ABSTRACT:Water is the most important resource for agricultural production. The understanding of water competition mechanisms may lead to the development of new control strategies or coexistence with certain weed species, especially in situations where water is scarce. The objective of this work was to evaluate the competition between cowpea and weeds by water under the effect on plant growth. It was carried out experiment in greenhouse in the period from September to November 2015, in a randomized complete block design, with four replications. The treatments were arranged in factorial 5 x 2, with the first factor corresponding to the competition arrangements between the species (V. unguiculata + C. benghalensis; V. unguiculata + W. indica; V. unguiculata, C. benghalensis and W. indica in monoculture), and the second of water regimes (irrigated and water deficit). The water deficit reduces the growth of cowpea plants, C. benghalensis and W. indica. The competition between plants increases the effects of temporary water deficit in the soil. The W. indica leaf is the organ most affected by the water deficit. The weed specie W. indica has greater capacity competition for water with V. unguiculata than C. benghalensis. Key words: Commelina benghalensis; interference; Vigna unguiculata; Waltheria indica; water stressCompetição entre feijão-caupi e plantas daninhas por água: Efeito no crescimento das plantas RESUMO: A água é o recurso mais importante para a produção agrícola. O entendimento dos mecanismos de competição por água pode propiciar o desenvolvimento de novas estratégias de controle ou convivência com determinadas espécies de plantas daninhas, principalmente nas situações em que a água é escassa. Objetivou-se com este trabalho avaliar a competição entre feijão-caupi e plantas daninhas por água sob o efeito no crescimento das plantas. Foi realizado experimento em casa de vegetação no período de setembro a novembro de 2015, em delineamento em blocos casualizado, com quatro repetições. Os tratamentos foram arranjados em fatorial 5 x 2, com o primeiro fator correspondente aos arranjos de competição entre as espécies (feijão-caupi + trapoeraba; feijão-caupi + malva-branca; feijão-caupi, trapoeraba e malva-branca em monocultivo), e o segundo dos regimes hídricos (irrigado e déficit hídrico). O déficit hídrico reduz o crescimento das plantas de feijão-caupi, Commelina benghalensis e Waltheria indica. A competição entre plantas aumenta os efeitos do déficit hídrico temporário no solo. A folha de W. indica é o órgão mais afetado pelo déficit hídrico. A espécie daninha W. indica tem maior capacidade de competição por água com o feijão-caupi do que a C. benghalensis. Palavras-chave: Commelina benghalensis; interferência; Vigna unguiculata; Waltheria indica; estresse hídricoCompetition between cowpea and weeds for water: Effect on plants growth Rev. Bras.
This study records the occurrence of eucoilines (Hymenoptera: Figitidae), parasitoids of the African fig fly Zaprionus indianus Gupta (Diptera: Drosophilidae), in the Brazilian semi-arid Caatinga biome. We obtained from mango (Mangifera indica L.) and guava (Psidium guajava L.) fruits Drosophilidae pupae, which developed into Z. indianus and two species of Eucoilinae parasitoids, Dicerataspis grenadensis Ashmead and Leptopilina boulardi (Barbotin, Carlton & Kelner-Pillaut). This is the first record of the parasitoids D. grenadensis and L. boulardi in the Caatinga biome.
Tetrastichus giffardianus Silvestri (Hymenoptera: Eulophidae) is a gregarious koinobiont endoparasitoid of frugivorous dipterans. In recent years, T. giffardianus has been detected parasitizing Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) in different Brazilian semiarid sites. Thus, T. giffardianus has potential to be used in the biological control of C. capitata in semi-arid conditions. However, one of the factors limiting the use of this parasitoid is the lack of detailed information on rearing methods and bioecological aspects. Therefore, the main objectives of this study were to demonstrate a rearing technique for T. giffardianus and to determine the increase in population under laboratory conditions. Specimens of T. giffardianus were obtained in the field through of the collection of fruits infested with C. capitata. The specimens obtained were used to adapt a rearing methodology for T. giffardianus under laboratory conditions. Information on demographic parameters for a T. giffardianus population was obtained using the same methodology. Based on the parameters evaluated, we found that the intrinsic rate of population increase of T. giffardianus was 0.34, the average time of one generation was 19.7 days, the population doubling time was 2.03 days and the finite rate of population increase (?) was 1.41. The demographic parameters obtained demonstrated that, with the rearing technique used, it is possible to maintain populations of T. giffardianus and enable them to multiply under laboratory conditions.
Tetrastichus giffardianus is a gregarious koinobiont endoparasitoid of tephritids, including Ceratitis capitata, which is one of the most important fruit pests worldwide. The objective of this study was to evaluate the effect of constant temperatures on the biology and development of the egg-adult period of T. giffardianus in larvae/pupae of C. capitata to construct a fertility life table. The study was carried out in climatic chambers at constant temperatures of 15, 20, 25, 30, and 35 ± 1°C, 70 ± 10% relative humidity and a photophase of 12 h. Complete egg and larval development occurred only at temperatures of 20, 25, and 30°C. The mean longevity of males and females was inversely proportional to temperature. The time of development of the pre-imaginal period was influenced by temperature and ranged from 41 days at 20°C to 11 days at 25°C. The best T. giffardianus performance occurred at 25°C when the intrinsic rate of increase was 0.21, the mean generation time was 20.43 days, the time required to double the population was 3.33 days, and the finite rate of population increase (λ) was 1.23. The results of this study provided information for the establishment of mass rearing and an evaluation of the adaptability of T. giffardianus to different environments, which is necessary for the use of this parasitoid in the biological control of tephritid pests, particularly C. capitata.
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