Search Results (133)

Establishing refuges is a primary strategy for managing resistance in target pests against Bt maize. The larval feeding and dispersal, and adult oviposition behaviors of Spodoptera exigua (Hübner) on Bt and non-Bt maize plants are critical factors in determining optimal refuge configurations. This study employed laboratory and field experiments to evaluate the larval feeding and dispersal behaviors, as well as the oviposition preferences of S. exigua moths, on Bt (Cry1Ab + Vip3Aa19) and non-Bt maize plants. Results showed that as time of the choice test increased, the larval selection rate on Bt maize leaves declined progressively, with all instars (1st–5th) preferring to feed on non-Bt maize. After 48 h, the selection rates of larvae for non-Bt and Bt maize were 40.63–66.25% and 9.38–33.75%, respectively. Female moths exhibited no significant oviposition preference between Bt and non-Bt plants under undamaged conditions; however, when non-Bt maize was infested by the larvae, females preferentially oviposited on Bt maize plants (73.55%). Under the seed-mixture refuge pattern in field conditions, increasing the proportion of non-Bt maize significantly enhanced larval dispersal distances and facilitated larval transit damage between Bt and non-Bt plants. Our research clarifies the behavioral patterns of S. exigua on Bt and non-Bt maize, provides a scientific basis for optimizing refuge strategy to delay the development of resistance. Full article

This study investigates the species composition and distribution of blackflies (Diptera: Simuliidae) in Kazakhstan, with a focus on two species newly recorded for the country: Simulium murmanum (Enderlein, 1935) and Simulium reptans (Linnaeus, 1758). The presence of S. murmanum in Kazakhstan is reported for the first time, supported by morphological and molecular genetic analyses. Diagnostic features of the larva, pupa, and adult stages are described in detail, including the structure and coloration of the larval head capsule, pupal cocoon, and genitalia of both sexes. Habitat preferences and pupal substrate attachment patterns are illustrated, with observations on variations in cocoon branching across different flow regimes. Species identification was conducted using the morphological keys of Rubtsov and Yankovsky, and taxonomic classification was confirmed using the framework proposed by Adler. Molecular confirmation of S. murmanum was performed via DNA analysis. The species was found to be restricted to the foothill regions of East Kazakhstan, suggesting a distribution closely associated with the Altai mountain systems and adjacent regions in Mongolia and China. Unlike its status as a dominant hematophagous species in parts of Russia, S. murmanum has not demonstrated biting activity in Kazakhstan, Mongolia, or China. Additionally, the study provides the first records of S. reptans within the fauna of Kazakhstan, initially identified in the Irtysh River (Pavlodar Region). Subsequent sampling conducted in June 2024 revealed a continuous distribution of S. reptans along the Irtysh River through to the mountain streams of East Kazakhstan. The species was found in mountainous, foothill, and lowland environments, highlighting its wide ecological plasticity. Full article

Alveolar echinococcosis (AE) is a zoonotic disease caused by the larval form of the tapeworm Echinococcus multilocularis, which is considered one of the most dangerous parasites for humans. E. multilocularis infections are most frequently observed in forestry workers, farmers, hunters, berry harvesters, and workers employed in animal shelters. The subject of this study was a four-year follow-up profile of cytokines, including tumor necrosis factor alpha (TNFα), interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-4 (IL-4), and interleukin-10 (IL-10), in a patient with advanced liver alveolar echinococcosis and non-optimal antiparasitic treatment. Ultrasound, computed tomography (CT) of the abdomen, X-ray, CT of the chest, and magnetic resonance imaging (MRI) of the head were performed during the observation and treatment of the AE patient. After antiparasitic treatment was initiated, decreased activity of the gamma-glutamyl transpeptidase (GGTP), decreased serum concentrations of immunoglobulin E, C-reactive protein (CRP), and the pro-inflammatory cytokines TNFα, IL-1, and IL-6 were observed, as well as slightly increased levels of the anti-inflammatory cytokines (IL-4 and IL-10). Conclusions. During a four-year follow-up in a patient with advanced hepatic alveolar echinococcosis and non-optimal antiparasitic treatment, a decrease in proinflammatory cytokines (TNFα, IL-1β, IL-6) and a slight increase in anti-inflammatory cytokines (IL-4, IL-10) were detected. A better understanding of cytokine regulation in infectious diseases may be important to the development of new therapeutic strategies aimed at antiparasitic treatment. We suggest that broad initiatives (preferably at the local community level) should be implemented to raise awareness of the threat of alveolar echinococcosis and methods for avoiding E. multilocularis infection. Full article

The annual bluegrass weevil (ABW), Listronotus maculicollis (Kirby), is a significant pest of short-mown turfgrass in eastern North America. Proper monitoring of this pest may reduce insecticide applications. We investigated the extraction rate and labor involved in modifications of the two currently available methods for sampling ABW larvae: submersion of turf cores in saturated saline solution and heat extraction of cores on modified Berlese funnels. Using 5.7 cm diameter cores, submersion extracted 1.8× more larvae in saline solution than in water. Among the salt extraction variants, splitting the cores into four pieces before submersion was the best compromise between extraction rate and time requirement. Using intact cores extracted 40% fewer larvae while taking 18% less time, whereas destructive searching cores before submersion extracted 24% more larvae but required 64% more time. Using smaller cores (3.5 cm diam) took 18% less time and extracted 23% more larvae, but required more time sampling in the field. Larval stage averages did not differ significantly between salt extraction variants. Heat extraction, including destructively searching the desiccated core, extracted 60% more larvae but required 87% more time than four-piece salt extraction. Excluding the desiccated core, heat extracted as many larvae as four-piece salt extraction and required 16% less time. However, heat extraction requires three to four days and space that can be kept at around 32 °C. The method of choice for ABW larval extractions depends on whether the sampler prefers a high extraction rate, less labor, or quicker results, and whether space for heat extractions is available. Full article

Cycads are being endangered by several anthropogenic threats, and invasions of non-native herbivores are among those threats. Various country invasions by the cycad blue butterfly Luthrodes pandava have threatened the local horticulture cycad trade and native cycad populations. Little is known about behaviors of the larval stage of this specialist herbivore, the life phase that causes damage to cycad leaf tissue. The objective here was to determine larval ability to discriminate among Cycas species that are known to exhibit contrasting susceptibility to L. pandava herbivory. Dual-choice cafeteria protocols were used whereby a single larvae was provisioned with one leaflet of minimally damaged species (low quality) and one leaflet of heavily damaged species (high quality). Consumption after an 8 h feeding cycle was measured as loss in leaflet area. Wild L. pandava populations derived from in situ Philippine and Thailand Cycas habitats preferentially fed on high quality leaflets. In contrast, invasive L. pandava populations from urban locations in Guam, Philippines, and Thailand exhibited no preferences in leaflet feeding choice. The findings indicated that larvae of this Lycaenidae specialist herbivore exhibit complex selection behaviors that depend on origin of the butterfly and feeding history. Discrimination capabilities of the in situ populations that evolved with a single native Cycas species demonstrated beneficial behaviors that appear to be lost over time by invasive populations that feed on numerous novel Cycas hosts within the invasive range. Full article

Ibisia marginata (Diptera, Athericidae) is an important species in macrozoobenthic communities in freshwater streams and rivers of Europe. It is a merolimnic insect whose larvae live in aquatic habitats and are predators. Pupation takes place out of water, mainly in moss, and adults live in terrestrial habitats in close proximity to water. The goals of this study were to determine the distributional patterns of I. marginata in Croatia, both as larvae and adults. Additionally, a goal was to recognize emergence patterns through the 16 years of research at Plitvice Lakes NP. The preference of larvae towards the different substrates represented at Plitvice Lakes NP was also analyzed. Samples of larvae and adults were collected at 50 sampling sites. Adults of I. marginata were collected monthly using pyramid-type emergence traps at four sampling sites in Plitvice Lakes National Park. At two of these sites, samples were collected from 2007 to 2008, while at the other two sites, sampling was conducted from 2007 to 2022. A total of 374 adult specimens were collected during the 16 years of the emergence study. Ibisia marginata is a univoltine species with a peak emergence in July and a flight period lasting from June to August, depending on the year. Preferred larval substrates were moss and gravel. Full article

In this study, the seeking behaviour and food acceptance of larvae of Plodia interpunctella Hübner (Lepidoptera: Pyralidae) were analysed under laboratory conditions. Larval orientation and feeding preferences were assessed using a selection arena for neonate larvae and a four-way olfactometer for third-instar larvae. Stimulants included amaranth bars with additives (honey and chocolate) and natural amaranth (toasted grain only). The results showed that amaranth volatiles influence the orientation and feeding behaviour of this polyphagous insect. A marked preference for sugar-rich foods was observed, with amaranth with honey and amaranth with chocolate being the food sources most frequently chosen by the neonate larvae. These individuals exhibited a gregarious feeding behaviour and did not engage in cannibalism. The third-instar larvae also showed a preference for sweet food but were more attracted to the amaranth–additive combination. In the four-way olfactometer bioassays, chocolate was the most frequently chosen stimulus, while cellophane did not differ significantly from air. An analysis of volatile compounds by gas chromatography mass spectrometry (GC-MS) revealed that amaranth with chocolate releases more volatile compounds (16) compared with honey (12) and natural amaranth (6), suggesting that these volatiles could possibly influence the larvae’s choice of food source. Full article

Substrate is an important component of a fish’s habitat environment. Fish preferences for substrate influence their growth and development, feeding, hiding, schooling, and reproduction. To explore the habitat preference of Brachymystax tsinlingensis, this study was conducted on the preferences of B. pre-smolts, post-smolts, and juveniles for three substrate colors, white, blue, and black, and four substrate types, sand (<0.5 cm in diameter), small gravel (1–2 cm in diameter), medium gravel (5–7 cm in diameter), and large gravel (12–16 cm in diameter), which were investigated in light (10–60 lx) and dark (no light) environments. The results showed that the individual populations of B. tsinlingensis in three periods of time had a clear preference for substrate color, preferring black substrate and staying away from blue substrate under both light and dark environmental conditions; B. tsinlingensis pre-smolts and post-smolts preferred sandy substrate, and juveniles preferred medium gravel substrate. The choice of substrate color and substrate type by B. tsinlingensis is a manifestation of the living environment characteristics of this species, which is conducive to their hiding, better avoidance of enemies, and improvement of their survival rate. Based on the research results and the early biological characteristics of B. tsinlingensis, it is recommended to use black or dark substrate during the cultivation of B. tsinlingensis fry. During the larval fish stage, a sandy substrate environment should be provided. During the juvenile fish stage, a medium-gravel environment should be provided. Full article

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), is a highly destructive pest that poses serious threats and causes significant losses to the production of maize in China. This study evaluated the feeding and oviposition preferences of S. frugiperda when reared on four maize cultivars—sweet, waxy, common, and silage—across three consecutive generations. It also compared population adaptability among these cultivars and analyzed population parameters between the F1 and F3 generations. The findings revealed that all four F1 generation populations showed a preference for feeding and oviposition on sweet maize. However, over time, S. frugiperda exhibited a stronger preference, in terms of feeding and oviposition behaviors, for the natal host plant across three consecutive generations of rearing. The fall armyworm completed its life cycle and oviposited on all four maize varieties over three generations. The sweet cultivar population had the highest intrinsic rate of increase, finite rate of increase, net reproductive rate, larval survival rate, pupation rate, eclosion rate, fecundity, and pupal weight, while the silage cultivar population had the shortest larval stage, pre-adult stage, and adult lifespan and the pupal weight and the fecundity were the lowest. Overall, the population fitness was the highest on the sweet cultivar, and the lowest on the silage cultivar. Compared with F1, the F3 generation of the FAW had a significantly shorter developmental duration in four maize cultivars. Except for the waxy maize cultivars, the fecundity of the other three cultivars did not differ significantly between F1 and F3. This study provides fundamental information on the trend of fall armyworm population changes in maize fields and serves as a reference for rational maize cultivar planting decisions. Full article

Insects rely on their innate immune system to defend against pathogens, and the Toll signaling pathway plays an important role in immune regulation. Our previous studies have shown that BmToll9-1 functions as a positive regulator in the Toll pathway. This study seeks to elucidate the role of BmToll9-1, as a sensor to bacterial challenge, in modulating larval development and downstream Toll signaling pathways. Silkworm larvae were subjected to infection with either Gram-negative Escherichia coli or Gram-positive Staphylococcus aureus bacteria following silencing of BmToll9-1 by RNA interference (RNAi). This bacterial challenge triggered a compensatory re-induction of BmToll9-1 expression, which resulted in the recovery of larval weight and size to levels observed in untreated controls. Furthermore, upon bacterial infection of BmToll9-1-silenced larvae, there was an up-regulation in the expression of both signaling genes in the Toll pathway and downstream effector genes, with a marked preference for Gram-negative bacteria. These results highlight the involvement of BmToll9-1 in the Toll signaling pathway as a positive regulator, influencing silkworm development. Additionally, BmToll9-1 and BmToll9-2 were cross-validated to be genetically distinct genes, even though they were confirmed to be functionally analogous in the silkworm. Full article

The fall armyworm, Spodoptera frugiperda, is a serious invasive pest of the family Noctuidae (Lepidoptera) that poses a significant threat to global crop production, with poaceae crops being particularly affected. Previous studies have indicated that, as a voracious insect, the fall armyworm possesses the potential for food source diversification. However, to date, limited research has been conducted on whether plants other than maize (Zea mays L.) and rice (Oryza sativa L.) can serve as potential food resources for the pest. In Yunnan Province, China, the distribution ranges of the fall armyworm and Ficus plants show a significant degree of overlap. Ficus species, including the widely distributed Ficus microcarpa L. f., commonly grow within or near cornfields. Our previous field studies have documented instances of fall armyworms in cornfields exhibiting feeding behavior on F. microcarpa. In this study, maize and F. microcarpa were selected as food resources for fall armyworms to compare larval feeding preferences, development time, survival rate, and reproductive capacity. The results demonstrated that when both maize and F. microcarpa were available simultaneously, fall armyworm larvae consumed both plant species. Further analysis revealed that larvae feeding on F. microcarpa exhibited a significantly longer developmental period from the third stage to pupation (14.08 ± 0.44 d) compared to those feeding on maize (9.21 ± 0.14 d). Moreover, the pupae size, pupae weight, and egg count were reduced by approximately 10%, 30%, and 30%, respectively, in larvae that fed on F. microcarpa. Despite these physiological challenges, our research findings indicated that, despite F. microcarpa not being the primary food source for fall armyworms under natural conditions, fall armyworms feeding on F. microcarpa were still capable of completing the life cycle from the third instar to the second generation when relying solely on F. microcarpa. Therefore, it is crucial to strengthen the observation and monitoring of fall armyworm populations feeding on F. microcarpa and implement targeted control strategies according to specific circumstances, thereby preventing F. microcarpa from acting as a potential host. Full article

Calosoma chinense Kirby, a generalist predator, consumes a variety of pests. To better understand its predatory behavior and capacity, particularly against Spodoptera frugiperda (J. E. Smith), we identified the field species and investigated the predation capacity of the third-instar larvae and adults of both sexes against the first- to sixth-instar larvae, pupae, and male and female adults of S. frugiperda. The predation preference for different developmental stages of S. frugiperda was further examined. Our results indicated that C. chinense can prey on S. frugiperda in various stages, including larvae and adults, demonstrating robust predatory abilities. Among them, female adults of C. chinense exhibited the strongest predatory ability against first-instar larvae of S. frugiperda, with the highest daily consumption of 38.90 ± 0.79 individuals. The first-instar larvae of C. chinense also showed a certain predatory ability towards S. frugiperda, with a daily consumption of 6.95 ± 0.88 individuals per predator. The predation ability of C. chinense larvae increased with larval growth, especially for the first to third instar of S. frugiperda larvae, and C. chinense female adults had the strongest predation ability, followed by male adults and then third-instar larvae. However, there was no significant difference in predation capacity against fourth- to sixth-instar larvae and male and female adults of S. frugiperda, nor between adults of both sexes and third-instar larvae of C. chinense. The predation choice experiment revealed that the third-instar larvae and male and female adults of C. chinense showed a positive preference for S. frugiperda larvae from the first to fourth instars, while for the fifth- to sixth-instar larvae, they exhibited a negative preference. Overall, C. chinense exhibited a strong ability to prey on S. frugiperda. Our study indicates that C. chinense has the potential for application in the biological control of S. frugiperda. Full article

This study aims to determine the local host plant range for Yuanjiang River Valley Danaus genutia (Cramer, 1779) and evaluate the effects of different host plants on its growth, development, and reproductive success. This research assesses adult oviposition preferences and larval feeding tendencies on various host plants. An age-stage, two-sex life table was constructed to analyze the butterfly’s growth, development, reproductive success, survival rates, and other physiological aspects on different host plants. Population dynamics over the next 60 days were simulated to offer a comprehensive evaluation of the host plant suitability for D. genutia. The results indicated that D. genutia adults preferred laying eggs on Cynanchum corymbosum, followed by C. annularium, C. rostellatum, and Asclepias curassavica, with very few eggs laid on Calotropis gigantea and Dregea volubilis. Larval feeding preferences were observed in the order of C. annularium > C. corymbosum > C. rostellatum, with A. curassavica consumed only by first-instar larvae, while C. gigantea and D. volubilis were avoided. Under identical room temperature conditions, larvae feeding on C. annularium and C. corymbosum completed a full generation. Larvae feeding on C. annularium exhibited shorter developmental periods and higher early survival rates compared to those feeding on C. corymbosum, with no significant differences in adult longevity, sex ratio, or number of eggs per female. Female adults did not die immediately after laying eggs. No significant differences in the intrinsic rate of increase (r), finite rate of increase (λ), net reproduction rate (R₀), or doubling time (T_d) were found between populations feeding on the two host plants. However, the gross reproductive rate (GRR) and mean generation time (T) were significantly lower in the population feeding on C. corymbosum. These results confirm C. annularium and C. corymbosum as host plants for D. genutia larvae and provide a theoretical and scientific basis for the conservation of the Yuanjiang River Valley D. genutia population. Full article

In this study, we sampled malaria mosquito larvae in natural and artificial breeding places to study the geographical distribution, ecological preferences, and chromosomal variability of different species of the genus Anopheles in the territory of the Crimean Peninsula and the Black Sea coast of the Caucasus. Species were diagnosed using a combination of morphological, cytogenetic, and molecular markers. The ecological conditions of the larval habitats, such as dissolved oxygen content in the water, acidity, salinity, and temperature, were measured. Seven species of malaria mosquitoes were identified in the pool of 2229 individual mosquitoes collected at 56 breeding sites, including An. atroparvus, An. claviger, An. daciae (formerly identified as An. messeae s. l.), An. hyrcanus, An. maculipennis s. s., An. plumbeus, and An. melanoon. The previously recorded species of An. algeriensis, An. messeae s. s., An. sacharovi, and An. superpictus were not found in this study. Anopheles maculipennis was dominant in typical anophylogenic water bodies. Anopheles plumbeus, which used to breed mainly in tree holes in coastal forests, has spread to urban settlements along the Black Sea coast and breeds in artificial containers. Chromosomal polymorphism was studied and found in An. atroparvus and An. daciae populations. Differences in the chromosomal composition of An. daciae populations in Crimea and on the Black Sea coast of the Caucasus were revealed. The Crimean population had a low level of polymorphism in autosomal inversions. The data obtained in this study can be used to inform a better control of potential malaria vectors in the Black Sea coastal region. Full article

The introduction of novel plant species to new habitats may have consequences for native herbivores. We examined the impact of Alliaria petiolata, a Eurasian invader of forest understories and edges in North America, on adult oviposition behavior and on larval preference and the performance of Anthocharis midea, a univoltine butterfly that specializes on plants in the Brassicaceae. We compared the usage of A. petiolata by this butterfly to that of one of its common native hosts, Cardamine concatenata, and additionally explored the impact of drought and larval age on the larval success of these hosts. In the field, adults oviposited on the native host preferentially earlier in the season, but they strongly preferred A. petiolata later in the season and laid more eggs overall and in multiples more often on this plant. Larvae strongly preferred to feed on leaves of C. concatenata over A. petiolata in the laboratory and survived to pupation at a high rate on it. Conversely, larvae fed little and died when offered A. petiolata. Larvae preferentially chose tissues of droughted C. concatenata over well-watered plants, but drought stress had no impact on larval mass and survival to pupation. Larvae showed no preference for droughted or non-droughted A. petiolata and while drought stress tended to extend survival on this plant, all larvae still died on it. Older larvae were no better at feeding and surviving on A. petiolata than young larvae. Our results indicate that A. petiolata currently serves as an ecological trap for A. midea, being both highly attractive to ovipositing adults yet lethal to larvae. This effect could cause both local declines in the abundance of this butterfly and drive selection for the altered behavior of adults and larvae to either avoid or better tolerate this plant. Full article