RESUMO

The ecological and economic contributions of pollinator bees to agricultural production have been threatened by the inappropriate and excessive use of pesticides. These pesticides are often applied in areas with ecological peculiarities (e.g., the Neotropical savannah-like region termed as Cerrado) that were not considered during the product development. Here, we conducted field experiments with melon (i.e., Cucumis melo L.) plants cultivated under Brazilian Cerrado conditions and evaluated the impacts of botanical (i.e., neem-based insecticide) and synthetic (i.e., the pyrethroid insecticide deltamethrin and the fungicides thiophanate-methyl and chlorothalonil) pesticides on the flower visitation rates of naturally occurring pollinator bees. Our results revealed that both honey bees (i.e., Apis mellifera L.) and non-Apis bees visited melon flowers and the intensity of bee visitation was moderately correlated with yield parameters (e.g., number of marketable fruits and fruit yield). Pesticide treatments differentially affected bee species. For instance, Plebeia sp. bees were not affected by any pesticide treatment, whereas both A. mellifera and Halictus sp. bees showed reduced visitation intensity after the application of deltamethrin or neem-based insecticides. Fungicide treatment alone did not influence the bee's visitation intensity. Deltamethrin-treated melon fields produced significantly lighter marketable fruits, and the melon yield was significantly lower in melon fields treated with the neem-based insecticide. Thus, our findings with such pollinator bees reinforce the idea that field applications of botanical pesticides may represent as risky as the applications of synthetic compounds, indicating that these alternative products should be submitted to risk assessments comparable to those required for synthetic products.

Assuntos

RESUMO

A recent review article entitled "Carbon and fullerene nanomaterials in plant system" published in this journal, misinterprets a component of our (published) work on the interactions of carbon nanotubes with plants. In this comment, we provide the rationale to counter this misconstruction.

Assuntos

RESUMO

Anastrepha grandis (Macquart) (Diptera: Tephritidae) is one of the main pests of cucurbits in Brazil. Losses occur due to the damage caused to the fruits and the embargo on exports, as A. grandis is considered a quarantine pest in countries that import Brazilian cucurbits. This study aimed to evaluate the development of A. grandis in hosts of the Cucurbitaceae family. The hosts used were stem squash (Cucurbita pepo L.), squash (Cucurbita moschata Duchesne), chayote [Sechium edule (Jacq.) Swartz], mini watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai], Spanish melon (Cucumis melo L.), hybrid squash "Tetsukabuto" (C. moschata×Cucurbita maxima Duchesne), and salad cucumber (Cucumis sativus L.). We evaluated the viability and duration of egg-to-pupa period, pupal weight, sex ratio, and average number of pupae per fruit under controlled conditions of temperature, relative humidity, and photophase. The preoviposition and oviposition periods, fecundity, fertility, and longevity of females were determined for adults. Hosts of the genus Cucurbita provided a better development of A. grandis in comparison with other hosts, and presented a greater number of insects on fruit as well as higher infestation rate. Fecundity and longevity were also higher for females that developed in hosts of the genus Cucurbita, although values of these biological parameters varied between stem squash, squash, hybrid squash "Tetsukabuto."

Assuntos

RESUMO

Sexual diversity expressed by the Curcurbitaceae family is a primary example of developmental plasticity in plants. Most melon genotypes are andromonoecious, where an initial phase of male flowers is followed by a mixture of bisexual and male flowers. Over-expression of the CmACS-3 gene in melon plants showed an increased number of flower buds, and increased femaleness as demonstrated by a larger number bisexual buds. Transformation of CmACS-3 in melons showed earlier development of and an increased number of bisexual buds that matured to anthesis but also increased the rate of development of the bisexual buds to maturity. Field studies showed that CmACS-3-overexpressing melons had earlier mature bisexual flowers, earlier fruit set, and an increased number of fruits set on closely spaced nodes on the main stem.

Assuntos

RESUMO

BACKGROUND: In water scarcity areas the use of saline water for irrigation is a common practice. In this study, experimental data from two two-year melon tests were collected for the calibration (2004 'Yellow Melon' (YeMe) type) and validation (2002 YeMe, 2005 and 2006 'Piel de Sapo' (PiSa) type) processes in melon crop simulation under deficit irrigation conditions using salt water. The simulations were carried out for Castilla-La Mancha (Spain) and Ceará (Brazil) using the MOPECO model, which includes optimized regulated deficit irrigation (ORDI) methodology. The objective was to determine the most suitable irrigation strategy for both areas. RESULTS: Under fresh water conditions, ORDI may increase yield by up to 20% (PiSa) and 7% (YeMe) compared with constant deficit irrigation. Higher water deficit should be induced during the vegetative development and ripening stages. The rainfall between irrigation periods is able to leach the salts supplied by the irrigation water. CONCLUSION: The combination of ORDI with different strategies for managing saline water may increase water use efficiency. In these areas it may be of interest not to apply the leaching fraction (saving up to 67% of irrigation water). However, leaching of the soluble salts accumulated before starting the most sensitive periods may be suitable.

Assuntos

RESUMO

Oriental melon (Cucumis melo L. var. makuwa) is an important fruit for human consumption. However, this plant species is one of the most recalcitrant to genetic transformation. The lack of an efficient in vitro system limits the development of a reproducible genetic transformation protocol for Oriental melon. In this study, an efficient transgenic production method for Agrobacterium-mediated transformation using cotyledon explants of Oriental melon was developed. Cotyledon explants were pre-cultivated for two days in the dark, and the optimal conditions for transformation of melon were determined to be a bacteria concentration of OD600 0.6, inoculation for 30 min, and two days of co-cultivation. Transgenic melon plants were produced from kanamycin-resistant shoots. A total of 11 independent transgenic plants were regenerated with a transformation efficiency of 0.8% of the inoculated explants. The transgenic plants were phenotypically normal and fully fertile, which might be a consequence of the co-cultivation time.

Assuntos

RESUMO

O melão de caroá é da família das curcubitáceas encontrada de forma nativa na região do Recôncavo Baiano, onde é muito utilizada pela medicina popular para diversas enfermidades, porém é espécie muito pouco explorada pela pesquisa. O trabalho teve por objetivo estudar diferentes substratos para avaliar o índice de germinação e vigor de sementes de melão de caroá (Sicana odorifera) na produção de mudas. Utilizaram-se como substratos areia lavada, areia lavada com húmus de minhoca (2:1) e substrato comercial Plantmax®. Foram realizadas as seguintes avaliações: teste de germinação, índice de velocidade de emergência (IVE), diâmetro de haste, altura de planta, comprimento da raiz, massa seca da raiz, haste e folhas. O substrato comercial Plantmax®promoveu melhor desempenho das sementes em relação aos demais, porém, o mais adequado e de baixo custo para produção de mudas através de sementes de melão de caroá (Sicana odorifera) foi a mistura de areia lavada e húmus de minhoca na proporção 2:1.

Caroá melon is a curcubitaceae found in its native form in the Recôncavo Region of Bahia, where it is used by popular medicine for many diseases. However, this species is little explored in research. The objective of the present work was to study different substrates in order to evaluate the germination index and seed vigor in caroá melon (Sicana odorifera) during seedling production. The following substrates were used: washed sand, sand washed with worm humus (2:1) and commercial substrate, Plantmax®.The following evaluations were carried out: germination test, speed of germination index (SGI), stem diameter, plant height, root length and root, stem and leaf dry matter. The commercial substrate Plantmax® presented the best performance compared to the others; however, the most adequate and least costly in seedling production using caroá melon (Sicana odorífera) seeds, was the mixture of washed sand and worm humus in the 2:1 ratio.

Assuntos

RESUMO

Sicyos polyacanthus is one of the most important weed in sugarcane crops of Tucumán (Argentina). The objective of this work was to establish strategies that would decrease the weed incidence in the crop to a minimum level. The study was carried out during 1998--2003 at five localities of sugarcane production of Tucumán (Argentina). The plots were 20 m long (192 m2) with 6 furrows and each plot was replicated five times. Treatments were: (i) Mechanical-chemical cultivation without fire; (ii) Mechanical-chemical culltivation with fire; (iii) Mechanical cultivation with handle pulled and with fire; (iv) Mechanical cultivation with handle pulled without fire; (v) Mechanical and chemical variants with fertilization and without fertilization; (vi) Mechanical and chemical variants with watering and without watering; (vii) Fallow and rotation, at the sugarcane crop renovation; (viii) Mechanical and chemical variants for plant cane and ratoon cane; and (ix) Mulching of harvest rests. The results suggest that besides the use of preemergent herbicides, fire marks the entry point of control, influencing fluxes and seed viability. It appears that fallow, mulching, and rotation of crops is fundamental for eliminating seeds that live short time in the soil and increase the mortality rate of species.

Assuntos