Lethal and Repellent Effects of the Botanical p-Anisaldehyde on Musca domestica (Diptera: Muscidae)

A review of Musca sorbens (Diptera: Muscidae) and Musca domestica behavior and responses to chemical and visual cues

Musca flies (Diptera: Muscidae) have been found culpable in the mechanical transmission of several infectious agents, including viruses, bacteria, protozoans, and helminths, particularly in low-income settings in tropical regions. In large numbers, these flies can negatively impact the health of communities and their livestock through the transmission of pathogens. In some parts of the world, Musca sorbens is of particular importance because it has been linked with the transmission of trachoma, a leading cause of preventable and irreversible blindness or visual impairment caused by Chlamydia trachomatis, but the contribution these flies make to trachoma transmission has not been quantified and even less is known for other pathogens. Current tools for control and monitoring of house flies remain fairly rudimentary and have focused on the use of environmental management, insecticides, traps, and sticky papers. Given that the behaviors of flies are triggered by chemical cues from their environment, monitoring approaches may be improved by focusing on those activities that are associated with nuisance behaviors or with potential pathogen transmission, and there are opportunities to improve fly control by exploiting behaviors toward semiochemicals that act as attractants or repellents. We review current knowledge on the odor and visual cues that affect the behavior of M. sorbens and Musca domestica, with the aim of better understanding how these can be exploited to support disease monitoring and guide the development of more effective control strategies.

Active Compounds with Medicinal Potential Found in Maxillariinae Benth. (Orchidaceae Juss.) Representatives-A Review

Orchids are widely used in traditional medicine for the treatment of a whole range of different health conditions, and representatives of the Neotropical subtribe Maxillariinae are not an exception. They are utilized, for instance, for their spasmolytic and anti-inflammatory activities. In this work, we analyze the literature concerning the chemical composition of the plant extracts and secretions of this subtribe's representatives published between 1991 and 2022. Maxillariinae is one of the biggest taxa within the orchid family; however, to date, only 19 species have been investigated in this regard and, as we report, they produce 62 semiochemicals of medical potential. The presented review is the first summary of biologically active compounds found in Maxillariinae.

Synthesis, Antifungal Activity and 3D-QSAR Study of Novel Anisaldehyde-Derived Amide-Thiourea Compounds

Succinate dehydrogenase (SDH) is an important target enzyme for designing agricultural chemical fungicides. In order to explore novel natural product-based antifungal agents, twenty-one unreported anisaldehyde-derived amide-thiourea compounds were designed and synthesized using the principle of active splicing, and structurally confirmed by ¹ H-NMR, ¹³ C-NMR, ESI-MS, FT-IR, and element analysis. In vitro antifungal activity of the target compounds was evaluated by the agar dilution method. The results showed that some target compounds exhibited better or comparable antifungal activity than that of the commercial fungicide chlorothalonil, in which compounds 5c, 5o, and 5r displayed excellent antifungal activity of 92.6 %, 92.6 % and 99.1 % against P. piricola, respectively, better than that of the positive control. In addition, 3D-QSAR analysis was carried out by the CoMFA method to reveal the relationship between the structures of the target compounds and their inhibitory activities. The simulative binding mode of the target compounds and SDH was also studied by molecular docking.

Binding Affinity Characterization of Four Antennae-Enriched Odorant-Binding Proteins From Harmonia axyridis (Coleoptera: Coccinellidae)

Harmonia axyridis is an important natural enemy that consumes many agricultural and forestry pests. It relies on a sensitive olfactory system to find prey and mates. Odorant-binding proteins (OBPs) as the first-step of recognizing volatiles, transport odors through sensillum lymph to odorant receptors (ORs). However, little is known about the molecular mechanisms of H. axyridis olfaction. In this study, four H. axyridis antenna specific OBP genes, HaxyOBP3, 5, 12, and 15, were bacterially expressed and the binding features of the four recombinant proteins to 40 substances were investigated using fluorescence competitive binding assays. Three-dimensional structure modeling and molecular docking analysis predicted the binding sites between HaxyOBPs and candidate volatiles. Developmental expression analyses showed that the four HaxyOBP genes displayed a variety of expression patterns at different development stages. The expression levels of HaxyOBP3 and HaxyOBP15 were higher in the adult stage than in the other developmental stages, and HaxyOBP15 was significantly transcriptionally enriched in adult stage. Ligand-binding analysis demonstrated that HaxyOBP3 and HaxyOBP12 only combined with two compounds, β-ionone and p-anisaldehyde. HaxyOBP5 protein displayed binding affinities with methyl salicylate, β-ionone, and p-anisaldehyde (K_i = 18.15, 11.71, and 13.45 μM). HaxyOBP15 protein had a broad binding profile with (E)-β-farnesene, β-ionone, α-ionone, geranyl acetate, nonyl aldehyde, dihydro-β-ionone, and linalyl acetate (K_i = 4.33–31.01 μM), and hydrophobic interactions played a key role in the binding of HaxyOBP15 to these substances according to molecular docking. Taken together, HaxyOBP15 exhibited a broader ligand-binding spectrum and a higher expression in adult stage than HaxyOBP3, 5, and 12, indicating HaxyOBP15 may play a greater role in binding volatiles than other three HaxyOBPs. The results will increase our understanding of the molecular mechanism of H. axyridis olfaction and may also result in new management strategies (attractants/repellents) that increase the biological control efficacy of H. axyridis.

Hybrid interaction network of guanidinium-biphenyldisulfonic acid for the structure determination of liquid molecules

Guanidinium−biphenyldisulfonic acid (GBPS) was used as a coformer for the co-crystallization of liquid compounds 1-8 [isoeugenol (1), (-)-isopulegeol (2), eugenol acetate (3), trans-anethole (4), p-anisaldehyde (5), methyl isoeugenol (6), 2,6-dimethylaniline...

Repellency of p-Anisaldehyde Against Musca domestica (Diptera: Muscidae) in the Laboratory

The house fly, Musca domestica L. (Diptera: Muscidae), is a nuisance pest often associated with livestock production, and it can also mechanically transmit the causal agents of human and veterinary diseases. We found that a 0.5% concentration of p-anisaldehyde, produced by many plants consumed by humans, repelled adult M. domestica in static air olfactometer tubes under laboratory conditions for ≥24 h, but by 48 h the repellent activity had worn off. Repellency, however, was not observed in response to 0.5% p-anisaldehyde that had been exposed to sunlight radiation lamps for 2 h. When p-anisaldehyde was aged in darkness for 48 h, it showed strong initial repellency for <1 h. The repellent action of 0.5% p-anisaldehyde was sufficient to keep adult M. domestica from landing on three different food sources when the botanical substance was misted onto the food sources, and when it was placed in proximity to, but not in contact with, the food sources. Extension of p-anisaldehyde's repellent action using solvents other than acetone is discussed.

p-Anisaldehyde Exerts Its Antifungal Activity Against Penicillium digitatum and Penicillium italicum by Disrupting the Cell Wall Integrity and Membrane Permeability

Penicillium digitatum and P. italicum are the two important postharvest pathogens in citrus, causing about 90% of the total loss of citrus fruit during storage and transportation. Natural fungicides such as essential oils have been widely used instead of chemical fungicides for preventing and controlling postharvest diseases. In this research, p-anisaldehyde exhibited a strong inhibitory effect on P. digitatum and P. italicum, with the minimum inhibitory concentration and minimum fungicidal concentration values of both being 2.00 μl/ml. Additionally, p-anisaldehyde visibly inhibited both the green mold and blue mold development of citrus fruits inoculated with P. digitatum and P. italicum. The mycelia morphologies of these pathogens were greatly altered, and the membrane permeability and cell wall integrity of mycelia were severely disrupted under p-anisaldehyde treatment. These results suggest that the antifungal activity of p-anisaldehyde against P. digitatum and P. italicum can be attributed to the disruption of the cell wall integrity.

Attraction of Chrysotropia ciliata (Neuroptera, Chrysopidae) Males to P-Anisaldehyde, a Compound with Presumed Pheromone Function

In a field-trapping experiment with plant volatiles, we observed notably high attraction of green lacewing (Chrysotropia ciliata) males to the compound p-anisaldehyde. Based on this finding, we initiated the present study to elucidate this phenomenon and to investigate the chemical ecology of C. ciliata. Scanning electron microscopy revealed elliptical glands abundantly distributed on the 2nd to 6th abdominal sternites of C. ciliata males, whereas females of the species completely lacked such glands. No p-anisaldehyde was found in extractions of body parts of C. ciliata. Methyl p-anisate and p-methoxybenzoic acid were identified exclusively in the extract from abdominal segments 2–8 of males. Field-trapping experiments revealed no attraction of C. ciliata to either methyl p-anisate or p-methoxybenzoic acid. In contrast, males showed marked attraction to p-anisaldehyde in the field and antennae showed strong responses to this compound. Headspace collections in the field from living insects in their natural environment and during their main daily activity period indicated that p-anisaldehyde was emitted exclusively by C. ciliata males. Our overall results suggest that p-anisaldehyde might serve as a male-produced pheromone that attracts conspecific C. ciliata males. Here, we discuss hypotheses regarding possible mechanisms involved in regulation of p-anisaldehyde production, including involvement of the compounds methyl p-anisate and p-methoxybenzoic acid, and the potential ecological function of p-anisaldehyde in C. ciliata.

Outstanding insecticidal activity and sublethal effects of Carlina acaulis root essential oil on the housefly, Musca domestica, with insights on its toxicity on human cells

Carlina acaulis (Compositae) is traditionally used for food and medicinal purposes in central and southern Europe. Its root essential oil (EO), mainly composed by carlina oxide, is included in the BELFRIT botanical list of food supplements. It is also recognized as a potent mosquito larvicide. It is matter of concern whether this EO could be endowed with intrinsic toxicity to limit its use on a food level. Focusing on the insecticidal activity of this EO, we investigated the acute toxicity and sublethal effects on Musca domestica. In topical assays, the EO was extremely effective (LD₅₀ = 2.74 and 5.96 μg fly^-1, on males and females, respectively). The exposure to a sublethal dose (LD₃₀) led to significant reductions of female longevity (LT₅₀ = 6.7-9.0 days vs. control LT₅₀ = 12.9-13.7 days). Treated females laid 2.5 times fewer eggs over control ones. F₁ vitality decreased: F₁ larvae and pupae showed high mortality, 2-4-fold higher over the control. The EO also showed high cytotoxicity on normal human fibroblasts (NHF-A12, IC₅₀ = 9.4-14.2 μg mL^-1 after 6-48 h). Overall, our findings support the employ of this EO for developing botanical insecticides. At the same time, they encourage food safety authorities to perform a full toxicological assessment for possible restrictions at food level.

Effects of Laboratory Grade Limonene and a Commercial Limonene-Based Insecticide on Haematobia irritans irritans (Muscidae: Diptera): Deterrence, Mortality, and Reproduction

The horn fly, Haematobia irritans irritans (L.) (Diptera: Muscidae), is an important and cosmopolitan blood feeding ectoparasite of cattle. Resistance to conventional insecticides is increasingly problematic and alternative pesticides, including natural products, are being investigated. Limonene is a cyclic monoterpene repellent to some insects that occurs in citrus fruit rinds and in other plants. We assessed laboratory grade limonene and a commercial product, Orange Guard (5.8% AI limonene), against H. irritans irritans in terms of their contact effects upon contact on egg mortality, adults, and larval and pupal development; adult repellency as well as sublethal and fumigation effects. Egg viability declined when they were exposed to Orange Guard at concentrations of 1.45%, 2.9%, and 5.8% whereas laboratory grade limonene at 5.8% and 11.6% was ovicidal. Contact exposure of adult H. irritans irritans to 5.8% laboratory grade limonene and 2.9% Orange Guard caused up to 100 and 88% knockdown (immobilization), respectively. At higher concentrations, laboratory grade limonene and Orange Guard resulted in less, and often shorter periods of knockdown. Although direct contact of 2.9 and 5.8% laboratory grade limonene caused mortality it was negligible when flies were sprayed directly with undiluted Orange Guard. Female H. irritans irritans exposed to sublethal concentrations of Orange Guard did not reduce the numbers of eggs produced, but the undiluted product reduced egg hatchability. Interestingly, limonene and Orange Guard attracted adult H. irritans irritans at concentrations <0.1%. We suggest that the attractancy of unformulated pure limonene might be useful for trapping H. irritans irritans adults.