Pest Management in CUPS

By Jawwad Qureshi

The Asian citrus psyllid (ACP, Figure 1) continues to feed on citrus trees infected with citrus greening and spread the disease to newly planted young trees. Therefore, it is not possible to produce a healthy citrus tree in an environment where citrus greening is endemic. Only the citrus under protective screen (CUPS, Figure 2) system allows the production of citrus free from ACP and citrus greening disease.

CUPS is a protected production system of screened enclosures where large acreages of citrus crops are produced. A decade of research conducted by University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) researchers has documented only a few rare occurrences of ACP and no establishment of citrus greening disease in CUPS. That suggests a significant potential in this system to produce citrus crops free of vector disease complex. The crops grown inside CUPS continue to produce quality fruit while the respective controls without such protection were decimated by citrus greening over the years.

It is important to understand that the CUPS system does not provide complete pest protection. It is prone to pest incursions and, besides rare detections of ACP, other pests such as mites, citrus leafminer (CLM), thrips, scales and mealybugs were able to selectively enter CUPS through the permeable screen or doors. However, the CUPS system does provide a significant barrier to the influx of these pests.

Most of these pests were detected at a much-reduced level in the CUPS compared to their populations outside. For example, citrus leafminer (CLM) was reduced by more than 80%. Similarly, significantly reduced populations of citrus rust mite were observed in the CUPS than outside. However, citrus red mite populations were high in the CUPS and flower thrips were only observed in the CUPS, suggesting that the environment inside these structures was more favorable for some pests.

The damage from pests such as mites and thrips also reflects on the fruit surface and reduces the quality and consumer acceptance of the produce, particularly of fresh fruits. Therefore, it is important to regularly monitor the CUPS to detect pests when they are at low levels to implement any maintenance treatments.

Simple visual observation of foliage helps with finding several pests and their damage, such as mites, CLM, mealybugs and scales, while thrips are easily detected through examination of flowers. Thrips are also detected on yellow sticky cards which are used to detect ACP adults while pheromone traps for CLM detect its males.

The suppression of pests at low levels helps with minimizing the use of chemical treatments, which may be less effective later if populations develop to high levels. The increased use of chemical control in CUPS could lead to issues of pest resistance and a negative impact on biological control, which we already observed in the traditional open production systems leading to increased costs of pest management.

Beneficial organisms providing biological control of several pests were detected in CUPS. Predatory mites that attack pest mites and neonates of insect pests of several species as well as parasitoids attacking CLM, scales and mealybugs were observed in the CUPS. That suggests that CUPS structures provide a suitable environment for biological control agents.

Overall, CUPS prevents ACP and citrus greening and significantly reduces several other pests while providing a suitable environment for biological control agents.

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