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

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 C-4 photosynthetic pathway. Here, we assessed the oviposition preferences of H. punctigera for naturally occurring C-3 and C-4 plants under glasshouse conditions, to establish their potential as hosts. We conducted bioassays on two C-4 plants, saltbushes Atriplex nummularia Lindl. and Atriplex vesicaria Heward ex Benth.; and two C-3 plants, legumes Medicago polymorpha L. (burr medic) and Cullen cinereum (Lindl.) J.W.Grimes (annual verbine). The two C-4 plants attract egg laying in the field; however, C-3 plants are the preferred hosts. Ovipositing females showed a preference for the C-3 over the C-4 plants but oviposition occurred on both. Of the C-4 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 C-4 plants such as saltbushes grow near C-3 plants, as occurs in inland regions, the C-4 plants could receive eggs along with the C-3 plants, enabling the initial stages of larval recruitment to occur in C-3 plants.

Automated summary

The study assessed the oviposition preferences of the native budworm for C-3 and C-4 plants, finding that females prefer to oviposit on C-3 plants but will still lay eggs on C-4 plants.