other economic insects other economic insects lesser grain borer (rhyzopertha dominica) it belongs...

Other economic insectsOther economic insects

Lesser Grain Borer (Rhyzopertha dominica) It belongs to family Bostrychidae and order Coleoptera

- Hosts: stored cereal grain as the main hosts; may attack grain products such as flour & other foodstuffs. Pulse grain may be attacked

- Damage: punchuring and eating the grains & food material. Within grains, endosperm region is preferred so the attacked kernels (if not entirely consumed) not able to germinate. It is a

serious pest on stored grains & other food stuffs worldwide, a primary insect pest of stored grain by penetrating them causing serious damage.

- Biology of the insect: Eggs (200-250/female) are laid between the grains of produce or in cervices of store house. More eggs are laid at high temperatures. Hatching may occur in few days. Larvae (contain 3 larval instars) are white in color & parallel-sided with a small head & prominent thoracic legs. Larval development takes 17 days at 34 deg. C & 70% RH on wheat.

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Pupation takes place inside the damaged grain. Adults (2-3

mm) are dark cylindrical beetles with head hidden under a large

hooded tuberculate prothorax. Antennae are 10-segmented with a club shaped (enlargement of the last three segments). The elytra have rows of punctures on their surfaces. Apically, they are rounded but with no ornamentations. Adults are long lived & feed extensively & fly quite well. They are usually observed inside the infested grains together with the larvae. The complete life cycle takes 3-4 weeks at 34 deg. C & 70% RH.

- Distribution: It is basically tropical species but it is cosmopolitan throuhgout the warmer regions of the world & in heated stores in temperate regions.

- Control: Population monitoring for this pest is important for the control. This is done by sieving sampling as the adults & larvae tend to be sedentary & do not move much in the infestations. Fumigation using methyl bromide or sulfur dioxide or phosphine for the infested grain. Also, Pirimiphos-methyl & various

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Bean Bruchid (Acanthoscelides obtectus ) It belongs to family Bruchidae and order Coleoptera

- Hosts: Beans of various species & other pulse crops.

- Damage: The adult & larvae bore into grains & get inside so infested seeds have mature larvae or pupae inside. Infested seeds have a small window with an emergence hole (2 mm diameter) for the adult emergence. It is a serious pest of beans worldwide especially in tropical regions.

- Life History: Infestation with this pest starts in the field when the female oviposits on the ripening pods of beans & other legumes in the field. The tiny larvae are dirty white to pale yellow with a dark brown head, strong mandibles & rudimentary legs. They bore their way into the seed & feed inside. The presence of mature larvae or pupae can be recognized by a small circular windows on the bean seeds. The life cycle is completed inside the seeds & the adult beetles emerge by pushing the window which falls off leaving a hole (2 mm diameter) used by

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adult for going out. The number of eggs laid per female = 40-60 eggs. Total period for the life cycle = 4-6 weeks at 28 deg. C & 70% RH.

- Distribution: Widely distributed in Europe, Africa, New Zeraland, USA, Canada, Central and South America.

- Control: * Chemical control by mixing bean seeds with gamma- BHC dust or spraying them with Pyrethroids insecticides.

* Fumigation of bean seeds may be also effective.

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Green Stink or Vegetable Bug ( Nezara viridula) It belongs to the family: Pentatomidae & order: coleoptera

- Hosts: vegetables, legumes & cotton as main hosts; many other crops & ornamentals as alternative hosts. Polyphagous (recorded from 100 different host plants).

- Damage: Death of the attacked leaves & fruits due to the necrosis & spotting caused by feeding & effect of toxic saliva secreted by the bugs.

- Life History: Adults hibernate in winter time among vegetables in the cooler regions. They emerge in the spring to mate then lay eggs. Eggs are barrel-shaped (1.2 x 0.75 mm dimensions) & laid

in clusters under the leaves. Females lay 100-300 eggs / female. The nymphs are orange & brown in color (5 nymphal instars). The development of this type of bugs is generally slow: 6-10 weeks from egg laying to adult emergence. The threshol

temperature for the development = 20 deg. C & 3 generations / year are produced in the mediterranean region. Adults are large

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Major groups of PestsMajor groups of Pests

green bugs (15-18 mm long & 8-10 mm wide) but some of them are brownish rather than green in color (not common).

- Distribution: Cosmopolitan in warmer regions of the world (from south Europe & Japan to South Africa & Australia). Sometimes, it is serious & found regularly on a wide range of crops in the warmer part of the world.

- Control: *Biological control using the egg parasitoid Teleonemus basalis (Hymenoptera: Scelionidae). It was introduced into Australia to control this pest. *Chemical control is not often required but may be used if numbers are high such as using Phorate, Malathion, Dimethoate, Phosphamidon etc.


Citrus thrips (Scirtothrips aurantii )

It belongs to family: Thripidae & order: Thysanoptera

- Hosts: Citrus spp. as the main hosts; over 30 indigenous trees & shrubs were recorded as hosts in South Africa.

- Damage: A ring of scaly, brownish tissue around the stem end of the fruit. Irregular areas of scarred tissue on other parts of fruit. Young leaves may be damaged.

- Life History: Eggs are bean-shaped (< 0.2 mm long) and inserted

into the soft tissues of the leaves, stems and fruits. Hatching takes 1-2 weeks. Nymphs (2 nymphal instars) have yellow to orange color, cigar-shaped and just visible to the naked eye. They feed on young fruits from petal-fall until they are about 25 mm in diameter. Feeding takes place at the stem end, under & near the button. In the absence of suitable fruits, young leaves may be attacked. Nymphal period lasts 8-15 days. Fully-grown

nymphs then pass in pre-pupa & pupa (duration = 1-2 weeks). Adult thrips (< 1 mm long). Males are rare & reproduction is

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parthenogenetical. Adult females may live for several weeks.

- Distribution: a serious pest at low altitudes where an attempt to produce unblemished fruits is being made. It is Known in Africa, Egypt, Malawi, Sudan, East Africa, Zimbabwi and most common in South Africa.

- Control: Spray the fruits towards the end of a main flowering period when ¾ of the petals have fallen using a water solution of lime-sulfur. The spray should be repeated after 10 days.

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Onion thrips (Thrips tabaci; Fam.: Thripidae) It belong to family: Thripidae & order: Thysanoptera

- Hosts: Onion & Leek as the main hosts; Tobacco, Tomato,

Cotton, peas, beet & other crops as alternative hosts. A polyphagous pest on many crops

- Damage: the leaves of attacked plants are silvered & flecked. Heavy attacks lead to the wilting of young plants. On cotton seedlings, the damage is more serious causing leaf shedding. Onion leaves are often distorted & sometimes die when attack is heavy. Occasionally, entire crop may die. A vector of virus diseases on tobacco, tomato & other crops.

- Life history: Eggs are laid in notches in the epidermis of the leaves & stems of young plants. They are white & need 4-10 days for hatching. Both nymphs & adults rasp the epidermis of leaves & suck the sap that exudes. Nymphs molt 2 times in about 5 days, they are white or yellow. Pupation occurs in the soil &

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takes 4-7 days. The adults are small (1 mm long), yellow-brown in color with darker transverse bands across the thorax & abdomen. They live 3-11 weeks. One generation takes 3 weeks & several generations per year (5-10 in the tropics) are produced.

- Distribution: Cosmopolitan but only few records from West Africa. The range of existence is from Canada & Scandinavia to South Africa & New Zealand.

- Control: * using parasitic Hymenoptera (some species of Eulophidae); * Ploughing after crop harvest to kill pupae hiding in the soil & adults hiding in the leaf litter; * Chemical control by soil application of DDT or HCH OR GRANULAR INSECTICIDES AS Phorate or Euradan; * Foliar spays with Dimethoate or Fenitrothion to kill nymphs.

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Red palm weevil (Rhynchophorus ferrugineus )

It belongs to family Curculionidae & order Coleoptera

- Hosts: Date palm, Oil palm, Coconut as main hosts; Other species of Palmacae as alternative hosts.

- Damage: The feeding larvae bore in the crown of the palm & may destroy it. At the beginning of infestation, the outer leaves turn chlorotic & die then gradually spreads to the innermost leaves. Later, the trunk becomes tunnelled & weakened & may break.

- Life history: “eggs “are laid in the crown of the palm often in holes made by other insects or by man. Sometimes, females may actively search for cut petioles as oviposition sites. Each female lays 200-500 eggs & hatching takes place after 3 days. “Hatched larvae” are yellowish-white & legless with a reddish-brown head. Full-grown larvae have 5-6 cm long. They penetrate, at first, the crown then most parts of the upper trunk making tunnels of up to 1 m long. They are voracious feeders & the damaged tissues turn necrotic & then decay resulting in a characteristic

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unplea-sant odour. As the galleries become more extensive, the trunk weakens & may be easily broken or decapitated. The larval period lasts 2-4 months. “Pupation” takes place under the bark of infested trees and completely developed larvae are surround by a cocoon (80 x 35 mm dimension). Pupal stage lasts 14-28 days. “young adults “ remain in the cocoon for 8-14 days before emergence. “Emerged adults “ (30-35 mm long) are reddish-brown weevils with either spots or red stripe on the thorax.

- Distribution: in many Asian countries especially in Pakistan, India, Sri Lanka, South East Asia, China, Taiwan.

- Control: * Using cultural control methods (e.g. elimination of breeding sites by restricting physical injury to plants) to decrease the population size; * Recommended insecticides are Aldrin & Dieldrin applied to crowns & trunks of infested palms; *Injection of insecticides (Carbaryl) into the infested galleries.

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Citrus Leaf Miner (Phyllocnistis citrella) It belongs to family Phyllocnistidae & order Lepidoptera

- 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. 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

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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.

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Mediterranean Fruit Fly or Medfly (Ceratits capitata)

It belongs to family Tephritidae and order Diptera

- Hosts: Stone fruits such as peach, plum, nectarine etc., Citrus fruits as the main hosts; Subtropical fruits as guava, mango etc.

- Damage: a very serious pest of many subtropical & deciduous fruits. Eggs are laid inside the fruits & maggots bore through the fruit while feeding; often associated with fungal & bacterial rots; severely attacked fruits often fall.

- Life history or biology of the insect: 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

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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 rays then released in the field.

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Olive Fruit Fly (Dacus oleae ) It belong to family Tephritidae and order Homoptera

- Hosts: Olive (all varieties both cultivated & wild) as the main hosts.

- Damage: It is the most serious pest of olive in the mediter-ranean region & 30% of crop may be lost is common in this region. 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.

- Life History or biology of insect: 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 ovipositing

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on the same fruit. 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 where olive trees are cultivated. Also in Canary Island, Pakistan, Ethiopia, South Africa & South West Australia.

- 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

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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.

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