**3. Groundnuts**

Groundnuts contain seeds of:

*Arachis villosulicarpa* Hoehne: known as groundnut; cultivated in some states of Brazil.

*Vigna subterranea* L.: known as Bambara groundnut; originated in West Africa and a traditional food plant in Africa.

*Macrotyloma geocarpum* Harms: known as geocarpa groundnut, Hausa groundnut, or Kersting's groundnut, in Sub-Saharan Africa.

*Arachis hypogaea* L.: known as peanut, earthnuts, ground nuts, goober peas, monkey nuts, pygmy nuts and pig nuts. About 41.5% of world production is in China, 18.2% in India and 6.8% in the United States of America.

Also, roots and: *Apios americana* Medik.: known as potato bean, hopniss, Indian potato or groundnut, native to eastern North America.

*Conopodium majus* Gouan: known as kippernut, cipernut, arnut, jarnut, hawknut, earth chestnut, groundnut, and earthnut, native to Europe and parts of North Africa.

*Panax* spp*.:* is in parts of north America and eastern Asia (Wikipedia, 2010).

A few of the insect pests that cause economic losses to groundnut are introduced here:

#### **3.1** *Tetranychus cinnabarinus* **(Bois.) (Acari: Tetranychidae)**

**Identification:** females are reddish, and more or less elliptical. The males are slightly smaller and wedge shaped. They have a black spot on either side of their relatively colorless bodies. Eggs are spherical, shiny, straw colored. Larvae are slightly larger than the egg, pinkish, and have three pairs of legs. They have two nymphal stages, the protonymph and deutonymph. The nymphal stage differs from the larval stage by being slightly larger, reddish or greenish, and having 4 pairs of legs (Mau & Kessing, 2007a).

**Life cycle and damage:** the females lay eggs singly on the underside of the leaf or attached to the silken webs spun which hatch in 3 days. The larval stage lasts a short time, perhaps a day and afterward formed the nymphs. Nymphal stage lasts about 4 days. Spider mites feed on the underside of the uppermost leaves. They can be very serious pests during extended dry periods (Mau & Kessing, 2007a). Resistance of peanut, and wild species of *Arachis* has been declared to the two spotted spider mite in the USA (Lynch, 1990).

**Monitoring:** monitor for areas of light colored (chlorotic) plants, especially along field edges. Look under the top leaves to see if mites are present (Linker et al., n.d.).

**Economic and action thresholds:** No threshold has been set for mites (Linker et al., n.d.).

**Control:** mites quickly resist to pesticide so consult with county Cooperative Service Extension agent which pesticides are associated with mite problems.

Oilseed Pests 133

**Monitoring:** Colored sticky traps or water traps are useful for monitoring thrips. The color spectrum of sticky traps influenced their efficacy. Blue, yellow or white colors are used

**Economic and action thresholds:** economic threshold level is when 25% of the leaves are damaged and live thrips are found in the field or 5 thrips per terminal shoot (Bhubaneswar,

**Control**: Spraying Monochrotophos 36 WSC, Dimethoate 30 EC, Methyldemeton 25 EC, or Monocrotophos 320 ml mixed with neem oil, 1 lit and 1 kg soap powder mixed in 200 lit of water twice at 10 days interval can be effective against thrips infestations (TNAU, n.d.-c).

**Identification:** *A. craccivora* is known as groundnut aphid or cowpea aphid. The adult is about 2 mm long, pear shaped, green greenish brown or greenish black in color. The nymphs are dark brown and turns to shiny dark. Adults are mostly wingless but few

**Life cycle and damage**: Both nymphs and adults feed on the growing tips, tender foliage, flowers and growing pegs causing stunting and distortion of the foliage and stems. They excrete honeydew on which sooty molds develop. Aphids are also known to transmit peanut stripe virus and groundnut rosette virus complex. They have 12-14 generations per year (TIFP, n.d.-a). In the USA Peanut and its wild species show resistance to the groundnut aphid (Lynch, 1990). Bottenberg & Subrahmanyam (1997) stated that aphids in central Malawi were first recorded when the crop was at the flowering stage, but after 2 weeks the

**Monitoring:** monitoring should be done during seedling, flowering and pegging stages of the crop. Monitor undersides of the leaves and yellow traps can use for monitoring aphids. **Economic and action thresholds:** on average recorded in 1986, *A. craccivora* was of economic importance with economic threshold of 22.3 aphids per plant. However, the economic damage of aphids varies with the stage of plant, with most damage caused if aphids infest

**Control**: releasing *Cheilomenes sexmaculata* (F.) or other biological control agents such as flower bugs (Anthocorids), and etc. would be effective in controlling aphids (Jasani, 2009).

**Identification:** Pod borer adults are dark brown to black with forceps like caudal cerci and white leg joints. Nymphs are white in early stages and later turns brown (TNAU, n.d.-c).

**Life cycle and damage: y**oung pods showing bore holes plugged with excreta. Sand particles or discolored pulps is also observed and the pods lose their kernel (TNAU, n.d.-c). **Monitoring:** monitoring can be accomplished with wheat bran or oat meal baits or traps. Likewise, traps take advantage of the natural tendency of earwigs to hide in crevices and can be used to detect presence of earwigs, and to estimate abundance (Capinera, 2009).

**Economic and action thresholds:** No action threshold has been set for pod borers.

especially and it seems bright colors attract more thrips than darker ones.

population of aphids decreased and the infestation ranged from 6 to 32%.

the growing points of groundnut early in the plant's development (CABI, 2011).

**3.5** *Anisolabis stalli* **(Dohrn) (Dermaptera: Forficulidae)** 

**3.4** *Aphis craccivora* **(Koch) (Homoptera: Aphididae)** 

winged forms also seen (TIFP, n.d.-a).

2008; Linker et al., n.d.).

#### **3.2** *Balclutha hortensis* **(Lindberg) and** *Empoasca kerri* **(Pruthi) (Homoptera Cicadellidae)**

**Identification:** *B. hortensis* adults are small and have a well developed appendix on the tegmen. Most species of *Balclutha* genus are green coloured although some of them are pink or red (NSW, 2001). *E. kerri* adults are yellowish green in color, wedge shaped and walked diagonally in a characteristic manner (Khanpara, 2011).

**Life cycle and damage**: the females insert eggs into the leaf tissue close to the midrib or into the petiole. The eggs hatch in a week and in 10 days nymphs change to the adult form. The nymphal stage passed through five instars. Both nymphs and adults suck sap from central surface of leaves; inject toxins resulting in whitening of veins and chlorotic patches especially at the tips of leaflets. This type of feeding cause 'V' shaped yellowing. Heavily attacked crops look yellow and give a scorched appearance known as 'hopper burn'. Also, stunting of crop growth is observed where they are endemic. life cycle is about 18-30 days in the case of male, while it is 20-34 days for female at an average temperature of 31.30±1.96°C and 73.96±3.02% r.h. (Ghewande & Nandagop, 1997; Khanpara, 2011). In the USA plant resistance has been confirmed to the leafhoppers (Lynch, 1990; Nandagopal & Reddy, 1987).

**Monitoring:** monitoring should be done weekly from 3 weeks after emergence (*R*1) up to maturity (*R*9) when the plants had no leafhoppers left on them. D-vac suction sampler can use for determining the number of adults and nymphs (select 10 sites in the field and five plants randomly per sample site). Also, determine the percentage of leaves affected by hopper burn (Linker et al., n.d.).

**Economic and action thresholds:** the economic threshold level is when 25% of the leaves are damaged or the presence of 5-10 nymphs or adults per plant. If the field is to be sprayed with fungicide, 15% threshold can be used (Linker et al., n.d.).

**Control**: planting tolerant varieties; crop rotation with non host crop; intercropping with pearl millet; avoidance of groundnut-castor inter crop; and once irrigation to avoid prolonged mid season drought are cultural techniques for preventing pests infestations. Applying safe insecticides such as Dimethoate 30 EC, or Monochrotophos 36SL can be effective against jassids (TIFP, n.d.-a).

#### **3.3** *Caliothrips indicus* **(Bagn.);** *Thrips palmi* **(Karny);** *Scrirtothrips dorsalis* **(Hood);**  *Frankliniella schultzei* **(Trybom) (Thysanoptera: Thripidae)**

**Identification:** in the case of *C. indicus* both adults and nymphs are dark colored with fringed wings. For *F. schultzei*, dults are dark colored with fringed wings but nymphs are yellowish. For identification *T. palmi* and *S. dorsalis* refer to the cotton (Krishworld, n.d.).

**Life cycle and damage**: symptoms of damage is different as tender leaves show yellowish green patches on the upper surface; brown necrotic areas and silvery sheen on the lower surface. Severe infestations cause stunted plants. For *C. indicus*, lower leaves showing white spots or streaks intermingled with black excreta on the surface. In *F. schultzei*  damage, young and terminal leaves showing white scars. They also transmit peanut bud necrosis. Peanut and its wild species show resistance to thrips species in the USA (TNAU, n.d.-c).

**Identification:** *B. hortensis* adults are small and have a well developed appendix on the tegmen. Most species of *Balclutha* genus are green coloured although some of them are pink or red (NSW, 2001). *E. kerri* adults are yellowish green in color, wedge shaped and walked

**Life cycle and damage**: the females insert eggs into the leaf tissue close to the midrib or into the petiole. The eggs hatch in a week and in 10 days nymphs change to the adult form. The nymphal stage passed through five instars. Both nymphs and adults suck sap from central surface of leaves; inject toxins resulting in whitening of veins and chlorotic patches especially at the tips of leaflets. This type of feeding cause 'V' shaped yellowing. Heavily attacked crops look yellow and give a scorched appearance known as 'hopper burn'. Also, stunting of crop growth is observed where they are endemic. life cycle is about 18-30 days in the case of male, while it is 20-34 days for female at an average temperature of 31.30±1.96°C and 73.96±3.02% r.h. (Ghewande & Nandagop, 1997; Khanpara, 2011). In the USA plant resistance has been confirmed to the leafhoppers (Lynch, 1990; Nandagopal & Reddy, 1987). **Monitoring:** monitoring should be done weekly from 3 weeks after emergence (*R*1) up to maturity (*R*9) when the plants had no leafhoppers left on them. D-vac suction sampler can use for determining the number of adults and nymphs (select 10 sites in the field and five plants randomly per sample site). Also, determine the percentage of leaves affected by

**Economic and action thresholds:** the economic threshold level is when 25% of the leaves are damaged or the presence of 5-10 nymphs or adults per plant. If the field is to be sprayed

**Control**: planting tolerant varieties; crop rotation with non host crop; intercropping with pearl millet; avoidance of groundnut-castor inter crop; and once irrigation to avoid prolonged mid season drought are cultural techniques for preventing pests infestations. Applying safe insecticides such as Dimethoate 30 EC, or Monochrotophos 36SL can be

**3.3** *Caliothrips indicus* **(Bagn.);** *Thrips palmi* **(Karny);** *Scrirtothrips dorsalis* **(Hood);** 

**Identification:** in the case of *C. indicus* both adults and nymphs are dark colored with fringed wings. For *F. schultzei*, dults are dark colored with fringed wings but nymphs are yellowish. For identification *T. palmi* and *S. dorsalis* refer to the cotton (Krishworld, n.d.).

**Life cycle and damage**: symptoms of damage is different as tender leaves show yellowish green patches on the upper surface; brown necrotic areas and silvery sheen on the lower surface. Severe infestations cause stunted plants. For *C. indicus*, lower leaves showing white spots or streaks intermingled with black excreta on the surface. In *F. schultzei*  damage, young and terminal leaves showing white scars. They also transmit peanut bud necrosis. Peanut and its wild species show resistance to thrips species in the USA (TNAU,

**3.2** *Balclutha hortensis* **(Lindberg) and** *Empoasca kerri* **(Pruthi) (Homoptera** 

diagonally in a characteristic manner (Khanpara, 2011).

with fungicide, 15% threshold can be used (Linker et al., n.d.).

*Frankliniella schultzei* **(Trybom) (Thysanoptera: Thripidae)** 

hopper burn (Linker et al., n.d.).

effective against jassids (TIFP, n.d.-a).

n.d.-c).

**Cicadellidae)**

**Monitoring:** Colored sticky traps or water traps are useful for monitoring thrips. The color spectrum of sticky traps influenced their efficacy. Blue, yellow or white colors are used especially and it seems bright colors attract more thrips than darker ones.

**Economic and action thresholds:** economic threshold level is when 25% of the leaves are damaged and live thrips are found in the field or 5 thrips per terminal shoot (Bhubaneswar, 2008; Linker et al., n.d.).

**Control**: Spraying Monochrotophos 36 WSC, Dimethoate 30 EC, Methyldemeton 25 EC, or Monocrotophos 320 ml mixed with neem oil, 1 lit and 1 kg soap powder mixed in 200 lit of water twice at 10 days interval can be effective against thrips infestations (TNAU, n.d.-c).
