Asad Shabbir

Estimating the Economic Cost of One of the World's Major Insect Pests, Plutella xylostella (Lepidoptera: Plutellidae): Just How Long is a Piece of String?

ABSTRACT Since 1993, the annual worldwide cost of diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), control has been routinely quoted to be US

Biology, ecology and management of the invasive parthenium weed (Parthenium hysterophorus L.)

1 billion. This estimate requires updating and incorporation of yield losses to reflect current total costs of the pest to the world economy. We present an analysis that estimates what the present costs are likely to be based on a set of necessary, but reasoned, assumptions. We use an existing climate driven model for diamondback moth distribution and abundance, the Food and Agriculture Organization country Brassica crop production data and various management scenarios to bracket the cost estimates. The “length of the string” is somewhere between US

Downscaling Pest Risk Analyses: Identifying Current and Future Potentially Suitable Habitats for Parthenium hysterophorus with Particular Reference to Europe and North Africa

1.3 billion and US

Invasive Weed Species – A Threat to Sustainable Agriculture

2.3 billion based on management costs. However, if residual pest damage is included then the cost estimates will be even higher; a conservative estimate of 5% diamondback moth-induced yield loss to all crops adds another US

Integrated use of biological approaches provides effective control of parthenium weed

2.7 billion to the total costs associated with the pest. A conservative estimate of total costs associated with diamondback moth management is thus US

Biocontrol efficiency of Zygogramma bicolorata at different growth stages of Parthenium hysterophorus

4 billion-US

Distribution of parthenium weed (Parthenium hysterophorus L.), an alien invasive weed species threatening the biodiversity of Islamabad

5 billion. The lower bound represents rational decision making by pest managers based on diamondback moth abundance driven by climate only. The upper estimate is due to the more normal practice of weekly insecticide application to vegetable crops and the assumption that canola (Brassica napus L.) is treated with insecticide at least once during the crop cycle. Readers can decide for themselves what the real cost is likely to be because we provide country data for further interpretation. Our analysis suggests that greater efforts at implementation of even basic integrated pest management would reduce insecticide inputs considerably, reducing negative environmental impacts and saving many hundreds of millions of dollars annually.

What do we really know about alien plant invasion? A review of the invasion mechanism of one of the world’s worst weeds

Parthenium weed (Parthenium hysterophorus L.) is one of the most aggressive invasive weeds, threatening natural ecosystems and agroecosystems in over 30 countries worldwide. Parthenium weed causes losses of crops and pastures, degrading the biodiversity of natural plant communities, causing human and animal health hazards and resulting in serious economic losses to people and their interests in many countries around the globe. Several of its biological and ecological attributes contribute towards its invasiveness. Various management approaches (namely cultural, mechanical, chemical and biological control) have been used to minimise losses caused by this weed, but most of these approaches are ineffective and uneconomical and/or have limitations. Although chemical control using herbicides and biological control utilising exotic insects and pathogens have been found to contribute to the management of the weed, the weed nevertheless remains a significant problem. An integrated management approach is proposed here for the effective management of parthenium weed on a sustainable basis.

CHEMICAL CONTROL OF Parthenium hysterophorus L.

Pest Risk Assessments (PRAs) routinely employ climatic niche models to identify endangered areas. Typically, these models consider only climatic factors, ignoring the ‘Swiss Cheese’ nature of species ranges due to the interplay of climatic and habitat factors. As part of a PRA conducted for the European and Mediterranean Plant Protection Organization, we developed a climatic niche model for Parthenium hysterophorus, explicitly including the effects of irrigation where it was known to be practiced. We then downscaled the climatic risk model using two different methods to identify the suitable habitat types: expert opinion (following the EPPO PRA guidelines) and inferred from the global spatial distribution. The PRA revealed a substantial risk to the EPPO region and Central and Western Africa, highlighting the desirability of avoiding an invasion by P. hysterophorus. We also consider the effects of climate change on the modelled risks. The climate change scenario indicated the risk of substantial further spread of P. hysterophorus in temperate northern hemisphere regions (North America, Europe and the northern Middle East), and also high elevation equatorial regions (Western Brazil, Central Africa, and South East Asia) if minimum temperatures increase substantially. Downscaling the climate model using habitat factors resulted in substantial (approximately 22–53%) reductions in the areas estimated to be endangered. Applying expert assessments as to suitable habitat classes resulted in the greatest reduction in the estimated endangered area, whereas inferring suitable habitats factors from distribution data identified more land use classes and a larger endangered area. Despite some scaling issues with using a globally conformal Land Use Systems dataset, the inferential downscaling method shows promise as a routine addition to the PRA toolkit, as either a direct model component, or simply as a means of better informing an expert assessment of the suitable habitat types.

Spread of parthenium weed and its biological control agent in the Punjab, Pakistan.

There are two main threats to biodiversity in the world. One of them is the direct inadvertent destruction of habitats by people which is done basically through inappropriate resource use or pollution the other highly serious but under estimated problem is the threat to natural and semi-natural habitats by invasion of alien organisms it is the lasting threat as compared to the first one because when exploitation stops the existing aliens do not disappear but continue to spread and consolidate. Our planet is quickly being taken over by hundreds of hardy aggressive species spread either knowingly or accidentally by human hands these are considered the second most significant threat to biodiversity after habitat destruction. These weeds are causing damages worth billions of dollars world wide and Pakistan being no exception. The countries rich repository of 6,000 of vesicular plants is highly threatened by a number of alien weeds among those some are worth mentioning such as Parthenium weed (Parthenium hysterophorus), Lantana (Lantana camara), Paper mulberry (Brossonetia papyrifera), Mesquet (Prosopis juliflora), Wild tamarind (Leucaena leucocephala), Khakiweed (Alternanthera pungens) etc. These weeds especially P. hysterophorus are highly noxious plant species and threatening the natural and agriculture ecosystem of the country. Parthenium is allergenic to both humans and animals and after invading Punjab is quickly moving towards NWFP. This is primarily because of unawareness about this plant and secondly that it is being constantly used in floral bouquets. Similarly there are many more in the list developed by IUCN in the year 2000 for Pakistan. Though it is difficult to manage these aggressive alien organisms but success stories have been documented regarding biological/chemical control and other integrated approaches. More over a careful revision of legislation regarding quarantine and enforcement of the same may prove useful to mitigate the threats of these weeds.