Plant age, crop stage and surrounding habitats: their impact on sucking pests and predators complex in cotton (Gossypium hirsutum L.) field plots in arid climate at district Layyah, Punjab, Pakistan

Sucking pests are major threat to cotton field crop which cause unbearable losses to the crop yield. Aim of the current study was to record seasonal dynamics of major sucking insect pests including whitefly, jassid, thrips and their natural arthropod predators i.e. green lacewings and spiders in cotton field plots. The effects of surrounding field crops on pests’ density and predatory efficiency of predators were also recorded. For sampling and survey of insects, the visual counting was found to be the most efficient method for recording the abundance of insects, trailed by net sweeping and tapping. Whitefly was the most dominant sucking pest found on the vegetative stage of cotton, followed by jassid and thrips. Fluctuated populations of predatory arthropods, spiders and green lacewings were also recorded during whole cropping season however, the densities of pests and predators varied with crop phenology. Spiders’ population was encouraging at both vegetative and flowering stage and also the same trend of jassid and whitefly were observed at both stages of the crop. Surrounding habitats showed non-significant effect on population densities of insect pests and predators. For abiotic factors, the spiders showed strong positive correlation with humidity and temperature. However, green lacewing was only positively correlated with humidity. On the other hand, the populations of whitefly, jassid and thrips showed non-significant correlation with both temperature and humidity. Overall densities of sucking insect pests were found above economic threshold level. The plant age, crop stage and surrounding habitats effect on the population fluctuation of pests as well as the predators’ abundance. The future studies are also warranted to investigate the altered habitats and multiple trap cropping to find out their impact on unattended insect predators and parasitoids in cotton crop.

Coastal and Marine Pollution in Bangladesh: Pathways, Hotspots and Adaptation Strategies

Marine and coastal pollution is a global issue for human health and biodiversity. We have investigated pollution sources, flow patterns, hotspots, challenges, and adaptation policies in Bangladesh. Industries, ship breaking yards, sewage, tourism, and transboundary depositions are the main sources of pollutions. The Ganges, Padma, Jamuna, Brahmaputra and Meghna carry wastes to the Bay of Bengal. Pollution hotspots are Dhaka, Gazipur, Narshingdi, Narayanganj, Chittagong, Khulna, Mongla port and Sylhet city. Textile and dyeing industries discharge 12.7–13.5 million m3 waste waters annually and pollute 20% of fresh water. Ship breaking yards dump about 22.5 tons polychlorinated biphenyls in a year. More than 50% of the marine oil pollution comes from urban activities. Plastic wastes at 3000 t day-1 and tourism are also contributing to the coastal pollution. Effluent releasing standards are not maintained, and thus higher concentrations of heavy metals are found with marine fishes. Use of heavy metal tolerant crops (rice: BRRI dhan47, potato: Cardinal, mustard: Brassica napus, flower: Marigold, vegetables: Cucumber, fibre: Kenaf, and so on), trap cropping, deep placement of fertilizers, integrated rice-fish-duck culture, etc can be adopted in polluted areas. There are laws for environmental issues, but coordination and financial capabilities does not warrant its effectiveness. Necessary steps are to be taken to improve infrastructure to ensure sanitation and benign discharge of industrial effluents. Systematic study on sources, fate and extent of current effluents dumping in water ways need to be assessed for wellbeing of aquatic life and human health.

Evaluation of Trap Cropping for Control of Diamondback Moth (Lepidoptera: Plutellidae) in a Broccoli Production System

Trap cropping, in which a trap crop is planted near a cash crop, has been used successfully for reducing pest damage in some agricultural systems. We used a meta-analysis of extensive data on two trap cropping systems, diamondback moth, Plutella xylostella (Linnaeus), exploiting cabbage and Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) exploiting maize, to show that oviposition preference for, and high larval mortality on trap crops are important indicators of effectiveness of trap cropping systems. We then evaluated Indian mustard (Brassica juncea var. juncea L. Czern.) (Capparidales: Brassicaceae) and yellow rocket (Barbarea vulgaris W. T. Aiton) (Brassicales: Brassicaceae) as trap crops for protecting broccoli (Brassica oleracea var. italica Plenck) (Capparidales: Brassicaceae) against diamondback moth in Yuma, AZ, using planting configurations compatible with current practices for commercial production and without use of insecticides. In oviposition choice tests, both yellow rocket and Indian mustard were highly preferred over broccoli in the field. Furthermore, the number of larvae and pupae was significantly lower on yellow rocket and Indian mustard compared to broccoli, indicating relatively high mortality on these trap crops. Nevertheless, during the fall and spring growing seasons, no significant differences in the number of individuals on broccoli or proportion of broccoli crowns infested at harvest occurred between plots with trap crops relative to plots exclusively planted to broccoli. Thus, with the plant density and planting patterns used and without use of insecticides, there was no evidence that trap cropping was effective for reducing diamondback moth infestation of broccoli.

Trap cropping: Principles and possibilities of application in root vegetable production

Vegetable production is one of the most intensive parts of agricultural production in Serbia. There are several different classifications of vegetable species, but the most common is based on the edible part of the plant. This classification emphasizes root vegetables as a special and very important category. During the entire vegetation period, root vegetables are exposed to numerous pests, which reduce the value and quality of the final product. In addition to insects, which represent the most numerous group of animals, vegetables are also damaged by mites, nematodes, snails, rodents and some species of birds. One of the ecologically acceptable methods in the protection of vegetables is trap cropping, whereby certain plant species, the so-called trap plants are used to attract pests, in order to reduce the damage of the main crop. In modern agricultural production, trap crops are used as a common tool in Integrated Pest Management. Rising interest of agricultural producers for trap cropping is primarily attributed to the public concern about the potential negative effects of pesticides to human and environmental health, as well as to the increasing problem of pest resistance to insecticides. Since root vegetables intended for the market are primarily in fresh condition, an important segment of production is the effective protection of vegetable crops, which implies production of healthy and safe food. In that sense, the consideration of trap crops application in protection of root vegetables is more than justified, because trap cropping represents an environmentally friendly method and an effective alternative to conventional protection of vegetables from economically important pests.