| Sumario: | Piezodorus guildinii Westwood and
Nezara viridula (L.) (Hemiptera: Pentatomidae)
are important soybean pests. P. guildinii causes
more injury and is less susceptible to insecticides
compared to N. viridula. N. viridula egg parasitoids
are well studied; however, little is known about
parasitoids of P. guildinii. Alfalfa, soybean
and red clover were sampled during several
seasons to characterize the abundance of both
stink bugs, to determine their egg parasitoids,
and to estimate parasitoids impact. In the field,
Telenomus podisi (Ashmead),Trissolcus urichi
(Crawford) and Trissolcus basalis (Wollaston)
(Hymenoptera: Platygastridae) emerged from
P. guildinii, while only T. basalis (Wollaston)
(Hymenoptera: Platygastridae) emerged from
N. viridula. The proportions of parasitized eggs
(i. e., the parasitoid impact) and egg masses,
as well as the number of parasitized eggs/total
number of eggs of the parasitized egg masses,
were similar for alfalfa and soybean. Parasitism
was not observed in red pclover. Parasitoid
impact was lower during the dry growing
seasons. Although P. guildinii field parasitism
by T. urichi was less significant, laboratory
experiments from the bibliography indicate that
this wasp species performs well on this host.
Trissolcus urichi would be an important biological
control agent against P. guildinii, principally when
the stink bug is more abundant.
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