Avaliou-se a bioatividade de derivados do nim (Azadirachta indica A. Juss.) como componente de isca para adultos e como regulador de crescimento de Ceratitis capitata (Wied.) e Anastrepha fraterculus (Wied.), determinando-se, ainda, o efeito de concentrações subletais de extratos de nim e o efeito deterrente de oviposição do extrato metanólico de folhas sobre C. capitata. Utilizando o extrato aquoso de amêndoas de nim, estimou-se a CL50 para adultos e imaturos, cujos valores foram 7.522 e 1.368 ppm para os adultos e 13.028 e 9.390 ppm para os imaturos de A. fraterculus e C. capitata, respectivamente. Subsequentemente, o óleo de amêndoas, os extratos de folhas, de ramos e de amêndoas de nim em diferentes solventes (água, metanol, diclorometano e hexano) foram comparados com base nas CL50 obtidas para adultos e para imaturos. Posteriormente, foram estimadas concentrações subletais (CL15 = 39 ppm, CL30 = 225 ppm e CL45 = 888 ppm) do extrato aquoso de amêndoas para adultos de C. capitata e avaliouse nessas concentrações o efeito do extrato aquoso de amêndoas, de folhas em metanol e de ramos em diclorometano sobre a reprodução e a longevidade dessa espécie. A deterrência de oviposição do extrato metanólico de folhas de nim em diferentes concentrações (10.000...
Leaf epicuticular waxes may affect substrate selection by leaf-cutting ants, and host recognition by several phytophagous insects. The influence of the crude epicuticular wax of Didymopanax vinosum E. March. (Araliaceae), and its major constituents lupeol and free primary alcohols, on substrate selection by the leaf-cutting ant Atta sexdens rubropilosa Forel, was investigated. Two ant colonies were used in laboratory bioassays. Corn flakes (zea) were impregnated with chloroform solutions of the substances being tested and fed to the adults. One of the colonies gave results, in most of the tests, not significantly different from the controls. The other colony, however, discriminated against the crude wax, a strong deterrent effect being observed from the first of a series of eight trials. The same colony was able to discriminate against lupeol after the second trial. The fraction of primary n-alcohols (22% C28, 66% C30 and 12% C32) deterred feeding only after the fifth trial. The results demonstrate that some constituents of epicuticular waxes may deter the foraging activity of A. sexdens rubropilosa, depending, however, on the colony under observation. It is suggested that lupeol, of the foliar wax of D. vinosum, is an important deterrent to leaf-cutting ants...
More than 50% of the lycaenid butterflies have an ant-associated lifestyle (myrmecophily) which may vary from coexistence to specific mutualistic or even parasitic interactions. Ant-related host-plant selection and oviposition has been observed in some myrmecophilous lycaenids. Therefore, it is remarkable that there is no evidence for this behaviour in the highly specialized, obligate myrmecophilous butterflies of the genus Maculinea. In contrast with previous findings, our results provide evidence for ant-related oviposition patterns in Maculinea alcon in relation to the distribution of specific host-ant nests (i.e. Myrmica ruginodis) based on repeated egg counts during the flight period in two populations. We also show that ant-related oviposition can be counterbalanced by intraspecific competition and oviposition deterrency when host plants already carry several eggs. Therefore, the absence of a correlation between egg load and the presence of host-ant nests at the end of the flight period should be interpreted carefully Whether ovipositional cues are obtained either directly (from ants or their nests) or indirectly (from vegetation structure), and whether alternative explanations based on the phenology and growth form of host plants are possible...
Nine alkaloids (acridine, aristolochic acid, atropine, berberine, caffeine, nicotine, scopolamine, sparteine, and strychnine) were evaluated as feeding deterrents for gypsy moth larvae (Lymantria dispar (L.); Lepidoptera: Lymantriidae). Our aim was to determine and compare the taste threshold concentrations, as well as the ED50 values, of the nine alkaloids to determine their potency as feeding deterrents. The alkaloids were applied to disks cut from red oak leaves (Quercus rubra) (L.), a plant species highly favored by larvae of this polyphagous insect species. We used two-choice feeding bioassays to test a broad range of biologically relevant alkaloid concentrations spanning five logarithmetic steps. We observed increasing feeding deterrent responses for all the alkaloids tested and found that the alkaloids tested exhibited different deterrency threshold concentrations ranging from 0.1 mM to 10 mM. In conclusion, it appears that this generalist insect species bears a relatively high sensitivity to these alkaloids, which confirms behavioral observations that it avoids foliage containing alkaloids. Berberine and aristolochic acid were found to have the lowest ED50 values and were the most potent antifeedants.
Use of insecticides can have disruptive effects on the environment. Replacing the chemical compounds in these insecticides with plant materials, however, can be a safe method with low environmental risk. In the current study, chemical composition and insecticidal activities of the essential oil from cardamom, Elettaria cardamomum L. (Maton) (Zingiberales: Zingiberaceae) on the adults of three stored product pests was investigated. Results indicated that essential oil of E. cardamomum toxic to the bruchid beetle, Callosobruchus maculatus Fabricius (Coleoptera: Bruchidae), the red flour beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), and the flour moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). Adults of E. kuehniella were more sensitive than the Coleoptera. Also, the highest mortality of these insects was seen after 12 hours. Results of the LT50 tests showed that the lethal time of mortality occurred between 10–20 hours in various test concentrations. Essential oil of E. cardamomum had a good efficacy on oviposition deterrence of C.
maculatus females, too. The chemical constituents of the essential oils were analyzed by gas chromatography—mass spectrometry. The major constituents of cardamom were identified as 1...
Laboratory experimental groups of 120 workers and 30 soldiers of Coptotermes formosanus Shiraki were given a choice of feeding on untreated pine blocks or pine blocks treated with one of five concentrations of methoprene (0, 4, 20, 100, and 500 ppm) or S-31183 (2-[1-methyl-2(4-phenoxy-phenoxy)ethoxy]pyridine) (0, 20, 100, 500, and 2,500 ppm) for 4, 8, or 12 wk. Soldier production and total mortality were significantly increased by 100 and 500 ppm methoprene at 8 and 12 wk. Biologically significant mortality (>50%) resulted from feeding on blocks treated with methoprene at 500 ppm after 8 wk. The response of C. formosan us to S-31183 was much reduced when compared with the response to methoprene. None of the concentrations of 5-31183 caused biologically significant mortality to the C. formosan us groups. In addition, the highest concentration of 5-31183 caused feeding deterrency that was apparently learned. Effective baits for remedial control of C. formosanus colonies should be evaluated under conditions that simulate actual use. These baits would require methoprene concentrations from 500 to 1,500 ppm, depending on the pattern of use.
Fonte: Universidade Federal de Pelotas; Biologia; Programa de Pós-graduação em Parasitologia; UFPel; BRPublicador: Universidade Federal de Pelotas; Biologia; Programa de Pós-graduação em Parasitologia; UFPel; BR
The extracts of vegetal origin have been largely studied with the aim of obtaining an
efficient and ecologically viable alternative to the control of plagues.The study of
substances with selective deterrent bioactivity that affects insect s behavior,
development and reproductive output is extremely important to avoid the problems
caused by non selective chemical insecticides.Based in the importance of Musca
domestica L.(Diptera,Muscidae)due to its high potential of carrying pathogens,its
occurrence in high populations and in the lack of studies about the effects of vegetal
extracts over insects,the present study was carried out with the objective of
evaluating the deterrent bioactivity of aqueous extracts of Eucalyptus sp. L'Hér.
(Myrtaceae)and Melia azedarach L.(Meliaceae)over larvae of M. domestica and the
influence of the aqueous extract of M. azedarach on the oviposition behavior of this
insect.To evaluate the influence of the aqueous extracts of Eucalyptus sp.and M.
azedarach on larvae of M. domestica...; Os extratos de origem vegetal têm sido amplamente estudados visando se obter
uma alternativa eficaz e ecologicamente viável para o controle de pragas.O estudo
de substâncias com bioatividade deterrente seletiva,que atuem sobre o