Isaías Cabrini

Electronic mosquito repellers induce increased biting rates in Aedes aegypti mosquitoes (Diptera: Culicidae)

ABSTRACT: Studies have demonstrated that electronic mosquito repellers are useless and that some of them could even increase the attraction of mosquitoes. While testing some electronic repellers, we noted that they also promoted an increase in biting rates. The present work has evaluated three commercial devices and a computer program working on five different sound frequencies. In a test chamber, the number of Aedes aegypti L. bite attempts was computed during four cycles of 3 min each by alternately turning the devices off and on. The mosquito biting rates for five sound frequencies (ranging from 9.6 kHz to 18.2 kHz) initially demonstrated a significant increase (ranging from around 20% to 50%), which decreased from 8.3% to 25.1% when the repellers were turned off. The biting rate significantly increased at 11.8 kHz (33.7%) when the device was turned on again. The danger of using electronic repellers and the role of sound frequencies stimulating mosquito biting are discussed.

Improvement of a test-chamber for behavioral studies on adult females of Aedes aegypti (Linnaeus) (Diptera, Culicidae)

A test-chamber (K&L-Chamber) made of cardboard and acrylic plastic, and consisting in four sections (A, B, C and D) was developed by Klowden & Lea (1978) for Aedes aegypti host-seeking behavior studies. Later, Foster & Lutes (1985) also used an identical chamber to successfully evaluate the efficacy of electronic repellers. It was described here a modified K&L-Chamber for behavioral studies of Ae. aegypti adults. The chamber was made in polystyrene, consisting of three sections (A, B and C) and using a human hand and a fluorescent lamp as stimulus to attract the mosquitoes. The suitability of the present test-chamber was validated assaying 80 replicates and releasing 10 Ae. aegypti females in each replicate. The females were released in the section A and allowed to fly to the section C. A mean of 96.0% (s.e. 0.213) Ae. aegypti females successfully reached section C. The present test-chamber is cheaper and easier to handle and as efficient as K&L-Chamber, when compared to Foster & Lutes (1978) that noticed 93.8% of Ae. aegypti reaching the trap section.

Evaluation of seven new electronic mosquito repellers

The urgent need to reduce mosquito nuisance and the diseases that they transmit has often stimulated the launching of news tools in the market, as in the case of electronic repellers. Since the early anecdotal report by Greenlee (1970) on the repellency of mosquitoes by sonic frequencies, a number of claims have been made by manufacturers in order to explain how their devices work, such as: (1) mated females are repelled by the sound of male wing beats, which the electronic device mimics, and (2) mosquitoes are repelled by the sound of predators such as dragonfly wing beats or the ultra-sonic cry of bats. More recently, other anecdotal reports have been made in the media on the efficacy of electronic mosquito repellers. In 1997, the Discovery Channel mentioned that the French radio FM – Compiègne used to broadcast antimosquito sonic waves along with its regular programmes, and indicated that listeners interviewed expressed divided opinions concerning the efficacy of the measure. Also, a popular science magazine in Brazil noted the development of an audio CD imitating bat ultrasounds (ABRIL, 2000). The article reported that a supposedly 80% efficacy in repelling Aedes aegypti L. (Diptera: Culicidae) females was achieved. Again, in 2002 the Discovery Channel reported that a Canadian broadcasting radio station (CIMI-FM Charlesbourg, Quebec, Canada) used to emit a sonic frequency with the same purpose. It mentioned that attendants of a local wedding party attested that the mosquitoes were repelled. Furthermore, in 2003, SK Telecom (Jung-gu, Seoul, South Korea) offered a service via mobile telephone that generated sound waves undetectable to the human ear but able to repel mosquitoes within a range of 1 m. Subscribers were able to download the service for about US

Copper II - polar amino acid complexes: toxicity to bacteria and larvae of Aedes aegypti

2.5 (Anonymous, O Estado de São Paulo – Tecnologia, 10 July 2003). Coro & Suárez (1998) reviewed many publications, confirming the lack of efficacy of electronic repellers, and the later papers of Sylla et al. (2000), Jensen et al. (2000), and Andrade & Bueno (2001) showed the same. However, despite the lack of any publication confirming efficacy, the commercialization of new electronic mosquito repellent devices is still ongoing in many countries. The reason for this could be either that a new electronic repeller system appearing on the market surprisingly has some efficacy in repelling mosquitoes, or that the local authorities again have failed to demand regulatory testing. In the present work, we evaluated six commercial devices and free software, claimed to be electronic mosquito repellers, which have not yet been dealt with in the scientific literature.

A potent larvicidal agent against Aedes aegypti mosquito from cardanol

Control strategies using insecticides are sometimes ineffective due to the resistance of the insect vectors.In this scenario new products must be proposed for the control of insect vectors.The complexes L-aspartate Cu (II) and L-glutamate-Cu (II) complexes were synthesized and characterized by elemental analysis, visible ultraviolet, infrared spectroscopy and potentiometric titration. The toxicity of these complexes was analyzed in Aedes aegypti (Diptera: Culicidae) larvae and Gram-negative and Gram-positive bacteria. The interaction between the ligands and the amino acid balance and the distribution of the species as a function of pH were discussed. The lethal concentration median (LC50) for Ae. aegypti larvae were: L-glutamic acid-Cu (II) - 53.401 mg L-1 and L-aspartate-Cu (II) - 108.647 mg L-1. The minimum inhibitory concentration (MIC) required for Staphylococcus aureus and Escherichia coli was: L-glutamate-Cu (II) 500-2000 mg L-1 and L-aspartate-Cu (II) 1000-2000 mg L-1. The concentrations demonstrated toxicity that evidence the potential of the complexes as bactericide and insecticide. Metal complexes formed by amino acids and transition metals are advantageous because of low environmental toxicity, biodegradability and low production cost.

Comparative Studies on Aedes aegypti and Aedes albopictus Adult Females Trespassing Commercial Nets

Cardanol is a constituent of Cashew Nut Shell Liquid that presents larvicidal activity against Aedes aegypti. The isolation of cardanol is somewhat troublesome, however, in this work we describe an efficient and inexpensive method to obtain it as a pure material. The compound was used as starting material to make chemical transformation leading to saturated cardanol, epoxides and, halohydrins. These derivatives were tested for toxicity against Aedes aegypti larvae. The results showed that iodohydrins are very promising compounds for making commercial products to combat the vector mosquito larvae presenting a LC50 of 0.0023 ppm after 72 h of exposure.

Synthesis and Biological Activity of Fe (III) Acetate for Microbial Control at Breeding Sites of Aedes aegypti (Diptera: Culicidae)

Abstract The abilities of Aedes aegypti and Ae. albopictus females in trespassing 5 different commercial nets, 2 nets impregnated with deltamethrin or permethrin and 3 non-impregnated nets (Guarany, Perame, and Ricca), were compared. The evaluating parameters were their percent trespassing success, the median trespassing time (TT50), and the relation between mosquito wing sizes and their trespassing success. Some mosquito behavioral traits were also observed. The trespassing success, directly related to opening areas, was found to be lower with impregnated nets for both species. The differences between the mosquito species were significant among all the nets except Ricca. Aedes albopictus showed a very high success rate in trespassing the non-impregnated Perame net and a lower success rate in trespassing Guarany. Aedes albopictus also showed a very high success rate in trespassing pyrethroid-impregnated nets. The TT50 values for the Ricca and Guarany nets were not significantly different between the species, but a significantly lower TT50 value was found for the net with the largest opening (Ricca). The smaller wingspan of Ae. albopictus seems to explain the higher trespassing success of this species.

Evaluation of Eosin-Methylene Blue as a Photosensitizer for Larval Control of Aedes aegypti by a Photodynamic Process

Unconventional approaches can be used control populations of disease-carrying insect to improve health, economic, social, and environmental standards. There is a need for prolonged reduction of vector populations, using low-toxicity and low-cost products in domestic settings. Metals such copper and iron have shown to be toxic to insect larvae, with a delay in reproduction, damage to the cells of the digestive system and the production of free radicals and oxidant species, resulting in tissue damage and death. To control insect breeding, we synthesized and characterized Fe (III) acetate via carbonate. Fe (III) acetate showed no toxic effect on mosquito larvae up to 1.000 mg L -1 , but was bactericidal for Gram-positive and Gram-negative bacteria, mainly due to the action of Fe (III) acetate. DOI: http://dx.doi.org/10.17807/orbital.v10i5.1135

A simple method for immobilising small dipteran insects and its validation for Aedes aegypti

Aedes aegypti (Ae. aegypti) is a competent vector for transmitting important viral diseases such as yellow fever, dengue, chikungunya, and Zika. Several strategies have been applied to avoid Ae. aegypti proliferation by using environmental management, biological, and chemical approaches. However, the development of new methods for effective control of the insect vector population is still needed. Photodynamic control is an alternative way to control the vector population by using a physical approach based on the larval phototoxicity of a photosensitizer. In this context, the present study evaluated the use of eosin-methylene blue (EMB) as a new photosensitizer for photodynamic control of Ae. aegypti larval populations. The photodynamic assays were performed submitting Ae. aegypti third-instar larvae to different EMB concentrations (0.0, 0.5, 1.0, 5.0, 10.0, 50.0, and 100.0 µg mL−1) in combination of three different light doses (24.3, 48.6, and 97.2 J cm−2) under either white-light radiation from RGB LEDs or sunlight. The results demonstrated that EMB presented a rapid internalization into the larvae and was phototoxic. The photodynamic action induced 100% of larval mortality after about 40 min of sunlight irradiation even using low EMB concentration (0.5 µg mL−1). The findings reveal EMB as an effective photoactive compound to control larval populations of Ae. aegypti by photodynamic process induced by either sunlight or white-light from RGB LEDs.

Richness and composition of Calliphoridae in an Atlantic Forest fragment: implication for the use of dipteran species as bioindicators

Isa ıas Cabrini*, Carlos Fernando S. Andrade, Marcelo da Costa Ferreira & Eduardo Jos e de Arruda Department of Animal Biology, Institute of Biology, State University of Campinas, Campinas, SP, Brazil, Faculty of Exact Sciences and Technology, Federal University of Grande Dourados, Dourados, MS, Brazil, and Faculty of Agricultural and Veterinary Sciences, Paulista State University, Jaboticabal, SP, Brazil