Oviposition preferences of the native budworm, Helicoverpa punctigera (Wallengren), on C3 and C4 plants

Abstract

<p>The native budworm, <i>Helicoverpa punctigera</i> (Wallengren), is an important economic insect pest of cotton and other crops. It is widely distributed in Australia and has been recorded on a range of host plants including native, non-crop hosts in inland regions. To date, there are few records of its occurrence on plants with the C₄ photosynthetic pathway. Here, we assessed the oviposition preferences of <i>H. punctigera</i> for naturally occurring C₃ and C₄ plants under glasshouse conditions, to establish their potential as hosts. We conducted bioassays on two C₄ plants, saltbushes <i>Atriplex nummularia</i> Lindl. and <i>Atriplex vesicaria</i> Heward ex Benth.; and two C₃ plants, legumes <i>Medicago polymorpha</i> L. (burr medic) and <i>Cullen cinereum</i> (Lindl.) J.W.Grimes (annual verbine). The two C₄ plants attract egg laying in the field; however, C₃ plants are the preferred hosts. Ovipositing females showed a preference for the C₃ over the C₄ plants but oviposition occurred on both. Of the C₄ plants, females preferred to oviposit on <i>A. nummularia</i> (77%) over <i>A. vesicaria</i> (24%) in both a multi- and two-choice test. In addition, ovipositing females preferred the upper leaf surface of <i>A. nummularia</i> (68%) and the under leaf surface of <i>A. vesicaria</i> (64%) as their oviposition site. Our findings suggest that under field conditions, when C₄ plants such as saltbushes grow near C₃ plants, as occurs in inland regions, the C₄ plants could receive eggs along with the C₃ plants, enabling the initial stages of larval recruitment to occur in C₃ plants.</p>