Citing challenging economic conditions, DuPont on Tuesday reported a net loss in the fourth quarter of $629 million, or 70 cents per share, on sales of $5.8 billion. The net loss compares with net income of $545 million in the same quarter of the previous year. Sales were down 17%. The Wilmington, Del.-based company said global industrial production dropped sharply in response to declining demand in construction, motor vehicle sales and consumer spending, as well as inventory destocking. Agriculture fundamentals remain strong, DuPont said. The company expects weak economic conditions to continue in 2009. As a result, it has revised its full-year 2009 earnings to a range of $2 to $2.50 per share. The previous outlook was $2.25 to $2.75. Full-year 2008 earnings were $2.20 per share versus $3.22 in 2007.