Apricot Insect Pests

Flat headed borers

Biology

Flat headed borers overwinter as larvae inside the tree, and emerge as adult beetles in June-August (India). Adults lay eggs on bark crevices and the newly hatched larvae immediately bore through the bark to feed in the phloem layer.

Life Cycle

Damage symptoms

• Flat headed borers are attracted to diseased or injured limbs of trees, such as those affected by sunburn, scale insects, bacterial canker, or major pruning cuts.
• The beetles lay eggs in the injured area. Eggs hatch and the larvae excavate large caverns just beneath the bark and bore tunnels deep into the heartwood of the tree.
• Excavations are usually filled with finely powdered sawdust. Injury by this borer will cause the sap to flow, and the affected area will appear as a wet spot on the bark. Later, these areas may crack and expose the mines.
• Feeding by flat headed borers may cause a portion of the bark on older trees to die, or it may girdle and kill young trees. This borer can be particularly damaging to new grafts in established orchards.

Hairy caterpillar

Hairy caterpillar populations will go through cycles in which the populations will increase for several years then decline, and then increase again. Area-wide outbreaks can occur for up to ten years, but generally population densities in localized areas remain high for two to three years.

Biology

• Egg: The eggs are covered with a dense mass of tan or buff-colored hairs. The egg mass is approximately 1.5 inches long and 0.75 inches wide. The eggs are the overwintering stage of the insect. Eggs are attached to trees, houses, or any outdoor objects. The eggs hatch in spring (April) into caterpillars.
• Larva: Hairy caterpillars are easy to identify, because they possess characteristics not found on other leaf-feeding caterpillars. They have five pairs of blue dots followed by six pairs of red dots lining on the back side. In addition, they are dark-colored and covered with hairs. Young caterpillars primarily feed during the day whereas the older caterpillars feed at night. When present in large numbers, the older caterpillars feed day and night. Young caterpillars spread to new locations by crawling to the tops of trees, where they spin a silken thread and are caught on wind currents. Older caterpillars are approximately 1.5 to 2.0 inches long. Larval period 66- 100 days.
• Pupa: In early summer (June to early July), hairy caterpillars enter a pupal or transitional stage. The pupae are dark brown, shell-like cases approximately two inches long and covered with hairs. They are primarily located in sheltered areas such as tree bark crevices or leaf litter.
• Adult: Adult moths emerge from the pupae in 10 to 14 days. Females have white to cream colored wings, a tan body, and a two-inch wingspan. Female moths cannot fly. Females lay between 500 to1,000 eggs in sheltered areas such as underneath the bark of trees. Males, which are smaller than females, with a 1.5-inch wingspan, are dark-brown and have feathery antennae. Both the adult female and male can be identified by the inverted V-shape that points to a dot on the wings. Moth has only one generation per year.

Damage symptoms

• Caterpillars are gregarious and voracious feeder.
• They eat voraciously on leaves at night time.
• Under heavy infestation entire leaf eaten sparing only hard vein.
• Defoliation of host completely results in failure of fruit formation.

Natural enemies of hairy caterpillar

Parasitoids :Telenomus sp, Cotesia melanoscela, Glyptapantelos sp, Tachinid (Pales sp), Brachymeria sp

Defoliating beetles

Biology

• Egg: Females lay eggs (app. 60) in June and the eggs develop into larvae after 12 days and are especially attracted to compost and manure piles. The eggs are whitish in appearance and be easily found over the soil.
• Larva: They have head and legs. They live on soil surface and have a length of 2 inches. Their life includes three instars of which first and second get completed by autumn and the final in the spring season of second year. At rest they curl into C shape. When the larvae get matured they become 2 inches long and become cream coloured. The body of larvae is stiff with brown hairs at the back of the thorax. These hairs are used for locomotion. They form hollow cells in the soil and pupate there.
• Pupa: After a few days it reaches a size of 12-50 mm. They develop by June- July. Its duration extends from 25-27 days. The pupae are of size 15 X 25 mm. They are whitish at initial stages and further change to cream coloured as that of larvae stage. At the maturing stages they slightly shift the colour to green.
• Adult: They develop by June- November. They lay their eggs in soil. They are white coloured and large sized approximately range about 12-50 mm in size. They feed on organic matter in soil surfaces. Adults are velvet green in colour. They occupy brownish bands around the edge of the wings and a bright metallic green at the ventral side. Adult females are 17 X 25 mm and adult males are 13 X 22 mm size. At the head portion they are equipped with horn like projections for penetrating into the fruit skin. Adults are tremendous fliers.

Damage symptom

• The plant part affected mainly includes flower parts like pollen, nectar and petals, fruit and larvae damage roots.

Leaf curling aphid

Biology

• It overwinters as an egg, hatches in the spring, feed in opening buds
• Both winged and wingless forms breed parthenogenetically.
• The nymphal period lasts for 7-9 days.
• Adults live for 2-3 weeks and produce 8-22 nymphs per day. Entire life cycle takes 22-25 days. It has 12-14 generations per year depending on weather condition.

Damage symptoms

• Damage is severe because the aphid colonizes young shoots, buds, grafts and young plants.
• Nymphs and adults suck the sap from leaves, shoots and fruits
• It causes tightly curled leaves
• Wilting of terminal shoots and can stunt tree growth

Favourable conditions

• Spring-time attacks are the most deleterious.

Natural enemies of leaf curling aphid

Predator: Scymnus sp, Chilomenes sexmaculatus, Chrysoperla zastrow sillemi, coccinellids, Predatory mite and parasitic wasps

Brown apricot scale

Biology

• Egg: The eggs are pink to dark red and they are laid under the adult female scale’s wax covering.
• Nymph: The first instars are called crawlers. Crawlers are pink andas soon as they hatch, the first instars disperse, find a suitable feeding place and settle. The wax scale females develop through the second and third instars before becoming adults. The wax covering secreted around them gives them a star-like appearance. Nymphs are found on the leaves and twigs.
• Adult: The adult scales are elliptical, reddish brown with short anal process. The adult female is coated with a thick layer of pinkish-white wax. Inside the wax, the body of the adult female is reddish. Adults are mostly found on twigs and branches. The size of the female is about 2 to 4 mm in length and 1 to 3.5 mm in width. Males are not known in this species.

Damage symptoms

The direct damage is caused by insertion of stylets into during feeding by the nymphs, which can cause premature leaf drop and twig dieback. High populations can cause host death. Severe infestations may result in shoot or branch dieback When large populations of scale occur, sooty mold may become a problem due to the mold’s growth on the large quantities of honeydew excreted by these scales

Natural enemies of brown apricot scale

Predator: Coccinellids

San Jose scale

Pest of 700 different species of fruits, shrubs and ornamental plants. Pest is active from March to December. Passes winter black cap stage in tree bark.

Biology

• Nymph: Female San Jose scales give birth to living young ones that emerge from under the edge of the scale covering. Each female gives birth to 200-400 nymphs. These tiny yellow crawlers wander in a random fashion until they find a suitable place to settle. Immediately upon settling, the crawlers insert their mouth parts into the host plant and begin feeding and secreting a white waxy material (white cap stage); eventually the waxy covering turns black and is known as the black cap stage. Later the covers turn various shades from gray to black.
• Adult: Immature male and female scales are indistinguishable until the first molt. At this time, the male scale covering begins to elongate, while the females remain circular. Males molt a total of four times. Following the final molt, adult male scales emerge from the scale covering as tiny, yellow winged insects. They mate with the females who remain under the scale covering. Female insect body covered with grey scales. Yellow lemon coloured female is visible when covering is lifted. Female scales are very prolific and over a 6-week period can produce approximately 400 young. San Jose scale produce living young ones called crawlers; most other scales produce eggs. Crawlers move around for a short period in search of a suitable place to settle. It takes 25 days two instars for males to mature and 31 days four nymphal instars for females Five to six generations in a year.

Life cycle

Damage symptoms

• Nymph and female scales attack all above ground parts.
• Feeding site turns into a characteristic purplish red colour.
• Initially growth of plant is checked but as scale increases in number plant may die.
• Fruits will have distinct “measles” spots on the surface.

Natural enemies of San Jose scale

• Parasitoids: Encarsia perniclosi, Aphytis diaspidis
• Predators: Coccinellid, Pharoscymnus flexibilis and Chilocorus bijugus

Tent caterpillar

Biology

• Egg: In late spring or early summer, female moths deposit an egg mass encircling small twigs or on tree trunks. Egg masses are present on trees during most of the summer, fall and winter. The adult moth uses a sticky, frothy substance called spumaline as an adhesive to attach eggs to bark or twigs. Spumaline is used as a hard protective covering around the egg mass. Pest inactive from March – May, passes 9 month of year in egg stage. Female lays the eggs in broad bands consisting of 200 to 400 eggs.
• Larva: Caterpillars hatch from the eggs in early spring about the time host plants leaf out. The tent caterpillar feed on new leaves, forming small webs within a few days after hatching and enlarging the webs as they grow. The web or tent is most often in a crotch of small limbs, and serves as a refuge for the larvae during the night and during rainy spells. Larvae move from the tents to feed on leaves, so damage can be found for some distance around the web. Tent caterpillars feed in groups, and thus concentrate their defoliation. The tent caterpillars form conspicuous, large webs that are easily recognized. Molting, or skin shedding, occurs several times as the larvae grow. The larvae do not live in these small webs at other times.
• Pupa: During the last stage of larval development, which occurs in late spring, larvae wander considerable distances and may feed on a variety of tree, shrubs and even herbs before finding a site for pupation, or cocoon spinning. Cocoons are formed in the web, under bark, in dead plant material on the ground, or inside a rolled leaf. Cocoons are loosely constructed of silk and have a white or yellowish crystalline substance scattered throughout the mass. Cocoons should not be handled since the crystalline substance may cause skin irritation, especially to people with allergies.
• Adult: Adult tent caterpillars are brown and yellowish moths with two diagonal markings on the front wings. Caterpillar is progeny of a light reddish brown moth with two whitish stripes running across each of the forewings.Their wingspread is about 1 inch. They are attracted to lights and can occasionally be very abundant. The moths live for only a few days, during which they mate and lay eggs. Adults do not feed. There is only one generation of tent caterpillars per year. Males are short lived and female may survive for 2 to 5 days.

Damage symptoms

• Caterpillars during the night rest at their nest and the day feeding on leaves.
• In severe infestation, the entire plant may be defoliated and subsequently the caterpillar may feed on bark of twigs.
• When severe infestation, 40 -50 percent plants in orchard may be defoliated producing a poor harvest.

Parasitoid: Tachnid fly

Blossom thrips

Biology

• Egg: The eggs of thrips are deposited within plant tissues singly.
• Larva and pupa: Larvae have two stages, which feed on plant tissues. The second instar larvae, when mature, fall to ground, where they molt to prepupae and pupae in the soil.
• Adult: After emergence, the adults move to the growing parts of the plants such as young leaves, flowers, or young fruits, where they feed and lay eggs (about 200 eggs per female). Adults are usually found on young leaves, while larvae are found on lower or older leaves. At 25°C, the life cycle is completed in approximately 17 days. Adults are winged sucking rasping insects ranging from 5-14 mm in length. Their slender bodies are shiny pale or black with silver stripes. Life cycle completed in 11-43 days. Produce many generations in a year heaviest damage occur in spring. In colder region, life cycle is longer with fewer generations.

Damage symptoms

• Most species of plant feeding thrips, have piercing and sucking mouth parts. Both nymphs adults lacerate all floral parts and delicate and unfolding of leaves of vegetative buds. Consequently brown spots develops
• The surface of the leaf develops a crinkled silvery appearance as a result of damage to cells below the surface.
• Lightly-infested plants show silvery feeding scars on the under surface of leaves, especially alongside the mid rib and veins
• Heavily-infested plants show silvering and browning of leaves, stunting of young leaves and terminal growth, with fruit scarred and deformed.
• Developing leaves become distorced in the growing tips.
• Heavily infested flowers bears sticky and faded appearance with indication of early senescence.

Natural enemies of blossom thrips

Predators: Coccinellid, predatory thrips, anthocorid bug, Tropidothorax leucopterus(Lygaeid bug)

Codling moth

The rate of development will vary with temperature, proceeding more rapidly in warmer weather and climates. Depending on the climate, codling moth can have two, three, and sometimes four generations per year.

Biology

• Egg: Eggs are deposited singly on apricot and leaves. Each egg is about the size of a pin head and is translucent, gradually darkening as the egg nears hatching (Figure 6). Eggs hatch in six to 14 days, depending on temperature. Within 24 hours of hatching the larvae burrow into the fruit. The first instar larvae have a pink body with a black head and are approximately 1/10 inch in length. The number of eggs laid per female ranges from 30 to 70.
• Larva: After the eggs hatch, young larvae seek out and bore into fruit or developing nuts. Codling moth overwinters as full-grown larvae within thick, silken cocoons under loose scales of bark and in soil or debris around the base of the tree. Larvae appears to be cannibalistics. Full grown larva pinkish or creamy white with brown head and pupates in the soil litter.
• Pupa: After completing development they leave the fruit and drop from the trees to search out pupation sites and continue the life cycle in the soil or on debris under the tree; some crawl back up the tree to pupate in bark crevices. The larvae pupate inside their cocoons in early spring and emerge as adult moths mid-March to early April. The moths are active only a few hours before and after sunset, and they mate when sunset temperatures exceed 62°F.
• Adult: Adults are about 1/2 to 3/4 inch long with mottled gray wings that they hold tent like over their bodies. Their appearance blends well with most tree bark, making them difficult to detect. If you are trapping the adults, you can distinguish codling moth from other moths by the dark, coppery brown band at the tip of their wings. Adult forewings are dark grayish with waxy lines with a copper colored eye like circle toward margin.

Life cycle

Damage symptom

• It is a direct pest and hence causes severe damage to the fruit.
• Neonate larva enters the fruit through calyx and feeds on seed.
• Infested fruits lose their shape and fall prematurely.

Natural enemies of codling moth

• Parasitoid: Trichogramma embryophagum, T. caeoeciaepallidum
• Predators: Parus major, Passer domesticus, birds

IPM for Apricot

To know the IPM practices for Apricot, click here.

Source : NIPHM; Directorate of Plant Protection, Quarantine & Storage