3rd Instar Nymphs Research Articles

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

Background/Objectives: 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. Methods: 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. Results: 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. Conclusions: 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.

Formulation and bio-efficacy of different isolates of Beauveria bassiana against adults and third nymphal instar of desert locust (Schistocerca gregaria Forskål)

Recently, the Horn of Africa witnessed a swift increase in the incidence of desert locust (Schistocerca gregaria) invasion. During outbreaks, pesticides are applied through aerial or ground spraying to kill the insects, and/or to prevent their spread to new grounds. However, after decades of extensive use, many drawbacks such as contamination of the environment, toxicity to non-target organisms, harmful residues on food, pest resistance, and bioaccumulation in the food chains emerged. Entomopathogenic fungi offer viable alternatives to chemical pesticides against many insect invasions, but few studies have tested their bio-efficacy in desert locusts. Therefore, the current study aimed at isolating, formulating local isolates 231, 334, 333, 341, 349, 351, 339 of Beauveria bassiana, and testing their bio-efficacy against larval and adult desert locusts. The 21-day experiment was conducted under controlled conditions in a greenhouse. Soil samples were collected from two agroecological zones in Isiolo and Laikipia Counties in Kenya. B. bassiana was isolated from the soil samples using the Galleria bait method and cultivated in Sabouraud Dextrose Agar Yeast (SDAY). The isolates were identified based on molecular techniques (DNA and PCR amplification). The conidia of the isolates were screened and bioassays on 30 locusts was conducted for 14 days. The best isolates eliciting over 90 % mortality during screening were used for formulations using three carrier materials (liquid paraffin, Diatomaceous Earth, and whey) which were again tested against adult and 3rd nymphal instars of the locusts. The stability of the formulations was also tested after 1 and 2 months. All the tested isolates of B. bassiana significantly outperformed the control and thus pathogenic to the adults and 3rd nymphal instars of S. gregaria under laboratory conditions. They caused mortality ranging from 57.8–100 % after 14 days post-incubation. The isolates 341, 231, and, 334 elicited 50 % mortality responses at concentrations 1.1 × 105 conidia/ml, 2.5 × 105 conidia/ml and 1.7 × 106 conidia/ml respectively in adults and 1.1 × 105 conidia/ml, 2.5 × 105 conidia/ml and, 1.7 × 106 conidia/ml respectively in 3rd nymphal instars. Formulations with 341–1, 341–2, and, 334–1 had the highest efficacy (>99 %) against the adult locusts. There was a significant 3-way interaction (P < 0.05) of isolate for the formulation, carrier material and, time in determining the Cfu of the B. bassiana formulations. After 1 month, the best Cfu occurred in formulation with isolates 231 and 341 formulated using Diatomaceous Earth, while the highest Cfu was observed in formulation with isolate 334 formulated with either liquid paraffin or whey. After 2 months, the highest Cfu occurred in formulation with isolates 231, 341, and, 334 formulated using liquid paraffin. This study provides encouraging data for the development of potential biopesticides formulated with different carrier materials against desert locusts.

Toxic effects of cadmium on the growth and predation capacity of the predator Orius sauteri

The heavy metal cadmium (Cd) leads to significant bottom-up effects on food chains of plants, herbivores, and predators in agroecosystems. Through the transfer and accumulation of Cd. In addition to the indirect effects of this cascading effects, predators Orius sauteri fed with artificial diets containing Cd also have a direct effect. We found that O. sauteri fed with sucrose solutions containing Cd at high concentrations of 125 mg/L and 625 mg/L significantly decreased the survival of the 3rd and 5th instar, female, and male adults (except 125 mg/L) of O. sauteri. However, the survival of O. sauteri nymphs was significantly increased when they fed with low concentrations of 1 mg/L, 5 mg/L and 25 mg/L Cd sucrose solutions. Cd stress has differing effects on the LC50 of each age of O. sauteri, the lowest LC50 for male adults (153 mg/L), followed by 3rd instar nymphs (192 mg/L), 5th instar nymphs (289 mg/L) and female adults (383 mg/L). It is interesting that 1 mg/L, 5 mg/L, and 25 mg/L of sucrose solutions containing Cd significantly improved the predation capacity of the nymphs of O. sauteri to the Bemisia tabaci pupa. The predation ability of the male adults of O. sauteri on B. tabaci pupa were significantly improved, but significantly decreased in the female adults when they fed with 125 mg/L and 625 mg/L sucrose solutions containing Cd. This difference needs to be studied in depth in the future, controlling Cd contamination and protecting natural enemies to enhance the biological control of pests.Graphical

Wing expansion functional analysis of ion transport peptide gene in Sogatella furcifera (Horváth) (Hemiptera: Delphacidae)

Ion transport peptide (ITP), a superfamily of arthropod neuropeptides, serves a crucial role in regulating various physiological processes such as diuresis, ecdysis behavior, and wing expansion. However, the molecular characteristics, expression profile, and role of ITP in Sogatella furcifera are poorly understood. To elucidate the characteristics and biological function of ITP in S. furcifera, we employed reverse transcription-polymerase chain reaction (RT-PCR) and RNA interference (RNAi) methods. The identified SfITP gene encodes 117 amino acids. The expression of SfITP gradually increased followed the formation of 3-day-old of 5th instar nymph, peaking initially at 40 min after eclosion, and reaching another peak 24 h after eclosion, with particularly high expression levels in thorax and wing tissues. Notably, SfITP RNAi in 3rd instar nymphs of S. furcifera significantly inhibited the transcript levels of SfITP, resulting in 55% mortality and 78% wing deformity. These findings suggests that SfITP is involved in the regulation of wing expansion in S. furcifera, providing insights into the regulation of insect wing expansion and contributing to the molecular understanding of this process.

Optimal dsRNA Concentration for RNA Interference in Asian Citrus Psyllid.

The Asian citrus psyllid (ACP) is a citrus pest and insect vector of "Candidatus Liberibacter asiaticus", the causal agent of citrus greening disease. Double-stranded RNA (dsRNA) biopesticides that trigger RNA interference (RNAi) offer an alternative to traditional insecticides. Standardized laboratory screening of dsRNA requires establishing the minimal effective concentration(s) that result in effective RNAi "penetrance" and trigger RNAi, resulting in one or more measurable phenotypes, herein, significant gene knockdown and the potential for mortality. In this study, knockdown was evaluated for a range of dsRNA concentrations of three ACP candidate genes, clathrin heavy chain (CHC), vacuolar ATPase subunit A (vATPase-A), and sucrose non-fermenting protein 7 (Snf7). Gene knockdown was quantified for ACP teneral adults and 3rd instar nymphs allowed a 48 h ingestion-access period (IAP) on 10, 50,100, 200, and 500 ng/µL dsRNA dissolved in 20% sucrose followed by a 5-day post-IAP on orange jasmine shoots. Significant gene knockdown (p < 0.05) in ACP third instar nymphs and adults ranged from 12-34% and 18-39%, 5 days post-IAP on dsRNA at 10-500 and 100-500 ng/µL, respectively. The threshold concentration beyond which no significant gene knockdown and adult mortality was observed post-48 h IAP and 10-day IAP, respectively, was determined as 200 ng/µL, a concentration indicative of optimal RNAi penetrance.

Functional response estimations of Chrysoperla carnea to different densities of Aphis craccivora and Gynaikothrips ficorum nymphs.

The functional responses of Chrysoperla carnea larvae were evaluated at different seven densities of the 3rd instar nymphs of Aphis craccivora and Gynaikothrips ficorum in order to find out the relationship between predator densities and its prey by the, and also to find out their capability for biological control of aphids and thrips. Results revealed that all tested larval instars of Ch. carnea exhibited a type II response in relation to the prey. Moreover, the coefficients of attack rate (a) and handling time (Th) was differed among various growing instars of predator and for the prey species. The 3rd instar larvae of Ch. carnea manifested the highest attacking rate (1.23 and 1.22) on the 3rd instar nymphs of A. craccivora and G. ficorum, respectively. In addition it exhibited the highest maximum predation (Na max) (50.00 and 52.63) on A. craccivora and G. ficorum nymphs, respectively as compared with the other treatments. Accordingly, Ch. carnea could be considered as a promising bio-control agent for A. craccivora and G. ficorum management.

Functional analysis of Ornithine decarboxylase in manipulating the wing dimorphism in Nilaparvata lugens (Stål) (Hemiptera: Delphacidae)

The brown planthopper (BPH, Nilaparvata lugens), a major insect pest of rice, can make a shift in wing dimorphism to adapt to complex external environments. Our previous study showed that NlODC (Ornithine decarboxylase in N. lugens) was involved in wing dimorphism of the brown planthopper. Here, further experiments were conducted to reveal possible molecular mechanism of NlODC in manipulating the wing dimorphism. We found that the long-winged rate (LWR) of BPH was significantly reduced after RNAi of NlODC or injection of DFMO (D, L-α-Difluoromethylornithine), and LWR of males and females significantly decreased by 21.7% and 34.6%, respectively. Meanwhile, we also examined the contents of three polyamines under DFMO treatment and found that the contents of putrescine and spermidine were significantly lower compared to the control. After 3rd instar nymphs were injected with putrescine and spermidine, LWR was increased significantly in both cases, and putrescine was a little bit more effective, with 5.6% increase in males and 11.4% in females. Three days after injection of dsNlODC, injection of putrescine and spermidine rescued LWR to the normal levels. In the regulation of wing differentiation in BPH, NlODC mutually antagonistic to NlAkt may act through other signaling pathways rather than the classical insulin signaling pathway. This study illuminated a physiological function of an ODC gene involved in wing differentiation in insects, which could be a potential target for pest control.

The Jinggangmycin-induced Mthl2 gene regulates the development and stress resistance in Nilaparvata lugens Stål (Hemiptera: Delphacidae)

Methuselah (Mth) belongs to the GPCR family B, which regulates various biological processes and stress responses. The previous transcriptome data showed jinggangmycin (JGM)-induced Mthl2 expression. However, its detailed functional role remained unclear in brown planthopper, Nilaparvata lugens Stål. In adult N. lugens, the Mthl2 gene showed dominant expressions, notably in ovaries and fat body tissues. The 3rd instar nymphs treated with JGM increased starvation, oxidative stress, and high temperature (34 °C) tolerance of the adults. On the contrary, under dsMthl2 treatment, completely opposite phenotypes were observed. The lipid synthesis genes (DGAT1and PNPLA3) of both females and males treated with JGM in the nymphal stage were observed with high expressions, while the lipolysis of the Lipase 3 gene was observed with low expressions. The JGM increased triglyceride (TG) content, fat body droplet size, and the number of fat body droplets. The same treatment also increased the Glutathione S-transferase (GST), catalase (CAT), and superoxide dismutase (SOD) activities. An increase in the heat shock protein (HSP70 and HSP90) expression levels was also observed under JGM treatment but not dsMthl2. The current study demonstrated the influential role of the Mthl genes, particularly the Mthl2 gene, in modulating the growth and development and stress-responsiveness in N. lugens. Thus, providing a platform for future applied research programs controlling N. lugens population in rice fields.

Sustainable Management for Spiralling Whitefly, Aleurodicus dispersus Russell (Hemiptera: Aleyrodidae) Infesting Guava and Its Effects on the Natural Enemies’ Complex

The spiralling whitefly, Aleurodicus dispersus (Hemiptera: Aleyrodidae), is one of the most notorious insect pests among tropical fruits and vegetables. A common pest management technique is the application of chemical insecticides. However, this has led to environmental degradation, natural enemy reduction, development of pesticide resistance and increased cost of production. This study, therefore, evaluated the efficacy of a sustainable and eco-friendly management strategy against the spiralling whitefly infesting guava (Psidium guajava L). The experiment was carried out with seven treatments replicated five times following the randomized complete block design. The treatments were negative control (T1), 0.8% soybean oil (T2), 1.6% liquid dishwashing (T3), 1.6% neem oil (T4), 0.4% soybean oil + 0.8% liquid dishwashing (T5), 0.8% neem oil + 0.8% liquid dishwashing (T6) and chemical control (Thiamethoxam 25 WG at 2g/L-1) (T7). Results showed that 1.6% liquid dishwashing was superior among treatments against the 1st, 2nd and 3rd nymphal instars with an average mortality of 84.28, 85.22 and 81.81%, respectively. Application of 0.8% soybean oil showed the highest efficacy against the eggs, 4th instar and adult population with an average mortality of 75.50, 81.36 and 93.50%, respectively. Application of these treatments showed no adverse effects on the natural enemies’ complex associated with guava. Integration of other eco-friendly pest management strategies against the invasive spiralling whitefly is recommended for future research.

Effects of different host plants on population fitness of pea aphid (Acyrthosiphon pisum)

BackgroundHost plants not only provide and living places and energy materials for insects, but also influence insect population parameters and population fitness. MethodsThis study examined the influence of various host plant species on the fitness of pea aphid (Acyrthosiphon pisum). The biological parameters and population parameters of pea aphid on 6 different host plants (Vicia fabae, Pisum sativum, Medicago sativa, Trifolium pratense, Onobrychis viciaefolia and Melilotus officinalis) were observed and counted by ecological experiments, which were carried out in a control chamber. ResultsThe results showed that the developmental duration of 1st and 2nd instar nymphs of pea aphids on T. pratense and P. sativum was significantly prolonged, whereas that of 3rd and 4th instar nymphs on O. viciaefolia and M. officinalis was significantly shortened. Compared with the pea aphid on the V. faba, the longevity of adults on M. officinalis and P. sativum was significantly prolonged, but only the generation time on P. sativum was significantly prolonged. Moreover, the survival rate of nymphs was significantly lower on O. viciaefolia and M. sativa than on others. Net reproductive rate and mean generation time on V. faba were significantly higher than in other host plants. The intrinsic rate of increase (rm) and finite rate of increase (λ) of pea aphid feeding of A. pisum on P. sativum and O. viciaefolia decreased. However, those on the double population time on P. sativum and O. viciaefolia were significantly higher than the others. ConclusionThe findings will clarify the population fitness of pea aphids on different hosts and guide the rational distribution of different host plants, and provide new references for aphid control strategies.

New Biocompatible Technique Based on the Use of a Laser to Control the Whitefly Bemisia tabaci

The whitefly Bemisia tabaci is among the most important agricultural pests in the world and one of the world’s top 10 most invasive insect pests. Bemisia tabaci is associated with severe yield and quality losses, mainly due to the transmission of plant viruses, as in the case of common beans (Phaseolus vulgaris L.). Reducing insecticide applications is a research priority, e.g., developing innovative and clean tools such as electromagnetic waves. The present work aims to determine the effective parameters of laser to reduce the Bemisia tabaci population in common beans. Preliminary assays were conducted by manually irradiating continuous-wave laser beams with different wavelengths (444 nm, 527 nm, and 640 nm) and optical intensities directly on the insects. Among these, the most effective wavelength was 444 nm. Later, we repeated the experiments using a homemade automated system to control the exposure time (t1 = 1 s, t2 = 2 s, t3 = 3 s and t4 = 4 s) of whiteflies to the incident beam at different optical intensities (I1 ≈ 10 Wcm−2, I2 ≈ 4 Wcm−2, I3 ≈ 2 Wcm−2). We have achieved 100% insect mortality by irradiating 454 nm laser wavelength on the 3rd instar nymphs of Bemisia tabaci, with the following parameters: I1(t1), I2(t3) and I3(t4). Moreover, the laser irradiation test did not affect plant yield and development, revealing that our preliminary results present a photonic technique that could control whiteflies without harming the plants’ development.

Interaction Analysis of lncRNA and mRNA Based on the Full-Length Transcriptome of the Nymph-to-Adult Developmental Transition of Sogatella furcifera

Little is known on how long noncoding RNAs (lncRNAs) and mRNAs cooperatively participate in regulating the nymph-to-adult development transition of Sogatella furcifera. Herein, lncRNA and mRNA libraries were constructed in three different developmental stages of S. furcifera, namely, prior to (PE), during (DE), and after (AE) ecdysis. Overall, 4649 lncRNAs were identified and divided into intergenic (53.90%), intronic (1.33%), sense (8.99%), antisense (21.75%), and bidirectional (3.94%) lncRNAs. Moreover, 795 differentially expressed lncRNAs were identified. Specifically, upon comparing PE and DE, 2719 target mRNAs were predicted for 574 lncRNAs. Upon comparing PE and AE, 2816 target mRNAs were predicted for 627 lncRNAs. Finally, upon comparing DE and AE, 51 target mRNAs were predicted for 35 lncRNAs. Kyoto Encyclopedia of Genes and Genome functional enrichment analysis revealed that the target genes of 795 lncRNAs were enriched in metabolic pathways, amino sugar and nucleotide sugar metabolism, and fatty acid metabolism. Subsequently, interaction analysis indicated that MSTRG.16086.1, MSTRG.16087.1, and MSTRG.2447.1 were functionally associated with cuticle protein and chitin biosynthesis. Finally, 11 differentially expressed lncRNAs were significantly enriched in 3rd and 4th instar nymphs. Our findings suggest that lncRNAs play a critical regulatory role during the molting of S. furcifera.

Changes in life history parameters and transcriptome profile of Serangium japonicum associated with feeding on natural prey (Bemisia tabaci) and alternate host (Corcyra cephalonica eggs)

BackgroundThe mass production of natural predators with prolonged shelf life is a prerequisite for their field application as pest control agents. The traditional methods used for the mass production of Serangium japonicum rely heavily on the consistent supply of natural prey. This study explains the effects of B. tabaci (natural prey) and C. cephalonica eggs (alternative food) on life history and transcriptome profile of S. japanicum.MethodsThis study compares the effects of B. tabaci (natural prey) and C. cephalonica eggs (alternative food) on biology, reproduction, and predatory efficacy, and transcriptome profile of S. japanicum.ResultsThis study revealed that S. japonicum was able to successfully complete its life cycle while feeding on B. tabaci (natural prey) and C. cephalonica eggs (alternative food). The C. cephalonica eggs fed S. japonicum individuals had longer developmental period and lower fecundity as compared to those feeding on whitefly but the survival rates (3rd instar nymphs, 4th instar nymphs and pupae) and predatory efficacy of C. cephalonica eggs fed S. japonicum individuals were significantly similar to to those feeding on whitefly.Transcriptome analysis showed that when faced with dietary changes, S. japanicum could successfully feed on C. cephalonica eggs by regulating genes related to nutrient transport, metabolism, and detoxification. Moreover, S. japanicum degraded excess cellular components through ribosomal autophagy and apoptosis, which provided sufficient materials and energy for survival and basic metabolism.ConclusionCorcyra cephalonica eggs can be used as an alternate host for the predator, Serangium japonicum, as the survival rates and predatory efficacy of the predator are similar to those feeding on the natural host (B.tabaci). When faced with dietary changes, S. japanicum could successfully feed on C. cephalonica eggs as revealed by upregulation of genes related to nutrient transport, metabolism, and detoxification. These findings are of great significance for studying the functional evolution of S. japonicum in response to dietary changes.

The Effect of the Crude Terpenoids Compounds of Melia Azedrach Leaves and Fruits on Some Biological Aspects of Whitefly Bemisia tabaci

This study was carried out to determine the effects of crude terpenoid compound extracts of Melia azedarach L. leaves and fruits on some biological aspects of whitefly Bemisia tabaci (Genn.) under laboratory conditions of 25 ± 2°C and relative humidity of 65-70%. The results indicated a significant effect on eggs and immature stages when treated with 0.5, 1, 1.5, and 2 mg/ml of leaves and fruits. The mortality rate increased with concentration. It reached 98.68, 100, 100, 95.70, 86.30, and 42.68% for eggs, 1st, 2nd, and 3rd nymphal instars, pupa, and adults, respectively, at a concentration of 2 mg/ml for leaves extract. At the same time, it reached 94.86, 100,100, 100, 87.89, and 44.90% for eggs, 1st, 2nd, and 3rd nymphal instars, pupa, and adults, respectively, at a concentration of 2 mg/ml for fruit extract. Also, the proportion of adults who emerged from sprayed eggs reduced to 91.53% and 95.72% when treated with 2 mg/ml of leaves and fruit extracts, respectively. While the developmental period increased to 23.50 and 24.00 days at 2 mg/ml when treated with terpenoid extracts of the leaves and fruits, respectively, compared with 21.00 and 20.83 days at control.

Topical delivery of dsRNA in two hemipteran species: Evaluation of RNAi specificity and non-target effects

Double-stranded (ds) RNA-based technologies could provide novel and potential tool for pest management with efficiency and specificity of action. However, before applying this technique in the field, it is necessary to identify effective delivery methods and evaluate the non-target effects that may occur. In this article, we evaluated the effectiveness of dsRNA by topical delivery on a species of great agricultural interest, Halyomorpha halys. The specificity of action of the dsRNA was also investigated in Rhodnius prolixus, an insect phylogenetically close to H. halys. Of the three investigated genes (putative ATPase N2B, ATPase, serine/threonine-protein phosphatase PP1-β catalytic subunit, PP1, and IAP repeat-containing protein 7-B-like, IAP), IAP and ATPase were able to induce higher mortality in H. halys nymphs compared to the control, with specific concentrations for each gene targeted. However, when the same RNAs were topically delivered to both R. prolixus 2nd and 3rd instar nymphs, no gene silencing and mortality were observed. For this reason, to assess dsRNA application-mediated non-target effects, we injected both H. halys and R. prolixus specific dsRNA in R. prolixus 5th instar nymphs. When the dsRNA targeting H. halys IAP was microinjected into R. prolixus 5th instar nymphs, no mortality was observed, suggesting a strong RNAi specificity. Together, these data suggest that the topical delivery could be suitable for the dsRNA to control H. halys population. Furthermore, its specificity of action would allow treatments towards single harmful species with limited non-target effects.

Functional Inquiry into ATP-Binding Cassette Transporter Genes Contributing to Spirotetramat Resistance in Aphis gossypii Glover.

ATP-binding cassette (ABC) transporters regulate the efflux of a broad spectrum of substrates to extracellular transporting, which play an important role in the detoxification process in arthropods. Here, we described a comprehensive approach to explore the involvement of ABC transporters in spirotetramat resistance in cotton aphids. In this study, synergism bioassays showed 17.05% and 35.42% increases in the toxicity to spirotetramat with the ABC inhibitor verapamil in adult and 3rd instar nymph aphids of the SR strain, respectively. In a competitive assay based on the microinjection of a fluorescent ABC transporter substrate, verapamil (a general ABC inhibitor) and spirotetramat significantly inhibited the elimination of Texas Red. Based on transcriptome data of midguts of spirotetramat-susceptible (SS) and -resistant (SR) strains, the expression levels of ABCB4, ABCB5, ABCF2, MRP11, and MRP12 were significantly upregulated in the SR strain midgut compared to that of the SS strain. Gene functional analysis based on ectopic expression and RNA interference (RNAi) proved that ABCB4, ABCB5, ABCF2, MRP11, and MRP12 were involved in the tolerance of cotton aphids to spirotetramat. Moreover, the upregulated ABCF2, ABCB4, and ABCB5 in the midgut of the SR strain contributed more to the resistance of spirotetramat in in vitro functional analysis. In summary, these results demonstrate that candidate ABC transporter genes in the midgut tissue were involved in spirotetramat resistance, which will help reveal the relationship between ABC transporters and the development of spirotetramat resistance in field populations.

Comparative transcriptional analysis and identification of hub genes associated with wing differentiation of male in Aphis gossypii

BackgroundAphis gossypii Glover (Hemiptera: Aphididae), a worldwide polyphagous phloem-feeding agricultural pest, has three wing morphs (winged parthenogenetic female, gynopara, and male) in the life cycle. The exclusive males could fly from summer hosts to winter hosts, which are essential for gene exchanges of cotton aphid populations from different hosts or regions. However, the molecular mechanism of wing differentiation of male in A. gossypii remains unclear.ResultsMorphological observation of male A. gossypii showed that there is no distinct difference in the external morphologies of the 1st and 2nd instar nymphs. The obvious differentiation of wing buds started in the 3rd instar nymph and was visible via naked eyes in the 4th instar nymphal stage, then adult male emerged with full wings. According to morphological dynamic changes, the development of wings in males were divided into four stages: preliminary stage (the 1st instar to 2nd instar), prophase (the 3rd instar), metaphase (the 4th instar), anaphase (the 5th instar). Results of feeding behavior monitoring via EPG (electrical penetration graph) technology indicated that although the male cotton aphids had strong desire to feed (longer duration of C 55.24%, F 5.05% and Pd waves 2.56%), its feeding efficiency to summer host cotton was low (shorter E1 3.56% and E2 waves 2.63%). Dynamic transcriptome analysis of male aphid at 5 different developmental periods showed that in the 3rd instar nymph, the number of up-regulated DEGs was significant increased, and time-course gene transcriptional pattern analyses results also showed that numerous genes categorized in clusters 3, 5, and 8 had the highest expressed levels, which were consistent with morphological changes of wing buds. These results indicate that the 3rd instar nymph is the critical stage of wing bud differentiation in males. Furthermore, through pathway enrichment analysis of DEGs and WGCNA, it revealed that the neuroactive ligand-receptor interaction, Ras signaling pathway, dopaminergic synapse, circadian entrainment and the corresponding hub genes of PLK1, BUB1, SMC2, TUBG, ASPM, the kinesin family members (KIF23, KIF20, KIF18-19) and the novel subfamily of serine/threonine (Aurora kinase A and Aurora kinase B) probably played an important role in the critical stage of wing bud differentiation.ConclusionThis study explored morphological changes and genes transcriptional dynamics males in cotton aphid, revealed the phenomenon of low feeding efficiency of winged males on summer host cotton, and identified key signaling pathways and potential hub genes potentially involved in wing bud differentiation of male in A. gossypii.

Metabolomic and Genomic Approach to Study Defense Induction by Nesidiocoris tenuis against Tuta absoluta and Tetranychus urticae in Tomato Plants.

The phytophagy of the predator Nesidiocoris tenuis (Hemiptera: Miridae) can trigger defense responses in tomato plants against pests, such as two spotted spider mite Tetranychus urticae (Acari: Tetranychidae) and South American leaf miner Tuta absoluta (Lepidoptera: Gelechiidae). The expression of genes governing Jasmonic Acid (JA) biosynthesis pathway and fluctuations in the levels of underlying metabolites have been rarely studied in mirid-infested plants. In the present study, fifteen 3rd instar nymphs of N. tenuis were caged on each top and lower leaf of tomato plants for 4 d to induce plant defense; after this period the predators were removed. With regard to T. absoluta, oviposition preference; larval period; and pupal weight were significantly reduced in N. tenuis-punctured plants. T. urticae adults exhibited a significantly higher escape tendency and reduced survival on punctured plants. Metabolomics confirmed such observations revealing substantial differences between N. tenuis-punctured and unpunctured (control) plants. Metabolites directly associated with the activation of the JA defense pathway, such as the precursor α-linolenic acid, had increased concentrations. The expression of the defense-related genes PI-II, MYC2, VSP2, and HEL was increased in the top leaves and only VSP2 and MBP2 in the lower leaves; interestingly, in the middle (unpunctured) leaves VSP2, HEL, and MBP2 were also upregulated, indicating systemic signaling. Collectively, phytophagy of N. tenuis caused adverse effects on T. absoluta and T. urticae, whereas the multi-omics approach (phenomics, metabolomics, and genomics) offered valuable insights into the nature of the plant defense responses and provided useful evidence for future applications in integrated pest management, plausibly resulting in the reduction in the required pesticide volumes.

Feeding potential and development of &lt;em&gt;Chrysoperla carnea&lt;/em&gt; (Neuroptera: Chrysopidae) on &lt;em&gt;Paracoccus marginatus&lt;/em&gt; (Hemiptera: Pseudococcidae) under no-choice conditions

Purpose: Considering the predatory effectiveness of Chrysoperla carnea (Neuroptera: Chrysopidae), studies were carried out at National Agricultural Research Centre, Islamabad, Pakistan to determine the feeding potential and developmental period of its larval instars on Paracoccus marginatus (Hemiptera: Pseudococcidae). Research Method: Eggs, 1st, 2nd, and 3rd nymphal instars and adults of P. marginatus was provided to all three larval instars of C. carnea in a Completely Randomized Design experiment, replicated ten times. Findings: Results indicated that all C. carnea larval instars were found to feed on all P. marginatus stages. Overall mean consumption of C. carnea larvae on P. marginatus eggs, 1st, 2nd and 3rd instar nymphs, and adults was 1359.8, 1409.1, 1012.4, 1165.7 and 130.30 individuals, respectively. Third instar C. carnea larvae was more voracious than 2nd and 1st instars. The shortest developmental period (12.40±0.37 days) of C. carnea larvae was recorded on 3rd nymphal instar of P. marginatus. Moreover, C. carnea larvae took 14.90±0.23, 14.00±0.25, 13.10±0.23, and 13.60±0.34 days on eggs, first, second nymphal instars and adults of P. marginatus, respectively to complete their development. Originality/value: Therefore, it is suggested that C. carnea should be included as a key component in the integrated management of P. marginatus, especially its 3rd larval instar

First Report on Voracity and Feeding Preference of Predatory Beetle, Thalassa montezumae (Coleoptera: Coccinellidae) on Croton Scale, Phalacrococcus howertoni (Hemiptera: Coccidae)

The croton scale Phalacrococcus howertoni Hodges &amp; Hodgson gen. nov., sp. nov. (Hemiptera: Coccidae), was first found in Florida, USA. This scale has become a pest because of its high reproductive rate and production of sooty mold. Here, we evaluated predation potential of the predatory beetle, Thalassa montezumae Mulsant (Coleoptera: Coccinellidae), as a biological control agent. To our knowledge, this is the first study of predation by T. montezumae on P. howertoni. Results of our studies showed that the predation by 4th instar T. montezumae was higher on 2nd stage nymphs than on 3rd stage nymphs P. howertoni; predation on adults was lowest. Mean consumption by adult T. montezumae was highest on 2nd stage nymphs followed by 3rd stage nymphs, and adult P. howertoni. There were no significant differences between male and female adult T. montezumae in the prey first visited when offered a choice of 2nd or 3rd instar nymphs, or adults of P. howertoni. Thus, the levels of acceptance did not vary significantly between stages of prey visited by the males and females. Females chose prey faster than males and used less energy to search for food. Egg fecundity did not vary among female beetles fed with different stages of croton scales. Should P. howertoni become a major pest, T. montezumae could be used as a biological control agent within a biologically based integrated pest management program.