Sex and stress modulate pupal defense response in tobacco hornworm.

In insects, larval and adult defenses against predators have been well studied. However, pupal (also known as resting stage) defenses have been overlooked and not examined thoroughly. Although some pupa possess antipredator strategies such as hairs, spines, cryptic coloration, and exudation of chemicals, few studies have tested these responses and the factors affecting them. Here, we investigated the behavioral responses in tobacco hornworm Manduca sexta that pupates in soil by introducing an external stimulus using vibrations from an electric toothbrush to mimic predation. We observed that M. sexta made violent wriggling (twitching), followed by pulsating movements in response to the vibrational stimulus. Detailed examination showed that these twitches and pulsating events occurred more frequently and for longer periods of time in male pupa and were dependent on the magnitude of the stress (high and low frequency). However, when we estimated the angular force exerted by pupa using radian and angular momentum of twitches, it was found to be independent of pupal sex. A follow-up experiment on possible cascading effects of stress exposure on eclosion success revealed that low- and high-frequency stress exposure didn't cause any of the common defects in eclosed adults. Our study clearly demonstrates that the so-called defenseless pupal stage uses a wide range of measurable defense behaviors that can actively defend against predators and should be examined further-linking observed behavior with underlying mechanisms.

Desktop scanning electron microscopy in plant-insect interactions research: a fast and effective way to capture electron micrographs with minimal sample preparation.

The ability to visualize cell and tissue morphology at a high magnification using scanning electron microscopy (SEM) has revolutionized plant sciences research. In plant-insect interactions studies, SEM-based imaging has been of immense assistance to understand plant surface morphology including trichomes [plant hairs; physical defense structures against herbivores], spines, waxes, and insect morphological characteristics such as mouth parts, antennae, and legs, that they interact with. While SEM provides finer details of samples, and the imaging process is simpler now with advanced image acquisition and processing, sample preparation methodology has lagged. The need to undergo elaborate sample preparation with cryogenic freezing, multiple alcohol washes, and sputter coating makes SEM imaging expensive, time consuming, and warrants skilled professionals, making it inaccessible to majority of scientists. Here, using a desktop version of SEM (SNE- 4500 Plus Tabletop), we show that the "plug and play" method can efficiently produce SEM images with sufficient details for most morphological studies in plant-insect interactions. We used leaf trichomes of Solanum genus as our primary model, and oviposition by tobacco hornworm (Manduca sexta; Lepidoptera: Sphingidae) and fall armyworm (Spodoptera frugiperda; Lepidoptera: Noctuidae), and leaf surface wax imaging as additional examples to show the effectiveness of this instrument and present a detailed methodology to produce the best results with this instrument. While traditional sample preparation can still produce better resolved images with less distortion, we show that even at a higher magnification, the desktop SEM can deliver quality images. Overall, this study provides detailed methodology with a simpler "no sample preparation" technique for scanning fresh biological samples without the use of any additional chemicals and machinery.

Local adaptation to continuous mowing makes the noxious weed Solanum elaeagnifolium a superweed candidate by improving fitness and defense traits.

The role of disturbance in accelerating weed growth is well understood. While most studies have focused on soil mediated disturbance, mowing can also impact weed traits. Using silverleaf nightshade (Solanum elaeagnifolium), a noxious and invasive weed, through a series of field, laboratory, and greenhouse experiments, we asked whether continuous mowing influences growth and plant defense traits, expressed via different avenues, and whether they cascade into offspring. We found that mowed plants produced significantly less number of fruits, and less number of total seeds per plant, but had higher seed mass, and germinated more and faster. When three herbivores were allowed to feed, tobacco hornworm (Manduca sexta) caterpillars, gained more mass on seedlings from unmowed plants, while cow pea aphid (Aphis craccivora), a generalist, established better on mowed seedlings; however, leaf trichome density was higher on unmowed seedlings, suggesting possible negative cross talk in defense traits. Texas potato beetle (Leptinotarsa texana), a co-evolved specialist on S. elaeagnifolium, did not show any differential feeding effects. We also found that specific root length, an indicator of nutrient acquisition, was significantly higher in first generation seedlings from mowed plants. Taken together, we show that mowing is a selective pressure that enhances some fitness and defense traits and can contribute to producing superweeds.

A quantum enhanced search for dark matter axions.

The manipulation of quantum states of light1 holds the potential to enhance searches for fundamental physics. Only recently has the maturation of quantum squeezing technology coincided with the emergence of fundamental physics searches that are limited by quantum uncertainty2,3. In particular, the quantum chromodynamics axion provides a possible solution to two of the greatest outstanding problems in fundamental physics: the strong-CP (charge-parity) problem of quantum chromodynamics4 and the unknown nature of dark matter5-7. In dark matter axion searches, quantum uncertainty manifests as a fundamental noise source, limiting the measurement of the quadrature observables used for detection. Few dark matter searches have approached this limit3,8, and until now none has exceeded it. Here we use vacuum squeezing to circumvent the quantum limit in a search for dark matter. By preparing a microwave-frequency electromagnetic field in a squeezed state and near-noiselessly reading out only the squeezed quadrature9, we double the search rate for axions over a mass range favoured by some recent theoretical projections10,11. We find no evidence of dark matter within the axion rest energy windows of 16.96-17.12 and 17.14-17.28 microelectronvolts. Breaking through the quantum limit invites an era of fundamental physics searches in which noise reduction techniques yield unbounded benefit compared with the diminishing returns of approaching the quantum limit.

The Multifunctional Roles of Polyphenols in Plant-Herbivore Interactions.

There is no argument to the fact that insect herbivores cause significant losses to plant productivity in both natural and agricultural ecosystems. To counter this continuous onslaught, plants have evolved a suite of direct and indirect, constitutive and induced, chemical and physical defenses, and secondary metabolites are a key group that facilitates these defenses. Polyphenols-widely distributed in flowering plants-are the major group of such biologically active secondary metabolites. Recent advances in analytical chemistry and metabolomics have provided an opportunity to dig deep into extraction and quantification of plant-based natural products with insecticidal/insect deterrent activity, a potential sustainable pest management strategy. However, we currently lack an updated review of their multifunctional roles in insect-plant interactions, especially focusing on their insect deterrent or antifeedant properties. This review focuses on the role of polyphenols in plant-insect interactions and plant defenses including their structure, induction, regulation, and their anti-feeding and toxicity effects. Details on mechanisms underlying these interactions and localization of these compounds are discussed in the context of insect-plant interactions, current findings, and potential avenues for future research in this area.

Exposure to polyphenol-rich purple corn pericarp extract restricts fall armyworm (Spodoptera frugiperda) growth.

Bioactive compounds such as polyphenols in plants have been well studied for their potential insecticidal activities. These are considered as safe alternatives against chemical pesticides because of their lower persistence in environment, lower toxicity to humans and other organisms. However, they are present constitutively in lower amounts in plants and have to undergo complicated extraction methods - hampering their commercial exploitation in pest management. Using an inexpensive extraction method developed to recover polyphenol-rich liquid extract from purple corn pericarp, we recently documented that this extract has anti-feeding effects that cascade from larval to adult stages in a model herbivore tobacco hornworm (Manduca sexta). However, M. sexta does not feed on corn or any other major crops other than the species in the nightshade family (Solanaceae). In this study, we explored the same idea but using a generalist and common herbivore on corn, the fall armyworm (Spodoptera frugiperda). We found that purple corn pericarp extract inhibited the larval growth and development as well as negatively affected the pupal stages of S. frugiperda. However, unlike on M. sexta, time to complete larval life cycle was unaffected. Our findings confirm the toxicity of this extract on a generalist, economically important herbivore, but also suggest potential species-specific effects that should be explored further.

Prevalence of Colour Vision Anomalies Amongst Dental Professionals and its Effect on Shade Matching of Teeth.

INTRODUCTION: The success of a restoration is dependent on accurate shade matching of teeth leading to studies evaluating the factors affecting the perception of shades. Colour vision anomalies including colour blindness have been found to exist in the population and it has been thought to be a potential factor affecting the colour perception ability. AIM: The present study was done to evaluate the prevalence of colour vision anomalies and its effect on matching of shades of teeth. MATERIALS AND METHODS: A total of 147 dental professionals were randomly selected for the study and were first tested for visual acuity using the Snellen's Eye Chart so as to carry on the study with only those operators who had a vision of 6/6. Then, the Ishihara's colour charts were used to test the operators for colour vision handicap. In the last stage of the study, test for accuracy of shade selection was done using the Vitapan Classical shade guide. The shade guide tabs were covered to avoid bias. Percentage was used to calculate the prevalence of colour vision handicap and its effect on matching of shades of teeth as compared to normal vision, which was evaluated using Chi square test. RESULTS: Nineteen operators had colour vision anomalies out of hundred operators and only two operators presented with colour blindness. Colour vision anomaly was more prevalent than colour blindness and it was also found that it was more prevalent in males than females. The difference between the accuracy of shade matching between the operators with normal vision and colour vision defect and operators with normal vision and colour blindness was statistically not significant. CONCLUSION: Colour blindness and colour vision handicap are rare conditions, with the latter being more common in the population. According to our study, it was concluded that no statistically significant difference existed amongst the operators with normal vision and colour vision anomaly or operators with normal vision and colour blindness during the matching of shades of teeth.