Every crop has insects that it evolves or coexists with, and citrus plants are no different. There are numerous insects of citrus that are harmless, some are beneficial while some are harmful. The harmful insects garner the most attention because if they are not managed they can devastate the citrus industry.

Insects can infest flowers, shoots, and roots of citrus plants and impact the production and life of trees. For example:

• Infestation of citrus flowers and young fruit can result in scarring and fruit drop.
• Repeated puncturing of fruit by some insects results in discoloration, water loss, and reduced aesthetic quality.
• Eggs and feeding larvae within the fruit lead to spoilage, decreased soluble solids, and altered juice content and flavor.
• Colonization of the leaves by insects leads to reduced vegetative growth, photosynthetic capacity, and vigor.
• Some insects serve as vectors of diseases which are usually more debilitating to citrus plants than the direct effects of insects.Insects and mites can cause plant diseases or transport and inoculate viruses and microorganisms such as bacteria and fungi that cause plant disease. Plant diseases spread by insect vectors can affect the profitable production of some crops.

Why control insects in citrus?

The most serious challenge facing the citrus industry today is the citrus greening disease (huanglongbing or HLB). HLB is devastating because when it infests a citrus plant the best solution to prevent further spread is to remove the citrus plant since there are no known curative measures for control of the disease. Removal of infected citrus plants is effective because it removes inoculum that could be spread by the only known vector of the disease, the Asian citrus psyllid.

To eliminate populations of the Asian citrus psyllids, insecticides are used aggressively in and around citrus groves.  There are a number of insecticides that can effectively control the Asian citrus psyllid, but care has to be exercised to prevent problems such as the development of insecticide resistance, which has recently been detected.

Steps in insect control

An orderly process of decision-making is essential to designing a strategy for insect control. The following steps provide a framework for an approach to insect management.

1. Detection – It is important to detect an insect infestation early before irreparable damage is done. In most cases, this requires careful examination of the field and adjacent areas.
2. Identification–The insect pest must be correctly identified before it can be controlled. If unable to identify the insect locally, assistance may be obtained from the land grant university extension services or the U.S. Department of Agriculture.
3. Insect biology and ecology – Understanding the enemy before attempting tocontrol it is essential for successful management. Knowledge of the seasonal cycles of an insect pest within a specific location is important in order to pinpoint the most effective time of treatment.
4. Economic significance – A determination needs to be made on the return on investment in treating the insect pest. Control measures need to be taken only if the insect pest has been determined to be of economic significance.
5. Selection of control method(s) – After the pest problem has been identified, the life cycle habits of the pest have been understood, and the economic significance established, a control strategy can be implemented. The choice of method, or combination of methods, must be the most effective, practical, economical, and safe for the environment and applicator.
6. Application – The selected control method(s) must be applied properly to be effective and safe. When using pesticides, the application must be done at the appropriate time, at the correct rate, and with suitable equipment. Detailed directions for using pesticides can be found on the label. Reading and understanding the written instructions on pesticide labels is important to obtain the best results.
7. Evaluation – An important step in a control operation is checking the field where treatments were applied to evaluate how well they worked. The results obtained should be recorded for future reference.
8. Recording – Records provide the basis for gaining from past experiences. It is especially important to have all chemical applications recorded.

Further Reading

• Limonene: An Environmentally Safe Compound for Pest Control
• Managing Insect PestOutbreaks

References

• Bohmont, B.L. 2007. The Standard Pesticide User’s Guide – 7th Ed. Pearson Prentice Hall. Pp. 38-61.
• Mead, F.W. and T.R. Fasulo. 2017. The Asian Citrus Psyllid. Univ. FL/IFAS, Univ. FL Entomol. and Nematol., and FL Dept. Ag. and Cons. Sci. (Accessed Oct. 2, 2022).
• Tiwari, S. et al. 2011. Insecticide Resistance in Field Populations of Asian Citrus Psyllid in Florida. Pest Manag. Sci. 67:1258-1268. (Accessed Oct. 2, 2022).