3.8 Caterpillars

Armyworms, cutworms, the strawberry leafroller, and saltmarsh caterpillars all feed on strawberry leaves and sometimes chew holes in fruit [3]. Cutworms will also feed on strawberry flowers. While armyworms, cutworms, and strawberry leafrollers are considered major strawberry pests, saltmarsh caterpillars rarely reach damaging levels.

on these areas [3, 7]. As with armyworms, young plants are especially vulnerable.

The strawberry leaf roller, Ancylis comptana (Frölich) is an occasional pest of strawberries in the United States [3, 18] The adults are small, reddish-brown moths

(Figure 10b) while later instar larvae are gray-brown with yellowish-brown heads. Early instar larvae feed on the underside of strawberry leaves near veins. They produce a silky covering for protection. They grow and eventually move to the top of the leaf and fold or roll leaf edges together. The rolled leaves protect them from predators and environmental factors. The caterpillars pupate in the leaf roll. Strawberries can tolerate 10–20% of their leaves being infested with leafrollers, so management is often unnecessary [3, 18]. Removal and destruction of infested leaves can prevent infestations from building up. If a spray is necessary, thorough cover-

Salt marsh caterpillars (Figure 11), Estigmene acrea (Drury), are the caterpillars of a species of tiger moth [17]. The adult moths are white with black spots with a pinkish to orangish abdomen that also has black spots. Female hind wings are white while male hind wings are yellowish to orangish in color. The caterpillars are

(Figure 10a). Early instar caterpillars are pale green with brown heads

Management of Strawberry Insect and Mite Pests in Greenhouse and Field Crops

DOI: http://dx.doi.org/10.5772/intechopen.82069

Strawberry leaf roller (a) adult and (b) caterpillar (photo credit J. Renkema, UF).

Later instar fall armyworm on velvet bean plant (photo credit: C. Scott, UF).

There are no established thresholds.

age is essential.

Figure 10.

111

Figure 9.

Armyworms, Noctuidae, are the caterpillars of brown, night flying moths [3, 7, 8, 17]. Eggs are laid in clusters and covered with scales from the female moth that laid them. Early instar larvae are light green with black head capsules and cluster together. The larvae become darker and develop white, vertical stripes that travel the length of the body as they mature (Figure 9). Armyworm larvae feed on the undersides of leaves. Early instar larvae leave the top layers of the leaf tissue intact while larger, later instar larvae consume all the leaf tissue and can quickly skeletonize leaves. Leaf injury can lead to a decrease in the quality and quantity of fruit produced. Armyworms can also cause direct injury by feeding on fruit. The fall armyworm, Spodoptera frugiperda (J.E. Smith) and southern armyworm, Spodoptera eridania (Stoll) are the species most commonly found on strawberries in Florida [8], whereas the beet armyworm, Spodoptera exigua (Hübner), is the main armyworm found in strawberries in California [7]. In California, beet armyworm adults are monitored using pheromone traps put out just prior to transplanting. If trap catches are high, the young strawberry plants should be examined for egg masses. It is important to time insecticide applications after egg hatch when larvae are early instars.

Cutworms are also the caterpillars of Noctuid moths [3, 17]. They can be a major pest in perennial strawberry systems. The caterpillars are smooth, like armyworms, and mottled brown or gray in color. The black cutworm, Agrotis ipsilon (Hufnagel), is the most common species causing damage in California [7]. Cutworms chew holes in leaves and cut stems. It is this stem cutting that gives them their common name. They will sometimes feed on flowers, which cause fruit to be deformed and unmarketable. Injury often occurs along field margins, so monitoring should focus

Management of Strawberry Insect and Mite Pests in Greenhouse and Field Crops DOI: http://dx.doi.org/10.5772/intechopen.82069

#### Figure 9.

important to properly identify any stink bug causing concern in strawberries to

Spittlebug protective frothy foam. The spittle bug nymphs are underneath the foam and cannot be seen (photo

Strawberry - Pre- and Post-Harvest Management Techniques for Higher Fruit Quality

Armyworms, cutworms, the strawberry leafroller, and saltmarsh caterpillars all feed on strawberry leaves and sometimes chew holes in fruit [3]. Cutworms will also feed on strawberry flowers. While armyworms, cutworms, and strawberry leafrollers are considered major strawberry pests, saltmarsh caterpillars rarely reach

Cutworms are also the caterpillars of Noctuid moths [3, 17]. They can be a major pest in perennial strawberry systems. The caterpillars are smooth, like armyworms, and mottled brown or gray in color. The black cutworm, Agrotis ipsilon (Hufnagel), is the most common species causing damage in California [7]. Cutworms chew holes in leaves and cut stems. It is this stem cutting that gives them their common name. They will sometimes feed on flowers, which cause fruit to be deformed and unmarketable. Injury often occurs along field margins, so monitoring should focus

Armyworms, Noctuidae, are the caterpillars of brown, night flying moths [3, 7, 8, 17]. Eggs are laid in clusters and covered with scales from the female moth that laid them. Early instar larvae are light green with black head capsules and cluster together. The larvae become darker and develop white, vertical stripes that travel the length of the body as they mature (Figure 9). Armyworm larvae feed on the undersides of leaves. Early instar larvae leave the top layers of the leaf tissue intact while larger, later instar larvae consume all the leaf tissue and can quickly skeletonize leaves. Leaf injury can lead to a decrease in the quality and quantity of fruit produced. Armyworms can also cause direct injury by feeding on fruit. The fall armyworm, Spodoptera frugiperda (J.E. Smith) and southern armyworm, Spodoptera eridania (Stoll) are the species most commonly found on strawberries in Florida [8], whereas the beet armyworm, Spodoptera exigua (Hübner), is the main armyworm found in strawberries in California [7]. In California, beet armyworm adults are monitored using pheromone traps put out just prior to transplanting. If trap catches are high, the young strawberry plants should be examined for egg masses. It is important to time insecticide applications after egg hatch when larvae are early

make sure it is not a beneficial predatory species.

3.8 Caterpillars

credit: E.M. Rhodes, UF).

Figure 8.

damaging levels.

instars.

110

Later instar fall armyworm on velvet bean plant (photo credit: C. Scott, UF).

on these areas [3, 7]. As with armyworms, young plants are especially vulnerable. There are no established thresholds.

The strawberry leaf roller, Ancylis comptana (Frölich) is an occasional pest of strawberries in the United States [3, 18] The adults are small, reddish-brown moths (Figure 10a). Early instar caterpillars are pale green with brown heads (Figure 10b) while later instar larvae are gray-brown with yellowish-brown heads. Early instar larvae feed on the underside of strawberry leaves near veins. They produce a silky covering for protection. They grow and eventually move to the top of the leaf and fold or roll leaf edges together. The rolled leaves protect them from predators and environmental factors. The caterpillars pupate in the leaf roll. Strawberries can tolerate 10–20% of their leaves being infested with leafrollers, so management is often unnecessary [3, 18]. Removal and destruction of infested leaves can prevent infestations from building up. If a spray is necessary, thorough coverage is essential.

Salt marsh caterpillars (Figure 11), Estigmene acrea (Drury), are the caterpillars of a species of tiger moth [17]. The adult moths are white with black spots with a pinkish to orangish abdomen that also has black spots. Female hind wings are white while male hind wings are yellowish to orangish in color. The caterpillars are

Figure 10. Strawberry leaf roller (a) adult and (b) caterpillar (photo credit J. Renkema, UF).

O. sulcatus Fabricius, are black flecked with yellow and larger at approximately 1.27 cm long [3, 7]. Adults of both species emerge in late spring and early summer and feed on leaves at night while sheltering near the base of plants during the daytime [3, 7]. They feed on the leaf margins, producing distinctive hook-shaped notches. Adults lay eggs in the fall and larvae feed on roots before burrowing deeper into the soil to overwinter. The larvae are legless, crescent shaped, creamy white to light pink grubs similar in size to the adults. As temperatures warm up in the spring, larvae again feed on roots before burrowing into plant crowns to pupate. Infested plants are dull and reddish, wilted, stunted, and extremely susceptible to stress. Injury in a field often occurs in a circular pattern. Adults emerge from these pupae

Management of Strawberry Insect and Mite Pests in Greenhouse and Field Crops

DOI: http://dx.doi.org/10.5772/intechopen.82069

Managing these weevil pests is difficult. Sanitizing farm equipment is important to avoid moving beetles from infested fields into fields that are not infested. Heavily infested fields should be plowed to prevent the spread of the weevil and repeated disking will continue to expose grubs to predation and weather. Soil fumigation after plowing is also effective. Two grubs per plant can cause economic damage, which makes for a low threshold [3, 7]. There are insecticides available to reduce the population of adults before they lay eggs, but efficacy is limited. Using nematodes that parasitize grubs in combination with insecticides to manage adults has shown some success. Steinernema feltiae (Filipjev) and Heterorhabditis bacteriophora (Poinar) are both commercially available and can be used in combination. Soil

The strawberry rootworm, Paria fragaria Wilcox, is the smallest of these beetle pests [3, 19]. Both adults and grubs are only 3.2 mm long. Adults are shiny and vary from brown in color with four black splotches to completely black. They chew holes in leaves and can skeletonize leaves when infestations are severe. Adults overwinter in sheltered places such as ground litter and become active as temperatures warm in the Spring. In the northern United States, high numbers can occur in May and June, though this is uncommon [19]. These adults lay eggs in the soil that hatch into grubs, which are milky white in color and have six legs. Larvae feed on roots, which can cause plants to be stunted, and then pupate in the soil. Adults emerge from these pupae in July and August. This second generation of adults will overwinter and begin the cycle again. Insecticide applications should be timed when adults are

White grubs, which are the larvae of Scarab beetles such as the June Beetle, Japanese Beetle, and Rose Chafer, can also be an issue in perennial strawberries [3, 20]. The grubs are C-shaped, milky white in color, have six legs, and vary in size depending on species. White grubs can grow as large as 2.5–3.8 cm long. They are a major pest of sod and can move into strawberry fields from adjacent grassy areas [3, 20]. June beetles lay their eggs in early summer. The larvae feed on roots and burrow deeper in the soil to overwinter. Larvae repeat this pattern for the next two seasons, pupating in the soil at the end of the 3rd summer. Most white grub adults have a similar 3-year life cycle [3, 20]. However, a few, like the Japanese beetle, have a 1-year life cycle. Fields planted to sod should be left fallow or planted to nonsusceptible hosts, such as squash and its relatives, for several seasons before strawberries are planted there [3, 20]. Prevention is key because grubs are difficult to

to begin the cycle again.

4.2 Strawberry rootworm

feeding [3, 19].

4.3 White grubs

control once they infest a field.

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should be moist when nematodes are released.

Figure 11. Later instar salt marsh caterpillar (photo credit: M. Lopez, UF).

covered in hairs that can be white, various shades of yellow and orange, and black. The early instars cluster together to feed and then disperse as they grow. Mature caterpillars can be 5 cm long and look even larger because of their hairs. Salt marsh caterpillars prefer grasses and rarely occur in large enough numbers in strawberry plantings to be of concern.
