Evaluation of ‘SNAP’ plants for supporting coccinellids that prey on the Asian citrus psyllid (Diaphorina citri) in south Florida

Authors: Patt, Joseph; Tarshis Moreno, Aleena; Ortega, Melanie

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/4/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: The Asian citrus psyllid is a tiny insect sucks tree sap and transmits citrus greening, a disease that threatens Florida’s citrus industry. Psyllids are attacked by many kinds of predatory insects, such as ladybugs. However, little information is available about how to attract and support ladybugs in citrus groves. Growing ‘SNAP’ plants (so-called because they provide shelter, nectar, alternate prey, and pollen) could be an effective way to attract and support predators to control psyllids. To identifying likely SNAP plants, the number of ladybugs was measured on 18 different kinds of plants. These plants were primarily flowers or vegetables and had nectar glands on the leaves or open flowers on which ladybugs could feed. Captures of 3 or more ladybugs each week were made on coriander, cowpea, dill, lima bean, portulaca, and field mustard. Ladybugs ate pollen from field mustard, coriander, buckwheat, oak and pine as well prey insects that lived on the flower and vegetable plants. The results showed that certain umbels, legumes, and cover crops functioned as SNAP plants and could be used to supporting ladybugs and other insect predators in citrus groves.

Technical Abstract: Asian citrus psyllid, Diaphorina citri, transmits citrus greening, a bacterial disease that has decimated Florida’s citrus industry. Psyllid eggs and immatures are vulnerable to predation by generalist insect predators. However, specific recommendations for utilizing ambient predators to reduce psyllid populations in citrus groves are lacking. Integrating so-called ‘SNAP’ plants (shelter, nectar, alternate prey, and pollen) into citrus groves could be an effective means of attracting and sustaining predators to control D. citri. To identifying potential SNAP plants, the occurrence of adult coccinellids, which are key psyllid predators, was measured with sticky card traps and hand collections on 18 plant species grown in small plots. Test plants were primarily annuals that had extrafloral nectaries or shallow, open flowers that were accessible to predators. Beetle fecal pellets were examined to determine whether they consumed pollen and alternate prey from SNAP plants. Captures of = 3 beetles per trap per week occurred on coriander (Coriandrum sativum), cowpea (Vigna unguiculata), dill (Anethum graveolens), lima bean (Phaseolus lunatus), portulaca (Portulaca umbraticola), and field mustard (Guillenia flavescens). Beetle fecal pellets with the highest mean number of pollen grains were obtained from field mustard (Mean number of pollen grains/fecal pellet = 333.3) and coriander (x ¯ = 226) in February and March. The abundance of exoskeleton fragments in the frass pellets indicated that the beetles fed on alternate prey provided by the test plants. The results showed that certain umbels, legumes, and cover crops, functioned as SNAP plants and have potential for supporting coccinellids and other generalist predators in citrus groves.