Storage of cannabinoids by Arctia caja and Zonocerus elegans fed on chemically distinct strains of Cannabis sativa

Assessing the adaptive role of cannabidiol (CBD) in Cannabis sativa defense against cannabis aphids

Cannabis sativa is known for having unique specialized or secondary metabolites, cannabinoids that are derived from an extension of the terpene pathway in the Cannabis lineage and includes more than 100 other similar metabolites. Despite the assumption that cannabinoids evolved as novel herbivory defense adaptations, there is limited research addressing the role of cannabinoids in C. sativa responses to insect herbivores. Here we investigated the role of cannabidiol (CBD), the predominant cannabinoid in hemp, in plant defense against cannabis aphid (Phorodon cannabis), one of the most damaging pests of hemp. We hypothesize that insect feeding may induce changes in cannabinoids as an adaptive strategy for defense. We found that mean fecundity, net reproductive rate (R0) and adult longevity of cannabis aphids was reduced on the high cannabinoid cultivar compared to the low- cannabinoid cultivar in whole plant assays. In contrast, supplementation of CBD in artificial feeding assays increased aphid fecundity from day 1 to day 3. Additionally, aphid feeding did not impact cannabinoid levels in leaf tissues with the exception of Δ9-tetrahydrocannabinol (THC). This suggests that other cannabinoids and/or metabolites such as terpenes are causing the observed decrease in aphid performance in the whole plant assays. In addition to cannabinoids, C. sativa also possesses a range of defense mechanisms via phytohormone signaling pathways that are well described in other plant species. Indeed, cannabis aphid feeding significantly increased levels of the major phytohormones, salicylic acid, jasmonic acid, and abscisic acid, which are known to be involved in plant defense responses against aphid species. These results highlight the interplay between cannabinoid synthesis and phytohormone pathways and necessitate further investigation into this complex interaction.

Biology and management of hemp russet mite (Acari: Eriophyidae)

Hemp is rapidly becoming a crop of global agricultural importance, and one of the more serious pests of this crop is hemp russet mite (HRM) Aculops cannabicola (Acari: Eriophyidae). Significant knowledge gaps presently exist regarding critical aspects of pest biology, quantification of crop damage, and efficacy of pesticides. Here we assessed the role of cannabidiol (CBD) on HRM performance, efficacy of sulfur treatments in field trials, and effect of hot water immersion with and without surfactants in reducing HRM counts on hemp cuttings. We found that HRM fecundity was reduced on a high-CBD cultivar compared with a low-CBD cultivar in detached leaf assays. In contrast, HRM fecundity and survival were not impacted when reared on high-CBD diet in artificial feeding assays. This suggests that cannabinoids other than CBD may aid in reduction of mite populations on the high-CBD cultivar. Sulfur sprays reduced HRM populations by up to 98% with the greatest effects seen in plants receiving dual applications, one during the vegetative period in July and the second at the initiation of flowering in August. Yields of plants treated with sulfur increased by up to 33%, and there was a further increase in cannabinoid production by up to 45% relative to untreated plants. Hot water immersion treatments with and without surfactant solution reduced HRM on infested hemp cuttings, and no phytotoxicity was observed. This study provides novel approaches to mitigating HRM at multiple stages in hemp production.

Dietary Challenges for Parasitoid Wasps (Hymenoptera: Ichneumonoidea); Coping with Toxic Hosts, or Not?

Many insects defend themselves against predation by being distasteful or toxic. The chemicals involved may be sequestered from their diet or synthesized de novo in the insects' body tissues. Parasitoid wasps are a diverse group of insects that play a critical role in regulating their host insect populations such as lepidopteran caterpillars. The successful parasitization of caterpillars by parasitoid wasps is contingent upon their aptitude for locating and selecting suitable hosts, thereby determining their efficacy in parasitism. However, some hosts can be toxic to parasitoid wasps, which can pose challenges to their survival and reproduction. Caterpillars employ a varied array of defensive mechanisms to safeguard themselves against natural predators, particularly parasitoid wasps. These defenses are deployed pre-emptively, concurrently, or subsequently during encounters with such natural enemies. Caterpillars utilize a range of strategies to evade detection or deter and evade attackers. These tactics encompass both measures to prevent being noticed and mechanisms aimed at repelling or eluding potential threats. Post-attack strategies aim to eliminate or incapacitate the eggs or larvae of parasitoids. In this review, we investigate the dietary challenges faced by parasitoid wasps when encountering toxic hosts. We first summarize the known mechanisms through which insect hosts can be toxic to parasitoids and which protect caterpillars from parasitization. We then discuss the dietary adaptations and physiological mechanisms that parasitoid wasps have evolved to overcome these challenges, such as changes in feeding behavior, detoxification enzymes, and immune responses. We present new analyses of all published parasitoid-host records for the Ichneumonoidea that attack Lepidoptera caterpillars and show that classically toxic host groups are indeed hosts to significantly fewer species of parasitoid than most other lepidopteran groups.

Comprehending and improving cannabis specialized metabolism in the systems biology era

Cannabis sativa is a source of food, fiber and specialized metabolites such as cannabinoids, with psychoactive and pharmacological effects. Due to its expanding and increasingly-accepted use in medicine, cannabis cultivation is acquiring more importance and less social stigma. Humans initiated different domestication episodes whose later spread gave rise to a plethora of landrace cultivars. At present, breeders cross germplasms from different gene pools depending on their specific use. The fiber (hemp) and drug (marijuana) types of C. sativa differ in their cannabinoid chemical composition phenotype (chemotype) and also in the accumulation of terpenoid compounds that constitute a strain's particular flavor and scent. Cannabinoids are isoprenylated polyketides among which cannabidiolic acid (CBDA) and (-)-trans-Δ⁹-tetrahydrocannabinol acid (THCA) have been well-documented for their many effects on humans. Here, we review the most studied specialized metabolic pathways in C. sativa, showing how terpenes and cannabinoids share both part of the isoprenoid pathway and the same biosynthetic compartmentalization (i.e. glandular trichomes of leaves and flowers). We enlist the several studies that have deciphered these pathways in this species including physical and genetic maps, QTL analyses and localization and enzymatic studies of cannabinoid and terpene synthases. In addition, new comparative modeling of cannabinoid synthases and phylogenetic trees are presented. We describe the genome sequencing initiatives of several accessions with the concomitant generation of next-generation genome maps and transcriptomic data. Very recently, proteomic characterizations and systems biology approaches such as those applying network theory or the integration of multi-omics data have increased the knowledge on gene function, enzyme diversity and metabolite content in C. sativa. In this revision we drift through the history, present and future of cannabis research and on how second- and third-generation sequencing technologies are bringing light to the field of cannabis specialized metabolism. We also discuss different biotechnological approaches for producing cannabinoids in engineered microorganisms.

Plant-feeding phlebotomine sand flies, vectors of leishmaniasis, prefer Cannabis sativa

Blood-sucking phlebotomine sand flies (Diptera: Psychodidae) transmit leishmaniasis as well as arboviral diseases and bartonellosis. Sand fly females become infected with Leishmania parasites and transmit them while imbibing vertebrates' blood, required as a source of protein for maturation of eggs. In addition, both females and males consume plant-derived sugar meals as a source of energy. Plant meals may comprise sugary solutions such as nectar or honeydew (secreted by plant-sucking homopteran insects), as well as phloem sap that sand flies obtain by piercing leaves and stems with their needle-like mouthparts. Hence, the structure of plant communities can influence the distribution and epidemiology of leishmaniasis. We designed a next-generation sequencing (NGS)-based assay for determining the source of sand fly plant meals, based upon the chloroplast DNA gene ribulose bisphosphate carboxylase large chain (rbcL). Here, we report on the predilection of several sand fly species, vectors of leishmaniasis in different parts of the world, for feeding on Cannabis sativa We infer this preference based on the substantial percentage of sand flies that had fed on C. sativa plants despite the apparent "absence" of these plants from most of the field sites. We discuss the conceivable implications of the affinity of sand flies for C. sativa on their vectorial capacity for Leishmania and the putative exploitation of their attraction to C. sativa for the control of sand fly-borne diseases.

Venomous caterpillars: From inoculation apparatus to venom composition and envenomation

Envenomation by the larval or pupal stages of moths occurs when the victim presses their hairs. They penetrate the subcutaneous tissue, releasing toxins such as proteolytic enzymes, histamine and other pro-inflammatory substances. Cutaneous reactions, including severe pain, oedema and erythema are frequent local manifestations of caterpillar envenomation, but, in some cases, the reactions can evolve into vesicles, bullae, erosions, petechiae, superficial skin necrosis and ulcerations. Alternatively, some individual can develop allergic reactions, renal failure, osteochondritis, deformity and immobilization of the affected joints and intracerebral bleeding. Caterpillars produce venom to protect themselves from predators; contact with humans is accidental and deserves close attention. Their venoms have not been well studied, except for toxins from some few species. The present review brings together data on venomous caterpillars of moths, primarily addressing the available literature on diversity among the different families that cause accident in humans, the structures used in their defense, venom composition and clinical aspects of the envenomations. Understanding the molecular mechanisms of action of caterpillars' toxins may lead to the development of more adequate treatments.

A phylogenomic analysis of lichen-feeding tiger moths uncovers evolutionary origins of host chemical sequestration

Host species utilize a variety of defenses to deter feeding, including secondary chemicals. Some phytophagous insects have evolved tolerance to these chemical defenses, and can sequester secondary defense compounds for use against their own predators and parasitoids. While numerous studies have examined plant-insect interactions, little is known about lichen-insect interactions. Our study focused on reconstructing the evolution of lichen phenolic sequestration in the tiger moth tribe Lithosiini (Lepidoptera: Erebidae: Arctiinae), the most diverse lineage of lichen-feeding moths, with 3000 described species. We built an RNA-Seq dataset and examined the adult metabolome for the presence of lichen-derived phenolics. Using the transcriptomic dataset, we recover a well-resolved phylogeny of the Lithosiini, and determine that the metabolomes within species are more similar than those among species. Results from an initial ancestral state reconstruction suggest that the ability to sequester phenolics produced by a single chemical pathway preceded generalist sequestration of phenolics produced by multiple chemical pathways. We conclude that phenolics are consistently and selectively sequestered within Lithosiini. Furthermore, sequestration of compounds from a single chemical pathway may represent a synapomorphy of the tribe, and the ability to sequester phenolics produced by multiple pathways arose later. These findings expand on our understanding of the interactions between Lepidoptera and their lichen hosts.

PKS activities and biosynthesis of cannabinoids and flavonoids in Cannabis sativa L. plants

Polyketide synthase (PKS) enzymatic activities were analyzed in crude protein extracts from cannabis plant tissues. Chalcone synthase (CHS, EC 2.3.1.74), stilbene synthase (STS, EC 2.3.1.95), phlorisovalerophenone synthase (VPS, EC 2.3.1.156), isobutyrophenone synthase (BUS) and olivetol synthase activities were detected during the development and growth of glandular trichomes on bracts. Cannabinoid biosynthesis and accumulation take place in these glandular trichomes. In the biosynthesis of the first precursor of cannabinoids, olivetolic acid, a PKS could be involved; however, no activity for an olivetolic acid-forming PKS was detected. Content analyses of cannabinoids and flavonoids, two secondary metabolites present in this plant, from plant tissues revealed differences in their distribution, suggesting a diverse regulatory control for these biosynthetic fluxes in the plant.

Sequestration of defensive substances from plants by Lepidoptera

A number of aposematic butterfly and diurnal moth species sequester unpalatable or toxic substances from their host plants rather than manufacturing their own defensive substances. Despite a great diversity in their life histories, there are some general features in the selective utilization of plant secondary metabolites to achieve effective protection from predators. This review illustrates the biochemical, physiological, and ecological characteristics of phytochemical-based defense systems that can shed light on the evolution of the widely developed sequestering lifestyles among the Lepidoptera.

The oral activity of delta'-tetrahydrocannabinol and its dependence on prostaglandin E2

1 delta'-trans-Tetrahydrocannabinol (THC) is more active orally in mice than previously thought, as cataleptic responses occur at doses from 0.06 mg/kg upwards, with peak activity at 2 to 4 h after dosing. These doses and peaks correspond well with the effects in man. 2 Comparison with chlorpromazine in mice shows that chlorpromazine and THC are equipotent as cataleptics during the first 2 h after dosing; thereafter the THC activity increases to a peak when it is 5.67 times as active as chlorpromazine. 3 The cataleptic effect of THC is abolished by aspirin, indomethacine, diffunisal and phenylbutazone which inhibit the biosynthesis of prostaglandins and is restored by exogenous prostaglandin E2 (PGE2) but not PGE1 and PGF2 alpha. This suggests that the effect of THC depends upon the presence of PGE2. 4 In contrast, the cataleptic effect of chlorpromazine is not affected by pretreatment with aspirin. 5 THC is very much less active intraperitoneally than orally; our results suggest this is not due to poor absorption or extraction into fat depots. 6 Cannabidiol has no cataleptic effect.

Mortality of the Monarch Butterfly (Danaus plexippus L.): Avian Predation at Five Overwintering Sites in Mexico

Analyses of predated butterflies on the forest floor at five monarch overwintering sites in Mexico and observations of birds foraging in mixed flocks indicate that individual birds of several species have learned to penetrate the monarch's cardenolide-based chemical defense. Predation is inversely proportional to colony size and appears to be one evolutionary explanation of the dense aggregations.