Plant secondary metabolites such as terpenes, phenolics, glycosides, and alkaloids play various functional roles including pigmentation, foliar and floral volatile synthesis, hormonal regulation, and direct and indirect defenses. Among these, phenolic compounds are commonly found in plants, but vary in the distribution of their specific compounds among plant families. Polyphenols, including anthocyanins and tannins, are widely distributed and have been well documented for their roles-primarily in plant pigmentation and also in plant defenses. However, commercialization of such compounds for use in insect pest management is severely hampered by expensive, inefficient, and time-consuming extraction protocols. Using a recently developed inexpensive and easy extraction method using the byproducts of pigmented (purple) corn processing, we examined whether the crude pericarp extract rich in polyphenols can affect the growth and development of tobacco hornworm (Manduca sexta L.) caterpillars. Our findings show that purple corn pericarp extract negatively affected M. sexta egg hatching and larval mass gain and prolonged developmental time compared to regular yellow corn extract or an artificial control diet. We also found that these effects were more severe during the early stages of caterpillar development. These results conclusively demonstrate that purple corn pericarp, an inexpensive by-product of the corn milling industry, is a valuable product with excellent potential as an insect antifeedant.
A major bottleneck in the commercialization of plant-based pest management compounds is that the extraction methods are complex, time-consuming, and even highly expensive. Using a recently developed inexpensive extraction and quantification methodology to isolate polyphenols (including anthocyanins and condensed tannins) from purple corn pericarp, we examined their effects on Manduca sexta, a common insect herbivore. Following up on our previous work which demonstrated the negative impacts of polyphenol-rich extract on larval stages, we further examined whether there are any cascading effects on subsequent life stages (pupal and adult) including any possible transgenerational effects. Our results show that polyphenol-rich purple corn extract-fed caterpillars had significantly lower pupal mass and survival. Moreover, adult moths also had lower mass when eclosed from caterpillars reared on the extract diet. To test whether there were any transgenerational effects, we allowed male and female adults fed on purple corn extract diet and control diet to mate and lay eggs in a full factorial experiment. We found that purple corn extract-fed adult pair laid a lower number of eggs compared to other treatments. In addition, we also found that second instar M. sexta caterpillars hatched from eggs laid by any mating combination with at least one parent reared on purple corn extract gained significantly lower mass compared to caterpillars with both parents reared on the control diet. Taken together, our results show that there are cascading negative effects for feeding purple corn pericarp extract on pupal, adult, and second generation of M. sexta, reaffirming its potential application as a cost-effective and environmentally friendly pest deterrent.
Recently, national attention has focused on the needs of family caregivers providing complex chronic care, noting the necessity to better understand the scope of challenges they encounter. Although a robust body of literature exists about the scope of family caregiving, little is known specifically about the experiences and perspectives of family caregivers who support participant directed (PD) participants, particularly across the caregiving trajectory. Therefore, the aim of this qualitative descriptive study was to describe what family caregivers of individuals with developmental disabilities, physical disabilities, aging, or chronic health conditions identify as the challenges they experience as complex, and their perceptions of the effectiveness and gaps in family support resources in PD. Semi-structured interviews were audio-recorded with a purposive sample of caregivers. Transcribed interviews were analyzed using conventional content analysis. Fifty-four caregivers of individuals with a range of disabilities participated (age 34-78, M 59.9 ± 8.8; male 19%; spouse 17%, parent 61%). Six categories emerged from the analysis: contextualizing complexity, complexity in transitions, coping with complexity: advocacy & isolation, supportive support, unsupportive support, and systems challenges. Caregivers emphasized the interplay between unpredictability, transitions, and complexity and the interaction between the person receiving support, the caregiver's own situation, and the environment. Findings highlight the need, and provide a guide, for family assessment and for tailoring interventions matched to the profiles and self-identified challenges of families living with disability. Social workers can learn what families see as complex and what support broker behaviors families find helpful, and which not.
In insects, larval and adult defences against predators have been well studied. However, pupal (also known as resting stage) defences have been overlooked and not examined thoroughly. Although some pupa possess anti-predator 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 behavioural 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 defenceless pupal stage uses a wide range of measurable defence behaviours that can actively defend against predators and should be examined further-linking observed behaviour with underlying mechanisms.
Plants are attacked by multiple insect pest species and insect herbivory can alter plant defense mechanisms. The plant defense responses to a specific herbivore may also contribute to the herbivore growth/survival on plants. Feeding by one insect species can modulate the plant defenses, which can either facilitate or hamper the colonization of subsequent incoming insects. However, little is known about the effect of sequential herbivory on sorghum plants. In this study, we demonstrate that a specialist aphid, sugarcane aphid (SCA; Melanaphis sacchari) grows faster on sorghum than a generalist aphid species, greenbug (GB; Schizaphis graminum). We also determined how the pre-infestation of SCA on sorghum affected the invasion of GB and vice-versa. Our sequential herbivory experiments revealed that SCA reproduction was lower on GB-primed sorghum plants, however, the reverse was not true. To assess the differences in plant defenses induced by specialist vs. generalist aphids, we monitored the expression of salicylic acid (SA) and jasmonic acid (JA) marker genes, and flavonoid biosynthetic pathway genes after 48 h of aphid infestation. The results indicated that GB infestation induced higher expression of SA and JA-related genes, and flavonoid pathway genes (DFR, FNR, and FNSII) compared to SCA infestation. Overall, our results suggested that GB-infested plants activate the plant defenses via phytohormones and flavonoids at early time points and hampers the colonization of incoming SCA, as well as explain the reproductive success of SCA compared to GB.
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