Instar Nymphs Research Articles

Functional diversity of the Osiris gene family in the brown planthopper

Abstract Osiris is a large insect-specific gene family with multiple functions. Owing to highly conserved sequences and similar expression patterns across insect species, the Osiris gene family is believed to play specific roles in the insect kingdom. However, current studies on Osiris gene functions have focused primarily on several holometabolous insects, such as Drosophila melanogaster and Bombyx mori, with few systematic studies on hemimetabolous insects. In this study, we identified 20 Osiris genes by searching the genome and transcriptome databases of the brown planthopper Nilaparvata lugens. The Nilaparvata lugens Osiris genes presented similar development- and tissue-specific expression profiles. A functional investigation using RNAi in 4th instar nymphs and newly eclosed adult females revealed that the knockdown of Osiris genes resulted in multiple phenotypes, including a lethal phenotype; morphological changes in the wing, ovary and ovipositor; and hatching and feeding failure. These observations suggested that the Osiris genes play different functional roles at the individual and tissue levels. This study expanded the knowledge of Osiris gene functions and provided a better understanding of the importance of the Osiris gene family in the development and reproduction of insects.

Ecological risks of a biopesticide from marine-derived amino-oligosaccharides in agriculture: Food chain effects on non-target organisms Frankliniella occidentalis and its natural predator Neoseiulus barkeri.

Ecological risks of a biopesticide from marine-derived amino-oligosaccharides in agriculture: Food chain effects on non-target organisms Frankliniella occidentalis and its natural predator Neoseiulus barkeri.

Species delimitation and taxonomic revision of Abana Distant, 1908 (Hemiptera: Cicadellidae: Proconiini): Intraspecific color variation and pseudocryptic diversity in Andean sharpshooters

The Neotropical proconiine sharpshooter genus Abana includes six previously described species, some of which have nearly identical male genitalia but differ in coloration. The taxonomy of the genus is here revised based on comparative morphological study and phylogenetic analysis of partial mitochondrial COI sequences coupled with the following molecular species delimitation methods: ABGD, ASAP, PTP (including bPTP) and GMYC. Phylogenies for the implementation of the tree-based methods for species delimitation were hypothesized based on maximum likelihood and Bayesian inference reconstructions. The results of the molecular species delimitation showed that A. horvathi is a species complex with sexual dimorphism, which is reported for the first time. In addition, two very different color morphotypes were found within A. tissa, recognized as the same species by all delimitation methods. The results of the revision, including photographs of the primary types of all nominal species, support the validity of the six previously known species of Abana. Seven new species are described from Colombia, Panama and Peru: Abana amazonica Sauceda-V & Takiya, sp. nov., A. colombiana Sauceda-V & Takiya, sp. nov., A. confusa Sauceda-V & Takiya, sp. nov., A. inornata Sauceda-V & Takiya, sp. nov., A. minuta Sauceda-V & Takiya, sp. nov., A. ochracea Sauceda-V & Takiya, sp. nov., and A. rufifrons Sauceda-V & Takiya, sp. nov. Abana sonora Melichar, stat. rev. is removed from synonymy with A. horvathi and placed as a valid species outside the genus as Cicadellini incertae sedis. A lectotype is designated for Abana regia Melichar to stabilize the nomenclature. Abana tissa is recorded for the first time in Colombia and the morphology of the last instar nymph of this species is also described and documented for the first time. A key to the species and new geographical records as well as a distribution map are also provided.

Repellence of δ‐nonalactone in German cockroaches of different stages, sexes, and ages

Abstractδ‐Nonalactone is a cyclic hydroxycarboxylic acid ester with a six‐membered ring found in several fruits and animal products for human consumption. It has shown repellent activity in tsetse flies Glossina pallidipes Wiedemann (Diptera: Glossinidae) and Glossina morsitans morsitans Westwood (Diptera: Glossinidae), as well as in first instar nymphs of the German cockroach, Blattella germanica Linnaeus (Hemiptera: Ecotibiidae). The aim of this study was to investigate the behavioral response of the German cockroach to the repellence produced by δ‐nonalactone and how this behavior changes according to nymph stage, age, sex, and presence or absence of antennae. Small, medium, and large nymphs, as well as adult males and females, were exposed to δ‐nonalactone‐treated filter paper. Small nymphs were the most affected by the repellent effect of δ‐nonalactone. No differences were observed in the response between males and females, nor in adult males aged ranging between less than 6 h to 90 days old. Likewise, no repellent effects were observed in antennectomized cockroaches. These results suggest that small nymphs of B. germanica are more sensitive to the repellent effect of δ‐nonalactone than other stages. Furthermore, the response to this repellent is independent of sex and age, and its receptors appear to be located exclusively on the antennae. The present study encourages us to further our investigations on the use of δ‐nonalactone in the integrated pest management of German cockroaches.

The effects of fluctuating temperatures on degree-day development and life history parameters of Pseudacysta perseae (Hemiptera: Tingidae).

Pseudacysta perseae (Heidemann 1908) (Hemiptera: Tingidae) is a foliar pest of avocados. The effects of 6 fluctuating temperature regimens, which averaged 15, 20, 25, 30, 32, and 35 °C over a 24-h period, on the developmental and reproductive biology of P. perseae were investigated. Selected temperature cycles are representative of avocado production regions in California (US). Fluctuating temperature regimens had significant effects on P. perseae development times, fecundity, fertility, longevity, and survivorship rates. One linear model (Ordinary Linear) and 7 nonlinear regression functions (Beta, Brière-2, Lactin-2, Lobry-Rosso-Flandrois, Performance-2, Ratkowsky, and Weibull) were utilized to investigate the correlation between fluctuating temperature profiles and P. perseae development times. The Beta and Weibull models failed to converge. Model parameters, T min, T opt, and T max, were estimated as 1.72 to 9.78 °C, 31.04 to 31.57 °C, and 34.05 to 39.38 °C, respectively. The thermal requirement for development, K, was estimated as 476.19 degree-days. At 32 °C, P. perseae females exhibited 4 egg-laying peaks around days 11, 35, 54, and 63 of life. A maximum daily average of eggs laid (i.e., fecundity) was 6.07 on day 35 and the average daily egg-laying rate was 3.08 eggs over a 69-day span. The maximum proportion of eggs that hatched (i.e., fertility) was 0.49 on day 31, and the average daily proportion of hatched eggs was 0.10. This study confirmed that P. perseae passes through 4 nymphal instars, not 5 as previously reported. In addition, sexual dimorphism with respect to the coloration of the fourth antennal segment is documented and is substantially darker in adult males.

Temperature-Dependent Modeling and Spatial Predictions for Identifying Geographical Areas in Brazil Suitable for the Use of Cordyceps javanica in Whitefly Control.

Lalguard C99 WP, based on the Cordyceps javanica BRM 27666 strain, is registered in Brazil for whitefly control. Spatial prediction is crucial for optimizing its field use and efficacy. In this study, the optimal temperature for mycelial growth and conidial production of C. javanica is 25-30 °C, with no growth at 33-35 °C. The highest nymphal mortality occurred at 25 and 30 °C, showing lower LT50 values at 30 °C. Mycelial growth was similar at 15, 20, 25, 30, and 35 °C when the fungus was exposed for 6 h and then transferred to a 27.4 °C environment; however, growth was slower at 35 °C with daily 6 h exposure alternating over 18 h at room temperature (mean of 28.5 °C). When the second instar whitefly nymphs were exposed for 6 h or 6 h daily at 15, 20, 25, 30, and 35 °C, followed by 7 days at fluctuating temperatures (mean of 28.4-30.2 °C), nymphal mortality was similar across temperatures. Although other abiotic factors (solar radiation, humidity, rainfall, etc.) must be considered for fungal efficacy, spatial predictions based on fluctuating temperatures indicated that C. javanica is suitable for use throughout Brazil, though its performance varied at constant temperatures in different locations.

Biological control of Schistocerca gregaria and Locusta migratoria migratorioides using Entomopathogenic bacteria

This study investigated the potential of indigenous entomopathogenic bacterial (EPB) strains from Egypt to control the two most prevalent locust species, Schistocerca gregaria (Forsskål) (Orthoptera: Acrididae), and Locusta migratoria migratorioides (Reiche & Fairmaire) (Orthoptera: Acrididae). To assess the efficacy of the EPB strains, experiments were conducted in the laboratory, semi field, and field. The results showed that Xenorhabdus nematophila (Thomas et Poinar) BA2 (Enterobacterales: Morganellaceae) and Photorhabdus luminescens (Thomas et Poinar) EGAP3 (Enterobacterales: Morganellaceae) were the most effective strains against S. gregaria and L. migratoria migratorioides in laboratory settings. Under semi-field conditions, X. nematophila BA2 recorded nymphal mortality rates of 89.31% and 85.00% against the 2nd and 5th nymph instars of S. gregaria, respectively, and P. luminescens EGAP3 showed nymphal mortality rates of 88.00% and 80.00% against the 2nd and 5th nymph instars of S. gregaria, respectively. In field trials, X. nematophila BA2 exhibited the highest nymphal mortality rate of 88.70% at 7 days after spraying. Overall, the findings of this study suggest that X. nematophila BA2 and P. luminescens EGAP3 are promising candidates for environment-friendly, safe locust pest management. Further research is needed to explore and develop these bacteria for commercial use in agriculture.

Effect of symbiont-targeted control of Halyomorpha halys on the co-occurring pentatomid community.

Several native species in the family Pentatomidae are recorded in north-western Italy, associated with different crops. The arrival of Halyomorpha halys led to a reorganization of the role of other pentatomids, some of them becoming secondary pests. Symbiont-targeted control strategies, which disrupt beneficial interactions in stink bugs, have so far been applied to H. halys. However, this approach could also be useful for controlling other pentatomid pests. Additionally, the effects of this strategy on non-target stink bug species need further investigation to assess its potential impact on agroecosystems. Here the effect of symbiont disruption was assessed for stink bugs that share host crops (e.g., hazelnut, wheat, soybean) or the environment (especially wild areas adjacent to crops) with H. halys in north-western Italy (Carpocoris purpureipennis, Dolycoris baccarum, Graphosoma italicum, Palomena prasina and Rhaphigaster nebulosa). Their symbionts were identified as allied to the genus Pantoea through 16S rRNA gene sequencing and also other bacteria were detected in the V4 ventricle of the midgut. Strikingly, variable symbiont infection was found across species. Laboratory tests were conducted assessing the consequences of symbiont deprivation during the first nymphal instar. Egg masses treatment with an anti-symbiont formulation affected hatching rates in D. baccarum and G. italicum, while the mortality rates during the first instar increased in C. purpureipennis and G. italicum. A correspondence between mortality induction and the alteration of symbiont infection rates was observed, with species showing the highest infection drop being the most affected by treatments. These results provide new insights into pentatomid symbionts and reveal significant variability in the response to symbiosis disruption, likely due to species-specific intensity of symbiotic interactions. The consequences of this variability are discussed.

Four new adelgid (Hemiptera: Adelgidae) species from Bhutan, including the first legless species of Aphidomorpha

A new subgenus and four new species of Adelges (Hemiptera: Adelgidae) are described from Bhutan. To support their taxonomic placement, we provide a phylogeny of Adelgidae reconstructed using mitochondrial and nuclear DNA sequence data. Cassiadelges subgen. nov is distinguished by the combination of feeding on Larix secondary hosts, having tergites of the head and pronotum fused into a cephaloprothoracic shield, and having only acuminate setae on the terminal abdominal segments. Adelges (Cassiadelges) coccipus sp. nov. feeds on Larix griffithii. This remarkable species is the only known member of Aphidomorpha that is lacking legs. The first instar nymph has legs, while the second instar to adult have vestigial legs present as small cuticular protrusions with clusters of setae. Its discovery presents an exciting opportunity to examine the evolutionary development of insect limb formation from a new perspective. Adelges (Cholodkovskya) changaphuensis sp. nov. feeds and forms galls on Picea spinulosa. Adelges (Aphrastasia) densae sp. nov. feeds on Abies densa. This may be the same as what was reported on this host in 1985 as Chermes abietispiceae Stebbing (nomen dubium). Adelges (Annandina) lepsimon sp. nov. feeds on Tsuga dumosa. It is separated from the only other member of its subgenus, Adelges (Annandina) tsugae Annand, by first instar exules having a pair of prominent anterior cephalic wax glands. It feeds between the needles on twigs in a similar fashion to A. (An.) tsugae Annand, which is also found in Bhutan, making it difficult to distinguish them in the field.

Period of time and movement distances between feeding and postfeeding defecation in Triatoma pallidipennis (Heteroptera: Reduviidae).

Period of time and movement distances between feeding and postfeeding defecation in Triatoma pallidipennis (Heteroptera: Reduviidae).

Effect of Temperature on Rice Stripe Virus Infection, Transmission Efficiency, and the Development Period in Laodelphax striatellus

ABSTRACTThe small brown planthopper, Laodelphax striatellus, is a major pest and the primary vector of the rice stripe virus, a harmful pathogen that significantly affects rice production across East Asia. This study aims to investigate the effects of different temperatures (24°C, 27°C, and 30°C) on the developmental period, rice stripe virus infection rates, and virus transmission efficiency of small brown planthopper at various developmental stages. Higher temperatures significantly shortened the developmental period of small brown planthopper. The time from egg to adult was approximately 5 days shorter at 30°C than at 24°C. The rice stripe virus infection rate gradually increased, peaking after the third instar nymph, with no significant differences observed between 24°C and 27°C. However, at 30°C, the infection rates in the second to fifth instar nymphs were lower compared to those at the other temperatures. Tissue‐specific analyses indicated that the thorax, midgut, and ovary serve as primary loci for rice stripe virus proliferation. Temperature significantly affects small brown planthopper development and rice stripe virus epidemiology. Accelerated development rates at higher temperatures may result in increased population turnover, whereas reduced rice stripe virus transmission efficiency under these conditions could alter viral spread dynamics. These findings are vital for developing pest management strategies that consider temperature fluctuations and climate change.

Detecting Brown Planthopper, Nilaparvata lugens (Stål) Damage in Rice Using Hyperspectral Remote Sensing.

Remote sensing is being increasingly used in agricultural stress management, offering real-time analysis of crop stress beyond what can be observed visually alone. Hopper burn, induced by brown planthopper (BPH, Nilaparvata lugens) is a significant challenge to rice production in India. This study aims to characterize the spectral reflectance of rice plants with different infestation levels of 2nd instar BPH nymphs across three varieties namely Pusa Basamti-1509, Pusa Basmati-1121, and TN-1 (susceptible variety to BPH). The differential infestation included 0, 5, 10, 20, 40, 80, 100, 200 number of nymphs. The spectral signatures of the crop were collected at 20 and 40 days after infestation (DAI). The results indicated a distinct change in reflectance pattern between healthy and infested rice plants across all three varieties in green (490-559 nm), yellow (560-584 nm), orange (585-639 nm), and red (640-699 nm) region of visible portion as affected by chlorophyll pigments and in NIR region (700-1800 nm) as affected by cell structure and in water absorption (1915 nm) region of SWIR portion. The specific wavelength band (470, 660,750, 1800, 1915 nm) showing a correlation above 0.8 with pest severity level, was identified as sensitive for assessing BPH damage. Analysis of reflectance changes across wavelengths highlighted that the first derivative has a strong correlation between BPH severity and reflectance in the green region (500-540 nm) and red edge position (680-760 nm). The amplitude of the red edge value decreased with an increase in the severity level of insects. This study identifies the sensitivity of visible and near-infrared regions in detecting and assessing BPH infestation severity.

Magnesium Oxide Nanoparticles Synthesized from Solanum elaeagnifolium and their Effect Against Mealybugs Phenacoccus solenopsis Tinsley

The excessive use of chemical insecticides and the emergence of accompanying environmental problems has led to a return to environmentally friendly plant extracts through nanotechnology and the production of particles loaded on many metals to control insects. Accordingly, the study was conducted in 2023 to investigate the efficiency of the nano- extract of the seeds and leaves of the nightshade Solanum elaeagnifolium Cav loaded on magnesium, producing MgO nanoparticles and the regular alcoholic seed extract with a concentration of 5% on the relative efficiency of killing the first and third nymph instars as well as the adults of the mealybug Phenacoccus solenopsis Tinsley, grown on moss rose seedlings. The results showed that the highest relative efficiency in killing the insects at the first instar was 100% three days after treatment with nano seed extract, 84% at the third instar, and 75% for mealybug adults after seven days of treatment. In contrast, nano extract of nightshade leaves recorded a relative mortality efficiency of 91.6, 47.4 and 54.3% for the first and third nymph instars and the adults, respectively, and 97.1, 55.0 and 58.7% for the regular alcoholic seed extract after seven days of treatment. Keywords: Alcoholic extract, nightshade, nanotechnology, nanoextract, mealybug.

Vacuolar (H+)-ATPase Genes Are Essential for Cuticle and Wing Development in Locusta migratoria.

Vacuolar (H+)-ATPases (V-ATPases) are crucial in several significant biological processes, including intracellular transport, endocytosis, autophagy and protein degradation. However, their role in the growth and development of insects remains largely unknown. This study aimed to explore the molecular and functional properties of V-ATPases in Locusta migratoria. LmV-ATPase genes were identified based on the locust transcriptome database and bioinformatics analysis. Quantitative reverse-transcription polymerase chain reaction was used to assess the relative expression of LmV-ATPases in different tissues and developmental stages. RNA interference combined with hematoxylin-eosin staining and transmission electron microscopy was used to explore the functions of LmV-ATPases. Ten V-ATPase genes were identified in L. migratoria and were named LmV-ATPase A, B, C, D, E, F, G, c″, d and e, respectively. These genes were highly expressed in the head, integument, gastric caecum, midgut, hindgut, fat body, trachea and ovary. The transcripts of LmV-ATPases were expressed in the developmental stages examined (from the 3rd to 5th instar nymphs). The injection of double-stranded RNA (dsRNA) against each LmV-ATPase induced high silencing efficiency in the 3rd instar nymphs. Knockdown of LmV-ATPases resulted in lethal phenotypes, with visible defects of the wing and cuticle. We further demonstrated that the deformation was caused by the defects of epidermal cells and fewer new cuticles. These findings suggest that LmV-ATPases are required for the wing and cuticle development of L. migratoria, which could be potential targets for the control of locusts.

The intestinal microbial community and function of Riptortus pedestris at different developmental stages and its effects on development.

Riptortus pedestris is a destructive pest that threatens multiple leguminous crops in China. The intestinal microbiota plays a crucial role in the growth and reproduction of host insects. However, the composition and function of the gut microbiota at different developmental stages remain unclear. Here, metagenomic sequencing was performed to clarify the gut microbial diversity and function in 2nd-, 3rd-, 4th-, and 5th- instar nymphs (2 N-5 N) and female adults (FAs) of R. pedestris and the effects of vital gut bacteria on development was detected. The gut bacteria have the stage specificity, indicating their function in the development of R. pedestris. Enterococcus and Caballerronia were the predominant bacteria present during the development of the 2 N-FAs. In addition, the microbial abundances in the 3 N and 4 N guts were significantly greater than those in the others guts. Furthermore, 5 N harbored the abundant microbiota Burkholderia-Paraburkholderia-Caballeronia. The metabolic pathways were significantly enriched from 2 N to FAs. Carbohydrate metabolism, including glycoside hydrolases (GHs) and glycosyl transferases (GTs), occurs throughout the entire developmental stage. Many antibiotic resistance genes (ARGs) were detected from 2 N to FAs. The bacteria from Pseudomonadota and Bacillota presented a broad spectrum of antibiotic resistance. Excitingly, Burkholderia bacteria eliminated by antibiotic treatment were unable to molt normally, and their lifespan was shortened in nymphs, indicating that the gut microbiota had a significant effect on nymph development. In summary, our results, for the first time, systematically illustrate the abundance and function across the gut microbiota from the different developmental stages of R. pedestris and demonstrate that the genera Burkholderia are crucial during the development of R. pedestris. This study provides the basis for stinkbug management strategies that focus on the pivotal gut microbiota.

Field evaluation of the delivery system of native predatory bug, <i>Eocanthecona furcellata</i> for the management of lepidopteran pests in pulse crops

Eocanthecona furcellata (Hemiptera: Pentatomidae) is predatory on most of the lepidopteran insect pests. This bug has been recorded in different regions of India from various crop ecosystems. In Uttarakhand, this predator has been found predating upon different pests of various crops viz. pulses, wheat, rice, soybean, maize, etc grown in plains, foothills, mid hills, valleys and high hills. The mass production technology of this predator has also been developed in the laboratory on hosts such as Spodoptera litura and Corcyra cephalonica. Further, the different release methods in crop fields and rates of release of this insect were studied on pulse crops. Cage experiments were conducted to evaluate the effective predacious stages of this bug and its field release doses in different pulse crop ecosystems. The experiments were carried out in the tarai region of Uttarakhand during 2020-2022. The results revealed that 4th and 5th nymphal instars as well as the adults were voracious feeders in the pulse ecosystem. The population of Maruca vitrata on mungbean and pigeonpea was reduced significantly by 4th and 5th nymphal instars as compared to other stages of the insect. Thus, the nymphal and adult stages were found to be appropriate to be employed for the management of insect pests in pulse crops. The experiments were also conducted on the dose determination in which different rates as 2, 3, 6, 9, 12 and 15 nymphs and adults per cage were used for the control of S. litura. The results revealed a 62.00 and 54.13% reduction of S. litura population in soybean, 60.89 and 62.50% in pigeonpea, 63.99 and 60.02% in mungbean in S. litura population was found at 10 days after release of the nymphs and adults of the bug respectively at the rate of 9 nymphs and 9 adults per cage. The present results indicate that the releasing rates of 9 nymphs and 9 adults per cage in the pulse ecosystem were satisfactory for suppressing S. litura population. This study will be of significant importance in achieving successful management of lepidopterous insect pests through field release of the predator at specified doses.

Assessing the lethal effects of pesticide residue exposure on beneficial parasitoids and their host, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae).

Chemical control is currently the main strategy for managing brown marmorated stink bug, Halyomorpha halys (Stål). However, chemical pesticides can harm nontarget species, including natural enemies of H. halys. Pesticides with high toxicity to H. halys and low toxicity to its parasitoids need to be identified to support H. halys management. This is not only for natural biological control but also for preemptive classical biological control of H. halys by parasitoids. Here, we assessed the contact toxicity of residues of eight insecticides against H. halys and three of its main parasitoid species (Anastatus japonicus Ashmead (Hymenoptera: Eupelmidae), Trissolcus japonicus Ashmead (Hymenoptera: Scelionidae), Trissolcus cultratus Mayr (Hymenoptera: Scelionidae)). This study aims to provide valuable insights for preemptive classical biological control of H. halys using these parasitoids. Our results showed that A. japonicus exhibited higher tolerance to the tested pesticides, while T. japonicus was the most sensitive species. Among the pesticides, chlorantraniliprole had the lowest overall impact on all three parasitoid species. Additionally, acetamiprid, azadirachtin, and rotenone were found to be harmless to A. japonicus. Acetamiprid, however, was slightly harmful to T. cultratus. The remaining pesticides showed moderate to significant harmful effects on the parasitoids. For H. halys adults and fifth instars, the pesticides tested caused no mortality within the 24 h exposure. However, young nymphs were susceptible to the tested pesticides. Fenpropathrin had the highest toxicity to H. halys, killing 83.3%, 52.8%, and 19.4% of second, third, and fourth instars in a 24 h exposure. Fenpropathrin, acetamiprid, cyfluthrin, azadirachtin, and dinotefuran were all slightly harmful to the first instar nymphs. The other pesticides were harmless to H. halys in a 24 h exposure. Halyomorpha halys mortality increased with the contact time with the residue. Mortality of fourth and fifth instars of H. halys was >70% for fenpropathrin, cyfluthrin, dinotefuran, abamectin-aminomethyl, and acetamiprid if exposure continued for 7 d. Acetamiprid was effective in controlling H. halys nymphs but exhibited varying levels of toxicity towards the three tested parasitoid species, depending on the residue age and exposure time. Azadirachtin showed lower overall toxicity to beneficial insects, suggesting that these materials could be used to manage H. halys while minimizing harm to key beneficial species.

Insecticidal effectiveness of Prunus laurocerasus leaf and seed extracts on Halyomorpha halys nymphs and adults

In this study, the toxicity of Cherry laurel, Prunus laurocerasus L. (Rosaceae) leaf and seed extracts at doses of 10, 15, and 20 mL/L against Brown Marmorated Stink Bug (Halyomorpha halys) adults and nymphs at 24., 48., 72., and 96. hours were investigated under laboratory conditions. All experiments were performed separately for five nymphal stages and adults and repeated three times for each dose. At the 96 hours of treatment, P. laurocerasus leaf extracts caused mortality between 21.5% and 100%, while the seed extract caused mortality between 30.3% and 100%. The highest mortality rate occurred in the N1 and N2 instar nymphs (100%) at the 20 mL/L dose, and the lowest mortality rate occurred in the adult stage (21.5%) at the 10 mL/L dose. The productivity rates of seed extracts were higher than those of leaf extracts. In all treatments, mortality rates increased with increasing dose and time. The results showed that P. laurocerasus leaf and seed extracts had a highly toxic effect against five nymphal stages and adult H. halys. The most toxic LD50 values in leaf extract were kept as 0.45 and 3.64 mL/L for N1 stage nymphs and juveniles, while the lowest LD90 values were determined as 4.54 and 6.64 mL/L for N5 instar nymphs and adults, respectively. The seed extract yielded the lowest LD50 values of 0.29 and 1.84 mL/L for N1 instar nymphs and adults, and the lowest LD90 values of 2.89 and 3.15 mL/L for N5 instar nymphs and adults, respectively. The results indicate that leaf and seed extracts of P. laurocerasus have excellent potential for the control of H. halys.

Evaluation of Trap Crops and the Presence of the Predator Nabis americoferus for the Management of the Tarnished Plant Bug in Strawberries

ABSTRACTThe polyphagous tarnished plant bug (TPB), Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae), inflicts substantial damage to strawberries and to several other valuable crops, impacting both yield quantity and quality. Effective control strategies are crucial to mitigate these losses. This study aimed to elucidate TPB host preferences and reproductive behaviours under various integrated pest management approaches. Experimental arenas with strawberry plants included treatments involving the predator Nabis americoferus (Carayon) (Hemiptera: Nabidae) and trap crops. In each arena, 30 adult TPBs were exposed to different configurations: (i) three strawberry plants, (ii) three strawberry plants with predators, (iii) one strawberry plant alongside two trap crop plants (buckwheat and canola), and (iv) one strawberry plant with the two trap crops and predators. TPB distribution among the arena, plant species and plant sites (flower, stem and adaxial and abaxial leaves) were monitored over 72 h. One week later, adults were removed and the number of emerged first instar nymphs (L1) was recorded three times postexperiment. The results indicate a preference shift in TPB behaviour influenced by plant diversity and predator presence. TPBs exhibited a reduced presence on strawberries when trap crops were introduced, with canola as a preferred plant. This preference for canola was supported by higher TPB offspring counts. Conversely, buckwheat, although less preferred, contributed to diluting TPB populations across plant species. The introduction of N. americoferus showed dual effects: While reducing TPB oviposition on canola, it increased TPB presence on strawberries, highlighting the importance of nonconsumptive effects (NCEs) of predators in agroecosystems. Nonetheless, the combination of canola as a trap crop and N. americoferus as a predator effectively reduces TPB presence on strawberry flowers, essential for fruit development. This approach shows promise when integrated with other strategies, such as vacuuming and pheromone‐enhanced coloured traps.

Morphological characteristics, developmental dynamics, and gene temporal expressions across various development stages of Aphis gossypii sexual female

BackgroundAphis gossypii (Hemiptera: Aphididae) is a worldwide polyphagous phloem-feeding agricultural pest, and it can produce offspring by sexual or asexual reproduction. Compared with dozens of generations by parthenogenesis, sexual reproduction is performed in only one generation within one year, and little is known about the sexual reproduction of A. gossypii. In this study, sexual females of A. gossypii were successfully obtained through a previously established induction platform, and the morphological characteristics, developmental dynamics, and temporal gene expression were examined. Subsequently, signaling pathways potentially involved in regulating the growth, development, and reproduction of sexual females were investigated.ResultsThe morphological observation showed that from the 1st instar nymph to adult, sexual females exhibited a gradually deepened body color, an enlarged body size, longer antennae with a blackened end, and obviously protruding cauda (in adulthood). The anatomy found that the ovaries of sexual females developed rapidly from the 2nd instar nymph, and the embedded oocytes matured in adulthood. In addition, time-course transcriptome analysis revealed that gene expression profiles across the development of sexual females fell into 9 clusters with distinct patterns, in which gene expression levels in clusters 1, 5, and 8 peaked at the 2nd instar nymphal stage with the largest number of up-regulated genes, suggesting that the 2nd instar nymph was an important ovary development period. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that a large number of genes in the sexual female adult were enriched in the TGF-beta signaling pathway and Forkhead box O (FoxO) signaling pathway, highlighting their important role in sexual female adult development and reproduction.ConclusionThe morphological changes of the sexual female at each developmental stage were revealed for the first time. In addition, time-course transcriptomic analyses suggest genes enriched in the TGF-beta signaling pathway and FoxO signaling pathway probably contribute to regulating the development and oocyte maturation of sexual females. Overall, these findings will facilitate the regulating mechanism research in the growth and development of sexual females by providing candidate genes.