The blue gum chalcid (Leptocybe invasa) is a serious invasive, galling insect pest of eucalypts grown outside Australia. Variability in resistance of species and genotypes of Eucalyptus to the pest is widely reported but without consideration of the influence of silviculture on the severity of galling. We assessed the variability of gall expression by 29 genotypes of E. camaldulensis by L. invasa in common nursery experiments and in 5 common garden arboreta planted in diverse climatic zones and soil types around Kenya. We quantified variation in growth and the concentrations of defensive chemical compounds (namely polyphenolic compounds) to assess possible genotype × environment interactions which we also relate to the climate of the parent seed trees in Australia. Generally, genotypes endemic to low latitude regions of Australia were more resistant to the pest while the concentration of quinic acid derivatives (QUIN) exhibited an interaction with arboretum location in Kenya. The concentration of QUIN in potted plants did not vary significantly with nitrogen supplementation. However, growth rates and total polyphenolic concentrations varied with arboretum location. Since QUIN, which have been previously shown to confer resistance against L. invasa, did not vary in different arboreta, resistant subspecies and genotypes of E. camaldulensis can be deployed in novel habitats and will not be galled. Our findings support the critical need to plant stock of known genotype(s) rather than planting stock grown from locally collected seed. This will require the establishment of eucalypt seed orchards if clonal production of planting stock is not possible.
Aphis gossypii Glover (Hemiptera: Aphididae) is a globally significant agricultural pest that has developed varying degrees of resistance to numerous classes of insecticides. Studies on the plant growth regulator mepiquat chloride (DPC) indicate that direct exposure inhibits development and reduces the reproductive capacity of A. gossypii. However, the effects of combining DPC with insecticides on the development and population dynamics of A. gossypii remain unclear. Therefore, this study investigated the effects of DPC in conjunction with sublethal doses of imidacloprid (IMI-LC30) and sulfoxaflor (SUL-LC30) on the toxicity and sublethal effects of A. gossypii, using life table parameters and qPCR analysis. The results showed that the combination of DPC with IMI or SUL did not enhance the toxicity of either IMI or SUL. Compared to treatments with IMI-LC30 or SUL-LC30 alone, the combination treatments showed no significant differences in longevity, fecundity, and population parameters of the F0 generation. However, the fecundity of the F1 generation was significantly reduced, and population parameters also exhibited a decreasing trend. Moreover, exposure of A. gossypii to IMI-LC30 or SUL-LC30 resulted in the upregulation of reproduction-related genes Vg and VgR in the F1 generation. This effect was suppressed when either IMI-LC30 or SUL-LC30 was co-applied with DPC. These findings demonstrate that combining DPC, in combination with IMI or SUL, can suppress the population resurgence of A. gossypii induced by sublethal exposure to these insecticides on their own. This research provides insights for the effective use of DPC and insecticides.
Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) is an important agricultural biocontrol agent that preys on various soft-bodied insect pests. This study was carried out to evaluate the fitness parameters of bifenthrin-selected (Bifen-Sel) and unselected (Unsel) strains of C. carnea and their reciprocal crosses (C1 and C2) by using an age-stage and two-sex life table approach. After continuous selection with bifenthrin (44 generations), the Bifen-Sel strain of C. carnea developed a 9.55-fold resistance level when compared to that of the Unsel. Biological parameters, such as the pupal period, pre-adult duration, male and female longevity, adult pre-oviposition period, and oviposition period of the Bifen-Sel strain, all were significantly different from that of the Unsel strain and their crosses C1 and C2. The larval period, total pre-oviposition period, female ratio, reproductive female ratio, and fecundity of the Bifen-Sel strain were significantly different from those of the Unsel strain. Demographic parameters, including intrinsic rate (rm), finite rate (λ), net reproductive rate (R0), mean generation rate (T), and gross reproductive rate of the Bifen-Sel strain, were similar to those of the Unsel strain but significantly higher than those of the C1 and C2 crosses of C. carnea. Bifenthrin resistance was stable in the Bifen-Sel strain of C. carnea. These findings provide valuable insights into bifenthrin resistance dynamics in C. carnea as it resulted in no fitness cost and support its selective use under controlled conditions, while highlighting the need for future research on predation potential of this resistant strain under field conditions with bifenthrin applications.
The legume pod borer, Helicoverpa armigera (Hübner), is one of the pervasive and destructive pests of legume crops, causing significant yield losses. In this study, we evaluated the nutritional performance and digestive enzyme activities of H. armigera when fed on ten mung bean varieties, including Baghmalek, India, Veys, Omrani, Parto, Simite1, Simite2, VC6371, VC3960, and VC6368. Additionally, biochemical profiling of these mung bean varieties, assessing starch, protein, anthocyanin, total phenolic and flavonoid content, was conducted to explore potential correlations with the nutritional physiology of H. armigera. The findings indicated that the larvae fed on Parto had lowest approximate digestibility, efficiency of conversion of ingested food, and relative growth rate, while those fed on VC6371 had the highest values. The values of efficiency of conversion of digested food were lower on Baghmalek and Parto and higher on VC6368 and VC6371. The lowest value of larval gain weight was on Parto. The highest proteolytic and amylolytic activities of larvae were observed on Veys and India, respectively; while the lowest enzyme activities were recorded on Parto. Our findings indicate that the low protein content combined with high levels of anthocyanin, total phenolics, and flavonoids may contribute to the potential tolerance of mung bean varieties against H. armigera. Cluster analysis revealed that VC6368 and VC6371 were the most suitable varieties for H. armigera development, whereas Baghmalek and Parto were nutritionally less suitable and may severe as promising candidates for breeding or cultivation to minimise damage caused by this pest.
Macrosiphum euphorbiae (Thomas) (Hemiptera: Aphididae), commonly known as potato aphid, is an economically damaging pest in tomato agroecosystem. Farmers often resort to chemical insecticides for its control, but this approach poses long-term ecological challenges. Biological control, which involves the strategic use of natural enemies, offers a more sustainable and effective alternative for managing insects. The syrphid, Episyrphus viridaureus (Weidemann) (Diptera: Syrphidae) is a natural predator of potato aphid within tomato fields. However, comprehensive information on its developmental biology, population growth parameters, predatory potential and functional response remain limited, prompting this study. In the present study, E. viridaureus was able to complete its lifecycle successfully while feeding on M. euphorbiae with an intrinsic rate of increase (r) (offspring/individual/day) of 0.103 and finite rate of increase (λ) (offspring/day) of 1.108. The larvae of E. viridaureus consumed 332.35 aphids out of which third instar larvae made the maximum contribution by consuming 232.69 aphids. All the three larval instars exhibited a type-II functional response against different densities of M. euphorbiae. Functional response parameters like attack rate (a) increased and handling time (Th) decreased as the larval stages advanced. This research highlights the potential of E. viridaureus as an effective biocontrol agent against M. euphorbiae, contributing to sustainable pest management.
Fruit flies are the most serious problem in fruit production worldwide, causing severe losses in production and fruit quality. The use of parasitoids, especially Diachasmimorpha longicaudata (Ashmead) (Hymenoptera, Braconidae), is an important tool for suppressing the fruit fly population. The objectives of this study were to determine the exposure time, density, and ideal larval instar of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) and to verify whether the parasitoid's previous experience affects its interaction with the host insect and the influence of these factors on the parasitism rate. In three bioassays, fly larvae were placed in 'parasitism units' to test different methods of exposure to female parasitoids. The variables included the previous experience of the female parasitoid with oviposition, the exposure time (30, 60, 120, 240, and 480 min) of the larvae to the parasitoid and the number (5, 10, 15, and 20) and instar (second and third) of the fly larvae. The flies and parasitoids that emerged were quantified, and the parasitism rate and sex ratio of the parasitoids were calculated. The results of the present study indicate that to increase the parasitism rate of D. longicaudata, third-instar larvae of C. capitata must be grouped into parasitism units of 20 larvae and exposed to a single female of the parasitoid for 8 h.
Brachycaudus helichrysi (Kaltenbach) (Hemiptera: Aphididae) is a destructive pests of Prunus domestica (L.) (Rosaceae), in India. Life table studies are essential tools for understanding population dynamics and predicting the control period of B. helichrysi on plum cultivation. Age-stage, two-sex life tables of B. helichrysi reared on six plum cultivars under controlled laboratory conditions were constructed. The total phenolic content in the leaves of each cultivar was quantified. Compared with the Red Beaut cultivar of plum, the fecundity, net reproductive rate, intrinsic rate of increase, finite rate of increase, and total longevity of B. helichrysi were significantly lower, and the mean generation time was significantly longer on the Fortune cultivar, followed by Angeleno, Friar, Black Amber, and Santa Rosa. The total phenolic compounds in the leaves of the different cultivars were as follows: Fortune > Angeleno > Friar > Black Amber > Santa Rosa and Red Beaut. The seasonal incidence of aphid was also studied under the field condition, which showed that the highest mean aphid population was recorded during March (113.17/10 leaves), followed by April (74.00/10 leaves), and declined in May (17.30/10 leaves). These findings suggest that the B. helichrysi resistance of cultivars, mainly Fortune and Angeleno, is influenced by the total phenolic compounds in their leaves. The negative correlation observed between phenolic compounds and aphid incidence suggested a potential role of phenolic compounds in mediating plant resistance to aphids. The findings will inform integrated pest management strategies for plum cultivation, promoting crop resilience and ensuring food security.
The green bug aphid, Schizaphis graminum, is one of the most serious pests of wheat which cause considerable yield loss in wheat fields. At present, beneficial microorganisms such as plant growth-promoting rhizobacteria (PGPR) need to be incorporated into wheat production to diminish the high risk of heavily insecticide application for environment and health hazards. This study aimed to assess the influence of several PGPR strains, Pseudomonas geniculata, Azospirillum oryzae, Pseudomonas brassicacearum, and Azotobacter chroococcum, applied as seed treatments of wheat, on the life table parameters and foraging behaviour of the green aphid, S. graminum. We investigated the physiological and biochemical responses of wheat plants under aphid stress to elucidate the induced resistance conferred by PGPRs. Preference tests revealed that plants treated with A. chroococcum were the least favoured by aphids at 24 h post-infestation. Furthermore, biological parameters of the aphids exhibited significant variation across treatments, with the highest values recorded in the control group and the lowest in plants treated with A. chroococcum. The intrinsic rate of increase (rm) of the aphids was diminished following the application of PGPR, with the lowest rm observed in the A. chroococcum treatment. The highest concentrations of proteins, carbohydrates, total phenols, and antioxidant enzymes were detected in infested plants treated with A. chroococcum 72 h post-infestation. According to our results, A. chroococcum emerged as the most effective treatment for enhancing both antixenosis and antibiosis resistance in wheat against S. graminum, suggesting its significant potential for integration into pest management strategies in wheat cultivation.
Low-density polyethylene (LDPE), a common polymer, resists environmental degradation because of its high molecular weight and hydrophobic nature. Although microbial agents have shown some potential for plastic biodegradation, their effectiveness is often limited. Recent studies have shown that insect larvae may also be promising candidates for the biological breakdown of plastic waste. This study aimed to quantify the biodegradation of commercial LDPE sheets by Tenebrio molitor (mealworm) larvae over 21 days. The extent of degradation was assessed by gravimetric analysis and by examining physical, morphological, and chemical changes in the polymer. Larval frass was analysed using Fourier-transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS) to identify metabolic by-products. The results showed that T. molitor larvae actively consumed and degraded LDPE sheets, leading to an average weight reduction of 34.28%. Scanning electron microscopy revealed significant surface deterioration, characterised by pits and cavities. FTIR analysis of frass indicated cleavage of polymer chains and oxidation, evidenced by the disappearance of C-H stretching bands and the appearance of new hydroxyl and carbonyl groups. GC-MS analysis detected several intermediate compounds, such as esters, alkanes, and fatty acids, confirming the metabolic breakdown of LDPE. This study supports the potential of T. molitor as an effective biological agent for degrading LDPE plastic.
Lygus hesperus is an economically important pest of many crops. An effective monitoring method for the early detection of L. hesperus could improve its management. A recently developed pheromone lure has been shown to attract L. hesperus males, however, fewer males were captured than expected. It is unknown whether this was an effect of pheromone responsiveness or the type of trap used. Thus, we compared the efficacy of the previously used white delta sticky traps to red cylindrical sticky traps in strawberry fields in California and cotton fields in Arizona. Collections were made 1 and 2 weeks after trap deployment. In strawberry, pheromone baited traps captured more L. hesperus males than unbaited traps. More males were collected from baited red cylindrical sticky traps compared with either type of unbaited trap. In cotton, baited red cylindrical traps captured more males than unbaited traps after 1 week of field exposure, but not after 2 weeks of deployment. Overall, red cylindrical traps caught more L. hesperus males than white delta traps. Diminished trap captures during the second week of monitoring may be attributed to high temperatures in cotton that likely shortened the lure's longevity and windy conditions in both strawberry and cotton that may have decreased the effectiveness of the trap's adhesive. Additional work to clarify the lure's field longevity and distinguish various elements of trap design (e.g. colour, adhesive, and shape) may further increase the operational effectiveness of pheromone-baited traps for L. hesperus.
The Hyphantria cunea (Drury) is a highly polyphagous invasive pest that has become widespread and destructive in China. Although sex pheromone components of H. cunea have been identified, the weak field attraction of synthetic sex pheromone has hindered the application of sex pheromone-based lures in efficient monitoring and management of this pest. In this study, the electroantennographic (EAG) and field responses of H. cunea male adults to three synthetic sex pheromone components, including Z9, Z12, Z15-18Ald (C18:Ald), Z3, Z6-9S,10 R-epoxy-21Hy (C21-2Epo), and 1, Z3, Z6-9S,10 R-epoxy-21Hy (C21-3Epo), were evaluated. Male antennae exhibited significant dose-dependent response to three individual components and a ternary mixtures. The younger and virgin male moths showed stronger electrophysiological activity to synthetic compounds, whereas sensitivity decreased significantly after mating. Among the three components, C21-3Epo elicited the strongest antennal responses. Field trapping revealed that neither single compounds nor binary blends attracted males, whereas only the ternary blend of C18:3Ald, C21-2Epo, and C21-3Epo (ratio 8:1:1; 10 mg total load) effectively captured large numbers of males. In addition, the field trapping indicated that the green rubber septum functioned as a practical dispenser for synthetic pheromones. The Unitraps baited with the green rubber septum showed significantly higher trapping efficiency than cotton wicks, highlighting the septum as a promising dispenser for field deployment of synthetic sex pheromones. Finally, the green rubber septum baited with a ternary blend monitored the dynamics of H. cunea occurrence and detected that the emergence period overlapped with the commercially available synthetic lure. In general, the bioactivity of the synthetic sex pheromone of H. cunea was validated. It could effectively capture H. cunea male adults, be used to monitor and control H. cunea, and further be incorporated into the integrated pest management programme.
Early detection of spider mite emergence is highly challenging due to the lack of visible symptoms and subtle physiological changes. To address the rapid monitoring of pest mite damage, this study provided a method based on hyperspectral imaging combined with a joint spatial-spectral attention (SSA) mechanism in a deep convolutional neural network (DCNN) for automated detection of pest mite infections. Leaves infested with varying degrees of spider mites Tetranychus urticae Koch (Acari: Tetranychidae) were captured daily to obtain multi-band spectral information of hyperspectral images. After data preprocessing, the joint SSA mechanism was applied to weigh and optimise the spatial and spectral features of the images, focusing specifically on infested regions. Furthermore, the super-pixel principal component analysis method (SPCA) dimensionality reduction method was applied to reduce model complexity and enhance classification accuracy. The spatial attention module automatically adjusted the weights of critical regions in the image, ensuring the network concentrated on the infected areas, while the spectral attention module improved sensitivity to the unique spectral features of infected regions. The proposed method can significantly enhance the accuracy of identifying mite infected areas, particularly in detecting mild infections of the leaves. Compared with traditional approaches, our proposed SPCA + DCNN + SSA model achieved notable improvements in classification accuracy and robustness, yielding the highest OA (up to 99.1% for specific severity levels) and Kappa coefficient (0.989). Importantly, it drastically reduced misclassification in the highly challenging mild infection stages.
Predatory mites are important biological control agents of spider mites in various crops. Long-term mass rearing on alternative foods, such as plant pollen, may affect their predatory efficiency, but data on Euseius scutalis are scarce. Therefore, this study aimed to evaluate whether long-term rearing of E. scutalis on cattail pollen influences its functional response when fed on Tetranychus turkestani. Functional and numerical responses of the predatory mite E. scutalis reared on cattail (Typha latifolia) pollen over 30 generations on different densities (2, 4, 8, 16, 32, 64, and 128) of T. turkestani were evaluated. The results indicated a type II functional response for E. scutalis on T. turkestani in all generations (G1, G10, G20, and G30) tested. The attack rate (a) of E. scutalis increased as the number of generations increased. The handling time decreased as the number of generations increased from G1 (0.330 h) to G10 (0.318 h), then increased in G20 (0.572 h) and then decreased again in G30 (0.385 h). In G1 and G30, the number of eggs deposited by the predator increased as prey density increased. However, in G10 and G20, egg deposition increased up to 64 prey and then slightly decreased at 128 prey. The results indicated that the quality of E. scutalis did not lessen against T. turkestani after different periods of rearing on cattail pollen. Based on this study, we recommend cattail pollen as a good candidate for the large-scale rearing of E. scutalis for use in biological control programmes against T. turkestani.
In tritrophic interactions, host plants could influence not only the population of insect pests but also that of their natural enemies. This study examined the effect of three wheat cultivars on demographic parameters of Schizaphis graminum Rondani (Hemiptera: Aphididae) and its predator, Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae). Furthermore, the secondary metabolites, photosynthetic pigments, and defence enzymes of wheat cultivars were evaluated at different times. According to the results, the highest and lowest developmental times of S. graminum were found on cultivar (cv.) Morvarid and cv. Ehsan, respectively. However, it was vice versa for the predator, being highest on cv. Ehsan and lowest on cv. Morvarid. Adults of S. graminum lived shorter on cv. Morvarid, while males and females of H. variegata lived longer on this cultivar. The intrinsic rate of natural increase (r) of S. graminum ranged from 0.347 to 0.456 day-1, and that of H. variegata from 0.118 to 0.176 day-1 on different cultivars. The value of this parameter was lowest for aphids but highest for their predator on cv. Morvarid. Based on the results, cv. Morvarid at 120 hours post-infestation by S. graminum contained the greatest concentrations of secondary metabolites and enzyme activities. The time-dependent loss of photosynthetic pigments occurred in each tested cultivar. The results revealed that cv. Morvarid had a suitable potential for reducing the population of S. graminum and enhancing the performance of H. variegata. However, further studies are needed to evaluate the complementary interactions of cv. Morvarid and H. variegata in controlling S. graminum population under natural conditions.
Aphids are among the most destructive insect pests of wheat, with their population dynamics strongly influenced by host genotype, sowing time, and prevailing environmental conditions. This study evaluated aphid infestation across seven sowing dates and 12 wheat genotypes, evaluating relationship with natural enemies and weather factors with a goal of identifying sowing dates and genotypes associated with low aphid density. Seasonal mean aphid density differed significantly among genotypes for each sowing date. Of the 12 genotypes of wheat studied, two were highly susceptible and two consistently showed lower infestation. Aphid outbreaks peaked between 14 and 27 February, with maximum populations recorded on 20 and 27 February across several genotypes. Natural enemies such as Coccinellids, Chrysopids, Syrphids, and parasitoids displayed significant positive associations with aphid abundance, suggesting they are able to track cues to find prey, and may play a regulatory role. Abiotic factors were strongly predictive of infestation: averaging across all genotypes of wheat, aphid abundance decreased with temperature, with temperature alone explaining 73.5% of the variation in abundance. Aphid abundance also decreased with hours of daylight (explaining an additional 14.1% of the variation in abundance). These findings demonstrate that aphid population dynamics in wheat are genotype-specific and environmentally driven, with mid-to-late February identified as the most critical infestation window. Selecting resistant/tolerant genotypes, adjusting sowing dates, and leveraging the role of natural enemies provide a sustainable pathway for aphid management. These insights are vital for refining integrated pest management strategies under changing climatic conditions.
Insect immunology represents a critical component of circulatory physiology research. Considering the ecological significance of mantids and their predatory roles, this study investigated the types of hemocytes and their modulation by starvation, prey quality, and temperature in Hierodula tenuidentata and Empusa fasciata. This study also documents the presence of these two species in Semnan province, Iran for the first time, expanding our knowledge of their distribution. Field-collected oothecae were incubated under controlled conditions (temperature 25 ± 1°C, relative humidity 50%, and a photoperiod of 14:10 light:dark hours) until nymphal emergence. Following hemolymph extraction and staining with Giemsa solution, four hemocyte types - prohemocytes, plasmatocytes, granulocytes, and oenocytoids - were identified in both species; spherulocytes appeared exclusively in adult H. tenuidentata under a light microscope. Differential hemocyte counts revealed granulocytes as predominant in H. tenuidentata, whereas both granulocytes and plasmatocytes were abundant in E. fasciata across developmental stages. Prohemocytes were more abundant in the early-instar nymphs than in the late-instar nymphs of both mantids. Hemocyte density declined progressively with prolonged starvation, reaching a minimum after 4 days. The highest hemocyte concentrations were observed in mantids fed grasshoppers after 1 week, whereas markedly lower counts occurred with low-quality prey, such as Musca domestica L. (Diptera: Muscidae) and Lycaena sp. (Lepidoptera: Lycaenidae). Heat stress significantly elevated hemocyte density, whereas cold exposure induced substantial reductions in hemocyte density. Hemocyte fluctuations were more pronounced after 48 hours than after 24 hours. These findings suggest that short-term dietary deprivation, prey type, and thermal stress may rapidly alter immune profiles in H. tenuidentata and E. fasciata.
The legume pod borer, Maruca vitrata F., is a pantropical insect pest causing substantial yield losses in legume crops. The larvae cause significant damage to crops like cowpea, beans, and pigeon pea. Intensive and indiscriminate use of insecticides is practised by legume growers across the world. The field control failures owing to the development of insecticide resistance were suspected in Indian populations of M. vitrata. Hence, the present study investigated the development of insecticide resistance in five field-collected populations of M. vitrata, collected from the Southern states of India. Dose-mortality bioassays indicated varying levels of insecticide resistance across populations as compared to the insecticide-susceptible laboratory-reared population. The estimated resistance ratios were as follows: 30.96- to 81.85-fold for lambda-cyhalothrin, 10.85- to 38.91-fold for emamectin benzoate, 12.02- to 48.55-fold for broflanilide, 8.42- to 54.89-fold for spinosad, and 19.46- to 28.37-fold for indoxacarb. Significant positive correlation was observed between emamectin benzoate and spinosad susceptibility, suggesting potential cross-resistance. These findings highlight the development of insecticide resistance in M. vitrata and underline the need for region-specific resistance management strategies, including insecticide rotation with non-cross-resistant compounds, to ensure sustainable insect pest control.
Alfalfa is a widely cultivated forage crop with high nutritional value, and it relies heavily on pollinators for successful reproduction owing to its keel petal structure. Numerous studies have shown the differences in pollinator diversity at different landscapes and/or regions, subsequently impacting plant reproduction. However, there is still insufficient evidence on variation in pollinator diversity at different sites with different landscapes and its effects on alfalfa reproduction. In this study, we investigated the diversity and abundance of floral visitors, and their impacts on alfalfa seed yield, across three sites represented by different landscapes, i.e. urban (Gongzhuling), semi-natural grassland (Changling), and farmland (Harbin) in north-eastern China. Our results showed that the diversity and abundance of all visitors, including bees in Changling were significantly higher than those of the other two sites. Changes in visitor diversity and abundance of alfalfa were closely related to climate variables, with positive effects of air temperature, and complex effects of precipitation. Meanwhile, the differences in pollinators may also be attributed to landscape types due to different habitat heterogeneity. Alfalfa seed yield in Changling was also significantly higher than that in the other two sites. Among these factors, air temperature, and diversity of floral visitors, particularly bees were positively related to alfalfa seed yield, indicating that pollinators combined with climate have an important contribution to changes in alfalfa seed yield. The findings from this study emphasise the importance of conserving pollinators to sustain and even enhance alfalfa yields, especially in the context of climate change and alterations in landscape types.
Aphis gossypii Glover is a highly polyphagous pest causing significant economic losses worldwide. In Greece, while the species is a primary threat to various crops, comprehensive molecular data regarding its insecticide resistance status remain scarce. This study, the first time in Greece, developed and implemented droplet digital PCR (ddPCR) to detect and quantify the frequency of key resistance mutations (R81T, S431F, A302S, L1014F/M918L, and A2666V - resistance to nicotinic acetylcholine receptor competitive modulators, dimethyl carbamates, organophosphates and carbamates, pyrethroids, and keto-enols, respectively) in field populations from citrus, cotton, and cucurbits plantations between 2021 and 2025. Our results identified four out of the six target mutations (L1014F and A2666V mutations were not found in any of the samples). Cucurbit populations exhibited the highest resistance levels, with S431F being fixed in seven populations and reaching a total resistance allele frequency (RAF) of 75%. The mutations A302S and M918L were also prevalent in cucurbits (total RAF of 40% and 49%, respectively), while the neonicotinoid-associated R81T mutation was detected at lower frequencies (total RAF of 9%). In contrast, citrus and cotton populations showed lower resistance diversity, with citrus populations possessing only the S431F mutation. The high resistance frequencies in cucurbits likely reflect intense selection pressure from specific insecticides used in these crops. Given the predominantly asexual reproduction of A. gossypii in Greece, the persistence of resistant genotypes poses a significant challenge. The ddPCR diagnostics developed here provide highly sensitive tools for monitoring target-site resistance, supporting effective insecticide resistance management.
The classification of the species in the genus Actias Leach, 1815 (Lepidoptera: Saturniidae) is challenging because many species have a highly similar morphology, while differences in database classification standards also provoke identification problems. To help resolve these issues, we conducted an integrative analysis of 741 cytochrome oxidase subunit I (COI) barcode sequences available by combining phylogenetic reconstruction, population genetic (Fst) metrics, and biogeographic data. This approach delineated 44 molecular operational taxonomic units (MOTUs) and established a genus-specific, empirical genetic distance threshold of 2.05% from a baseline of 29 morphologically validated MOTUs. These 29 MOTUs/morphospecies were then utilized to assess the interspecific genetic distance gap of this genus and further used as the species-level genetic distance to delimit the remaining morphospecies. Applying this multi-evidence framework allowed us to propose a significant re-evaluation of species boundaries, including several taxonomic reclassifications, and to generate the molecular inventory for Actias. Our study illustrates the power of an integrated molecular approach to resolve complex taxonomic issues and provides a robust, data-driven foundation for future research on Actias.