No abstract

BACKGROUND: The house mosquito, Culex pipiens L. is a harmful species, widespread in urban areas, and considered the primary enzootic vector of West Nile arbovirus. Widespread insecticide resistance in mosquito populations and the environmental risks and toxicity hazards of chemical pesticides make insecticides an inadequate mosquito control strategy. Seeking ecofriendly tools for mosquito control tools has become necessary. RESULTS: Essential oil (EO) was hydrodistilled from the fruits of Brazilian pepper, Schinus terebinthifolius Raddi and analyzed using gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. An oil-in-water nanoemulsion (particle size 41.3 nm) was developed and characterized from EO using a green low-energy approach. EO, its nanoemulsion and monoterpenes showed mosquitocidal, repellent and acetylcholinesterase inhibitory activities against Cx. pipiens. A nanoemulsion concentration of 30 ∼l L -1 caused 100% larval mortality after 24 h of exposure, whereas EO, D-limonene and ⊍-phellandrene at 60 ∼l L -1 caused 100%, 92.4% and 88.2% larval mortality, respectively. The concentration that killed 50% of organisms (LC 50 ) for larvae after 24 h ranged between 6.8 and 40.6 ∼l L -1 . Upon fumigation, 15.0 ∼l L -1 of nanoemulsion killed 94.5% of adults after 24 h of exposure. LC 50 values against adults ranged between 5.3 and 31.2 ∼l L -1 . EO products exhibited repellence activity at concentrations between 0.5 and 4.0 ∼l cm -2 . Test materials effectively inhibited the acetylcholinesterase activity of mosquito and were safe toward the non-target organisms Gambusia affinis and Eisenia fetida.CONCLUSION: There is a potential for using S. terebinthifolius EO, its nanoemulsion and monoterpenes as ecofriendly natural mosquitocides.

No abstract

We investigated the effects of switching from conventional management to organic management on the abundance and community composition of soil-living oribatid mites in clover fields in an experimental agricultural station at Al-Fayoum, Egypt. The site had two adjacent fields with identical vegetation cover but different management. Fifteen random soil samples were collected monthly from each of three plots per field, from October to March. We characterized the soils with respect to various physicochemical variables as well as fungal community composition, and estimated mite densities through core sampling. Organic fields had a significantly more abundant oribatid community than did conventional fields. Also the abundance of soil fungi was greater in the organically managed field. Organic management promoted common oribatid mite species with a wide ecological amplitude that already had a high abundance where such common species are more responsive to changes in agricultural management. However, some species of mite responded indifferent or negative to the switch from conventional to organic management. Overall, the differences between the two ecological systems were mainly quantitative. Species diversities of both mite and fungal communities did not differ much between the two management systems. Diversity (H0) and equitability (E) of soil oribatid communities were higher in conventional plots than in the organic plots during the first 2 months but indistinguishable thereafter. Our study confirmed that organic management stimulates soilorganic matter build-up, with positive effects on both fungal and oribatid mite abundance and possible long-term effects on soil function.