agricultural University, Sabour, Bhagalpur, Bihar, in laboratory settings to validate the presence of this pest. The investigation involved detailed measurements of the various larval stages, pupa, adult male, and female, of tobacco caterpillar including the wingspan. The first to sixth instars of S. litura exhibited significantly greater length and width as well as width of head capsule, when reared on the tomato as a host. The pupae of S. litura reached at their maximum length and width when raised on marigold (16.75 mm and 4.36 mm), while the minimum pupal measurements (14.10 mm and 4.42 mm) was observed in case of maize. In regards to the adult moths, both male and female specimens displayed the longest length and wing span when associated with tomato (16.71 mm and 18.22 mm for length, 38.47 mm and 38.73 mm for wingspan, respectively), whereas the smallest measurements were recorded for those associated with maize (14.35 mm and 16.95 mm for length, 35.10 mm and 35.12 mm wingspan respectively). The present study confirmed the presence of S. litura that require immense attention to prepare the management strategy against it.

Microbiome changes in Akanthomyces attenuatus JEF-147-infected two-spotted spider mites

The two-spotted spider mite (Tetranychus urticae Koch) is an agriculturally serious polyphagous pest that has acquired strong resistance against acaricides because of its short life cycle and continuous exposure to acaricides. As an alternative, mite-pathogenic fungi with different modes of action could be used to control the mites. The spider mite has symbiotic microorganisms that could be involved in the physiological and ecological adaptations to biotic stresses. In this study, mite-pathogenic fungi were used to control female adults, and the microbiomes changes in the fungus-infected mites were analyzed. The acaricidal activity of 77 fungal isolates was tested, and Akanthomyces attenuatus JEF-147 exhibited the highest acaricidal activity. Subsequently a dose–response assay and morphological characterization was undertaken For microbiome analysis in female adults infected with A. attenuatus JEF-147, 16S rDNA and ITS1 were sequenced using Illumina Miseq. Infected mite showed a higher Shannon index in bacterial diversity but lower index in fungal diversity. In beta diversity using principal component analysis, JEF-147-treated mites were significantly different from non-treated controls in both bacteria and fungi. Particularly in bacterial abundance, arthropod defense-related Rickettsia increased, but arthropod reproduction-associated Wolbachia decreased. The change in major bacterial abundance in the infected mites could be explained by a trade-off between reproduction and immunity against the early stage of fungal attack. In fungal abundance, Akanthomyces showed up as expected. Foremost, this work reports microbiome changes in a fungus-infected mite and suggests a possible trade-off in mites against fungal pathogens. Future studies will focus on gene-based investigations related to this topic.

The chromosomal-scale genome sequencing and assembly of Athetis lepigone

Athetis lepigone is an emerging highly polyphagous insect pest reported to cause crop damage in several European and Asian countries. However, our understanding of its genetic adaptation mechanisms has been limited due to lack of high-quality genetic resources. In this study, we present a chromosomal-level genome of A. lepigone, representing the first species in the genus of Athetis. We employed PacBio long-read sequencing and Hi-C technologies to generate 612.49 Mb genome assembly which contains 42.43% repeat sequences with a scaffold N50 of 20.9 Mb. The contigs were successfully clustered into 31 chromosomal-size scaffolds with 37% GC content. BUSCO assessment revealed a genome completeness of 97.4% with 96.3 identified as core Arthropoda single copy orthologs. Among the 17,322 genes that were predicted, 15,965 genes were functionally annotated, representing a coverage of 92.17%. Furthermore, we revealed 106 P450, 37 GST, 27 UGT, and 74 COE gene families in the genome of A. lepigone. This genome provides a significant and invaluable genomic resource for further research across the entire genus of Athetis.

Rapid Bioassay for Detection of Insecticide Resistance in Aphis gossypii Glover, 1877 (Hemiptera: Aphididae)

Cotton aphid, Aphis gossypii Glover, 1877 (Hemiptera: Aphididae) is one of the most economically important polyphagous pests that shows rapid resistance to chemical control. Determination of resistance levels is important within resistance management. The insecticide activities of Acetamiprid, Dimethoate, Imidacloprid, L-cyalothrin were investigated on different aphid populations to develop a faster and more economical bioassay method. Resistance levels were compared by making bioassays with insecticides using the leaf dipping method for 72 hours, 120 minutes and different doses. Resistance rates varying between 1-10 times were observed in both methods. The rapid application of 120 minutes is more advantageous in terms of speed, application time and economy of the method in the detection of resistance against Acetamiprid, Dimethoate, Imidacloprid, L-cyalothrin insecticides, and will contribute to the detection of resistance and the development of bioassay method.

Investigation of the insecticidal potential of curcumin derivatives that target the Helicoverpa armigera sterol carrier protein-2

Cotton bollworm (Helicoverpa armigera) is a highly polyphagous, widely prevalent, and persistent Old World insect pest that affects numerous important crops that are directly consumed by people, including tomato, cotton, pigeon pea, chickpea, rice, sorghum, and cowpea. Insects do not synthesize steroids but obtain them from their diet. Inhibition of dietary uptake of steroids by insects is a potentially effective insecticidal mechanism that should not be toxic to humans and other mammals, who synthesize their steroids. Ten curcumin derivatives were tested against H. armigera sterol carrier protein-2 (HaSCP-2) for their potential as insecticidal agents. Curcumin derivatives were initially docked at the binding site of HaSCP-2 to determine their binding affinities and plausible binding modes. The binding modes predominantly show hydrophobic interactions of derivatives with Phe53, Phe110, and Phe89 as core interacting residues in the active site. Validation of in silico results was carried out by performing a fluorescence binding and displacement assay to determine the binding affinities of curcumin derivatives. Among a collection of curcumin derivatives tested, Cur10 showed the lowest IC50 value of 9.64 μM, while Cur07 was 19.86 μM, and Cur06 was 20.79 μM. There was a significant negative correlation between the ability of the curcumin derivatives tested to displace the fluorescent probe from the sterol binding site of HaSCP-2 and to inhibit Sf9 insect cell growth in culture, which is consistent with the curcumin derivatives acting by the novel mechanism of blocking sterol uptake. Then molecular dynamics simulation studies validated the predicted binding modes and the interactions of curcumin derivatives with HaSCP-2 protein. In conclusion, these studies support the potential use of curcumin derivatives as insecticidal agents.

Vivir dentro de cestas: un nuevo árbol frutal hospedante para Oiketicus kirbyi Guilding, 1927 (Lepidoptera: Psychidae) en Brasil

The bagworm Oiketicus kirbyi is an extremely polyphagous insect pest that attacks several crops of economic importance in various Brazilian regions. In this paper, we are made the first record of O. kirbyi in Maranhão state, northeast Brazil region. Additionally, the Jabuticabeira tree Plinia grandifolia, an economically important Brazilian fruit tree, is presented as a new fruit tree host for O. kirbyi. Two larvae specimens of this species were collected in a garden of a residential condominium, on an individual of the P. grandifolia. This found is of great importance given the economic relevance of Jabuticabeira tree and the high level of damage that can be caused by O. kirbyi larvae on fruits production.

Effect of yeast and mineral fertilisers on the level attack of the solenopsis mealybug and productivity okra plants

Mineral fertilisers are one of the most important nutrients that plants need in large quantities, which help to greatly increase crop yields, and yeast is considered a bio-stimulator of plants. However incorrect implementation of both can make them more susceptible to pest infestations. The mealybug, Phenacoccus solenopsis (Hemiptera: Pseudococcidae), is an economically important polyphagous pest that destroys okra plants in Egypt. This work focused on the evaluation of mealybug infestations and okra plant productivity responses to mineral fertilisers (nitrogen and phosphorus), yeast (without and with) and their interactions. This study was executed in a private okra field (‘Balady’ cultivar) in Luxor Governorate, Egypt, during 2021 and 2022 seasons. A split plot design was applied, where two levels (with and without yeast) were used in the main plots, where seven levels of nitrogen and phosphorus were applied in the split plots. The results indicated that the addition of 286 kg N∙ha –1, 143 kg P∙ha –1 and yeast to okra plants led to a maximum increase in the population densities of pest, and this caused a decrease in the vegetative stage of okra that would affect the final yield as compared to the other treatments throughout the two seasons. However, the application of 190 kg N∙ha –1, 107 kg P∙ha –1, and yeast to okra plants gave the highest values for vegetative growth characteristics and resulting yield during the two studied seasons. This work aids farmers in improving okra production by comprehending good farming practices and avoiding the spread of mealybugs.

Gene Cloning, Heterologous Expression, and In Silico Analysis of Chitinase B from Serratia marcescens for Biocontrol of Spodoptera frugiperda Larvae Infesting Maize Crops.

Spodoptera frugiperda, the fall armyworm (FAW), is a highly invasive polyphagous insect pest that is considered a source of severe economic losses to agricultural production. Currently, the majority of chemical insecticides pose tremendous threats to humans and animals besides insect resistance. Thus, there is an urgent need to develop new pest management strategies with more specificity, efficiency, and sustainability. Chitin-degrading enzymes, including chitinases, are promising agents which may contribute to FAW control. Chitinase-producing microorganisms are reported normally in bacteria and fungi. In the present study, Serratia marcescens was successfully isolated and identified from the larvae of Spodoptera frugiperda. The bacterial strain NRC408 displayed the highest chitinase enzyme activity of 250 units per milligram of protein. Subsequently, the chitinase gene was cloned and heterologously expressed in E. coli BL21 (DE3). Recombinant chitinase B was overproduced to 2.5-fold, driven by the T7 expression system. Recombinant chitinase B was evaluated for its efficacy as an insecticidal bioagent against S. frugiperda larvae, which induced significant alteration in subsequent developmental stages and conspicuous malformations. Additionally, our study highlights that in silico analyses of the anticipated protein encoded by the chitinase gene (ChiB) offered improved predictions for enzyme binding and catalytic activity. The effectiveness of (ChiB) against S. frugiperda was evaluated in laboratory and controlled field conditions. The results indicated significant mortality, disturbed development, different induced malformations, and a reduction in larval populations. Thus, the current study consequently recommends chitinase B for the first time to control FAW.

Status of fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera : Noctuidae) and its natural enemies at major maize growing areas of Haveri district

Fall armyworm (Spodoptera frugiperda) belongs to the family Noctuidae which has got economic importance as polyphagous and extreme pest of many important crops, including maize in India and elsewhere.In this context, roving survey was conducted on two cropping seasons at fortnightly interval during kharif and rabi of 2019-20 to know the status of fall armyworm in all the seven talukas of Haveri district viz., Hirekerur, Ranebennur, Byadagi, Haveri, Shiggaon, Savanur and Hangal. The results revealed that the mean larval population and per cent infestation of fall armyworm was ranged from 0.30 to 0.44 larvae per plant and 23.10 to 33.77 per cent, respectively in different talukas surveyed. In overall view Haveri district registered the mean larval population and per cent infestation of 0.37 larvae per plant and 28.99 per cent, respectively, in kharif and rabi. During the study period, it was observed for two different species of parasitoids viz., Campoletis chlorideae (Hymenoptera: Ichneumonidae) and Exorist axanthaspis (Diptera:Tachinidae) were parasitizing FAW larvae. Along with parasitoids, one entomopathogenic fungi, Metarhizium rileyi was known to infect the larvae which was collected during the survey period.

The Diversity of Wolbachia and Other Bacterial Symbionts in Spodoptera frugiperda.

Bacterial symbionts associated with insects can be crucial in insect nutrition, metabolism, immune responses, development, and reproduction. However, the bacterial symbionts of the fall armyworm Spodoptera frugiperda remain unclear. S. frugiperda is an invasive polyphagous pest that severely damages many crops, particularly maize and wheat. Here, we investigated the infection, composition, abundance, and diversity of bacterial symbionts, especially Wolbachia, in different tissues of S. frugiperda female adults. The infection prevalence frequencies of Wolbachia in five provinces of China, namely Pu'er, Yunnan; Nanning, Guangxi; Sanya, Hainan; Yunfu, Guangdong; and Nanping, Fujian, were assessed. The results indicated that Proteobacteria, Firmicutes, and Bacteroidetes were the three most dominant bacterial phyla in S. frugiperda adults. At the genus level, the abundant microbiota, which included Enterobacter and Enterococcus, varied in abundance between tissues of S. frugiperda. Wolbachia was found in the ovaries and salivary glands of S. frugiperda adults, and was present in 33.33% of the Pu'er, Yunnan, 23.33% of the Nanning, Guangxi, and 13.33% of the Sanya, Hainan populations, but Wolbachia was absent in the Yunfu, Guangdong and Nanping, Fujian populations. Further phylogenetic analyses revealed that all of the Wolbachia strains from the different S. frugiperda populations belonged to the supergroup B and were named the wFru strain. Since there were Wolbachia strains inducing cytoplasmic incompatibility in supergroup B, these findings may provide a foundation for developing potential biocontrol techniques against S. frugiperda.

Effect of four host plants on the life history and nutritional indices of Spodoptera Littoralis

The Egyptian cotton leafworm Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) is a pervasive and highly polyphagous insect pest. As S. littoralis has developed resistance to major classes of conventional insecticides and the use of these insecticides has caused negative impacts on the ecosystems, it is necessary to search for eco-friendly, cost-effective, and sustainable agents to control. This can be achieved by identifying the preferred host plant. The present study aimed at evaluating the impacts of four host plants– castor bean, tomato, potato, and cucumber on the various life-history traits and nutritional indices of S. littoralis. The concentrations of nitrogen, potassium, and phosphorous in the tested host plants were quantified. Newly hatched larvae were divided into four groups. Each group was fed only on one type of the four tested host plants until pre-pupal stage. Then, the life-history traits and nutritional indices were determined. Larvae fed on castor bean showed the highest adult emergence, weight of full-grown larvae, number of eggs per female, and egg-hatch percent, food consumption, relative growth rate, and food utilization efficiencies. Whereas, larvae fed on cucumber showed the lowest egg-hatch percent, food consumption, relative growth rate, and food utilization efficiencies. There was a positive correlation between nitrogen and phosphorous concentrations in the tested host plants and larval weight, with the highest concentrations in castor bean. Castor bean was the most preferred host plant.

Screening of Popular Maize Hybrids against fall Armyworm, Spodoptera frugiperda

Fall armyworm (Spodoptera frugiperda) was the member of noctuidae family which has got economic importance as polyphagous and extreme pest of many important crops, including maize in India and elsewhere. In this context, screening experiment was conducted by using 15 different maize cultivars viz., CP 818, NK 6240, GPMH 1110, GH 0727, 900 M Gold, NK 6801, SM- 2, S- 4717, GK 3207, KMH 225, KMH 8333, Sunny NMH 777, 30 B07, PMH 2244 and Kaveri minchu in MARS, Dharwad. The results revealed that PMH 2244 was recorded the least mean larval load (0.67 larvae per plant) compared to rest of the cultivars. Among fifteen different cultivars screened, Kaveri minchu recorded the highest mean leaf damage score (4.62) whereas, the hybrid PMH 224 recorded the least mean leaf damage score (0.73). The cultivars, PMH 2244, NK 6801 and 900 M Gold were recorded with the least egg mass (0.33 per plant) whereas, the hybrids SM- 2 and Kaveri minchu were recorded with the highest egg mass of 0.63 and 0.61 per plant, respectively. Biophysical parameters of plant such as plant height, leaf area, stem girth and trichome density have been implicated in maize resistance to the fall armyworm. All the plant characters except leaf area which are mentioned above showed significant negative correlation with fall armyworm infestation whereas, leaf area was found significantly positive correlation.

Effect of Date of Sowing on Incidence of Fall Armyworm, Spodoptera frugiperda in Maize

Fall armyworm (Spodoptera frugiperda) is a member of the Noctuidae family which has economic importance as a polyphagous and extreme pest of many important crops, including maize in India and elsewhere. In this context, an experiment regarding the influence of different dates of sowing on the incidence of fall armyworm was conducted in MARS, Dharwad. The results revealed that the least mean larval load of fall armyworm was recorded in crop sown during the July 2nd fortnight (0.75 larvae per plant) and the highest was recorded in crop sown during the August 2nd fortnight (1.53 larvae per plant). Whereas, the lowest mean leaf damage score of 2.95 was observed in crop sown during 2nd fortnight of July and the highest was recorded in the crop sown during 2nd fortnight of August (4.82).

Differential feeding on ornamental plants by Duponchelia fovealis (Lepidoptera: Crambidae) larvae.

Duponchelia fovealis (Zeller) (Lepidoptera: Crambidae) is a polyphagous pest that feeds on a variety of ornamental and crop plants. At least 47 plant families have been identified as hosts for D. fovealis in literature based on empirical data and observations. This list is surely incomplete based on the broad feeding habits of D. fovealis. We sought to expand the list of known D. fovealis host plants and to identify species that may be less preferred or not fed upon by D. fovealis. We used laboratory feeding assays to measure D. fovealis consumption rate of leaf disks from 32 herbaceous plant species and 32 woody species grown outdoors throughout the Southeastern United States, and 24 tropical species typically grown as house plants. These plants were from 65 genera and 36 families. Between the 3 ornamental plant groups, we tested (herbaceous, woody, and tropical) that, after 24 h, plants in the tropical group were the least consumed by D. fovealis. After 24 h, the average proportion of leaf disks eaten by D. fovealis was 0.80 or higher for 5 herbaceous and 12 woody species. Proportions of leaf disks eaten varied at the family and genus level in many cases. Our research can improve integrated pest management of D. fovealis by informing growers that plants may be at more or less risk of infestation and damage by larvae.

Sublethal effect and detoxifying metabolism of metaflumizone and indoxacarb on the fall armyworm, Spodoptera frugiperda

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera, Noctuidae), is a highly polyphagous invasive pest that damages various crops. Pesticide control is the most common and effective strategy to control FAW. In this study, we evaluated the toxicity of metaflumizone and indoxacarb against third-instar FAW larvae using the insecticide-incorporated artificial diet method under laboratory conditions. Both metaflumizone and indoxacarb exhibited substantial toxicity against FAW, with LC50 values of 2.43 and 14.66 mg/L at 72 h, respectively. The sublethal effects of metaflumizone and indoxacarb on parental and F1 generation FAW were investigated by exposing third-instar larvae to LC10 and LC30 concentrations of these insecticides. Sublethal exposure to these two insecticides significantly shortened adult longevity, extended pupal developmental times and led to reduced pupal weight, pupation rates, and adult fecundity in the treated parental generation and F1 generation at LC10 or LC30 concentrations, in comparison to the control group. The larval developmental times were shortened in the parental generation but prolonged in the F1 generation, after being treated with sublethal concentrations of metaflumizone. Furthermore, larvae exposed to LC10 or LC30 concentrations of indoxacarb exhibited elevated activity levels of cytochrome P450 monooxygenase and glutathione S-transferase, which coincides with the observed synergistic effect of piperonyl butoxide and diethyl maleate. In conclusion, the high toxicity and negative impact of metaflumizone and indoxacarb on FAW provided significant implications for the rational utilization of insecticides against this pest.

Feeding ability of the agave weevil Scyphophorus acupunctatus (Coleoptera: Dryophthoridae) on different agave hosts susceptible to infestation

The agave weevil Scyphophorus acupunctatus is a polyphagous pest of agave, yucca and related taxa. Although its many host species differ in their mortality rates, little is known about the factors involved in host selection by the weevil and the defensive response of the infested plants. We compared the suitability of Agave americana subsp. americana, A. americana var. franzosini and A. oteroi as a food source for adult individuals of S. acupunctatus. Feeding rates on leaf samples of the selected taxa were measured under laboratory conditions. The amount of the flavonoids flavone and kaempferol in the leaves was also quantified. The observed consumption rates were significantly lower for A. americana var. franzosini, but only for measurements made on a fresh weight basis and not when consumption was adjusted to leaf dry weight. The leaves of the three agave taxa did not differ in the contents of the two selected flavonoids. We conclude that the three agave taxa are equally suitable as a food source for the weevil, but the observed differences in the consumption of fresh material provides evidence that agaves can differ in the amount of damage caused by the feeding activities of S. acupunctatus.