Field evaluation of the predatory bug, Orius tantillus (Mots), (Anthocoridae:Hemiptera) for the control of the Asian corn borer, Ostrinia furnacalis (Guenee)

The corn borer, Ostrinia furnacalis (Guenee), remains the major pest of corn. The predatory anthocorid bug, Orius tantillus (Mots.), has been observed in corn fields by some workers but studies on its predatory capacity on corn borer have not been done. Earlier studies on O. tantillus against Thrips palmi Karny showed that it is an ideal biological control agent because of its high reproductive rate, short generation time and high predatory capacity. The females oviposit in plant tissues thereby ensuring protection of the eggs from the attack of parasitoids and predators and from ovicidal effects of pesticides. The adults forage on inflorescence of crops and weeds and breed all year round on Amaranthus spinosus. To understand the potential role of this predator in the control of corn borer in corn fields, the development and functional responses of the insect at various developmental stages were observed in detail on egg masses and first instar larvae of corn borer in the laboratory before releasing the predators in the field. O. tantillus was released at the rate of 10,000 individuals per ha at 3 WAP (weeks after planting), 4 WAP, and 6 WAP plus A. spinosus as trap plant, and compared with the effect of application of granular insecticide, carbofuran, Trichogramma chilonis (egg parasitoid) plus O. tantillus, and with the present IPM [integrated pest management] scheme (Trichogramma plus carbofuran plus detasseling). The levels of corn borer control provided by O. tantillus was comparable to those from the other treatments used. Results also showed that O. tantillus has very high functional and numerical responses in corn that made possible the successful colonization of the predator in corn. The tassel and silk provide optimum conditions for reproduction and development of the subsequent generations of O. tantillus. A. spinosus provides oviposition sites and optimum conditions for development of subsequent generations of O. tantillus for colonization at tasseling stage of corn. O. tantillus is susceptible to carbofuran by direct contact with the insecticide applied on the whorl and silk. The controlling effect of detasseling is not comparable to that of O. tantillus because of the loss of breeding sites and pollen for the predator. The effect of T. chilonis, however, is comparable to that of O. tantillus because the predator seems not to prefer feeding on parasitized eggs of corn borer