Effects of the Mating Disruption Strategy on In-Season Damage and Overwintering Population of Cydia pomonella (L.) in Karaman Province

In the quiet rows of an apple orchard, a silent war is often waged against a tiny but devastating enemy: the codling moth. This small insect lays its eggs on developing fruit, and once the larvae hatch, they burrow deep inside the apple to feed on the seeds, leaving the fruit ruined and unsellable. For decades, farmers have fought back with sprays of chemical insecticides, but the moth is a resilient foe. It reproduces quickly, has multiple generations each year, and has learned to survive many of the chemicals meant to kill it. This resistance, combined with concerns about chemical residues and environmental harm, has pushed scientists to look for smarter, more targeted ways to manage the pest. One such approach is called mating disruption. Instead of poisoning the insects, this method floods the air with a synthetic version of the female moth's natural scent. By saturating the orchard with this scent, the males become confused and cannot find the females to mate with. If they cannot find a partner, they cannot reproduce, and the next generation of larvae never appears. This strategy offers a way to protect crops without relying on broad-spectrum poisons, but its success depends heavily on local conditions, such as the size of the orchard and the surrounding landscape.

In the central region of Karaman Province in Türkiye, where apple farming is a vital part of the local economy, a researcher named Said Efe Dost set out to test how well this scent-based strategy works in practice. The study took place over two growing seasons, 2018 and 2019, comparing two neighboring orchards. One orchard, covering about four hectares, was treated with the mating disruption method using special dispensers that released the synthetic scent. The other orchard, covering about three hectares, was managed in the traditional way, relying on frequent applications of insecticides. The goal was simple: to see if the scent-filled orchard could keep the fruit safe and reduce the number of moths that survived the winter, all while using far fewer chemicals.

The researchers monitored the moths closely throughout the summer. They used sticky traps baited with the natural scent to count how many male moths were flying around. In the Karaman climate, which features hot, dry summers, the moths were active from late spring until early autumn, completing three full generations in a single year. The peak activity occurred in late July and early August, a time when the high temperatures and low humidity help the larvae develop rapidly. In the orchard treated with the synthetic scent, the researchers placed one thousand dispensers per hectare, hanging them high in the tree canopy where the moths fly. These dispensers released a steady stream of the synthetic scent, creating a confusing cloud that masked the natural signal of the females.

The results were striking. By the time the apples were ready to be harvested, the difference between the two orchards was clear. In the orchard managed with the synthetic scent, the damage to the fruit was minimal. In 2018, only 0.70 percent of the apples were damaged, and in 2019, the number dropped even further to 0.35 percent. In contrast, the conventionally managed orchard, which relied on chemical sprays, saw much higher damage rates. There, 5.70 percent of the apples were damaged in 2018, and 4.25 percent in 2019. When the researchers calculated the reduction in damage, the scent-based method prevented roughly 91 percent of the damage in the first year and nearly 95 percent in the second. These numbers suggest that the method was highly effective at protecting the crop, keeping the damage well below the one percent threshold that commercial growers typically consider acceptable.

The benefits extended beyond just the current season's harvest. The researchers also looked at what happened to the moth population after the apples were picked, specifically checking how many larvae survived to overwinter. They placed strips of corrugated cardboard around the trunks of fifty trees in each orchard, providing a cozy hiding spot for the larvae as they prepared to sleep through the cold winter. When they collected these strips a month later, the difference was again dramatic. In the orchard with the synthetic scent, there were fewer than one larva per tree on average in 2018, and even fewer in 2019. In the conventionally managed orchard, the numbers were much higher, with more than six larvae per tree in 2018 and over four in 2019. This indicates that the mating disruption method not only protected the fruit during the summer but also significantly lowered the number of pests that would emerge to attack the trees the following spring.

However, the study also highlighted the limits of what can be concluded from this specific setup. The researchers noted that they did not directly check whether the female moths had failed to mate, which would be the most direct proof that the scent was working as intended. Instead, they observed the results: fewer damaged apples and fewer overwintering larvae. Because the study compared two whole orchards rather than multiple small plots within the same orchard, the results show a strong association between the method and the positive outcome, but they cannot definitively prove that the scent was the sole cause of every change observed. The orchard treated with the scent was also more isolated from other fruit trees than the control orchard, a factor that naturally helps mating disruption work better by reducing the number of mated females flying in from outside.

Despite these nuances, the findings offer a compelling picture of how this technology can function in a real-world setting. The study suggests that in the specific climate of Karaman, where the heat accelerates the moth's life cycle, the use of synthetic scents can successfully suppress the population and protect the harvest. It demonstrates that this approach can be a reliable part of a broader strategy to manage pests, reducing the need for repeated chemical sprays. While the method may not work exactly the same way in every orchard everywhere, the data from these two years shows that it has the potential to keep apple crops healthy and sustainable, offering a quieter, more precise way to defend the harvest against a persistent enemy.