The Fuller Rose Beetle is a leaf-chewing pest on citrus trees. Damage from the beetle feeding, generally does not cause economic damage on citrus, but the presence of eggs on exported fruit can be a concern. For this reason, the Fuller Rose Growing Degree Day Model may be used to determine when fruit is able to be harvested for exported following an insecticide treatment. Once adult Beetles are treated, enough time needs to be given for already laid eggs to hatch before harvest.

Fuller Rose Beetle Life Cycle Stages

The Fuller rose beetle has one generation a year. Eggs are laid in a mass of several dozen on fruit, especially underneath the button, or in cracks and crevices in the tree. When eggs hatch, larvae drop to the ground and live in the soil where they feed on roots of citrus for 6 to 10 months or longer. They pupate in the soil and the adults emerge 1.5 to 2 months later.

Viable eggs need to be avoided on exported fruit, and the Fuller Rose Growing Degree Model can be used to estimate the timing when eggs will hatch and larvae drop.

Calculating Growing Degree Day Units

The Fuller Rose Beetle Emergence Growing Degree Day model uses a lower threshold of 10.2C. It can be calculated with daily high and low temperatures, using the sine model to estimate growing degree day units, or the Pest Prophet app can be used to calculate GDD accumulation from hourly temperature data for a specific field.

The “biofix” date, or starting point for accumulation, should be set to coincide with treatment to eliminate adult beetles. 99% of egg hatch will have occurred at approximately 352 GDD(C) which is the optimum time for harvest.

Source:

Lakin, K. R., and J. G. Morse. 1989. A degree-day model for Fuller’s rose beetle, Pantomorus cervinus (Boheman) (Col., Curculionidae) egg hatch. J. Appl. Ent. 107: 102-106.