Brazilian forest producers have developed integrated management programs to increase the effectiveness of the control of leaf-cutting ants of the genera Atta and Acromyrmex. These measures reduced ...the costs and quantity of insecticides used in the plantations. Such integrated management programs are based on monitoring the ant nests, as well as the need and timing of the control methods. Chemical control employing baits is the most commonly used method, however, biological, mechanical and cultural control methods, besides plant resistance, can reduce the quantity of chemicals applied in the plantations.
Leaf-cutting ants have great potential for damage to agricultural and forest crops. Although chemical control is the most used method for the management of this pest, more friendly alternative ...methods have been investigated. Thus, this study aimed to evaluate the insecticidal and antifungal potential of essential oils obtained from
Aristolochia trilobata
, as well as the potential of two chemotypes of
Myrcia lundiana
and their major compounds (isopulegol and citral) on
Acromyrmex balzani
and its symbiotic fungus
Leucoagaricus gongylophorus
. Toxicity and synergism and/or antagonism tests were performed using essential oils and their major compounds on
A. balzani
ants. The antifungal activity of these compounds was tested on the fungus
L. gongylophorus
. The essential oils and their major compounds were toxic to
A. balzani
. The mixture of essential oils of
A. trilobata
with those of
M. lundiana
had higher toxicity to the ants. This synergistic effect is mainly due to the interactions between the citral compound and the major compounds present in
A. trilobata
essential oil. The essential oils of
M. lundiana
chemotypes showed antifungal properties against
L. gongylophorus
, and the citral compound proved to have fungicidal activity. These results show that the use of
M. lundiana
and
A. trilobata
essential oils and their major compounds is a potential alternative for the management of leaf-cutting ants
A. balzani
, as they have a toxic effect on worker ants and antifungal activity on their symbiotic fungus.
The endoparasitoid wasp, Tetrastichus howardi Olliff, is used for insect pest control in agricultural systems. The toxic effects of proteins produced by Bacillus thuringiensis Berliner (Bt) were ...evaluated over two generations of T. howardi parasitizing Bt-resistant Spodoptera frugiperda. Lower survivorship was detected in both generations of parasitoid wasps of both sexes that developed on S. frugiperda larvae resistant to Bt. Deleterious effects including disrupted host-searching behavior and lower performance were found in T. howardi individuals that emerged from Bt-resistant S. frugiperda. Also, Bt caused repellency and reduced immature parasitoid wasp production in T. howardi. The findings revealed that Bt causes side-effects on T. howardi which has implications for assessing the risks of Bt insecticides in biological control programs for sustainable crop production.
•Effects of Bacillus thuringiensis (Bt) were assessed on Tetrastichus howardi, a parasitoid wasp of agricultural pest pupae.•Bt effects on two generation T. howardi parasitizing Bt-resistant Spodoptera frugiperda were investigated.•First and second generation parasitoids emerged from Bt-treated S. frugiperda pupae showed lower survivorship than controls.•Exposure to Bt reduced immature production and reproductive performance over the generations of the parasitoid.•Results indicate low compatibility between the bacterium and the parasitoid wasp.
Pest control based exclusively on the use of organosynthetic insecticides can cause several problems including the reduction of populations of natural enemies. Thus, the use of selective insecticides ...is essential for efficient pest control. In this study, we evaluated the lethal effects of the essential oil of Lippia sidoides and its major compound thymol on the fall armyworm, Spodoptera frugiperda, as well as the selectivity and behavioral effects of these compounds on Podisus nigrispinus, an important predator of defoliating caterpillars. The botanical compounds were more selective to the predator than the insecticide deltamethrin, which was about 2.7 times more toxic to P. nigrispinus than to S. frugiperda. The insecticide deltamethrin caused rapid mortality to nymphs of P. nigrispinus with LT50 = 0.36 h. Additionally, the mortality of individuals exposed to this treatment reached 100% in less than 3 h. The essential oil (LT50 = 119 h) and the thymol (LT50 = 93 h) acted more slowly on the predator. On the contrary, for the pest, the botanical compounds acted faster than the synthetic insecticide. Nymphs exposed to deltamethrin and thymol showed behavioral changes, as there was an increase and decrease in speed and distance covered, respectively. All insects stayed longer on the untreated side of the arenas. The present study reveals the potential of the essential oil and thymol for the control of the S. frugiperda pest and, at the same time, the selectivity of these compounds over P. nigrispinus.
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•Effect of Lippia sidoides and its major compound on Spodoptera frugiperda and Podisus nigrispinus.•Botanical compounds showed faster action for S. frugiperda than the synthetic insecticide deltamethrin.•Selectivity and behavioral effects of L. sidoides essential oil about the predatory stink bug P. nigrispinus.•Essential oil of L. sidoides and its major compound can be an alternative for control against S. frugiperda.
Leptocybe invasa is a fast-spreading alien pest infesting eucalyptus in several countries. This study examined the damage caused by the gall wasp, recorded in eucalyptus plants in the municipalities ...of Itaporanga D'Ajuda and São Cristóvão, state of Sergipe, Northeastern Brazil.
Stenoma impressella Busck (Lepidoptera: Elachistidae) is an important oil palm pest and its life history and life table parameters were studied at various temperatures, from 16 °C to 40 °C. Females ...and males developed successfully into adults between 20 °C and 36 °C. However, no eggs were found at 10 °C and all the adults died after exposure to 40 °C. The developmental time from egg to adult was higher (170.5 days) at 15 °C and lower (76.6 days) at 35 °C. Therefore, temperature has a strong effect on the development of S. impressella from 15 °C to 35 °C. The reproductive period varied between 15–35 °C with 6.82 to 3.24 days for pre-oviposition, 17.5 to 4.89 days for oviposition, and 5.29 to 0.82 days for the postoviposition period. Female longevity was longer than that of the male, at all temperatures. The population growth parameters of S. impressella net reproductive rate (R0), intrinsic rate increase (rm), finite increase rate (λ), mean generation time (T) and doubling time (D) were significantly affected by temperature. Temperature affects S. impressella populations by reducing or increasing their possible occurrence in the palm trees. The effect of temperature on the development, survival and reproduction of S. impressella can be useful for predicting its long-term population fluctuation as an invasive pest of oil palm plantations.
Bee pollen, which is the material that adheres to honeybees as they collect nectar from flowers, is agglutinated into balls with nectar and bee saliva substances and is important to the survival of ...colonies of these insects. Damage to bee pollen stored at 10% RH was found in samples collected in Sergipe State, Brazil. Insects found in the pollen were identified as Lasioderma serricorne (Fabricius, 1792) (Coleoptera: Anobiidae), a cosmopolitan insect and one of the main insects infesting tobacco and many stored food products. This is the first record of damage by this insect in dehydrated pollen balls, which makes this product unfit for human consumption.
The aim of this study was to evaluate the toxicity of aqueous extracts of Annona squamosa L. (Magnoliales: Annonaceae), Azadirachta indica A. Juss (Sapindales: Meliaceae), Corymbia citriodora Hook. ...(Myrtales: Myrtaceae), Cymbopogon winterianus Jowitt ex Bor (Poales: Poaceae), Lippia sidoides Cham. (Lamiales: Verbenaceae), Mentha arvensis L. (Lamiales: Lamiaceae), Ricinus communis L. (Malpighiales: Euphorbiaceae), and Sapindus saponaria L. (Sapindales: Sapindaceae) on the developmental stages (eggs, 5th instars, and adults) of a generalist predator Podisus nigrispinus (Dallas) (Hemiptera: Pentatomidae). The eggs were dipped in extract concentrations of 0, 1, 3, 5, 7, and 10%, and the nymphs and adults received 1 µL of each extract on the dorsal thorax. The extracts affected hatching, with the extracts of A. indica (flowers), A.squamosa, and R.communis being the most toxic. None of the extracts affected the mortality in the nymphal stage, whereas S. saponaria,A. indica (flowers), and L.sidoides extracts caused relatively high mortality rates in adults. Due to the insecticidal effect of these extracts, they need to be used with care because they affect the life cycle of the predator P.nigrispinus.
ABSTRACT Knowing how a wildfire will behave is extremely important in order to assist in fire suppression and prevention operations. Since the 1940’s mathematical models to estimate how the fire will ...behave have been developed worldwide, however, none of them, until now, had their efficiency tested in Brazilian commercial eucalypt plantations nor in other vegetation types in the country. This study aims to verify the accuracy of the Rothermel (1972) fire spread model, the Byram (1959) flame length model, and the fire spread and length equations derived from the McArthur (1962) control burn meters. To meet these objectives, 105 experimental laboratory fires were done and their results compared with the predicted values from the models tested. The Rothermel and Byram models predicted better than McArthur’s, nevertheless, all of them underestimated the fire behavior aspects evaluated and were statistically different from the experimental data.
RESUMO Saber como o fogo irá se comportar durante um incêndio florestal é de fundamental importância a fim de aprimorar e desenvolver atividades de prevenção e combate. Desde a década de 1940, modelos matemáticos para estimar o comportamento do fogo têm sido desenvolvidos no mundo inteiro, entretanto, nenhum deles, até hoje, teve sua eficiência avaliada em plantações comerciais de eucalipto no Brasil nem, tampouco, em outras vegetações encontradas no país. Este estudo tem por objetivo verificar a eficiência do modelo de propagação do fogo superficial de Rothermel (1972), do modelo de comprimento das chamas de Byram (1959) e das equações de velocidade de propagação e comprimento das chamas baseadas nas tabelas de McArthur (1962). Para tal, 105 queimas laboratoriais foram realizadas e seus resultados comparados com os valores estimados pelos modelos testados. O modelo de Rothermel e de Byram previram melhor que o de McArthur, no entanto, todos eles subestimaram as variáveis do comportamento do fogo analisadas e seus valores foram significativamente diferente dos valores experimentais.
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