Distribuição espacial e plano de amostragem sequencial de Pseudoplusia includens (Walker) (Lepidoptera: Noctuidae), em dois sistemas de plantio de soja

O controle de pragas da soja representa até 36,50% do custo de produção. As lagartas desfolhadoras podem comprometer a produção de soja causando desfolhas de até 100%. A dificuldade de controle, associada ao aumento populacional e seriedade dos danos causados colocam a subfamília Plusiinae em destaque nacional, sendo mais abundante a espécie Pseudoplusia includens (Walker). Portanto, objetivou-se com este trabalho estudar a distribuição espacial da P. includens em dois sistemas de cultivo de soja, bem como, elaborar um plano de amostragem sequencial para a praga. Para monitoramento dos insetos foram realizadas coletas semanais através do método do pano de batida. Estudou-se a distribuição espacial do inseto, através de índices de dispersão e testes de ajuste às principais distribuições de probabilidade. Testaram-se os ajustes às distribuições de Poisson e binomial negativa. Os valores dos índices de dispersão, para lagartas de P. includens, em sistema de plantio convencional de soja, indicaram distribuição agregada para as duas categorias de lagartas (pequenas e grandes). Os resultados na área com sistema de plantio direto foram semelhantes. Desta forma, é possível afirmar que lagartas de P. includens apresentaram disposição agregada no campo independentemente do sistema de plantio. Lagartas de P. includens apresentam disposição agregada no campo independentemente do sistema de plantio. O ajuste do número de lagartas coletadas à distribuição de probabilidades binomial negativa possibilitou a elaboração de plano de amostragem sequencial para monitoramento da praga independentemente do sistema de plantio. O número mínimo de unidades amostrais necessário para tomada de decisão é quatroThe soybean pest control represents to 36.50% of the cost of production. The defoliating caterpillars may compromise the production of soy causing defoliation of up to 100%. The difficulty of control, with increased population and seriously damage the subfamily Plusiinae put into national prominence, being the most abundant species Pseudoplusia includens (Walker). Therefore, the aim of this work was to study the spatial distribution of P. includens in two systems of land use, as well as develop a sequential sampling plan for the pest. The insects were collected weekly by the ground cloth method. The spatial distribution of the insect was studied, using dispersion indices and testing the main probability distributions. Tested the adjustments to the distributions of Poisson and negative binomial. The values of aggregation index to P. includens larvae in conventionally tilled soybean indicated aggregated distribution for the two categories of larvae (small and large). The results in the area with no-tillage system were similar. Caterpillars of P. includens present aggregate provision in the field regardless of tillage system. Adjusting the number of caterpillars collected the negative binomial probability distribution enabled the development of sequential sampling plan for monitoring the pest regardless of tillage system. The minimum number of sample units required for decision making is fourCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

ESCALA DE DESENVOLVIMENTO FENOLÓGICO E EXIGÊNCIA TÉRMICA ASSOCIADA A GRAUS¿DIA DO FEIJÃO-CAUPI

The cowpea (Vigna unguiculata (L.) Walp.) is one of the most cultivated leguminous in the world. In spite of being a very studied species, there are theoretical models for the development for different habits of culture. The concept of thermal time, replacing the chronological time, has been used frequently, with the advantage to be independent of location and time of sowing. Considering the relevance of the activity for the State of Piauí, this work had the purpose of describing fenology of the variety BR 17 - Gurguéia, relating the number of day-degrees necessary to the development of each fenological state. An experiment was realized in the Departamento de Fitotecnia of Centro de Ciências Agrárias of Universidade Federal do Píauí, Teresina- Piauí. It was found that the number of vegetative stages is indefinite and that the variety shows at least six reproductive stages. The vegetative stage V1 (2º in the main branch with leaflets fully open) was the longest and from the stadium V10 (11º in the main branch with leaflets fully open) was overlap of vegetative and reproductive stages. The cultivar BR 17 - Gurguéia in rainfed crop, requires 818.2 degree-days from sowing until the early reproductive stage and 1103.5 degree days from planting to the end of the reproductive cycle, with wide adaptability for the State of Piauí; the cultivar BR 17 - Gurguéia presents six reproductive stages, LV the stadium is the longest among the vegetative and reproductive stages, individually, need a greater number of degree- days that the vegetatio

NÍVEL DE DANO ECONÔMICO PARA INSETOS DESFOLHADORES EM FEIJÃO-CAUPI

The cowpea bean (Vigna unguiculata (L.) Walp.) is often attacked by defoliator insects. There are a great number of species of these defoliator insects and they cause huge damage to the plants. The most important being: Diabrotica speciosa e Cerotoma arcuata (both Coleóptera), Spodoptera frugiperda, Mocis latipes e Spodoptera cosmioides (both Lepidoptera). Understanding the relationship between the plague infestation and the productivity of the culture is one of the keys to the success of the integrate management of the cowpea bean. Studying the artificial defoliation process in order to simulate similar insect damages to the plants is useful. There are few research studies about the artificial defoliation in the cowpea bean plant. So, this study was developed to determine the level of economical damage inflicted by defoliator insects in cowpea bean plants in the Cultivar BR-17 Gurguéia. The experiments were conducted in the do Departamento de Fitotecnia do Centro de Ciências Agrárias da Universidade Federal do Piauí. The defoliation were in the order of 0%; 25%; 50%; 75% and 100%. The experiment was taken 25 days and 40 days after planting the cowpea bean plants. The production loss threshold of the cowpea bean in local condition in Teresina-PI is R$ 61.00.ha-1, which allows, through regression analysis, the following conclusion: the level of control of defoliator insects during the vegetative state is about 60% of defoliation; while in the reproductive state it is about 47%

Extrato de folhas de Anadenanthera macrocarpa sobre a biologia de Spodoptera frugiperda criada em dieta artificial

This research was conducted to evaluate the effect of leaf extract Angico-Preto (Anadenanthera macrocarpa ) on the biology of larvae of Spodoptera frugiperda. The larvae were reared on artificial diet, as Bowling, plus three different concentrations of extract. The following treatments were used: "T1" Diet without artificial extract Angico-Preto (control), "T2" artificial diet plus 2% of the extract Angico-Preto; "T3" artificial diet plus 4% of extract Angico-Preto, and "T4" artificial diet plus 6% of the extract Angico-Preto. To assess the biological S. frugiperda, was observed duration and viability of larval and pupal stages, and number of eggs per clutch every adult in the different treatments. Data were subjected to analysis of variance, followed by comparison of means using the Tukey test (P <0.05). It was found that the average duration of the larval stage (days) was lower in treatments whose diet was increased Angico-Preto Extract that differed significantly from the control (T1), with 28.22%. The viability of the larval phase (%) was also affected, treatment with the extract values were higher than T1 (65.0%), being higher in T4 (97.50%). The duration of the pupal stage (days) did not differ statistically different treatments. The viability of the pupal stage (%) was lower in T1 (47.71%) and highest in T4 (92.14%), and the number of eggs / mass was higher in treatments plus extract. We conclude that: the use extract Angico-Preto feeding S. frugiperda changed its biology; Different sources Angico-Preto on artificial diet can influence the duration and feasibility of the larval stage of S. frugiperda; Different sources Angico-Preto did not influence the duration, but may affect the viability of S. pupal frugiperda; Including extract Angico-Preto on artificial diet can influence the fecundity of S. frugiperda.O trabalho foi conduzido com o objetivo de avaliar o efeito do extrato de folhas de Angico-Preto (Anadenanthera macrocarpa ) sobre a biologia de larvas de Spodoptera frugiperda. As lagartas foram criadas em dieta artificial, acrescida de três diferentes concentrações de extrato. Os seguintes tratamentos foram utilizados: "T1" Dieta artificial sem extrato de Angico-Preto (controle); "T2" Dieta artificial acrescida de 2% do extrato de Angico-Preto; "T3" Dieta artificial acrescida de 4% do extrato de Angico-Preto; e "T4" Dieta artificial acrescida de 6% do extrato de Angico-Preto. Para avaliar a biologia de S. frugiperda, foi observada a duração e viabilidade da fase larval e pupal, e numero de ovos por postura de cada adulto, nos diferentes tratamentos. Os dados foram submetidos a análise de variância, seguido de comparação de médias usando Teste de Tukey (P < 0,05). Constatou-se que a duração média da fase larval (dias) foi inferior nos tratamentos cuja dieta foi acrescida do extrato de Angico-Preto que diferiram significativamente do controle (T1), com 28,22%. A viabilidade da fase larval (%)foi afetada, os tratamentos com extrato obtiveram valores superiores ao T1 (65,0 %), sendo maior no T4 (97,50%). A duração da fase pupal (dias) não diferiu estatisticamente nos diferentes tratamentos. A viabilidade da fase pupal (%) foi menor no T1 (47,71 %) e maior no T4 (92,14%), e o número de ovos/postura foi superior nos tratamentos acrescidos de extrato. Conclui-se que a utilização do extrato de Angico Preto na alimentação de S. frugiperda altera a biologia, duração e viabilidade da fase larval, pupal e a fecundidade de S. frugiperda. Extract of Anadenanthera macrocarpa on Spodoptera frugiperdabiology created with artificial dietThis research was conducted to evaluate the effect of leaf extract Angico-Preto (Anadenantheramacrocarpa) on the biology of larvae of Spodoptera frugiperda. The larvae were reared on artificialdiet, as Bowling, plus three different concentrations of extract. The following treatments were used:“T1” Diet without artificial extract Angico-Preto (control), “T2” artificial diet plus 2% of the extractAngico-Preto; “T3” artificial diet plus 4% of extract Angico-Preto, and “T4” artificial diet plus 6% ofthe extract Angico-Preto. To assess the biological S. frugiperda, was observed duration and viabilityof larval and pupal stages, and number of eggs per clutch every adult in the different treatments.Data were subjected to analysis of variance, followed by comparison of means using the Tukey test(P <0.05). It was found that the average duration of the larval stage (days) was lower in treatmentswhose diet was increased Angico-Preto Extract that differed significantly from the control (T1), with28.22%. The viability of the larval phase (%) was also affected, treatment with the extract valueswere higher than T1 (65.0%), being higher in T4 (97.50%). The duration of the pupal stage (days) didnot differ statistically different treatments. The viability of the pupal stage (%) was lower in T1 (47.71%)and highest in T4 (92.14%), and the number of eggs / mass was higher in treatments plus extract. Weconclude that: the use extract Angico-Preto feeding S. frugiperda changed its biology; Differentsources Angico-Preto on artificial diet can influence the duration and feasibility of the larval stageof S. frugiperda; Different sources Angico-Preto did not influence the duration, but may affect theviability of S. pupal frugiperda; Including extract Angico-Preto on artificial diet can influence thefecundity of S. frugiperda