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

Abstract

The native budworm, Helicoverpa punctigera (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 H. punctigera for naturally occurring C3 and C4 plants under glasshouse conditions, to establish their potential as hosts. We conducted bioassays on two C4 plants, saltbushes Atriplex nummularia Lindl. and Atriplex vesicaria Heward ex Benth.; and two C3 plants, legumes Medicago polymorpha L. (burr medic) and Cullen cinereum (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 A. nummularia (77%) over A. vesicaria (24%) in both a multi- and two-choice test. In addition, ovipositing females preferred the upper leaf surface of A. nummularia (68%) and the under leaf surface of A. vesicaria (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.