What is "veha'Boshes"?
Rashi: It is idolatry, like it says "va'Yinazru la'Boshes" (Hoshe'a 9:10). Radak - [the idolatry] Ba'al is called Boshes, for it is shameful for one who engages in it. Also "Yeruboshes" (Shmuel II, 11:21) is called "Yeruba'al" (Shoftim 6:32).
How did it consume the Yegi'a of our fathers"?
Rashi: Due to the sin of idolatry, their [property attained via] exertion was plundered.
Radak: Yegi'a is produce of the field. Due to the sin of idolatry, it was stricken, or consumed by locusts or enemies. [The latter] consumed also their flock and cattle. Their sons and daughter died via plague.
Radak citing Targum Yonasan: In the shame of debts (sin), the toil of our fathers was finished off.
Why does it say "mi'Ne'ureinu"?
Radak: We saw this from our youth.
Why are we saying all this?
Malbim: [This explains why] we are in the ultimate despair; we cannot do anything.
