AI performs an essential step in fruit fly management

Written by Diana Perez Staples, Ph.D., and Horacio Tapia McClung, Ph.D.

The Mediterranean fruit fly is one of the most harmful pests in the world (Ceratitis capitataMexican fruit flyAnastriva Ludens), causing billions of dollars in damage to agriculture. Fortunately, sterile insect technology is currently being used as part of integrated area management programs to control these flies in certain regions of the world.

The sterile insect technique (SIT) is a form of birth control, and it consists of raising millions of these flies in factories, irradiating them with X-rays or gamma rays to make them sterile, and then releasing them into areas where the pests are. When sterile males mate with wild females, the females will not have fertile eggs to lay in the fruits. Thus, population levels decrease. SIT has good green credentials because it only targets pest species, does not introduce foreign genetic material into the population, and it reduces the use of pesticides.

The irradiation process in the decimal sterilization technique is the key to its success. For teeming flies, irradiation is usually performed 2 days before the pupae emerge as adults. If the pupae are irradiated too early or too late in their development process, this can lead to problems with movement and behavior as adults. However, even during controlled conditions, the pupae can vary in their growth time. Thus, one of the tests that is performed before irradiation is to determine the physiological age of the virgins.

Currently, in these fruit fly plants around the world, technicians must determine the appropriate time to irradiate by taking a sample of the pupae, removing the pupal case to reveal the eyes, and then checking eye color against the color chart. This can be daunting and subject to human error, as it depends on the skill, experience and expertise of the technician, as well as natural biases in interpreting colors. Technicians can get tired of this repetitive work, while sick days and vision problems can also cause differences in correct identification.

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