The diversity of plants in agricultural systems benefits natural enemies. Herbicides are used in weed management in corn
(
Zea mays
L.) to reduce competition and productivity losses, but they can impact natural enemies and contaminate the
environment. The objective was to evaluate toxicity of herbicides on pupae parasitoid
Palmistichus elaeisis
Delvare and
LaSalle, 1993 (Hymenoptera: Eulophidae). The treatments were represented by the host pupae
Tenebrio molitor
L., 1785
(Coleoptera: Tenebrionidae) and herbicides atrazine, nicosulfuron, paraquat, and tembotrione in commercial doses compared
to a control treatment with water. Pupae of
T. molitor were immersed in the solution of herbicides and exposed to parasitism
by six females of
P. elaeisis each. The herbicides atrazine and paraquat were highly toxic and, therefore, not selective to
P.
elaeisis. Nicosulfuron reduced the sex ratio of
P. elaeisis (0.20 ± 0.03), which may affect subsequent generations. Moreover,
the herbicide tembotrione was selective to
P. elaeisis, showing results comparable to the control. Floristic diversity of
weeds can increase food source, habitat, shelter, breeding places and microclimates for insect parasitoids but herbicides
formulations can be toxic and these products can affect
P. elaeisis or its hosts by direct or indirect contact, showing the
importance of selectivity studies for this natural enemy. However, the herbicide tembotrione was selective to
P. elaeisis and
it can be recommended for programs of sustainable management of weeds in corn crop with this parasitoid.
