Neonicotinoids can cause arrested pupal ecdysis in Lepidoptera

AbstractRecently, we reported a novel mode of action in monarch butterfly (Danaus plexippus) larvae exposed to neonicotinoid insecticides: arrest in pupal ecdysis following successful larval ecdysis. In this paper, we explore arrested pupal ecdysis in greater detail and propose adverse outcome pathways to explain how neonicotinoids cause this effect. Using imidacloprid as a model compound, we determined that final-instar monarchs, corn earworms (Helicoverpa zea), and wax moths (Galleria mellonella) showed high susceptibility to arrested pupal ecdysis while painted ladies (Vanessa cardui) and red admirals (Vanessa atalanta) showed low susceptibility. Fall armyworms (Spodoptera frugiperda) and European corn borers (Ostrinia nubilalis) were recalcitrant. All larvae with arrested ecdysis developed pupal cuticle, but with incomplete shedding of larval cuticle and unexpanded pupal appendages; corn earworm larvae successfully developed into adults with unexpanded appendages. Delayed initiation of pupal ecdysis was also observed with treated larvae. Imidacloprid exposure was required at least 26 h prior to pupal ecdysis to disrupt the molt. These observations suggest neonicotinoids may disrupt the function of crustacean cardioactive peptide (CCAP) neurons, either by directly acting on their nicotinic acetylcholine receptors or by acting on receptors of inhibitory neurons that regulate CCAP activity.

Download Full-text

Pretty Picky for a Generalist: Impacts of Toxicity and Nutritional Quality on Mantid Prey Processing

Environmental Entomology ◽

10.1093/ee/nvx038 ◽

2017 ◽

Vol 46 (3) ◽

pp. 626-632 ◽

Cited By ~ 2

Author(s):

Jamie L. Rafter ◽

Justin F. Vendettuoli ◽

Liahna Gonda-King ◽

Daniel Niesen ◽

Navindra P. Seeram ◽

...

Keyword(s):

C:N Ratio ◽

Danaus Plexippus ◽

Monarch Butterfly ◽

The Body ◽

Gut Contents ◽

Corn Borers ◽

Body Tissues ◽

Heterogeneous Quality ◽

Behavioral Trials

Abstract Prey have evolved a number of defenses against predation, and predators have developed means of countering these protective measures. Although caterpillars of the monarch butterfly,Danaus plexippus L., are defended by cardenolides sequestered from their host plants, the Chinese mantidTenodera sinensis Saussure guts the caterpillar before consuming the rest of the body. We hypothesized that this gutting behavior might be driven by the heterogeneous quality of prey tissue with respect to toxicity and/or nutrients. We conducted behavioral trials in which mantids were offered cardenolide-containing and cardenolide-freeD. plexippus caterpillars and butterflies. In addition, we fed mantids starved and unstarvedD. plexippus caterpillars from each cardenolide treatment and nontoxicOstrinia nubilalis Hübner caterpillars. These trials were coupled with elemental analysis of the gut and body tissues of bothD. plexippus caterpillars and corn borers. Cardenolides did not affect mantid behavior: mantids gutted both cardenolide-containing and cardenolide-free caterpillars. In contrast, mantids consumed bothO. nubilalis and starvedD. plexippus caterpillars entirely.Danaus plexippus body tissue has a lower C:N ratio than their gut contents, whileO. nubilalis have similar ratios; gutting may reflect the mantid’s ability to regulate nutrient uptake. Our results suggest that post-capture prey processing by mantids is likely driven by a sophisticated assessment of resource quality.

Download Full-text

Nicotinic modulation of hierarchal inhibitory control over prefrontal cortex resting state dynamics: modeling of genetic modification and schizophreniarelated pathology

10.1101/301051 ◽

2018 ◽

Author(s):

Marie Rooy ◽

Fani Koukouli ◽

Uwe Maskos ◽

Boris Gutkin

Keyword(s):

Nicotinic Acetylcholine Receptors ◽

Acetylcholine Receptors ◽

Activity Patterns ◽

Genetic Mutation ◽

Inhibitory Neurons ◽

Dynamics Modeling ◽

Single Nucleotide ◽

Chronic Nicotine ◽

Firing Rate Models ◽

Activity State

AbstractNicotinic acetylcholine receptors (nAChRs) strongly modulate the cholinergic drive to a hierarchy of inhibitory neurons in the superficial layers of the PFC, critical to cognitive processes. Genetic deletion of various types of nAChRs, located on specific interneurons, impacts the properties of ultra-slow transitions between high and low activity states (H-states and L-states, respectively), recorded in mice during quiet wakefulness. In addition, recent data indicate that a genetic mutation of the α5 nAChR subunit located on vasoactive intestinal polypeptide (VIP) inhibitory neurons, the rs16969968 single nucleotide polymorphism (α5 SNP), appears to be responsible for “hypofrontality” observed in schizophrenia. Chronic nicotine application to α5 SNP mice restores neural activity to control levels. Using firing rate models of hierarchically organized neural populations, we showed that the change of activity patterns recorded in the genetically modified mice can be explained by a change of activity state stability, differentially modulated by cholinergic inputs to parvalbumin (PV), somatostatin (SOM) or VIP inhibitory populations. A change in amplitude, but not duration of H-states fully account for the lowered pyramidal (PYR) firing rates recorded in α5 SNP mice. We demonstrate that desensitization and upregulation of β2 nAChRs located on SOM interneurons, but not activation of α5 nAChRs located on VIP interneurons, by chronic nicotine application could account for activity normalization recorded in α5 SNP mice. The model implies that subsequent nicotine withdrawal should lead to PYR activity depression more severe than the original hypofrontality caused by SNP mutation.

Download Full-text

Interaction of maternal choline levels and prenatal Marijuana's effects on the offspring

Psychological Medicine ◽

10.1017/s003329171900179x ◽

2019 ◽

Vol 50 (10) ◽

pp. 1716-1726 ◽

Cited By ~ 4

Author(s):

M. Camille Hoffman ◽

Sharon K. Hunter ◽

Angelo D'Alessandro ◽

Kathleen Noonan ◽

Anna Wyrwa ◽

...

Keyword(s):

Brain Development ◽

Nicotinic Acetylcholine Receptors ◽

Acetylcholine Receptors ◽

Self Regulation ◽

Fetal Brain ◽

Marijuana Use ◽

Maternal Serum ◽

Inhibitory Neurons ◽

Fetal Brain Development ◽

Gestational Week

AbstractBackgroundThis study investigated whether higher maternal choline levels mitigate effects of marijuana on fetal brain development. Choline transported into the amniotic fluid from the mother activates α7-nicotinic acetylcholine receptors on fetal cerebro-cortical inhibitory neurons, whose development is impeded by cannabis blockade of their cannabinoid-1(CB1) receptors.MethodsMarijuana use was assessed during pregnancy from women who later brought their newborns for study. Mothers were informed about choline and other nutrients, but not specifically for marijuana use. Maternal serum choline was measured at 16 weeks gestation.ResultsMarijuana use for the first 10 weeks gestation or more by 15% of mothers decreased newborns' inhibition of evoked potentials to repeated sounds (d’ = 0.55, p < 0.05). This effect was ameliorated if women had higher gestational choline (rs = −0.50, p = 0.011). At 3 months of age, children whose mothers continued marijuana use through their 10th gestational week or more had poorer self-regulation (d’ = −0.79, p < 0.05). This effect was also ameliorated if mothers had higher gestational choline (rs = 0.54, p = 0.013). Maternal choline levels correlated with the children's improved duration of attention, cuddliness, and bonding with parents.ConclusionsPrenatal marijuana use adversely affects fetal brain development and subsequent behavioral self-regulation, a precursor to later, more serious problems in childhood. Stopping marijuana use before 10 weeks gestational age prevented these effects. Many mothers refuse to cease use because of familiarity with marijuana and belief in its safety. Higher maternal choline mitigates some of marijuana's adverse effects on the fetus.

Download Full-text