The giant African snail Achatina fulica was introduced in Brazil and since then has become an important pest, because of its resistance to abiotic conditions, hermaphroditism, polyphagia, and absence of natural predators. This study aims to evaluate the control of A. fulica in lettuce, in Alagoas, Brazil. Bioassays for the determination of lethal dose and lethal time to adults of A. fulica and the egg mortality were performed in the laboratory by applying commercial synthetic products, commercial and non-commercial alcoholic botanical extracts on mollusk adults. Additionally, the protein concentration, lipase activity and enzyme acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE), in the stomach, intestine, nervous ganglion and liver were determined. The alcoholic extract of Capsicum frutescens caused higher mortality of A. fulica, and the alcoholic extract of C. frutescens and Piper tuberculatum oil can prevent the hatching of A. fulica. The lipase activity was present and in greater quantities in tissues, stomach, intestine, liver and ganglia of A. fulica, before and after exposure of the alcoholic extract of C. frutescens. The enzymatic activity of BuChE was present in the ganglia and liver of A. fulica, prior to exposure of the alcoholic extract of C. frutescens. The enzymatic activity of AChE was present only in the ganglion and absent in liver of A. fulica, prior to exposure of the alcoholic extract of C. frutescens. The concentration of 10% of the alcoholic extract of C. frutescens caused 84% mortality of adult A. fulica in lettuce in field conditions.
The African snail Achatina fulica (Bowdich, 1822), originally from Africa, was introduced in Brazil and since then became an important pest, because of its resistance to abiotic conditions, hermaphroditism, polyphagia and absence of natural enemies. Considered as one of the 100 worst pests in the world, with the record of establishment in almost all Brazilian states, it causes sanitary, ecological and economic losses. In this context, the objective of this study was to determine the population dynamics and food preference of the giant snail in three areas of lettuce, located in Alagoas, Brazil. There was no statistical difference between food preference tests with and without choice among the varieties offered. To the fluctuation of the population of A. fulica, the Pearson correlation coefficients were negative only for temperature, and there was no correlation with precipitation and relative humidity.
Predator species under field conditions can face different and variable densities of prey species. This work evaluated the functional response of the neotropical lady beetle Eriopis connexa(Coleoptera: Coccinellidae) subjected to different densities of the aphids Brevicoryne brassicaeand Aphis craccivora(Hemiptera: Aphididae). Thus, predation rates were analyzed of fourth-instar larvae and one-day old adults of the lady beetle preying upon the aphids at constant densities of 20, 40, 50, 60, and 70 aphids with 15 repetitions per density. The aphids were offered on 5 cm leaf discs of each plant host. The handling times and attack rates were 0.03 h-1and 0.27 h-1for larvae and 0.03 h-1and 0.15 h-1for adults fed B. brassicae and 0.59 h-1and 0.35 h-1for larvae and 0.70 h-1and 0.95 h-1for adults fed A. craccivora, respectively. Both larva and adult lady beetles increasedpredation rate as a function of prey density offered, with an estimated maximum number of prey consumed of 30.3 and 31.6 B. brassicae and 36.3 and 34.6 of A. craccivora by larva and adult lady beetles at the highest prey density, respectively. In conclusion, larvae and adults of E. connexaexhibited a type II functional response.
The effects of ethanolic and hexanic extracts of soursop and sugar apple (EES, EHS, EESA and EHSA, respectively) on Aphis gossypii (Hemiptera: Aphididae) and its natural enemy Eriopis connexa (Coleoptera: Coccinellidae) by contact exposure, residual effect and ingestion tests were evaluated. The estimated LC 50 and LC 99 values for A. gossypii were 0.39% and 5.47% for (EESA); 0.23% and 1.19% for (EES); 0.47% and 4.39% for (EHSA); and 0.42% and 6.38% for (EHS), respectively. Considering contact exposure, EES at 0.23% was innocuous, and EHS at 0.42% was slightly harmful; for adult ladybugs, only EESA (5.47%) was classified as slightly harmful, with the other treatments classified as harmless. The results were similar for the residual effect. For selectivity in ingestion tests, EES and EHS at the LC 50 did not affect the survival rate of the predator, but EESA (0.39% and 5.47% for the LC 50 and LC 99 , respectively) reduced the survival rate to zero in less than 7 days, resembling chemical treatment with Decis ®. Extracts applied to the eggs of an alternative prey reduced the consumption of eggs and therefore the predatory capacity of the ladybug, which led to a decrease in oviposition, egg viability and ultimately a reduction in predator fecundity. EES at a concentration of 0.23% was effective in the control of A. gossypii and was selective and did not affect the survival rate of the its natural enemy E. connexa.
O objetivo deste trabalho foi acompanhar o desenvolvimento das plantas de pimenta Cayene (Capsicum frutensces L.) e do pimentão (Capsicum annuum L.) em vasos com diferentes substratos, avaliando a fenologia das plantas que pertencem à família das solanaceas. No Brasil as pimentas são cultivadas em quase todos os Estados. Sendo utilizadas como aromatizantes, realçadoras do sabor na culinária, como planta medicinal e ou nutricional. O delineamento experimental foi em blocos casualizados com quatro tratamentos e dez repetições, solo normal(t0), solo com esterco bovino (t1), solo com esterco ovino (t2) e solo com esterco aviário (t3). As sementes das duas variedades foram semeadas em bandejas de isopor e após a emergência foram transplantadas para os vasos de poliestireno. As plântulas foram irrigadas com lâmina de 100 mm diários, sempre que não havia precipitação pluviométrica. Com os resultados obtidos, verificou-se diferença significativa entre os tratamentos das duas espécies, quanto ao desenvolvimento da fenologia das plantas.
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