Search

Recent agricultural expansion into regions of the Brazilian savannah or Cerrado has improved agricultural knowledge and management practices. Under this biome’s favorable conditions, the incidence of diseases such as gummy stem blight (GSB) could be a limiting factor for some crops (i.e., Cucumis melo L.), due to high losses in productivity and fruit quality. We conducted field experiments to assess the temporal progression of the incidence and severity of GSB disease in melon plants under five pesticide treatments and three growing seasons (dry, rainy, and transition periods). Furthermore, the susceptibility of six cultivars of melon to GSB was evaluated with and without pesticide application. In the dry season, although the incidence of the disease was high and dependent on the applied pesticides, its severity was low, allowing the crop cycle to be completed and marketable fruits to be harvested. However, in the rainy and transition periods, the high incidence and severity of the disease recorded in all plants, independent of the pesticides used, resulted in a premature end to the growth of the melon crops. Moreover, the commonly cultivated cultivar (Eldorado 300) showed a higher incidence and severity of the disease than the other potential cultivars. The results suggest that melon crops should be grown exclusively under the Brazilian Cerrado conditions during the dry season, dominated by favorable climatic conditions for the melon and unfavorable conditions to the pathogen. Other cultivars need to be investigated for their suitability to this region.

The tomato pinworm Tuta absoluta (Lepidoptera: Gelechuidae) is native to South America and has now become the main tomato pest in Europe, Africa and Asia. The wide range of host plants attacked by this pest has been reported as one of the main reasons for the success of this important insect species. However, the information currently available on the biological performance of T. absoluta on Solanaceae has been obtained from a limited number of host species. The Solanaceae family is composed of thousands of species, many of which are potential hosts for T. absoluta. Our results showed that the highest oviposition rates occurred on cultivated tomato plants, potato and wild tomato. The lowest rates occurred on “gilo”, “jurubeba”, green pepper and pepper. The highest survival rates of the immature stages occurred on potato and the lowest on pepper, green pepper and “jurubeba”. Female fertility, following infestation of the different plant species, was highest for insects that developed on tomato or potato and the lowest rates were seen on American black nightshade. The net reproductive rate and the intrinsic growth rate were highest on potato and tomato. Cluster analysis grouped tomato and potato as highly susceptible to attack, American black nightshade, juá, eggplant, gilo and wild tomato as moderately susceptible, whilst pepper, green pepper and jurubeba were categorized as resistant to T. absoluta. These results clearly demonstrate that the choice of solanaceous host plant species has a direct impact on the fitness parameters of the tomato pinworm as well as survival potential, dispersion and establishment at new sites. These results are important for the planning of integrated pest management strategies.

Ants (Hymenoptera: Formicidae) are social insects and important pests in the urban environment. The main groups of pest ants in the urban environment are leafcutter and house ants. Leaf-cutter ants cause crescent-shaped defoliation of plants, where in the urban environment it causes problems in gardens and ornamental plants. Domestic ants cause human health problems, contaminate food and cause problems in equipment and buildings. In this work, we propose an integrated ant management program in urban environments. For that, a bibliographic review was carried out addressing the following topics: life cycle of ants, main groups of pest ants, factors that influence their attack, decision-making systems, management strategies and tactics. It is observed that ants are pests that are difficult to control, and successful control is related to the correct execution of the various components of integrated pest management. Regarding control tactics, chemical control is the main method used to control ants in urban environments because the effectiveness of other methods (ie, biological and behavioral control) is poor.

The optimal defense theory stipulates that a plant prioritizes the defense of young tissue against herbivory, which may affect the spatial distribution of the attacking insect and its impact on plant performance. In this study, we evaluated the feeding and oviposition site preferences of the citrus mealybug, Planococcus citri (Risso, 1813) (Hemiptera: Pseudococcidae), when comparing different parts of the canopy of two coffee varieties as well as its fertility and life history parameters. We evaluated the feeding preference, oviposition site choice, and the distribution of different development stages of P. citri on different strata (apical, median, base, and trunk regions) of two coffee varieties, Coffea arabica and Coffea canephora, as well as the associated variations in life history parameters and fertility. The citrus mealybug preferred to feed and oviposit on young leaves despite the presence of high levels of defense compounds. On average, more than 38% of P. citri preferred the apical leaves of cv. Coffea arabica compared to the other parts of the plant. However, in cv. C. canephora, the proportion that preferred the apical leaves was greater than 55%. The net reproduction rate (R0) and the intrinsic rate of increase (rm) of P. citri reared on C. canephora were significantly higher than those seen on C. arabica. The generation time (T) of P. citri reared on C. arabica was significantly longer than that observed on C. canephora. The estimated population growth rate of mealybugs on C. canephora varieties over 15 generations was more than twice that of the population on C. arabica. The dispersion ability and choice of the most nutritious plant strata by nymphs and adults on coffee plants are fundamental to the fitness of these mealybugs. Mealybugs showed a distinct preference for C. canephora.

High adoption rates of single-gene Bacillus thuringiensis (Bt) Cry1Ac soybean impose selection pressure for resistance in the soybean looper, Chrysodeixis includens, a major defoliator in soybean and cotton crops. To anticipate and characterize resistance profiles that can evolve, soybean looper larvae collected from field crops in Brazil in 2013 were selected for resistance to Cry1Ac. Using two methods of selection viz., chronic exposure to Cry1Ac cotton leaves and the seven-day larval exposure to purified Cry1Ac on the artificial diet, 31 and 127-fold resistance was obtained in 11 and 6 generations of selection, respectively. The resistance trait had realized heritability of 0.66 and 0.72, respectively, indicating that most of the phenotypic variation in Cry1Ac susceptibility of the soybean looper larvae was due to additive genetic variation. The Cry1Ac-selected populations showed positive cross-resistance to Cry1Ab (6.7–8.7 fold), likely because these Bt toxins have a very similar molecular structure. Importantly, the Cry1Ac-selected populations became more susceptible to Cry2Aa and Cry1Fa, showing negative cross-resistance (up to 6-fold, P

Bacillus thuringiensis (Bt) corn producing the Cry1F protein was the first highly efficacious Bt corn deployed against the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in Brazil, but reduced efficacy of this technology against the fall armyworm has been reported in some regions of the country. Here, we surveyed Cry1F resistance allele frequency and susceptibility of eight S. frugiperda populations collected in 2013 from non-Bt fields in different regions of Brazil. In F1 screen experiments, the overall frequency of the Cry1F resistance alleles in Brazilian populations was estimated at 0.24, with 95% credibility interval between 0.18 and 0.25. In concentration-response bioassays, five of the eight populations surveyed exhibited significant resistance levels, which were over 32 times higher than that of the standard susceptible laboratory strain. The estimates of Cry1F resistance allele frequency were positively correlated with those of median effective or lethal concentrations (i.e., EC50 or LC50). These results show that the allelic frequency and the magnitude of Cry1F resistance are high in field populations of S. frugiperda in Brazil, indicating a challenging situation for resistance management.

Life table studies allow for a better understanding of mortality factors against insect pests. It assesses each mortality factor and its parameters in population suppression. Neoleucinodes elegantalis (Guenee) (Lepidoptera: Crambidae) is one of the major pests of solanaceous crops in South America. The background information provided by life table studies might be used for developing management strategies for controlling N. elegantalis. Thus, the aim of this study was to identify and quantify the mortality factors of N. elegantalis in tomato cultivation by using life tables. The results were obtained from 64 ecological life tables. The mortality factors for eggs, larvae and pupae were due to rain, fruit drop, predation, parasitism and unviability caused by physiological disorder and diseases. The percentage of total death for eggs, larvae and pupae were 64.2%, 24.9% and 5.93%, respectively. The highest rates of mortality were caused by predation and parasitism. Thus, mortality of N. elegantalis ca...

The savanna cashew (Anacardium humile A. St. Hil.) nut is a native shrub species distributed in the savanna biome of Central Western Brazil. This species is similar to the cashew (Anacardium occidentale L.) nut, and its edible pseudo-fruits have been used for various purposes. However, A. humile is at risk of extinction. One reason for this is the phytosanitary issues. Therefore, phytosanitary studies of the serious plant diseases caused by fungal pathogens are necessary. The aim of this study was to survey the savanna cashew nut (Anacardium humile) in Central Western Brazil from August 2013 to October 2014. Serious damage caused by anthracnose to the plant’s leaves and fruits was consistently detected. The pathogen fungal species was Colletotrichum gloeosporioides. It was identified by morphological characteristics and molecular analyses. Additional experiments showed evidence that C. gloeosporioides can be transmitted by cashew seeds. We observed anthracnose symptoms on the surfaces of the floral peduncle, leaves, and peduncle of the A. humile cashew nuts. The genomic DNA sequences of the selected strains for molecular characterization have had 99% identity with the analogous sequences of C. gloeosporioides. Naturally occurring C. gloeosporioides infection of the leaves of A. humile was low (20.3%) compared with that of the nuts (79.7%). Our results can be used to design strategies to prevent the introduction and establishment of C. gloeosporioides in new areas. They can also be helpful in monitoring programs in areas with a current occurrence of C. gloeosporioides. Finally, these results can be used in future research plans of C. gloeosporioides infection management.

BACKGROUND Ceratocystis fimbriata recognized among the species that induce mango sudden decline (MSD), causes plant death within a short period. The beetles Hypocryphalus mangiferae and Xyleborus affinis (Curculionidae: Scolytinae) are the vectors of MSD. Thorough understanding of the spatial distribution of the pest is crucial to designing control techniques and drawing up sampling plans. This study aimed to identify the beetles and their dispersal pattern in mango trees in MSD-infected commercial orchards, and the association with the severity of the C. fimbriata infestation. RESULTS Beetle attacks were observed to be maximal on mango tree trunks revealing severe infestation. From the geostatistical analysis, an aggregated pattern was evident as galleries in the trunks and branches of mango trees. CONCLUSION This is the first study to employ geostatic tools on a plant scale in MSD-infested mango orchards and to study the incidence of beetle attack. The results may prove a highly effective tool for mango growers, with respect to the management of beetles and MSD, as this will facilitate the monitoring of specific sites where the frequency of beetles and MSD is high. © 2018 Society of Chemical Industry.

Currently, biomonitoring is a methodology used to verify the environmental impact of new technologies in the agricultural environment, highlighting edaphic entomofauna that is traditionally used as a bioindicator in this sort of research. Therefore, the objective of this study was to investigate the edaphic entomofauna variation depending on glyphosate application in Roundup Ready soybeans. The experiment was carried out in Coimbra, MG during the 2007/2008 and 2008/2009 cropping seasons. The experimental design was a randomized block design with five replications. The treatments were: non-transgenic soybean with mechanical weeding of weeds; transgenic soybean with mechanical weeding of weeds; transgenic soybean with one glyphosate application and transgenic soybean with three glyphosate applications. The populations of the edaphic entomofauna were sampled during two crops. The insertion of the glyphosate tolerance gene did not affect the richness and the abundance of arthropods in the soil. The arthropod richness was reduced in treatments where glyphosate was applied one and three times. The glyphosate application in transgenic soybean reduced the density of the predatory mite Galumnidae (Acari); predator ants Neivamyrmex sp. (Hymenoptera: Formicidae) and Solenopsis sp. (Hymenoptera: Formicidae); and springtails Entomobryidae (Collembola), Hypogastrura sp. (Collembola: Hypogastruridae) and Onychiuridae (Collembola). Therefore, it is essential to follow the use recommendations of the herbicide glyphosate and adopt good agricultural practices that promote pesticide biodegradation, thereby contributing to the reduction of the toxicological potential of glyphosate on the edaphic entomofauna. RESUMO: Atualmente, o biomonitoramento tem sido uma metodologia bastante adotada para se verificar o impacto ambiental das novas tecnologias no meio agrícola, com destaque para a entomofauna edáfica, que é tradicionalmente utilizada como bioindicadora nesse tipo de pesquisa. Assim, objetivou-se com este estudo investigar a variação da entomofauna edáfica em função da aplicação do herbicida glyphosate em cultivos de soja Roundup Ready. O experimento foi realizado em Coimbra, MG, nas safras agrícolas de 2007/2008 e 2008/2009. Utilizou-se o delineamento experimental em blocos casualizados com cinco repetições. Os tratamentos estudados foram: soja não transgênica com capina mecânica das plantas daninhas; soja transgênica com capina mecânica das plantas daninhas; soja transgênica com uma aplicação de glyphosate; e soja transgênica com três aplicações de glyphosate. As populações da entomofauna edáfica foram amostradas ao longo dos dois cultivos. A inserção do gene de tolerância ao herbicida glyphosate não afetou a riqueza e a abundância de artrópodes do interior do solo. A riqueza dos artrópodes foi reduzida nos tratamentos que receberam uma e três aplicações de glyphosate. A aplicação de glyphosate na soja transgênica reduziu a densidade do ácaro predador Galumnidae (Acari); das formigas predadoras Neivamyrmex sp. (Hymenoptera: Formicidae) e Solenopsis sp. (Hymenoptera: Formicidae); e dos colêmbolos Entomobryidae (Collembola), Hypogastrura sp. (Collembola: Hypogastruridae) e Onychiuridae (Collembola). Diante disso, torna-se essencial atender às recomendações de uso do herbicida glyphosate e adotar boas práticas culturais que favoreçam a biodegradação de pesticidas, para assim contribuir com a redução do potencial toxicológico do glyphosate sobre a entomofauna edáfica.

Lipaphis erysimi (L.) Kaltenbach (Hemiptera: Aphididae) is one of the most important pests of brassica crops, mainly causing losses due to sap sucking, toxin injection and viral transmission. Knowledge about the main natural factors that regulate populations of this pest, as well as its critical mortality stage, is crucial for the development of integrated pest management of L. erysimi. Here, we determined the critical stage and key mortality factors for L. erysimi in cabbage using an ecological life table. Causes of mortality at each stage of L. erysimi development were monitored daily in the field for seven seasons. From the experimental data, we determined the key factor and critical stage of mortality through correlation and regression analyses. The nymphal stage, especially first instar nymphs, was critical for L. erysimi mortality. The key mortality factors were, in descending order of importance, physiological disturbances and predation by Syrphidae, Coccinellidae and Solenopsis ants. Therefore, control measures should target early stages of L. erysimi and the use of cabbage cultivars that have negative effects against L. erysimi may be a promising strategy for its management. Our results may be useful for plant geneticists who could develop new cabbage cultivars based on these findings. In addition, conservation measures of the main predators of L. erysimi may contribute to the natural control of this pest.

In this study, we constructed crop life tables for Bacillus thuringiensis Berliner (Bt) Cry1Ab and non-Bt corn hybrids, in which yield-loss factors and abundance of predaceous arthropods were recorded during 2 yr at two locations. Corn kernel/grain was the yield component that had the heaviest losses and that determined the overall yield loss in the corn hybrids across years and locations. Yield losses in both corn hybrids were primarily caused by kernel-destroying insects. Helicoverpa zea (Boddie) and Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) were the key loss factors at one location, while at the other, the key loss factor was the silk fly larvae, Euxesta spp. (Diptera: Ulidiidae). Although the realized yield of corn grains was not different (P > 0.05) between Cry1Ab and non-Bt corn hybrids, the Bt corn hybrid reduced (P < 0.05) the damage by H. zea and S. frugiperda in three of the four field trials, particularly at the location where Lepidoptera were the key loss factors. As expected, no reduction in the abundance of predaceous arthropods was observed in Cry1Ab corn fields. Various species of natural enemies were recorded, particularly the earwig Doru luteipes (Scudder) (Dermaptera: Forficulidae), which was the most abundant and frequent predaceous insect. These results indicate that integration of pest management practices should be pursued to effectively minimize losses by kernel-destroying insects during corn reproductive stages when growing non-Bt or certain low-dose Bt corn cultivars for fall armyworm and corn earworm, such as those producing Cry1Ab or other Cry toxins.

Diclidophlebia smithi Burckhardt, Morais and Picanco (Hemiptera: Psyllidae) is a promising biological control agent of Miconia calvescens DC. (Melastomataceae), a neotropical invasive weed in forest ecosystems in French Polynesia and Hawaii and a threat in Australia, where it was also introduced. A study on the reproductive performance of D. smithi under laboratory conditions through life expectancy and fertility tables is presented. Results indicated that this psyllid has a high reproductive capacity (R 0>1 and r m >0) and a short life cycle (46–47 days) and can have up to nine generations per year. The critical period of its life cycle is during the nymphal stage which is clearly inadequate for field introductions. The best age for introducing D. smithi against M. calvescens is the 4th day of the adult stage. D. smithi is easily mass-reared and has a short life cycle and a high reproductive capacity, which are desirable characteristics for a biological control agent.

The diamondback moth Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae) is an herbivorous specialist on Brassicaceae species. Brassicas spp. plants developed a range of defenses (chemical, physical, and morphological) to prevent herbivores attack. In this study, we reported the antixenotic and antibiotic effects of outermost layer of two species of epicuticular wax of Brassicaceae, Brassica oleracea L. var. “Santo Antonio,” and Hybrid Kope F1 100MX, on larvae and adult of P. xylostella. In the choice experiment, P. xylostella adults showed an oviposition preference for collard cultivars Santo Antonio (control) and Hybrid Kope F1 100MX with wax removal. In the no-choice experiment, oviposition was 6.4 times higher in the Hybrid Kope F1 100MX with wax removal than without wax removal. There were significant differences among larvae feeding on leaf disks of Hybrid Kope F1 100MX in the treatments with (65.3 mg) and without wax removal (23.5 mg). The net reproduction rate (R 0 ), and intrinsic (rm) and finite rates of increase (λ) of P. xylostella in the cv. Santo Antonio were bigger in the treatment without wax removal (R 0 = 50.4, rm = 0.23 and λ = 1.26) than treatment with wax removal (R 0 = 28.5, rm = 0.20 and λ = 1.22). However, only the R 0 value was affected by mechanical wax removal in the Hybrid Kope F1 100MX (with wax removal R 0 = 43.3 and without wax removal R 0 = 30.8). In conclusion, the results indicate that collard’s wax is important to accessibility and development of P. xylostella, and its removal changes the resistance of collard’s varieties to P. xylostella.

Chemical control is the main method for controlling the tomato leafminer, Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae). Reported techniques for the evaluation of insecticide toxicity to the tomato leafminer are not in agreement with field conditions and do not allow us to verify whether doses used in the field are efficient for control. Thus, the objective of this work was to develop a bioassay methodology to study the toxicity of insecticide formulations to T. absoluta that represent field conditions for fast-acting insecticides (neurotoxics and inhibitors of respiration) and slow-acting insecticides (Bacillus thuringiensis and insect growth regulators). The leaf-dip method was the most efficient method for toxicity studies of insecticides formulations to T. absoluta. We verified that bioassays with fast-acting insecticides should be performed with glass Petri dishes containing one tomato foliole from the 4th leaf from the plant apex infested with 10 larvae of 3rd instar and these bioassays can last 48 hours. Conversely, bioassays with slow-acting insecticides should be performed with two-liter transparent PET bottles containing the 4th leaf from the plant apex, with their petioles immersed in a glass bottle containing 120 mL of water, and this leaf should be infested with 10 larvae of 2nd instar and this bioassays can last seven days. O principal método utilizado no controle da traça-do-tomateiro Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) é a aplicação de inseticidas. As técnicas atuais de avaliação da toxicidade de inseticidas sobre essa praga não simulam a situação de campo e não possibilitam a verificação se as doses usadas no campo são eficientes no seu controle. Assim, neste trabalho, objetivou-se desenvolver uma metodologia que represente as condições de campo para inseticidas de ação rápida (neurotóxicos e inibidores respiratórios) e de ação lenta (Bacillus thuringiensis e reguladores de crescimento. A metodologia mais eficiente para estudos de toxicidade de formulações comerciais a T. absoluta foi a imersão de folhas em calda inseticida. Para os bioensaios de inseticidas de ação rápida, sugere-se que estes sejam realizados em placas de Petri, contendo folíolos de tomate da 4ª folha a partir do ápice da planta, infestados com 10 larvas de 3º ínstar e eles podem durar 48 horas. Quanto aos bioensaios de toxicidade de inseticidas de ação lenta, sugere-se que sejam realizados em garrafas PET transparentes, de dois litros, contendo a 4ª folha de tomate a partir do ápice da planta infestada com 10 larvas de 2º ínstar e seu pecíolo inserido em vidro de 120 mL contendo água. Nesse caso, o bioensaio pode durar sete dias sem prejuízo na eficiência.