Spodoptera eridania
(southern armyworm)

Spodoptera eridania is a polyphagous generalist feeder recorded on 200 plants species belonging to 58 botanic families. It is native to the USA and occurs throughout southern USA, Central and South America, and the Caribbean (Pogue, 2002). Due the fact that S. eridania occurs all across the USA and is present in many host plants, several regions around the world are in risk of invasion due to the global trade of vegetables, ornamental and aromatic plants, which can transport larvae and eggs. Even though it is not established in Europe, it has been detected on imported plants from the New World (Karsholt, 1994). The detection of S. eridania in Africa, demonstrates its high dispersal ability, indicating the importance of closely monitoring this species.

Spodoptera eridania occurs throughout southern USA, Central and South America, and the Caribbean (Pogue, 2002). Although it is not established in Europe, S. eridania is commonly recorded as an accidental introduction from the New World, for example, in Denmark (Karsholt, 1994).

The distribution map incudes records based on specimens of S. eridania from the collection in the Natural History Museum (BMNH, London, UK).

A record of S. eridania in Guernsey (CABI/EPPO, 2006) published in previous versions of the Compendium was erroneous. Guernsey is not included in the list of countries for S. eridania in CABI/EPPO (2006).

Spodoptera eridania is now classed as an EPPO A1 list of quarantine pests, but it is not listed as a quarantine pest by any other regional plant protection organization. As a subtropical species, it is most likely to become established in southern Europe. In the New World it is not especially recorded as a glasshouse pest, but it could become so in Europe. S. eridania occurs very regularly in Europe on imported plant produce from the New World. S. eridania is commonly intercepted in Europe on plants and tomato fruit (Seymour, 1978; EUROPHYT).

S. eridania is a polyphagous generalist feeder recorded on more than 200 plant species belonging to 58 families, mainly including Asteraceae, Fabaceae, Solanaceae, Poaceae, Amaranthaceae and Malvaceae (Montezano et al., 2014). Crops damaged include aubergines, species of Beta and Capsicum, cassava, cotton, several members of the Brassicaceae, a wide range of legumes, maize and other Poaceae, potatoes, sweet potatoes, tobacco, tomatoes, yams, and many pot plants and vegetables.

Many potential crop hosts are available in Europe, especially those more commonly grown in the southern part of the region. Sugarbeet and field tomatoes could be especially vulnerable, as well as a wide range of vegetables and flowers, including those grown in glasshouses.

One female can oviposit 1500-3000 eggs over its lifetime. Eggs are laid in large batches on the leaves of the host plant, protected by a layer of grey bristles from the female abdomen. Observations made at 20-25°C using different host plants and artificial diets show that the incubation period of S. eridania is invariable and lasts 4 days (Chittenden and Russel, 1909; Valverde and Sarmiento, 1987; Mattana and Foerster, 1988; Montezano et al., 2014). Larvae, as with some other Noctuidae, are gregarious and remain together on the leaf for the first two instars, resulting in leaf skeletonization. The third-instar larvae disperse and become more solitary and nocturnal. During the day they hide in the leaf litter or plant foliage, and emerge to feed on the leaves at night. Larval development usually takes 14-21 days and undergoes six and, rarely, seven instars. As with other Noctuidae, the rate of larval development is affected by the quality of diet and prevailing temperatures; the latter also affects the adult condition. Larvae sometimes swarm and migrate to adjacent fields when food is scarce. Occasionally, large larvae have been recorded acting as cutworms.

Pupation takes place in the soil in a weak earthen cell and typically requires 9-12 days. Adults are nocturnal in habit.

S. eridania is essentially a subtropical species and so a temperature of 20-25°C is optimum for development, and breeding may be continuous. The life-cycle can be completed in 28-30 days, but up to 40 days is common. There are several to many generations per year, the number depending on local conditions. Experiments in Brazil by Foerster and Dionizio (1989) showed that development at temperatures of 17 (115 days) and 30°C (33 days) was retarded. At 30°C, pupae weighed less and survival rates were lower.

The sex pheromone produced by female moths has been described, comprising of (Z)-9-tetradecenyl acetate (59.7%), (Z,E)-9,12-tetradecadienyl acetate (23.8%), (Z)-9-tetradecenol (8.4%), (Z)-11-hexadecenyl acetate (5.1%), (Z,Z)-9,12-tetradecadienyl acetate (3%) and (Z,E)-9,11-tetradecadienyl acetate (trace).

Numerous parasitic wasps from the Hymenoptera family and true flies from the Tachinidae family are of importance for natural control in the field. King and Saunders (1984) list important species on Caribbean Islands. Biological control was attempted on a number of Commonwealth Caribbean islands, resulting in the establishment of Telenomus remus (Cock, 1985).

Adults of S. eridania can be confused with some European Hadeninae and Cuculliinae, especially some species of Cucullia, but these latter moths usually do not have hindwings with translucent white colouration. The forewing margin of S. eridania is also squarer and less oblique than those of Cuculliinae, which have more slender, elongate and pointed wings than species of Spodoptera.

An EPPO standard provides guidance for the identification of S. littoralis, S. litura, S. frugiperda and S. eridania (OEPP/EPPO, 2015).

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Chemical Control

As S. eridania is often only a minor pest, control is only occasionally required. Insecticidal sprays are the usual means of killing the larvae on the plant foliage when damage is seen. Insecticides recommended for Helicoverpa control can be used for S. eridania: suitable chemicals are listed by COPR (1983) and King and Saunders (1984).

Phytosanitary measures

Plants used for production should come from locations found free from the pest during the previous 3 months. Certain types of plants (for example, cuttings) may be treated by being held at low temperatures <1.7°C) for 2-4 days, followed by fumigation.

09/10/2019 Review by:

Debora Montezano, Department of Entomology, University of Nebraska at Lincoln, Nebraska, USA

Alexandre Specht, EMBRAPA Cerrados, Planaltina, DF, Brazil