After spraying crops with DDT for several years, farmers found that populations of pests rebounded. One reason was that the insects had developed resistance to the insecticide. Suggest another reason, based on what you know about populations, food chains, predators and competition.
2007-05-24 13:18:28 · 1 answers · asked by H.A. 2 in Science & Mathematics ➔ Biology
It's possible that populations of different species increased when the DDT susceptible ones were gone and left an open niche for others to inhabit.
It's also possible that the populations of predators decreased because they didn't have enough food. Then the populations of the pests would rebound.
It's also possible that pests moved in from neighboring populations that were in areas where DDT wasn't being sprayed.
2007-05-24 13:26:45 · answer #1 · answered by ecolink 7 · 1⤊ 0⤋