A new study finds that mealybug destroyer lady beetles (Cryptolaemus montrouzieri), left, and Chrysoperla rufilabris lacewings (larva at right) will readily eat eggs of the invasive Asian citrus psyllid, making them promising potential helpers in integrated pest management efforts for psyllid infestations in citrus groves. Images not shown to relative scale. (Beetle photo by Matt Tudor via iNaturalist, CC BY-NC 4.0; lacewing photo courtesy of Thomson Paris)

By John P. Roche, Ph.D.

Asian citrus psyllids (Diaphorina citri) are plant-feeding insects that pose a threat to citrus crops in many parts of the world, including the southern U.S. They can damage citrus trees by feeding on their sap, but the largest threat they pose is by spreading the bacterium (Candidatus Liberibacter asiaticus) that causes citrus greening disease, also known as Huanglongbing. Most citrus trees that get infected with this bacterium eventually die.

Some generalist predators such as lady beetles, lacewings, and spiders significantly suppress Asian citrus psyllid populations by preying on immatures and adults, which can help protect trees from citrus greening disease. It is not yet known, though, how effective these predators are against the egg stage of Asian citrus psyllids. Romain Exilien, Ph.D., Jawwad Qureshi, Ph.D., and Xavier Martini, Ph.D., of the Institute of Food and Agricultural Sciences at the University of Florida sought to answer that question in a study published in March in the Journal of Economic Entomology. They evaluated four insect predators for control of Asian citrus psyllid egg infestations:

1. Orius insidiosus, known as the insidious flower bug (and also sometimes as the minute pirate bug);
2. Chrysoperla rufilabris, a species ofgreen lacewing;
3. Cryptolaemus montrouzieri, a lady beetle known as the mealybug destroyer;
4. Amblyseius swirskii, a species of predatory mite.

The project was sponsored by the U.S. Department of Agriculture’s National Institute of Food and Agriculture and its Organic Agriculture Research and Extension Initiative.

The Asian citrus psyllid (Diaphorina citri) is a plant-feeding insect that poses a severe threat to citrus crops in the U.S. by spreading a bacterium that causes citrus greening disease, also known as Huanglongbing. In a new study, Romain Exilien, Ph.D., Jawwad Qureshi, Ph.D., and Xavier Martini, Ph.D., of the Institute of Food and Agricultural Sciences at the University of Florida tested the efficacy of four insect predators on reducing Asian citrus psyllid egg infestations. They found that Chrysoperla rufilabris lacewings and mealybug destroyer lady beetles (Cryptolaemus montrouzieri) were both highly effective at controlling Asian citrus psyllid egg infestations. (Photo by Rosa Vazquez via iNaturalist, CC BY-NC 4.0)

In their experiments, Exilien, Qureshi, and Martini quantified predator efficiency on Valencia orange shoots infested with eggs in the laboratory for 24 to 48 hours and on whole Valencia orange plants for two to four days.

They found that, when foraging for Asian citrus psyllid eggs on shoots, insidious flower bug adults, lacewing adults, and mealybug destroyer larvae all significantly reduced egg numbers. Predatory mites did not cause a significant reduction in eggs. Similarly, when tested on whole plants, insidious flower bug adults, lacewing adults, and mealybug destroyer larvae all significantly reduced egg numbers. However, the best results were obtained with lacewing adults and mealybug destroyer larvae.

The investigators’ data allowed them to examine how the magnitude of predation by the predators varied with changes in prey density, something ecologists call a functional response. In a Type I functional response, the amount of prey taken per predator increases linearly with an increase in prey density. In a Type II functional response, the amount of prey taken per predator gradually decreases with an increase in prey density because predator efficiency becomes limited by the amount of time they have to expend processing food items.

Containers holding shoots of Valencia orange trees were used experimentally to test the predation efficacy of the four insect predators. (Photo originally published in Exilien et al 2026, Journal of Economic Entomology)

In the experiments on foraging on citrus shoots, mealybug destroyers showed a Type I linear functional response at 24 hours, but they showed a Type II diminishing functional response at 48 hours. Lacewings, on the other hand, displayed a Type II functional response at 24 hours and a Type I linear functional response at 48 hours. Insidious flower bugs showed a Type II functional response at both 24 hours and 48 hours. The predatory mite showed a Type I linear response at both 24 and 48 hours but consumed very few eggs (three at 24 hours and three at 48 hours).

In the more realistic experiments of foraging on whole plants, mealybug destroyers showed a Type I linear functional response at both two days and four days. They showed high predation rates and consumed 153 eggs by two days and 167 eggs by four days. Lacewings showed a Type II functional response at two days, consuming 111 eggs. At four days, the lacewings showed a Type I linear functional response on whole plants and had consumed 170 eggs. Insidious flower bugs showed a Type II functional response at both two days and four days, consuming 67 eggs by two days and 57 eggs after four days. Predatory mites were not tested on whole plants because of their lack of efficacy in the bioassay on citrus shoots.

This study was innovative because it looked at whole plants in addition to individual shoots and focused on the egg stage of the Asian citrus psyllid. The use of whole plants presented prey with a more realistic environment that more closely paralleled spatial complexity in field environments. It also allowed for a comparison of predation under low and high plant structural complexity.

One aspect of the experiments that was particularly interesting was that mealybug destroyer adults consistently consumed many eggs in both simple and complex environments. Their functional response curves suggest that they are very efficient at searching for prey and that their foraging efficiency is not very limited by prey handling time or by plant complexity.

“Overall,” Martini says, “the study fuels the idea that generalist predators can play a meaningful role in suppressing Asian citrus psyllid populations, but their contribution is context-dependent and should be evaluated within realistic plant structures.”

“One aspect worth emphasizing is the implication of this study for integrated pest management (IPM),” Martini adds, “particularly in organic citrus production systems, where chemical control options are limited or unavailable. Our findings highlight the potential for naturally occurring and augmentative predators to contribute meaningfully to the suppression of Asian citrus psyllid populations.”

The results of these experiments suggest that mealybug destroyer lady beetles and Chrysoperla rufilabris lacewings have promising potential for biocontrol of Asian citrus psyllid infestations and can help with long-term reduction of citrus greening disease infections in citrus groves.

John P. Roche, Ph.D., is an author, biologist, and scientific writer with a Ph.D. and postdoctoral fellowship in the biological sciences and a dedication to creating compelling narratives for readers. He authors books and writes materials for universities, scientific societies, and publishers. Professional experience includes serving as a scientist and scientific writer at Indiana University, Boston College, and the UMass Chan Medical School; and as editor of science periodicals at Indiana University and Boston College.