DuPont Co. said it will cut about 1,500 jobs and take other steps to increase competitiveness after weak demand for a key industrial pigment and uncertainty in the solar panel market led to a sharp drop in third-quarter earnings. The chemical company reported net income of $10 million, or a penny per share, compared with $452 million, or 48 cents per share, a year earlier. Excluding one-time items, it earned 44 cents per share. CEO Ellen Kullman attributed the results to weaker-than-expected demand for titanium dioxide — a whitening pigment used in products ranging from paint to toothpaste — and overcapacity and uncertainty in the market for solar energy products.