In vitro insecticidal effects of fipronil and beta-cyfluthrin on larvae of the blowfly Lucilia sericata

Insecticidal Activity of Hyoscyamus niger L. on Lucilia sericata Causing Myiasis

Background: Hyoscyamus niger L. (Solanaceae) generally known as henbane, is commonly distributed in Europe and Asia. In Turkey, henbane seeds have been used in folk medicine to remove worms from the eyes. The present study aimed to investigate the insecticidal activity of H. niger seeds. Methods: n-hexane, ethyl acetate, methanol and alkaloid extracts were prepared from the seeds of the plant and their insecticidal activities on Lucilia sericata larvae were evaluated. EC₅₀ and EC₉₀ values of the alkaloid extract were calculated and morphological abnormalities were investigated. Results: Alkaloid extract prepared from the seeds of this plant displayed significant insecticidal activity. EC₅₀ values of H. niger seeds alkaloid extract were found to be 8.04, 8.49, 7.96 μg/mL against first, second and third instar, respectively. It was determined that malformations of larvae included damaged larvae with small size, contraction and weak cuticle. Furthermore, HPLC analysis was performed on alkaloid extract of H. niger seeds and main components of the extract were determined. It was determined that alkaloid extract mainly contain hyoscyamine and scopolamine. Conclusions: These results confirm the folkloric usage of the plant and suggest that the alkaloid content of the plant could be responsible for the insecticidal activity.

Alginate–copper microspheres as efficient and reusable heterogeneous catalysts for the one-pot synthesis of 4-organylselanyl-1H-pyrazoles

This study demonstrates the facile preparation and use of alginate–Cu²⁺ microspheres in the catalysis of a new class of organoselenium substituted pyrazoles through one-pot reactions.

Looking for the right mate-What we really know on the courtship and mating of Lucilia sericata (Meigen)?

Lucilia sericata is well known for causing myiasis in humans, livestock, pets and wildlife. It also vectors microbial pathogens, including paratuberculosis agents. This species can be exploited in maggot therapy to treat necrotic wounds, particularly those infected by multidrug-resistant pathogens. Despite its high medical and veterinary importance, our knowledge about its courtship and mating behavior is still limited. In this study, we quantified the courtship and mating behavior of L. sericata, shedding light on the potential impact of lateralization of selected behavioral traits during sexual interactions. When a male identified a female, he approached her with head pushing followed by foreleg tapping acts. Courtship lasted 7.65 ± 0.4 s. During copulation attempts, the male continued foreleg tapping acts on the female body, and tried to achieve genital contact. Copula lasted 14.88 ± 0.41 min, while male mating success was 85%. Several courtship and mating traits were found lateralized at population-level. Most of males approached the female with head pushing acts on her left side of the body. Both during courtship and copulation attempt phases, males mainly used the right foreleg to perform leg tapping acts on females. However, the impact of lateralized head pushing and foreleg tapping on the main behavioral parameters characterizing L. sericata courtship and mating was not significant, except for a higher number of foreleg tapping acts during copulation attempts displayed by right-biased males over left-biased ones. Overall, these results contribute to improve our basic knowledge on the reproductive behavior of L. sericata. Besides, selected behavioral parameters characterized here can be exploited as benchmarks to monitor mate quality during mass-rearing, as well as to select males with boosted mating competitiveness, helping to improve the success of SIT programs and behavior-based control tools.

The prevalence of Gasterophilus intestinalis (Diptera: Oestridae) in donkeys (Equus asinus) in Egypt with special reference to larvicidal effects of neem seed oil extract (Azadirachta indica) on third stage larvae

Gasterophiline larvae are of veterinary and medical importance caused specific equine intestinal myiasis. Gasterophilus intestinalis (Botfly larvae) had a wide geographical distribution. The present study explores the prevalence rate of G. intestinalis 3^rd stage larvae in Egypt from January- December 2017; besides, in vitro trials to control of this larvae and evaluation of this trial using Scanning Electron Microscope (SEM) and histopathology of treated larvae. In the present study, the 3^rd larval stage of G. intestinalis was found in clusters in the epithelium of the investigated stomach and infested with prevalence rate 97.2%. The highest collected numbers of larvae were found in two months; March and August (570 & 520 larvae) and lowest numbers (200 larvae) were collected in October, November, and December. The calculated LC₅₀ and LC₉₀ values of neem seed extract were 707.9 ppm and 1090.7 ppm. The different alteration was recorded after exposure to oil extract which showed some destruction on cuticle surface as folded and corrugated cuticle, destruction of maxillae with pits on its surface, disfigure and irregularity of cephalic spines. Histopathology of exposed G. intestinalis larvae showed different changes as thinning of cuticle at the different level (exocuticle, endocuticle, cell layers), degeneration of epithelial cells of the gut and different degree of necrosis was described. Life cycle of G.intestinalis was followed up after treatment with neem seed extract.

Effectiveness of Fipronil as a Systemic Control Agent Against Xenopsylla cheopis (Siphonaptera: Pulicidae) in Madagascar

Fipronil was evaluated as a systemic control agent for the rat flea Xenopsylla cheopis (Rothschild), the main vector of Yersinia pestis (Yersin), the causative agent of plague, in Madagascar. The effectiveness of fipronil as a systemic control agent against X. cheopis was assessed by determining the toxicity values of the "Lethal Dose 50" (LD50). Two techniques were used to evaluate the systemic action of the insecticide on the vector: 1) an artificial feeding device filled with blood-fipronil mixture from which X. cheopis was fed and 2) rodent hosts, Rattus norvegicus (Berkenhout) and Rattus rattus (L.), which fed on fipronil-treated bait. As a standardized control method, the susceptibility of X. cheopis to fipronil was evaluated by exposure to impregnated paper within World Health Organization (WHO) insecticide test protocol to compare its effect to the systemic activity of the studied insecticide. Results showed that when administered in a systemic way, fipronil appears to be more effective: the toxicity level was evaluated to be ninefold higher compared with the WHO test. Compared with other methods, which require indiscriminate dusting of rodent burrows and human dwellings, fipronil applied in a systemic way enables the direct targeting of the plague vector. Thus, this method appears to be a superior alternative to fipronil-dusting for the control of the main plague vector in Madagascar. However, subsequent tests in the field are necessary to confirm the suitability of fipronil administration in a systemic way on large scales.

In vitro effects of household products on Calliphoridae larvae development: implication for forensic entomology

Several parameters can delay the first arrival of flies on a corpse and the subsequent development of the larvae. This study focuses on the development of Lucilia sericata (Diptera: Calliphoridae) (Meigen, 1826) on household chemical-contaminated substrates. bleach, perfume, hydrochloric acid, caustic soda, insecticide, mosquito repellent, and gasoline in quantities consistent with an amount that could possibly be spilled on a corpse were mixed with beef liver to simulate contaminated fleshes. Larvae were bred at 25 °C on these media until emergence. Four developmental parameters were followed: survival rates, development times, sex ratios, and adult sizes. Hydrochloric acid, insecticide, and gasoline killed all larvae. In low quantities, caustic soda and mosquito repellent increased the development time and decreased the adult size. However, high quantities of these chemicals killed all larvae. Lastly, bleach and perfume did not affect the survival rate and barely impacted the development time or adult size. These results demonstrate common household products spilled on a corpse can strongly affect the development of Calliphoridae larvae. The effects of such products should be considered in forensic entomology cases.

Control of the myiasis-producing fly, Lucilia sericata, with Egyptian essential oils

BACKGROUND

Myiasis caused by Lucilia sericata (Diptera: Calliphoridae) is widely distributed throughout the world and affects both humans and animals. In addition, L. sericata larvae and adults may play a role in spreading causal agents of mycobacterial infections. Therefore, it is important to establish new and safe alternative methods of controlling this blowfly.

METHODS

The insecticidal effectiveness of four commercially available essential oils [lettuce (Lactuca sativa), chamomile (Matricaria chamomilla), anise (Pimpinella anisum), rosemary (Rosmarinus officinalis)] against third larval instars of L. sericata was evaluated. The effects of sublethal concentrations of these oils on pupation rates, adult emergences, sex ratios, and morphological anomalies were also determined.

RESULTS

The oils were highly toxic to L. sericata larvae, with median lethal concentrations (LC(50) ) of 0.57%, 0.85%, 2.74%, and 6.77% for lettuce, chamomile, anise, and rosemary oils, respectively. Pupation rates were markedly decreased after treatment with 8% lettuce oil, and adult emergence was suppressed by 2% lettuce and chamomile oils. Morphological abnormalities were recorded after treatment with all tested oils, and lettuce was the major cause of deformation. There was a predominance of males over females (4 : 1) after treatment with lower concentrations of chamomile and rosemary; such a skew toward males would lead to a population decline.

CONCLUSIONS

The four tested oils are inexpensive and may represent new botanical insecticides for controlling blowflies.