VII) Order Diptera : It contains the following species of insect pests: 1) Mediterranean Fruit Fly or Medfly ( Ceratits capitata ; Fam: Tephritidae): - Hosts : Stone fruits such as peach, plum, nectarine etc., Citrus fruits as the main hosts; Subtropical fruits as guava, mango etc.
VII) Order Diptera: It contains the following species of insect pests:
1)Mediterranean Fruit Fly or Medfly (Ceratits capitata ; Fam: Tephritidae):
- Hosts: Stone fruits such as peach, plum, nectarine etc., Citrus fruits as the main hosts; Subtropical fruits as guava, mango etc.
- Damage: Eggs are laid inside the fruits & maggots bore through the fruit while feeding; often associated with fungal & bacterial rots; severely attacked fruits often fall.
- Pest status: a very serious pest of many subtropics & deciduous fruits. Many countries have legislation to control accidental introduction of this pest.
- Life history: Eggs are laid in groups, under the skin of the fruit by the female’s protrusible ovipositor; each female lays 200-500 eggs, incubation period = 2-3 days. The maggots bore through the pulp of the fruit as they feed & develop; they are white & typically muscoid in appearance. Typically, 10-12 maggots per fruit, but sometimes up to 100 have been recorded. The larval
instars take 10-14 days under warm conditions. Pupation takes place in the soil under the trees in a thin brown puparium because infested fruits fall when the larvae leave to pupate. Pupal period takes 14 days. The adult fly (5-6mm long) is brightly decorative with red/blue iridescent eyes & the body is blackish with yellow & white markings. Female flies sexually mature after 4-5 days of emergence & first eggs are laid at 8 days after emergence. Adult flies feed on sugary foods & may live for 5-6 months. Life cycle takes 30-40 days under warm conditions. 8-10 generations were produced per year.
- Distribution: essentially subtropical species but recorded throughout Southern Europe, Middle East, Africa, South Western Australia, Hawai & Central and South America.
- Control: *Collection & destruction of all infested fruits; *The maggots are can not be easily destroyed because they are inside fruits but some success is claimed for the systemic insecticide Fenthion; *Use of protein bait sprays (20 g protein solids + 10 g malathion per liter of solution) & sex attractants; *Sterile insect
release method (SIRM) where male flies can be sterilized using gamma raysthen released in the field.
2)Olive Fruit Fly (Dacus oleae ; Fam: Tephritidae):
- Hosts: Olive (all varieties both cultivated & wild) as the main hosts.
- Damage: infested fruits fall prematurely. Before falling, infested fruit become mottled with a hollowed interior inhabited by a white maggot. Early damage shown as slightly sunken brown necrotic spots. No damage on the stone of the fruit due infestation with the fly. Yield can be reduced as much as 80-90% & the oil produced from attacked fruits is inferior & has unpleasant flavor.
- Pest Status: It is the most serious pest of olive in the mediterranean region & 30% of crop may be lost is common in this region.
- Life History: The female fly lays a single egg on the young olives (about the size of pea grain). Usually one egg is laid per olive
fruit but if several maggots are found in one fruit, they come from eggs laid by different females. The egg is deposited under the skin of the fruit. Hatching takes 2-3 days. The larva (maggots) are ranging from 1 to 6 mm long according to their age. Larval development takes 10-15 days according to the temperature. During the summer, pupation takes place in fruits but the last generation maggots pupate in the soil under the tree where they overwinter at the depth of 5-10 cm. The adults (5 mm long) are small, dark-brown flies with hyaline wings aith a small dark terminal spot. Female flies have a prominent ovipositor. The complete life cycle takes 4 wks in summer & 3-4 generations /year are produced.
- Distribution: in the Mediterranean region, Canary Island, Pakistan, Egypt, Ethiopia & South Africa.
- Control: Owing to the site of oviposition under the fruit skin, only systemic insecticides are effective against the larvae (maggots) such as methyl parathion. In Greece, they control this insect using 4-12% protein hydrolysate bait sprays. These sprays also
contain malathion at a rate of 10 g /Liter. This viscous spray attract & kill the adults if sprayed onto plants.These sprays should be repeated (2-3 treatments per season).
* There are other types of fruit flies such as Oriental fruit fly (Dacus ferrugineus) on guava, mango, Citrus, Banana, avocado & papaya; Melon fly (Bactrocera cucurbitae ) on melon & other cucurbits.
1)Citrus Leaf Miner (Phyllocnistis citrella ; Fam: Phyllocnistidae):
- Hosts: Citrus species as the main hosts; Other members of family Rutaceae as alternative hosts.
- Damage: the feeding larvae make broad serpentine galleries (mines ) in the attacked leaves leaving a distinctive dark line of fecal pellets along the center of the tunnel. In young leaves, the lamina folds over & twist with a high degree of distortion. Badly damaged leaves dry out & are clearly of little use photosynthe-tically.
- Pest Status: In young plants, the damage can be very serious and important but on older plants, infestation levels may be occasional & less important except on young shoots.
- Life History: Eggs (flattened, oval and white) are laid singly near the midrib on the underneath of the leaf. Incubation for 3-4 days. Hatched larvae penetrate the epidermis & commences burrowing, eventually making a long serpentine convoluted mine
which is conspicuously silvery in color owing to the air trapped under the epidermis. Larval development usually takes 16-18 days & the mature larvae (3.5 mm long) are yellowish-white in color. Pupation takes place at the edge of the leaf & lamina margin is turned over to protect the pupa underneath. The adult is tiny moth (2-3 mm body lenthg with 5-8 mm wing span) with grayish-white color & black eyes & 4 black spines across each forewing but hind wings are feather-like. Total life cycle takes 3 weeks & there are 5 generations /year .
- Distribution: in South East Asia up to China, Korea, Japan, Philippines, Indonesia, North & north-East Australia. Also, in Easdt Africa (Sudan & Ethiopia.
- Control: Chemical control by spraying insecticides (e.g. Vertimec, Phosphamidon , Dimethoate) is the main control measure. The treatment should be repeated especially in spring & summer. Pruning of infested leaves, branches & shoots to reduce the infestation then burning them to avoid re-infestation.
2)Diamond Backmoth (Plutella xylostella ; Fam: Yponomeutidae):
- Hosts: crucifers crops of Brassica spp. as the main hosts; other cultivated & wild crucifers as the alternative hosts.
- Damage: 1st instar larvae mine the leaves entering from the underside but later instars also eat the lower epidermis making small “windows” in the leaf; after a while, the upper epidermis often ruptures so that a small hole results. If the infestation is heavy, the entire plant is devastated.
- Pest Status: a very common & wide spread pest of cruciferae. It is often serious especially in some of the warmer parts of the world (the attack is severe at hot dry weather).
- Life history: Tiny yellow eggs of the insect are laid on the upper surface of the leaves (singly or in small groups). Hatching takes place after 3-8 days. Each female lays 50-150 eggs. Hatched larvae (caterpillar-like) are pale green with a tapering body (widest in the middle). Head is black when hatched but turns paler yellow when mature. Mature larvae may reach 12 mm. If
disturbed, the larvae wriggle violently & may drop off the leaf suspended by a silken thread. Larval development takes 14-28 days. Pupation takes place in a gauzy silken cocoon (9 mm long) stuck to the plant foliage & pupal development takes 5-10 days under warm conditions. The adults (6 mm body length & 15 mm wing span) are small gray moth with three pale triangular marks on the hind margin of each fore wings & when the wings are closed, the marks form a diamond pattern indicating the common name of the insect. The adult moth lives for 2 weeks. 2-3 generations per year in British Columbia (cold region) but 15 generations /year were recorded in lowland Malaysia (warm region). The life-cycle takes 12-15 days in warmer regions.
- Distribution: Cosmoplitan in distribution. They are found in cold, temperate & warmer regions of the world.
- Control: In many parts of the world, this insect pest has develo-ped resistance to the usual insecticides so alternating insecti-cides or searching for alternative control methods is sought such as using biological control with parasitoids (e.g. Diadegma
semiclausum ) or biological control using entomopathogenic fungi (e.g. Beauveria bassiana & Metarhizium anisopliae) on the larvae of this insect.
3)Potato tuber moth (Phthorimea operculella ; Fam: Gelechiidae):
- Hosts: Potato & tobacco as the main hosts; Tomato, Eggplant & other solanaceous crops as alternative hosts.
- Damage: The leaves have silver blotches caused by the young larvae mining in the leaves. Leaf veins, petioles & stems are tunnelled followed by wilting of plants. Eventually the tubers are bored by the larger caterpillars & they often become infected with fungi & bacteria.
- Pest status: an important pest of potato in warmer countries. Infestation arising in the field & continuing during storage of the tubers. There is a serious risk of transportation from one country to another through infested tubers.
- Life history: The egg (0.5 x 0.4 mm) is minute & oval and yellow in color. They are laid singly on the underside of the leaf or on tubers (usually in the storage) near the eye or on the sprout. Number of eggs laid per female = 150-250. Incubation period 3-15 days. 1st instar larvae bore into the leaf where they make
mines. Larvae are pale-greenish. They gradually eat their way into the leaf veins and into the petioles then gradually down the stem & sometimes into the tubers. The full-grown larvae reach 9-11 mm long & larval development is completed in 9-33 days according to the temperature. Pupation is taking place in a cocoon in the surface litter or in the tuber (duration = 6-26 days). Adult moth is small (wing span = 15 mm). One generation takes 3-4 weeks & up to 12 generations /year may be produced.
- Distribution: almost completely cosmopolitan but with limited records from Asia & none from West Africa.
- Control: Effective insecticides as sprays may be applied as DDT, Dicroto-phos, Dinethoate & Parathion. Preventive sprays every 14 days following the 1st mine on the leaves. In stores, the application of Permethrin, Deltamethrin & Phosphine give good control. Pheromone traps in the field give good control.
- Hosts: polyphsgous especially on the seedlings of most crops
such as cotton, rice, potato, tobacco, cereals & crucifers.
- Damage: The young larvae feed on the leaves of many crops. The older larvae (caterpillars) feed on the bases of crop plants or on the roots or stems underground. One caterpillar may destroy a number of seedlings in this manner in a single night.
- Pest Status: A cosmopolitan pest of sporadic importance on many crops in different parts of the world.
- Life history: Eggs (0.5 mm diameter) are white & globular. Egg hatching takes place 2-9 days. Each female may lay high number reaching at 1800 eggs. The larvae are brownish above with a broad pale gray band along the mid-line & with gray-green sides with lateral blackish stripes. The head is brownish-black with 2 white spots. The general appearance of the larvae (caterpillar) is blackish & full-grown larvae have 25-35 mm long. Larval development takes 28-34 days. The first two instars feed on the
foliage of the plant but the 3rd instar hides in the soil & become canibalistic. The pupae are dark-brown (20 mm long) & takes 10-30 days before giving the adults. Adult moths are large noctuids (40-50 mm wing span) with gray body & gray forewings with dark brownish-black markings. The hind wings are almost white basically but with a dark terminal fringe. The life cycle takes 32 days at 30 deg. C, 41 days at 26 deg. C & 67 days at 20 deg. C
- Distribution: Almost completely cosmopolitan from northern Europe, Canada, Japan down to New Zealand, South Africa & South America.
- Control: *Cultural control by weed destruction, hand collection & deep ploughing (to bring larvae & pupae to soil surface). *Chemical control by spraying infested plants & soil around with effective insecticides (DDT, Chlorpyrifos, Cypermethrin or Fenitrothion). *Soil application of Bromophos or Chlorpyriphos granules. *Application of poison baits containing bran + DDT or Lindane or Endrin. These baits are to be spread on the soil around infested plants.