Keep Coriander Aphids At Bay

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Coriander aphid  Photo by Charles Olsen

Photo by Charles Olsen

Crops Affected
The coriander aphid (Hyadaphis coriandri Das) is a pest of umbelliferous plants, including celery, parsley, coriander (cilantro), carrots, and dill.

Identification
The coriander aphid was recently detected in Immokalee, FL. This aphid is a newcomer to Florida, which was found for the first time in North America on fennel in Orange County, and subsequently on coriander and dill in Hillsborough County in 1998. It has been found sporadically in low numbers in Central and South Florida since that time.
Coriander aphids are yellow-green in color, dusted with greyish wax. They have short, dusky, slightly swollen siphunculi (or cornicles) that are about twice as long as wide. They form dense and often damaging colonies on leaves, heads, and stems of their host plants.
In Florida, several other aphid species occur with the coriander aphid. These include the green peach aphid and the rice root aphid. Both species have siphunculi that are much longer than twice their diameter. Rice root aphids live underground.

Survival And Spread
Coriander aphids are likely native to Central Asia. Distribution includes the Mediterranean area, Central and Southeast Asia, Africa, and California and Florida in the U.S. In its native lands, the life cycle of the coriander aphid is similar to that of other host-alternating aphids and is associated with winter hosts (Caprifoliaceae) and/or summer hosts (Umbelliferae). A fundatrix (or stem mother) hatches from an egg in the spring. Her offspring are parthenogenetic, winged-female spring migrants. They colonize summer host plants in the family Umbelliferae. During the summer, there can be many generations. All individuals are parthenogenetic females and may be either winged or wingless, depending on host plant quality and crowding in the colony. If the host plant quality declines, or the colony becomes crowded, winged individuals form that can establish colonies on new plants. In autumn, parthenogenetic female fall migrants occur in response to cooler temperatures and/or short days. These return to the winter hosts where they give birth to egg-laying females. Similarly, the summer colonies produce winged males in the fall. The males also return to the winter host plants where they mate with the egg-laying females to produce the overwintering eggs.

In Florida, the overwintering part of the life cycle probably will not occur. More likely, colonies of summer forms, both winged and wingless, will persist on Umbelliferae throughout the year. To date, the coriander aphid has only been found in Florida on umbelliferous plants previously mentioned. There are records of sporadic colonies on miscellaneous hosts including horsemint, spiny pigweed, and soybean.

Management Methods
Scouting is important to detect infestations. Softer pesticides including insecticidal soaps, neonicotinoids like Admire (imidacloprid, Bayer CropScience), Provado (imidacloprid, Bayer CropScience), Assail (acetamiprid, United Phosphorus Inc.) and other chemistries including Beleaf (flonicamid, FMC Corp.), Movento (spirotetramat, Bayer CropScience) and Fulfill (pymetrozine, Syngenta) will provide good control and help reduce impact on beneficials.
Check labels as available materials may be limited because many of the host plants of coriander aphids are minor crops.

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