Less is More: Treatment with BTH and Laminarin Reduces Herbivore-Induced Volatile Emissions in Maize but Increases Parasitoid Attraction

Chemical plant strengtheners find increasing use in agriculture to enhance resistance against pathogens. In an earlier study, it was found that treatment with one such resistance elicitor, BTH (benzo-(1, 2, 3)-thiadiazole-7-carbothioic acid S-methyl ester), increases the attractiveness of maize plants to a parasitic wasp. This surprising additional benefit of treating plants with BTH prompted us to conduct a series of olfactometer tests to find out if BTH and another commercially available plant strengthener, Laminarin, increase the attractiveness of maize to three important parasitic wasps, Cotesia marginventris, Campoletis sonorensis, and Microplitis rufiventris. In each case, plants that were sprayed with the plant strengtheners and subsequently induced to release volatiles by real or mimicked attack by Spodoptera littoralis caterpillars became more attractive to the parasitoids than water treated plants. The elicitors alone or in combination with plants that were not induced by herbivory were not attractive to the wasps. Interestingly, plants treated with the plant strengtheners did not show any consistent increase in volatile emissions. On the contrary, treated plants released less herbivore-induced volatiles, most notably indole, which has been reported to interfere with parasitoid attraction. The emission of the sesquiterpenes (E)-β-caryophyllene, β-bergamotene, and (E)-β-farnesene was similarly reduced by the treatment. Expression profiles of marker genes showed that BTH and Laminarin induced several pathogenesis related (PR) genes. The results support the notion that, as yet undetectable and unidentified compounds, are of major importance for parasitoid attraction, and that these attractants may be masked by some of the major compounds in the volatile blends. This study confirms that elicitors of pathogen resistance are compatible with the biological control of insect pests and may even help to improve i

Emerging thermal imaging techniques for seed quality evaluation: Principles and applications

Due to the massive progress occurred in the past few decades in imaging, electronics and computer science, infrared thermal imaging technique has witnessed numerous technological advancement and smart applications in non-destructive testing and quality monitoring of different agro-food produces. Thermal imaging offers a potential non-contact imaging modality for the determination of various quality traits based on the infrared radiation emitted from target foods. The technique has been moved from just an exploration method in engineering and astronomy into an effective tool in many fields for forming unambiguous images called thermograms eventuated from the temperature and thermal properties of the target objects. It depends principally on converting the invisible infrared radiation emitted by the objects into visible two-dimensional temperature data without making a direct contact with the examined objects. This method has been widely used for different applications in agriculture and food science and technology with special applications in seed quality assessment. This article provides an overview of thermal imaging theory, briefly describes the fundamentals of the system and explores the recent advances and research works conducted in quality evaluation of different sorts of seeds. The article comprehensively reviewed research efforts of using thermal imaging systems in seed applications including estimation of seed viability, detection of fungal growth and insect infections, detection of seed damage and impurities, seed classification and variety identification.info:eu-repo/semantics/acceptedVersio

Tomato treatment with chemical inducers reduces the performance of Spodoptera littoralis (Lepidoptera: Noctuidae)

The evolving understanding of plant signaling pathways has promoted the possibility of using chemical inducers as an effective tactic for crop protection. In this study, under greenhouse conditions, we conducted a growth assay of Spodoptera littoralis (Boisduval) larvae on tomato plants treated with BTH (S-methyl benzo [1, 2, 3] thiadiazole 7 carbothioate) as a salicylic acid mimic, PDJ (propyl [1RS, 2RS]-[3-oxo-2-pentylcyclopentyl] acetate) as a jasmonic acid-mimic or both chemicals as a combined treatment. The larval body weight of S. littoralis was drastically reduced with each chemical compared to control plants, and there was a significant synergistic interaction. Overall, the total weight gain of surviving larvae fed on treated plants was distinctly tenfold less than for those fed on control plants. Moreover, incorporating the chemical inducers in artificial diets had no direct or toxic impact on the larval body weight of S. littoralis under laboratory conditions. Larval survival rates were significantly lower (35–40 %) on treated plants with either combined or independent inducers’ treatments compared with control plants after 15-day feeding. In contrast, incorporating the chemical inducers in artificial diets had no direct effect on larval survival rates under laboratory conditions. The applied concentrations of BTH and PDJ had no detectable phytotoxicity to tomato plants. Our results demonstrate that BTH and PDJ can act synergistically when applied to tomato to reduce the performance of S. littoralis. These findings stress that the application of chemical inducers could provide an environment-friendly tactic to help manage insect pests and thereby play multiple roles in improving the overall plant resistance to herbivore pests.status: publishe

Tomato treatment with chemical inducers reduces the performance of Spodoptera littoralis (Lepidoptera: Noctuidae)

The evolving understanding of plant signaling pathways has promoted the possibility of using chemical inducers as an effective tactic for crop protection. In this study, under greenhouse conditions, we conducted a growth assay of Spodoptera littoralis (Boisduval) larvae on tomato plants treated with BTH (S-methyl benzo [1, 2, 3] thiadiazole 7 carbothioate) as a salicylic acid mimic, PDJ (propyl [1RS, 2RS]-[3-oxo-2-pentylcyclopentyl] acetate) as a jasmonic acid-mimic or both chemicals as a combined treatment. The larval body weight of S. littoralis was drastically reduced with each chemical compared to control plants, and there was a significant synergistic interaction. Overall, the total weight gain of surviving larvae fed on treated plants was distinctly tenfold less than for those fed on control plants. Moreover, incorporating the chemical inducers in artificial diets had no direct or toxic impact on the larval body weight of S. littoralis under laboratory conditions. Larval survival rates were significantly lower (35–40 %) on treated plants with either combined or independent inducers’ treatments compared with control plants after 15-day feeding. In contrast, incorporating the chemical inducers in artificial diets had no direct effect on larval survival rates under laboratory conditions. The applied concentrations of BTH and PDJ had no detectable phytotoxicity to tomato plants. Our results demonstrate that BTH and PDJ can act synergistically when applied to tomato to reduce the performance of S. littoralis. These findings stress that the application of chemical inducers could provide an environment-friendly tactic to help manage insect pests and thereby play multiple roles in improving the overall plant resistance to herbivore pests

Effect of different types of ovipositional substrates and shelters on the mass rearing parameters of Orius albidipennis (Reuter) (Hemiptera: Anthocoridae)

The effects of different types of ovipositional substrates and shelters on egg deposition, hatchability and survival rate of Orius albidipennis (Reuter) (Hemiptera: Anthocoridae) were studied under laboratory conditions of 26±1°C, 60±10 % RH and 16:8 L/D photoperiod, using eggs of Anagasta kuehniella (Zell.) as food. Four types of ovipositional substrates were investigated; i.e., bean Phaseolus vulgaris (L.) pods, geranium leaves, sweet pepper seedlings and corn ear silk in free and non-free choice tests. For egg deposition, results showed that this parameter was significantly affected by the tested ovipositional substrate in free (P=0.0001) and non-free (P=0.0001) choice tests and oviposition was in the order of bean pods ! geranium leaves ! sweet pepper seedling ! corn ear silk. Moreover, hatchability also differed significantly among the tested materials being highest of 72.61 % in bean pods and lowest of 52.52% in sweet pepper seedling. In addition, white foam balls, small rolled carton, vermiculate and rice hull were evaluated as shelters to reduce cannibalism under lab conditions. Data indicated that the highest egg-adult survivorship was recorded when using white foam balls, with an average of 92.57 %.status: publishe

Effects of different temperature levels on the biological attributes of Orius albidipennis (Reuter) (Hemiptera: Anthocoridae)

The effect of four degree of temperature (22, 26, 30, and 34 ±1 °C) on the bio-parameters of Orius albidipennis (Reuter) was studied under controlled conditions of 60±10 % RH and photoperiodic regime of 16L/8D. Egg of Anagasta kuheniella (Zell.) were supplied as prey and bean Phasolus vulgaris (L.) pods were used as ovipositional substrate. Results indicated that temperature greatly affected the developmental and reproductive biology of O. albidipennis. For the immature stages, results showed that there was a negative correlation between temperature and the developmental period of O. albidipennis. The shortest developmental period (10.20 days) was recoded at 34 °C and the longest (22.46 days) was recorded at 22 °C. The same trend of relation was found in the adult longevity: with temperature increasing adult longevity decreased. The optimum temperature for nymphal feeding consumption was found to be 26 °C with an average of 61.00 eggs of A. kuheniella. Analogously, the greatest feeding consumption for both males (39.00 eggs) and females (325.89 eggs) were recorded at the same temperature regime. Also, O. albidipennis females showed the greatest fecundity of 163.00 eggs at 26 °C. Thus, 26 °C associated with above mentioned relative humidity and photoperiodic regime is considered the best temperature for rearing the predatory bug O. albidipennis.status: publishe

Recent Applications of Multispectral Imaging in Seed Phenotyping and Quality Monitoring—An Overview

As a synergistic integration between spectroscopy and imaging technologies, spectral imaging modalities have been emerged to tackle quality evaluation dilemmas by proposing different designs with effective and practical applications in food and agriculture. With the advantage of acquiring spatio-spectral data across a wide range of the electromagnetic spectrum, the state-of-the-art multispectral imaging in tandem with different multivariate chemometric analysis scenarios has been successfully implemented not only for food quality and safety control purposes, but also in dealing with critical research challenges in seed science and technology. This paper will shed some light on the fundamental configuration of the systems and give a birds-eye view of all recent approaches in the acquisition, processing and reproduction of multispectral images for various applications in seed quality assessment and seed phenotyping issues. This review article continues from where earlier review papers stopped but it only focused on fully-operated multispectral imaging systems for quality assessment of different sorts of seeds. Thence, the review comprehensively highlights research attempts devoted to real implementations of only fully-operated multispectral imaging systems and does not consider those ones that just utilized some key wavelengths extracted from hyperspectral data analyses without building independent multispectral imaging systems. This makes this article the first attempt in briefing all published papers in multispectral imaging applications in seed phenotyping and quality monitoring by providing some examples and research results in characterizing physicochemical quality traits, predicting physiological parameters, detection of defect, pest infestation and seed health

Utilization of computer vision and multispectral imaging techniques for classification of cowpea (Vigna unguiculata) seeds

Abstract Background The traditional methods for evaluating seeds are usually performed through destructive sampling followed by physical, physiological, biochemical and molecular determinations. Whilst proven to be effective, these approaches can be criticized as being destructive, time consuming, labor intensive and requiring experienced seed analysts. Thus, the objective of this study was to investigate the potential of computer vision and multispectral imaging systems supported with multivariate analysis for high-throughput classification of cowpea (Vigna unguiculata) seeds. An automated computer-vision germination system was utilized for uninterrupted monitoring of seeds during imbibition and germination to identify different categories of all individual seeds. By using spectral signatures of single cowpea seeds extracted from multispectral images, different multivariate analysis models based on linear discriminant analysis (LDA) were developed for classifying the seeds into different categories according to ageing, viability, seedling condition and speed of germination. Results The results revealed that the LDA models had good accuracy in distinguishing ‘Aged’ and ‘Non-aged’ seeds with an overall correct classification (OCC) of 97.51, 96.76 and 97%, ‘Germinated’ and ‘Non-germinated’ seeds with OCC of 81.80, 79.05 and 81.0%, ‘Early germinated’, ‘Medium germinated’ and ‘Dead’ seeds with OCC of 77.21, 74.93 and 68.00% and among seeds that give ‘Normal’ and ‘Abnormal’ seedlings with OCC of 68.08, 64.34 and 62.00% in training, cross-validation and independent validation data sets, respectively. Image processing routines were also developed to exploit the full power of the multispectral imaging system in visualizing the difference among seed categories by applying the discriminant model in a pixel-wise manner. Conclusion The results demonstrated the capability of the multispectral imaging system in the ultraviolet, visible and shortwave near infrared range to provide the required information necessary for the discrimination of individual cowpea seeds to different classes. Considering the short time of image acquisition and limited sample preparation, this stat-of-the art multispectral imaging method and chemometric analysis in classifying seeds could be a valuable tool for on-line classification protocols in cost-effective real-time sorting and grading processes as it provides not only morphological and physical features but also chemical information for the seeds being examined. Implementing image processing algorithms specific for seed quality assessment along with the declining cost and increasing power of computer hardware is very efficient to make the development of such computer-integrated systems more attractive in automatic inspection of seed quality

Less is more: treatment with BTH and laminarin reduces herbivore-induced volatile emissions in maize but increases parasitoid attraction

Chemical plant strengtheners find increasing use in agriculture to enhance resistance against pathogens. In an earlier study, it was found that treatment with one such resistance elicitor, BTH (benzo-(1, 2, 3)-thiadiazole-7-carbothioic acid S-methyl ester), increases the attractiveness of maize plants to a parasitic wasp. This surprising additional benefit of treating plants with BTH prompted us to conduct a series of olfactometer tests to find out if BTH and another commercially available plant strengthener, Laminarin, increase the attractiveness of maize to three important parasitic wasps, Cotesia marginventris, Campoletis sonorensis, and Microplitis rufiventris. In each case, plants that were sprayed with the plant strengtheners and subsequently induced to release volatiles by real or mimicked attack by Spodoptera littoralis caterpillars became more attractive to the parasitoids than water treated plants. The elicitors alone or in combination with plants that were not induced by herbivory were not attractive to the wasps. Interestingly, plants treated with the plant strengtheners did not show any consistent increase in volatile emissions. On the contrary, treated plants released less herbivore-induced volatiles, most notably indole, which has been reported to interfere with parasitoid attraction. The emission of the sesquiterpenes (E)-β-caryophyllene, β-bergamotene, and (E)-β-farnesene was similarly reduced by the treatment. Expression profiles of marker genes showed that BTH and Laminarin induced several pathogenesis related (PR) genes. The results support the notion that, as yet undetectable and unidentified compounds, are of major importance for parasitoid attraction, and that these attractants may be masked by some of the major compounds in the volatile blends. This study confirms that elicitors of pathogen resistance are compatible with the biological control of insect pests and may even help to improve it.status: publishe