hundreds of varieties of corn is now just a few.

几百种减少到了现在的几种
As I'll explain later in class,

稍后我会详细解释
in Florida there used to be many, many, many varieties of oranges

在佛罗里达州曾经有很多种类的橙子
and now there are about four

而现在那里大概仅剩四种
and there are commercials reasons for this occurring.

这一切的发生归咎于商业上的原因
The biodiversity has shrunk for various reasons of profitability

生物多样性的减少源自利益的驱动
and as a consequence of that things like corn crops,

和玉米一样
and the orange crops in Florida are particularly susceptible

佛罗里达的柑橘作物很容易受到
to certain environmental conditions,

一定环境条件的影响
certain pests, and certain types of blight.

还有虫害和枯萎病
Because of that large amounts of particular types of

由于上述原因人们大剂量使用某些
pesticides and fertilizers

杀虫剂和化肥