Pod Wall Research Articles

Registration of ‘S13‐3851C’ soybean as a high‐yielding conventional cultivar with high oil content and broad disease resistance and adaptation

Abstract‘S13‐3851C’ (Reg. no. CV‐541, PI 698653) is an early maturity group IV (relative maturity 4.4) conventional soybean [Glycine max (L.) Merr.] cultivar released by the University of Missouri–Fisher Delta Research Center Soybean Breeding Program. It was developed from a conventional breeding scheme focusing on parental traits including high oil content, multiple disease resistance, and high yielding potential. S13‐3851C has purple flowers, light tawny pubescence, tan pod wall, and indeterminate growth habit. Seeds of S13‐3851C have a black hilum and intermediate seed luster, with 230.8 g kg−1 of oil and 404.1 g kg−1 of protein content on a dry‐weight basis. S13‐3851C is resistant to stem canker, sudden death syndrome, charcoal rot, and Phytophthora root rot. S13‐3851C showed high yield potential and broad adaptability in 113 environments across 12 states, yielding 102% of the check average and 103% of the test average in Missouri and other southern states during the testing period (2014–2018).

English

Brassica is the second-largest oilseed crop after Soybean. The total production of Brassica in the overall world is 71 million tons. In Pakistan, its total production per unit area is very low. Biotic and abiotic stresses mainly affect the brassica crop. In agriculture, shattering is the dispersal of crops seeds before their ripening. The pod wall shatters and breaks apart when it loses its hydration and cells split in a dehiscence zone organized at a suture between the edge of the lignified pod and the vascular tissue replum. The degeneration of middle lamella and loss of cellular cohesion in the dehiscence zone are the main reasons for pod shattering and seed losses. Grain yield losses in Brassica vary from 10 to 25 percent due to shattering. More than 400 kg has-1 or 12% seed losses can be occurred due to pod shattering under unfavorable conditions. Insect pest and disease damage also accelerate ripening and pod shattering. The main breeding techniques for developing rapeseed grain yield potential are a good knowledge and application of the morphological, physiological, and genetic basis of grain yield. Modern technologies, such as embryo rescue, marker-assisted breeding, and novel variation (mutation), may make it much simpler to introduce new rapeseed types having shattering tolerance than traditional methods. Thus, an overview of anatomical and physiological aspects and genetics of shattering is presented in the context of recent advances in molecular genetics and several agronomic managements to avoid shattering in Brassica.

‘S13‐1955C’: A high‐yielding conventional soybean with high oil content, multiple disease resistance, and broad adaptation

AbstractThe conventional Maturity Group V soybean [Glycine max (L). Merr.] cultivar ‘S13‐1955C’ (Reg. no. CV‐540, PI 695317) was developed and released by the University of Missouri–Fisher Delta Research Center soybean breeding program in 2019. Plants of S13‐1955C have determinate growth habit, white flowers, tawny pubescence, tan pod wall, and seed with black hilum. It has high oil content (227.4 g kg−1) and broad disease resistance including soybean cyst nematode, southern root‐knot nematode, reniform nematode, sudden death syndrome, and frogeye leaf spot. S13‐1955C was tested in 177 environments across 13 states and averaged 101% of the check yield in Missouri and the southern states from 2014 to 2019.

Registration of ‘S13‐2743C’ as a conventional soybean cultivar with high oil content, broad disease resistance, and high yield potential

AbstractHigh demand for early‐maturing conventional (non‐genetically modified [GMO]) high‐oil soybean [Glycine max (L.) Merr.] cultivars in the food and special niche markets led to the development and release of ‘S13‐2743C’ (Reg. no. CV‐538, PI 695097). It is a tall, early maturity group IV (relative maturity 4.1) non‐GMO soybean developed and released by the University of Missouri–Fisher Delta Research Center soybean breeding program. This early maturing, indeterminate type cultivar is desired by growers in the southern United States to plant along with later maturity groups to allow flexibility during the harvest season. S13‐2743C has high oil content (238.4 g kg−1) and a broad disease resistance package, including resistance to soybean cyst nematode race 3, phytophthora root rot, stem canker, sudden death syndrome, and frogeye leaf spot. It has white flowers, grey pubescence, and brown pod walls. Seeds have buff hila and intermediate luster. S13‐2743C was tested in 103 environments across eight states and showed high yield potential in Missouri and other southern states, including Arkansas, Kansas, Kentucky, Louisiana, Mississippi, and Tennessee.

Registration of ‘R13‐13997’ soybean cultivar

Abstract‘R13‐13997’ (Reg. no. CV‐539, PI 695314) is an early Maturity Group V (relative maturity 5.4), determinate, conventional soybean [Glycine max (L.) Merr.] cultivar developed and released by the Arkansas Agricultural Experiment Station in 2020. R13‐13997 was evaluated across 62 environments in Arkansas and other southern states and yielded higher than the check cultivars in most test environments. Across the 62 test environments, R13‐13997 yielded on average 4,371 kg ha−1 compared with 4,243 kg ha−1 for the check mean. It has white flowers, tawny pubescence, and tan pod walls at maturity. Seeds of R13‐13997 have yellow cotyledons with dull yellow seed coats and black hila. Seeds average 408 g kg−1 protein and 226 g kg−1 oil, on a dry‐weight basis. R13‐13997 is resistant to stem canker and frogeye leaf spot; moderately susceptible to soybean cyst nematode races 2, 3, and 5 and peanut root‐knot nematode; and susceptible to southern root‐knot nematode. The high yield potential, broad adaptation, and adequate disease resistance package make R13‐13997 an appealing choice for southern soybean growers and breeders.

Power tiller operated relay seeder as a possible solution for the late sowing of wheat crop

Field testing against pod borer and pod fly of 30 genotypes and cultivars revealed that RPS 2008-5, RPS 2008-4, and RPS 2007-109 were less infested by pod borer complexes and pod fly and produced higher grain yields. There was no significant relationship noticed between plant height, growth habit, pod length, pod breadth & days to maturity and borer complex and pod fly infestation, whereas, highly negative correlation was observed between morphological characters viz. pod wall thickness, calyx trichome length, calyx trichome density and pod trichome density against pod borer and pod fly infestation.

Study of Alcoholic Extract of Acacia Farnesiana (L.) Willd Pods

Identification of bioactive compound from alcoholic extract of Acacia farnesiana leguminosae pods by using preliminary phytochemical test or thin layer chromatography and the quantification of total phenolic content by folin-ciocalteu reagent method. shade dried grounded powder of Acacia farnesiana pods was successively extracted with petroleum ether, chloroform and alcohol in soxhlet apparatus, alcoholic compound obtained in more amount as compare to other two extract so alcoholic extract was used for identification of bioactive compound. The alcoholic extract of leguminosae pods indicates the presence of major bioactive compound. Analysis of the alcoholic extract by TLC have identified naringenin from extract, and the total phenolic content in alcoholic extract was found to be 22%(w/w). Therefore the present study deals with qualitative analysis of alcoholic extract of legumae pericarp (pod wall) of Acacia farnesiana L. In which we analyze various phytochemical which are useful for contoling various diseases TLC method used for identification of the content of naringenin from active extract of Acacia farnesiana pods. It is concluded that, legume pods contain maximum phytoconstituents or phenolic content.

Pod shattering in grain legumes: emerging genetic and environment-related patterns.

A reduction in pod shattering is one of the main components of grain legume domestication. Despite this, many domesticated legumes suffer serious yield losses due to shattering, particularly under arid conditions. Mutations related to pod shattering modify the twisting force of pod walls or the structural strength of the dehiscence zone in pod sutures. At a molecular level, a growing body of evidence indicates that these changes are controlled by a relatively small number of key genes that have been selected in parallel across grain legume species, supporting partial molecular convergence. Legume homologs of Arabidopsis thaliana silique shattering genes play only minor roles in legume pod shattering. Most domesticated grain legume species contain multiple shattering-resistance genes, with mutants of each gene typically showing only partial shattering resistance. Hence, crosses between varieties with different genes lead to transgressive segregation of shattering alleles, producing plants with either enhanced shattering resistance or atavistic susceptibility to the trait. The frequency of these resistance pod-shattering alleles is often positively correlated with environmental aridity. The continued development of pod-shattering-related functional information will be vital for breeding crops that are suited to the increasingly arid conditions expected in the coming decades.

Concurrent overexpression of amino acid permease

Using pea as our model crop, we sought to understand the regulatory control over the import of sugars and amino acids into the developing seeds and its importance for seed yield and quality. Transgenic peas simultaneously overexpressing a sucrose transporter and an amino acid transporter were developed. Pod walls, seed coats, and cotyledons were analysed separately, as well as leaves subtending developing pods. Sucrose, starch, protein, free amino acids, and endogenous cytokinins were measured during development. Temporal gene expression analyses (RT-qPCR) of amino acid (AAP), sucrose (SUT), and SWEET transporter family members, and those from cell wall invertase, cytokinin biosynthetic (IPT) and degradation (CKX) gene families indicated a strong effect of the transgenes on gene expression. In seed coats of the double transgenics, increased content and prolonged presence of cytokinin was particularly noticeable. The transgenes effectively promoted transition of young sink leaves into source leaves. We suggest the increased flux of sucrose and amino acids from source to sink, along with increased interaction between cytokinin and cell wall invertase in developing seed coats led to enhanced sink activity, resulting in higher cotyledon sucrose at process pea harvest, and increased seed number and protein content at maturity.

Identification of redgram resistant genotypes and morphological bases of resistance to pod fly, Melanagromyza obtusa (Malloch)

Screening of 49 redgram genotypes conducted to identify pod fly resistant genotypes and morphological basis of resistance to pod fly revealed consistently resistance reaction of ICP 8864 (mean PSI 3.0) and VRG–59-1(mean PSI 3.3) to redgram pod fly. Pod length of various redgram germplasm ranged between 3.55 and 4.84 cm. Pod width ranged from 0.64 to 1.28 cm. Pod wall thickness ranged from 0.21 to 0.43 mm. Trichome density ranged between 302 and 375 per 9 mm2. Redgram pod width was the important morphological factor that influenced the redgram pod fly seed damage to a tune of 34.2 per cent. Pod length and width were positively correlated with the redgram pod fly seed damage while pod wall thickness and trichome density were negatively correlated. However, relationship between pod width and seed damage only was found to be significantly positive and rest of the morphological factors were not significant.

Registration of ‘S14‐9017GT’ soybean cultivar with high yield, resistance to multiple diseases, and high seed oil content

Abstract‘S14‐9017GT’ (Reg. no. CV‐536, PI 693755) is a Maturity Group V high‐yielding glyphosate‐tolerant soybean [Glycine max (L) Merr.] cultivar developed and released in 2017 by the University of Missouri–Fisher Delta Research Center Soybean Breeding Program. S14‐9017GT was developed by conventional breeding from a cross between ‘LD07‐3419’ and ‘S08‐9727RR1’. The parent S08‐9727RR1 is a breeding line that carries the GTS 40‐3‐2 transgene discovered by Monsanto Co. The other parent, LD07‐3419, is a breeding line developed by the University of Illinois soybean breeding program. Before release, S14‐9017GT was tested in 122 environments in Missouri and other southern states from 2015 to 2018 for yield and other agronomic traits. On average, S14‐9017GT yielded 4,314 kg ha−1, which is higher than the mean of all the tests, which was 4,124 kg ha−1. S14‐9017GT seed contains 378 g kg−1 protein and 246 g kg−1 oil on a dry seed weight basis. It exhibits a relative maturity of 5.3, determinate growth habit, white flowers, light tawny pubescence, and tan pod wall. It has yellow seed with intermediate luster and black hila and a seed weight of 14.9 g per 100 seed. Plants of S14‐9017GT are 81 cm tall with resistance to lodging. It is resistant to stem canker, frogeye leaf spot, cyst nematode (races 1, 2, 3, and 5), reniform nematode, peanut root‐knot nematode, and sudden death syndrome and has field tolerance to phytophthora root rot. In addition to its high yield potential, high seed oil content, and broad adaptation across southern states, S14‐9017GT is also a suitable alternative for farmers who want to grow and save seed of glyphosate‐tolerant soybean cultivars.

Registration of ‘S14‐15138GT’ soybean as a high‐yielding RR1/STS cultivar with broad disease resistance and adaptation

Abstract‘S14‐15138GT’ (Reg. no. CV‐537, PI 693754) is a late maturity group IV (relative maturity 4.8) indeterminate high‐yielding soybean [Glycine max (L) Merr.] cultivar with glyphosate and sulfonylurea tolerance developed and released in 2017 by the University of Missouri–Fisher Delta Research Center soybean breeding program. S14‐15138GT is an F4 plant selection from the cross ‘S09‐10871’ × ‘S08‐9727RR1’. S14‐15138GT was tested in 83 environments across 11 states and showed high yield potential and wide adaptation in Missouri and other southern states. In the University of Missouri yield trials, S14‐15138GT yielded, on average, 110% of the tests mean across 19 locations in 4 yr (2015–2018). Plants of S14‐15138GT are 84 cm tall and have white flower color, tawny pubescence, and tan pod walls. On average, S14‐15138GT seed contains 406 g kg−1 protein and 221 g kg−1 oil on a dry seed weight basis. S14‐15138GT has a broad disease resistance package including resistance to soybean cyst nematode races 3 and 14 (HG Type 5.7 and Type 1.3.6.7), stem canker, frogeye leaf spot, sudden death syndrome, and phomopsis seed decay. In addition to its high yield potential, strong disease resistance package, and broad adaptation, S14‐15138GT is a suitable alternative for farmers who want to grow and save seed of glyphosate‐tolerant soybean cultivars.

Management of Pod fly, Melanagromyza obtusa on Pigeonpea (Cajanus cajan L.)

Background: Pod fly, Melanagromyza obtusa is one of the most obnoxious pest causing grain damage ranging from 10-80% with a monitory loss of US$ 256 million annually. Being an internal feeder, infested pods do not show any external symptoms of damage until the fully grown maggots chew the pod wall, leaving a thin papery membrane intact called as window, through which adults exit from the pod. Several field studies were conducted to determine the efficacy of insecticides for the control of pod fly. However, these findings did not find acceptability and led to partial success. Insecticides that should leave lesser residues and pose lesser environmental threat have become imperative. The present study aimed to evaluate the efficacy of certain new insecticide molecules against pod fly in pigeonpea ecosystem. Methods: Two field experiments were conducted at Regional Agricultural Research Station, Lam, Guntur during Kharif, 2012 and 2013 in a randomized block design (RBD) using pigeonpea cv. ICPL 85063 (Lakshmi) with 17 treatments including untreated control and 3 replications. Two sprays were given at 10 days interval starting from pod initiation stage. At maturity, number of pods showing pod fly damage were recorded and expressed as percentage. Grain yield was recorded and cost–benefit ratio was worked out. Result: Among different insecticides, thiacloprid 21.7 SC, followed by diafenthiuron 50 WP, flubendiamide 480 SC and dimethoate 30 EC were very effective against pod fly with more grain yield and registered highest incremental cost benefit ratio (ICBR). It was further suggested that effective insecticides may be alternated in order to avoid development of resistance to pod fly in pigeonpea.

Ultrastructural and Photosynthetic Responses of Pod Walls in Alfalfa to Drought Stress.

Increasing photosynthetic ability as a whole is essential for acquiring higher crop yields. Nonleaf green organs (NLGOs) make important contributions to photosynthate formation, especially under stress conditions. However, there is little information on the pod wall in legume forage related to seed development and yield. This experiment is designed for alfalfa (Medicago sativa) under drought stress to explore the photosynthetic responses of pod walls after 5, 10, 15, and 20 days of pollination (DAP5, DAP10, DAP15, and DAP20) based on ultrastructural, physiological and proteomic analyses. Stomata were evidently observed on the outer epidermis of the pod wall. Chloroplasts had intact structures arranged alongside the cell wall, which on DAP5 were already capable of producing photosynthate. The pod wall at the late stage (DAP20) still had photosynthetic ability under well-watered (WW) treatments, while under water-stress (WS), the structure of the chloroplast membrane was damaged and the grana lamella of thylakoids were blurry. The chlorophyll a and chlorophyll b concentrations both decreased with the development of pod walls, and drought stress impeded the synthesis of photosynthetic pigments. Although the activity of ribulose-1,5-bisphosphate carboxylase (RuBisCo) decreased in the pod wall under drought stress, the activity of phosphoenolpyruvate carboxylase (PEPC) increased higher than that of RuBisCo. The proteomic analysis showed that the absorption of light is limited due to the suppression of the synthesis of chlorophyll a/b binding proteins by drought stress. Moreover, proteins involved in photosystem I and photosystem II were downregulated under WW compared with WS. Although the expression of some proteins participating in the regeneration period of RuBisCo was suppressed in the pod wall subjected to drought stress, the synthesis of PEPC was induced. In addition, some proteins, which were involved in the reduction period of RuBisCo, carbohydrate metabolism, and energy metabolism, and related to resistance, including chitinase, heat shock protein 81-2 (Hsp81-2), and lipoxygenases (LOXs), were highly expressed for the protective response to drought stress. It could be suggested that the pod wall in alfalfa is capable of operating photosynthesis and reducing the photosynthetic loss from drought stress through the promotion of the C4 pathway, ATP synthesis, and resistance ability.

LuluDB-The Database Created Based on Small RNA, Transcriptome, and Degradome Sequencing Shows the Wide Landscape of Non-coding and Coding RNA in Yellow Lupine (Lupinus luteus L.) Flowers and Pods.

Yellow lupine (Lupinus luteus L.) belongs to a legume family that benefits from symbiosis with nitrogen-fixing bacteria. Its seeds are rich in protein, which makes it a valuable food source for animals and humans. Yellow lupine is also the model plant for basic research on nodulation or abscission of organs. Nevertheless, the knowledge about the molecular regulatory mechanisms of its generative development is still incomplete. The RNA-Seq technique is becoming more prominent in high-throughput identification and expression profiling of both coding and non-coding RNA sequences. However, the huge amount of data generated with this method may discourage other scientific groups from making full use of them. To overcome this inconvenience, we have created a database containing analysis-ready information about non-coding and coding L. luteus RNA sequences (LuluDB). LuluDB was created on the basis of RNA-Seq analysis of small RNA, transcriptome, and degradome libraries obtained from yellow lupine cv. Taper flowers, pod walls, and seeds in various stages of development, flower pedicels, and pods undergoing abscission or maintained on the plant. It contains sequences of miRNAs and phased siRNAs identified in L. luteus, information about their expression in individual samples, and their target sequences. LuluDB also contains identified lncRNAs and protein-coding RNA sequences with their organ expression and annotations to widely used databases like GO, KEGG, NCBI, Rfam, Pfam, etc. The database also provides sequence homology search by BLAST using, e.g., an unknown sequence as a query. To present the full capabilities offered by our database, we performed a case study concerning transcripts annotated as DCL 1–4 (DICER LIKE 1–4) homologs involved in small non-coding RNA biogenesis and identified miRNAs that most likely regulate DCL1 and DCL2 expression in yellow lupine. LuluDB is available at http://luluseqdb.umk.pl/basic/web/index.php.

Defense Response in Chickpea Pod Wall due to Simulated Herbivory Unfolds Differential Proteome Profile.

The pod wall of legumes is known to protect the developing seeds from pests and pathogens. However, the mechanism of conferring defense against insects has not yet been deciphered. Here, we have utilized 2-dimensional gel electrophoresis (2D-GE) coupled with mass spectrometry (MS/MS) to identify over expressed proteins in the pod wall of two different cultivars (commercial cultivar: JG 11 and tolerant cultivar: ICC 506-EB) of chickpea after 12h of application of Helicoverpa armigera oral secretions (simulated herbivory). The assays were performed with a view that larvae are a voracious feeder and cause substantial damage to the pod within 12h. A total of 600 reproducible protein spots were detected on gels, and the comparative analysis helped identify 35 (12 up-regulated, 23 down-regulated) and 20 (10 up-regulated, 10 down-regulated) differentially expressed proteins in JG 11 and ICC 506-EB, respectively. Functional classification of protein spots of each cultivar after MS/MS indicated that the differentially expressed proteins were associated with various metabolic activities. Also, stress-related proteins such as mannitol dehydrogenase (MADH), disease resistance-like protein-CSA1, serine/threonine kinase (D6PKL2), endoglucanase-19 etc. were up-regulated due to simulated herbivory. The proteins identified with a possible role in defense were further analyzed using the STRING database to advance our knowledge on their interacting partners. It decoded the involvement of several reactive oxygen species (ROS) scavengers and other proteins involved in cell wall reinforcement. The biochemical analysis also confirmed the active role of ROS scavengers during simulated herbivory. Thus, our study provides valuable new insights on chickpea-H.armigera interactions at the protein level.

Estimation of neomycin phosphotransferase-II (NPT-II) protein in vegetative and reproductive tissues of transgenic chickpea (Cicer arietinum L.) and biosafety perspectives

Chickpeas are consumed in various edible forms and hence presence of NPT-II proteins encoded by kanamycin resistance gene, NPT-II, in transgenic chickpea seeds raises biosafety concerns related to human health in particular. We estimated the NPT-II protein from various tissues like leaf, pod wall, immature seeds and mature dried seeds of five different transgenic chickpea lines expressing NPT-II. Quantitative ELISA studies indicated that the amount of NPT-II proteins decrease, as chickpea plants approached physiological maturity with mature seeds having lowest NPT-II content (0.98–1.32 ng/mg Total Soluble Protein). Mature chickpea seeds are most commonly used for edible purpose and the content of NPT-II estimated possess no discernible biosafety concern. Further, bioinformatics studies also indicate that NPT-II proteins are innocuous and possibly should not be active in acidic environment in the human gut.

Narrowing Down a Major QTL Region Conferring Pod Fiber Contents in Yardlong Bean (Vigna unguiculata), a Vegetable Cowpea.

Yardlong bean (Vigna unguiculata (L.) Walp. ssp. sesquipedalis), a subgroup of cowpea, is an important vegetable legume crop of Asia where its young pods are consumed in both fresh and cooked forms. Pod fiber contents (cellulose, hemicellulose and lignin) correlates with pod tenderness (softness/hardness) and pod shattering. In a previous study using populations derived from crosses between yardlong bean and wild cowpea (V. unguiculata ssp. unguiculata var. spontanea), three major quantitative trait loci (QTLs), qCel7.1, qHem7.1 and qLig7.1, controlling these fibers were identified on linkage group 7 (cowpea chromosome 5) and are co-located with QTLs for pod tenderness and pod shattering. The objective of this study was to identify candidate gene(s) controlling the pod fiber contents. Fine mapping for qCel7.1, qHem7.1 and qLig7.1 was conducted using F2 and F2:3 populations of 309 and 334 individuals, respectively, from the same cross combination. New DNA markers were developed from cowpea reference genome sequence and used for fine mapping. A QTL analysis showed that in most cases, each pod fiber content was controlled by one major and one minor QTLs on the LG7. The major QTLs for cellulose, hemicellulose and lignin in pod were always mapped to the same regions or close to each other. In addition, a major QTL for pod shattering was also located in the region. Although there were several annotated genes relating to pod fiber contents in the region, two genes including Vigun05g266600 (VuBGLU12) encoding a beta glucosidase and Vigun05g273500 (VuMYB26b) encoding a transcription factor MYB26 were identified as candidate genes for the pod fiber contents and pod shattering. Function(s) of these genes in relation to pod wall fiber biosynthesis and pod shattering was discussed.

Seed transmission of a distinct soybean yellow mottle mosaic virus strain identified from India in natural and experimental hosts

Soybean yellow mottle mosaic virus (SYMMV) is a newly identified member of the genus Gammacarmovirus from grain legumes in India. As the modes of transmission of this virus have not been described, we assessed the possibility of SYMMV to be transmitted through seed collected from field infected mungbean plants and mechanically sap inoculated French bean plants using serological and molecular techniques followed by progeny assays. Direct antigen coated enzyme linked immunosorbent assay (DAC-ELISA) and reverse transcription polymerase chain reaction (RT-PCR) results are inconsistent with field infected mungbean seed tissues to ensure seed transmissibility irrespective of seed number used. Seed from mechanical sap inoculated French bean showed higher absorbance values in DAC-ELISA and amplification corresponding to replicase, movement and coat protein regions of SYMMV genome. The relative accumulation of SYMMV was higher in pod walls, immature seed and stamens and stigma of mechanical sap inoculated French bean. Progeny assays with infected seed revealed the seed transmissibility of SYMMV at the rate of 63.33% in mungbeanand 73.33% in French bean. Mechanical sap inoculation of mungbean progeny seedlings on French bean cv. Pusa Parvati produced characteristic symptoms of SYMMV. The results obtained from this study demonstrate that SYMMV is seed borne in nature and can be transmitted to next generation seedlings. This is the first report of seed transmission of SYMMV in mungbean and French bean.

Feeding Behavior of Nezara viridula First Instars: EPG Analysis and Effect of Food Availability on Subsequent Development

Assertions that first-instar pentatomids “do not feed” are pervasive in the literature. Recent research using rifampicin-resistant marked bacteria demonstrated that first-instar southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae), ingest from green bean. The technique of electropenetrography (EPG), coupled with histology, has allowed researchers to elucidate feeding behavior within plant tissue, and recordings of several species (including N. viridula) have shown that internal stylet probes of adults and late-instar nymphs may terminate in xylem as well as in seed endosperm, inner pod wall, or stem parenchyma. The seeming contradiction regarding “feeding” could be explained if first instars were simply hydrating from plant tissue to maintain water balance. In this study, first-instar N. viridula were supplied with either water or green bean, and subsequently given a traditional rearing diet (green bean and peanut) from second instar onward. We noted aggregations of first instars forming on water wicks and on beans along the carpellary bundles and at both tips. Availability of food (green bean) in first instar did not affect subsequent development. Using EPG, we recorded first-instar N. viridula probing on soybean leaves and found the primary waveform to be xylem ingestion. Probing and ingestion behavior did not differ between first instars previously exposed to high and moderate humidity conditions. We conclude that these insects ingest from xylem, but nutrients other than water are not required in the first instar for successful nymphal development.