Fuller’s rose weevil

Description

Fuller’s rose weevil adults are grey-brown wingless and about 8 mm long, with a distinct short white line midway down their body. Females produce eggs without mating. Eggs are oval shaped and creamy-yellow in colour measuring about 1.5 mm long. Mature larvae are yellow, legless and about 6 mm long.

Eggs are laid in masses which are glued together in bark crevices, on curled leaves, on fruit (citrus), inside irrigation parts (particularly microsprinklers and drippers) or on the soil. Once hatched, larvae fall to the ground and burrow into the soil, where they feed on tree roots for six to ten months prior to pupation. Larvae pupate in the soil emerging as adults anywhere from six weeks to two months later.

Although larvae feed on roots they usually cause minimal damage. In contrast, adult FRW chew holes around the leaf edge and attack young shoots and buds. Foliage closest to the ground, or touching the trunk is often targeted by FRW. In severe infestations, the whole leaf (not including the veins) as well as the soft bark on twigs and pedicels can be consumed. This can cause premature fruit drop, reduced fruit size and water stress. Fuller’s rose weevils are mostly active at night and damage is often more severe on young trees. Fuller’s rose weevil damage can be mistaken with that of light brown apple moth, the main difference being that FRW target leaf edges rather than the leaf surface. Fuller’s rose weevils only have one generation per year, with peak adult emergence occurring from mid-summer to autumn.

Control

Once weevils are established in an orchard it can be hard to eradicate them. Vigilant monitoring combined with cultural and chemical control methods should be used to try and prevent eggs being laid on fruit, particularly in citrus. Several natural predators such as wasp (Fidiobia citri), assassin bugs, praying mantises and parasitic nematodes can help control FRW. Therefore, the use of broad-spectrum insecticides should be limited.

Fuller’s rose weevils are easily spread on machinery and equipment. It is important to practice good hygiene and check equipment for the presence of FRW to prevent them spreading to non-infested areas. Weeds and debris provide alternative feeding and breeding sites, therefore maintaining a clean inter-row is important. Remove lower branches to ensure they are not touching the ground, weeds or cover crops. Weevils live a large portion of their life underground and favour lighter soil types. Cracks which form in the soil when it dries out provide easy entry points. This can be prevented by the addition of mulch to minimise soil drying out.

Fuller’s rose weevils are known to block irrigation parts with their sticky egg masses. Where FRW is a known pest, growers should use irrigation that is less attractive for breeding, which in turn will minimise blockages. Sticky bands can be used on the base of trees to prevent weevils climbing the trees, however where dusty conditions are common the use of these may be impractical.

Vigilant monitoring is important so timely control measures can be employed. Monitor soil at the base of trees with a shovel for the presence of larvae and pupae, if large numbers are found control options should be considered. Once emerged, adult weevils initially move to weeds, therefore their presence on weeds may indicate an infestation. Cardboard traps placed around tree trunks can be an effective tool to measure weevil numbers. These should be checked fortnightly. Fruit trees should be monitored for signs of leaf damage, particularly low hanging foliage, which may indicate a FRW infestation.

Once weevil populations reach threshold levels, an application of an insecticide may be required. Vayego® is a novel insecticide that provides fast cessation of feeding and good residual activity on a broad spectrum of pests. Vayego should be applied no earlier than petal fall and is registered for the control of FRW in pome fruit and stone fruit.

References

Crisp, P and Baker, G (2012), ‘Field management of Fuller’s Rose Weevil in Citrus’ Citrus Australia, Field management of Fuller’s Rose Weevil in citrus (mvcitrus.org.au)

Crisp, P, Taverner, P and Cunningham, N (2016), ‘Fuller’s Rose Weevils in citrus’, Fact Sheet South Australian Research and Development Institute (SARDI) Fullers_Rose_Weevil_in_Citrus_Fact_Sheet.pdf (pir.sa.gov.au)

Hertherington, S and Munroe, A (2009), ‘Integrated pest management for Australian apples and pears’, The State of New South Wales, Industry and Investment NSW, Apple and Pear Limited p 128 -133, https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0009/321201/ipm-for-australian-apples-and-pears-complete.pdf

Jenkins, C (1952), ‘Fuller’s Rose Weevil’, Journal of Agriculture Vol.1 p 813 – 817, Insect Pest - Fuller's rose weevil (agric.wa.gov.au)

Malipatil, M, Williams, D and Semeraro, L (2019), ‘Pests of Pome and Stone Fruit and their Predators and Parasitoids’, Agriculture Victoria p 93, 11821-DEDJTR-AG-Pests-of-Pome-and-Stone-Fruit-Pocket-Guide-e-book_WEB-V1.pdf (hin.com.au)

Mo, J and Hardy, S (2005), ‘Fuller’s Rose Weevil’, Department of Primary Industries NSW, Fuller's rose weevil (nsw.gov.au)