Essential oils enhance the toxicity of permethrin against Aedes aegypti and Anopheles gambiae

Insecticide resistance and growing public concern over the safety and environmental impacts of some conventional insecticides have resulted in the need to discover alternative control tools. Naturally occurring botanically‐based compounds are of increased interest to aid in the management of mosquitoes. Susceptible strains of Aedes aegypti (Linnaeus) (Diptera: Culicidae) and Anopheles gambiae (Meigen) (Diptera: Culicidae) were treated with permethrin, a common type‐I synthetic pyrethroid, using a discriminate dose that resulted in less than 50% mortality. Piperonyl butoxide (PBO) and 35 essential oils were co‐delivered with permethrin at two doses (2 and 10 µg) to determine if they could enhance the 1‐h knockdown and the 24‐h mortality of permethrin. Several of the tested essential oils enhanced the efficacy of permethrin equally and more effectively than piperonyl butoxide PBO, which is the commercial standard to synergize chemical insecticide like pyrethroids. PBO had a strikingly negative effect on the 1‐h knockdown of permethrin against Ae. aegypti, which was not observed in An. gambiae. Botanical essential oils have the capability of increasing the efficacy of permethrin allowing for a natural alternative to classic chemical synergists, like PBO.     

Aminoacyl-tRNA Synthetases in Triticum aestivum L. During Seed Development and Germination

Changes in the level of total and individual aminoacyl-tRNAsynthetase activity in the various tissues of wheat (Triticumaestivum L.) were followed by the ATP-pyrophosphate (ATP-PP₁)exchange procedure throughout seed maturation and germination. During seed development the total synthetase activity in theendosperm increased up to the 5th week after fertilization andthereafter decreased rapidly. Over the same period, synthetaseactivity in the testa-pencarp decreased markedly, whilst theactivity in the developing embryo increased. Many of the individualsynthetases conformed with this general pattern although therewere several exceptions. The total synthetase activity of both the coleoptile and coleorhiza(root) increased rapidly during the first 2 d of germinationwhilst the total activity of these enzymes in the scutellumremained constant. After an initial increase on germination,aminoacyl-tRNA synthetase activity in the testa-aleurone layerremained almost constant until most of the endosperm had beendigested. With a few exceptions the relative levels of individualsynthetases in the various tissues did not change significantlyduring seed maturation or germination.     

The periotic bones of possums and cuscuses: cuscus polyphyly and the division of the marsupial family Phalangeridae

Detailed examination of the periotic bones of ten species of phalangerid marsupials revealed the existence of three distinctive classes of periotic morphology, termed ailuropine, trichosurin and phalangerin. Cladistic analysis of fifteen characters of the periotic suggested the ailuropine periotic to be the most plesiomorphic in morphology, with the trichosurin and phalangerin periotics representing a more derived clade. This character distribution would support recent taxonomic schemes, in which the cuscuses are seen as a paraphyletic grouping: the greater and lesser Sulawesi cuscuses ( Ailurops ursinus and Strigocuscus celebensis ) exhibiting respectively ailuropine and trichosurin periotics, with all other cuscuses possessing phalangerin periotics. However, it does not support the assertions of some authors that the Moluccan cuscuses ( Phalanger ornatus and P. rothschildi ) and the ground cuscus ( P. gymotis ) are trichosurins.     

Temperature response and flowering of white clover (Trifolium repens) varieties in controlled environments and the field

Floral initiation of 10 white clover varieties growing in three controlled day/night temperature regimes, 22“/10°C, 20°/10°C, 17°/10°C, was recorded. Effects of artificial soil heating on floral initiation of the same plants subsequently transferred to the field were also examined. In the controlled environments only a slight increase in day temperature (2–5°C) was necessary to significantly increase flowering. Defoliation at the three temperatures had contrasting effects on subsequent flower production. Results from the soil heating experiment suggested that increased temperature might compensate for short daylengths, by bringing forward reproductive bud initiation by 1 month. Soil heating increased the total number of inflorescences produced.