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Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/5/2005 Publication Date: 6/1/2006 Citation: Tillman, P.G. 2006. Susceptibility of pest Nezara viridula (Heteroptera: Pentatomidae) and parasitoid Trichopoda pennipes (Diptera: Tachinidae) to selected insecticides. Journal of Economic Entomology. 99(3):648-657. Interpretive Summary: In 2004, stink bugs were responsible for an estimated $6.5 million dollars in costs associated with crop loss and insecticide costs across the US. Since resurgence of key pests and outbreaks of secondary pests can occur with treatments that destroy natural enemies, insecticide selectivity is an important issue in integrated pest management. Thus, the objective of this research was to compare the toxicity of the insecticides Assail, Baythroid, Bidrin, Centric, Steward, and Vydate to the pest stink bug, the Southern green stink bug (SGSB), and a fly parasite of this stink bug, Trichopoda pennipes, when exposed to dried residues of these insecticides and when feeding on these insecticides. Generally, Bidrin, Vydate, Baythroid, and Centric were highly toxic to both the SGSB and T. pennipes. Feeding on food contaminated with Steward was basically non-toxic to N. viridula, but highly toxic to T. pennipes. Since none of these six insecticides were selective to T. pennipes, chemical interventions with these insecticides should be applied only when this pest reaches economic threshold in cotton to conserve this natural enemy of the SGSB and other natural enemies in cotton fields. Technical Abstract: Susceptibility of a pest stink bug, the brown stink bug (BSB), Euschistus servus (Say) (Heteroptera: Pentatomidae), and the predatory stink bug, the spined soldier bug, Podisus maculiventris (Say) (Heteroptera: Pentatomidae), to cyfluthrin, dicrotophos, indoxacarb, oxamyl, and tralomethrin, insecticides used for stinkbug control in cotton, was compared in residual and feeding tests. Both insect species responded very similarly to dicrotophos, oxamyl, and tralomethrin in tarsal contact and feeding toxicity studies. Dicrotophos and oxamyl residues were highly toxic to nymphs and adults, but tralomethrin only slightly toxic to nymphs and non-toxic to adults. Feeding on dicrotophos-treated food resulted in moderate mortality for nymphs, but little mortality for adults. Oxamyl and tralomethrin showed little feeding activity for nymphs and adults. Feeding through dry residues of cyfluthrin did not result in mortality for nymphs and adults of either insect species. However, P. maculiventris nymphs and adults were more susceptible to prolonged tarsal contact with dry cyfluthrin residues than BSB. Prolonged tarsal contact with dry indoxacarb residues did not result in mortality for nymphs and adults of either stink bug species. However, Podius maculiventris nymphs and adults were highly susceptible to indoxacarb when feeding through dried residues of the insecticide on fall armyworm, Spodoptera frugiperda (J. E. Smith)(FAW), larvae. In contrast, feeding on indoxacarb residues on shelled pole beans (Phaseolus vulgaris L.) had very little adverse effect on E. servus. Unfortunately, none of the insecticides were selective against BSB so chemical interventions should be applied only when this pest reaches economic threshold in cotton to conserve P. maculiventris and other natural enemies in cotton fields. |
