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Simple Summary: Houseflies (Musca domestica L.) are an important medical and livestock pest that not only annoy animals and humans but can also transmit several human and animal diseases. Synthetic chemical repellents have been the first option for fly management, but most have negative impacts on humans, non-target organisms, and the environment generally. Plant essential oils are active against repelling insect pests and affecting their life cycles. Repellents from these oils are an important strategy as a new, effective, and environmentally friendly alternative for housefly management and reducing disease transmission. We investigated the housefly repellency and storage stability of fennel (Foeniculum vulgare) and anise (Pimpinella anisum) EOs and their combinations using the repellency of α-cypermethrin as a reference. Combinations (fennel + anise; 1:1) were the most effective and stable and more stable repellents than single EOs and α-cypermethrin. Most significantly, all single and combination essential oils were safe for two non-target species: guppies (Poecilia reticulata) and earthworms (Eudrilus eugeniae). The combinations make excellent, natural, and stable repellents for housefly management and are suitable to be developed into environmentally friendly products. Essential oils (EOs) are effective repellents and eco-friendly alternatives. We tested single and combination EOs of fennel and anise for repellency and stability against houseflies. All treatments were stored at 27 °C for up to 360 days. Efficacies were compared against α-cypermethrin as a reference. Safety bioassay used on two representative non-target species (guppies and earthworms) confirmed safety. The strongest repellency and stability, 100% repellency and RC50 of 0.4 mL/m3 on day 1, was achieved by a fennel + anise EO combination (1:1). After 360 days, these combinations remained effective (95% repellency), and RC50 = 0.8 mL/m3. The EO combinations were more effective than all single EOs and α-cypermethrin at all times, showing strong synergy with a synergistic repellent index of 2.4 to 3.3. This fennel + anise EO combination was more than 24 times more effective as a repellent than α-cypermethrin. Morphological damage included damaged antennae with twisted flagella and abnormal aristae. All single and combination EOs were not toxic to the non-targets and could be considered safe, whereas α-cypermethrin was highly toxic to them. Thus, the fennel + anise EO combination has great potential to be developed as a safe, natural repellent for managing housefly populations. [ABSTRACT FROM AUTHOR]

Simple Summary: Organic insecticides against Aedes aegypti L. mosquitoes are regarded as one of the most important tools for containing arboviruses transmitted by this species, such as dengue, Zika, and chikungunya in tropical countries including Thailand, considering the development of mosquito resistance to synthetic chemical larvicides. The most critical way to contain outbreaks is to control the vector that transmits pathogens. Monoterpenes are new, effective, and eco-friendly alternatives. This study investigated the larvicidal and pupicidal activities of two monoterpenes—geranial and trans-cinnamaldehyde—and their combinations. The efficacies of each formulation were compared against each other and temephos. Binary mixtures were significantly more effective than single formulations or temephos. They are safe for the non-target aquatic predator, guppies (Poecilia reticulata). These combinations make excellent insecticides for both larvae and pupae mosquito vector control, and the results open up the opportunity for both compounds to be developed into eco-friendly products. Monoterpenes are effective and eco-friendly alternatives to conventional chemical larvicides. We tested single and binary mixtures of monoterpenes—geranial and trans-cinnamaldehyde—for their larvicidal and pupicidal activities against Aedes aegypti L. and for non-target toxicity on guppies (Poecilia reticulata Peters), using 1% (w/w) temephos as a reference. Geranial and trans-cinnamaldehyde at 250 ppm showed stronger larvicidal and pupicidal activities with a 100% mortality rate and an LT50 ranging from 0.3 to 0.6 h. All combinations were strongly synergistic against larvae and pupae compared to single formulations, with an increased mortality value (IMV) of 6% to 93%. The combination of geranial + trans-cinnamaldehyde (1:1) at 200 ppm showed the highest impact, with an IMV of 93%. The strongest larvicidal and pupicidal activities, a 100% mortality rate, and an LT50 of 0.2 h were achieved by geranial + trans-cinnamaldehyde (1:1) 500 ppm. They were thirty times more effective than a 1% temephos solution (LT50 ranging from 6.7 to 96 h) and caused obviously shriveled cuticles and a swollen respiratory system. All single and binary mixtures were not toxic to the guppies. Thus, the combination of geranial + trans-cinnamaldehyde has great potential as a safe insecticide for controlling mosquito larvae and pupae. [ABSTRACT FROM AUTHOR]

Simple Summary: Houseflies (Musca domestica: Diptera) are serious medical and veterinary vectors of several human and animal pathogens. Ovicides reduce breeding housefly populations and the risk of housefly vector diseases. The natural ovicides of plant essential oils (EOs) and their main ingredients were suitable and sustainable options at this time against houseflies. This study evaluated the housefly ovicidal activities of four single-component formulations and two combination formulations of essential oils and their main constituents. The efficacy of each treatment was compared to that of α-cypermethrin (a synthetic insecticide). Two combinations: lemongrass (Cymbopogon citratus) EO + trans-anethole and star anise (Illicium verum) EO + geranial, were at least 1.1 times as effective in ovicidal activity as all single-component treatments and α-cypermethrin. They induced embryonic damage and mortality inside the activities of the eggs, disrupting the eggshell, hatching line, aeropyles, plastron, and micropyle. More significantly, the two combinations and all single-component formulations were safe for two non-target aquatic species: guppy (Poecilia reticulate: Poeciliidae) and molly (Poecilia latipinna: Poeciliidae), while α-cypermethrin was not safe for them. The two combinations could be developed into an effective and safe natural ovicide for reducing housefly populations and managing housefly vector diseases. This study attempted to evaluate the ovicidal activity of single-component formulations and combination formulations of lemongrass and star anise essential oils (EOs) and their main constituents against housefly eggs. The efficacies of the combinations were compared with those of single-component formulations and α-cypermethrin. Safety bioassays of all treatments and α-cypermethrin on non-target predators—guppy and molly—were conducted. Two combinations: 1% lemongrass EO + 1% trans-anethole and 1% star anise EO + 1% geranial, exhibited a strong ovicidal activity with an inhibition rate of 94.4 to 96.2%. They were 1.1 times as effective as α-cypermethrin. The two combinations also showed high synergistic activity compared to single-component formulations, with a high synergistic index and a high increased inhibition value of 37.4 to 57.7%. All EO treatments were benign for all non-target aquatic species with a high 50% lethal time (LT50) and safety index. In contrast, α-cypermethrin was highly toxic to them with a low LT50. The morphological abnormalities observed in housefly eggs at death were those such as the shrivelling of the eggs, aberrations and damage to the eggshells, hatching lines, aeropyles, plastron, and micropyle. The potential of these two combinations as a cypermethrin replacement is compelling. [ABSTRACT FROM AUTHOR]

Simple Summary: The housefly (Musca domestica) is a global vector of several pathogens and a nuisance to humans and animals. Repellents reduce the risk of housefly vector diseases. Green repellents from plant essential oils (EOs) and their active compounds were, at the time, a promising option against houseflies. This study evaluated the housefly-repellent activities of every tested EO, their main constituents, and several combinations of them. The combinations were lemongrass (Cymbopogon citratus) EO + trans-anethole, lemongrass EO + star anise (Illicium verum) EO, geranial + trans-anethole, and star anise EO + geranial. The efficacies of every formulation were compared against each other and DEET (a synthetic repellent). All combinations were more effective in repellency than all single-component formulations and DEET. More significantly, all of them were safe for four non-target species: guppy (Poecilia reticulata), molly (Poecilia latipinna), dwarf honeybee (Apis florea), and stingless bee (Tetragonula pagdeni). These combinations could be developed into valuable green repellents for housefly vector disease management. The present study evaluated the housefly repellency of single-component formulations and combinations of lemongrass and star anise essential oils (EOs) and their main constituents. The efficacies of the combinations were compared against those of single-component formulations and DEET. Safety bioassays of all formulations and DEET on non-target species—guppy, molly, dwarf honeybee, and stingless bee—were conducted. GC–MS analysis showed that the main constituent of lemongrass EO was geranial (46.83%) and that of star anise EO was trans-anethole (92.88%). All combinations were highly synergistic compared to single-component formulations, with an increased repellent value (IR) of 34.6 to 51.2%. The greatest synergistic effect was achieved by 1.0% lemongrass EO + 1.0% trans-anethole combination, with an IR of 51.2%. The strongest, 100% repellent rate at 6 h was achieved by 1.0% geranial + 1.0% trans-anethole. They were twice as effective as DEET and caused obvious damage to housefly antennae under microscopic observation. All single-component formulations and combinations were benign to the four tested non-target species. In contrast, DEET was highly toxic to them. The synergistic repellency and biosafety of these two combinations are compellingly strong support for developing them into an effective green repellent. [ABSTRACT FROM AUTHOR]