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Insects - Pigeonpea

Contributors to this page: ICRISAT, Patancheru, India (RP Thakur, AG Girish, VP Rao).

Contents:
Stored grain pest
Khapra beetle

Stored grain pest

Scientific name

Callosobruchus analis Fabricius.

Other scientific names

Bruchus analis, Bruchus glaber, Bruchus jekelii, Bruchus obliquus, Bruchus ciceri, Callosobruchus glaber, Callosobruchus jekelii.

Importance

Medium.

Significance

Infested chickpea lose their viability and are unfit for human consumption. In Africa, Asia, and Oceania, C. analis is considered a pest of economic importance for stored-legume grains (Southgate 1979).

Symptoms

Chickpea pods are seldom infested in the field. The pests attack nearly mature and dried pods during storage. The round exit hole and the white eggs on the pod wall are conspicuous. Infested stored seed can be recognized by the eggs on the seed surface, and the round exit holes with the ‘flap’ of seed coat.

Hosts

Cicer arietinum (chickpea), Cajanus cajan (pigeonpea) and other grain legumes.

Geographic distribution

Callosobruchus analis is wide spread in Asia.

Biology and transmission

Adults are small, 3 mm long brown beetles with black spots on the elytra. Eggs are laid on the seed surface. Larvae feed and pupate entirely within the seed. One generation is completed in 4-5 weeks (Ranga Rao and Shanower 1999).

Detection/indexing methods used in CGIAR

Treatment/control

Procedures followed at the centers in case of positive test

References and further reading

Chakrabarty SK, Anitha K, Girish AG, Sarath Babu B, Prasada Rao RDVJ, Varaprasad KS, Khetarpal RK, Thakur RP. 2005. Germplasm exchange and quarantine of ICRISAT mandate crops. Information Bulletin No. 69. Rajendranagar 500 030, Andhra Pradesh, India: National Bureau of Plant Genetic Resources; and Patancheru 502 324, Andhra Pradesh, India: International Crops Research Institute for the Semi Arid Tropics. 80pp.

Ghanekar AM, Ranga Rao GV, Murthy KS, Surender A, Shaik Babu Saheb. 1996. Seed protectants for healthy exports. Indian Journal of Plant Protection 24: 37-43.

Ranga Rao GV, Shanower TG. 1999. Identification and Management of Pigeonpea and Chickpea Insects Pests in Asia. Information Bulletin No. 57, Patancheru, 502 324, A.P., India: International Crops Research Institute for the Semi Arid Tropics. 96pp.

Southgate BJ. 1979. Biology of the Bruchidae. Annual Review of Entomology 24: 449-473.

Stored Grain Pest (Callosobruchus analis) of pigeonpea: (A)adult (photo: www.invasive.org/brows/detail=066007); (B)infested pods and (C)infested seed and white eggs (photos: ICRISAT).

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Khapra beetle

Scientific name

Trogoderma granarium Everts.

Other scientific names

Trogoderma afrum, Trogoderma khapra, Trogoderma quinquefasciata.

Importance

High.

Significance

Trogoderma granarium is a serious pest of stored products under hot dry conditions. Established infestations are difficult to control because of the beetle’s ability to live without food for long periods of time and to survive on foods of low moisture content, its habit of crawling into tiny cracks and crevices and remaining there for long periods, and its relative tolerance to many surface insecticides and fumigants.

Symptoms

The khapra beetle is one of the world’s most feared stored-product pests. The obvious signs of a khapra beetle infestation are the larvae and cast skins. Larvae and adults are best identified by microscopic examination. Larvae are mostly seen just before dusk, since they are more active at that time (Anonymous 1981).

Khapra Beetle (Trogoderma granarium) of pigeonpea: (A)adults and (B)larvae and damaged grains (photos: www.agspsrv34.agric.wa.gov.au).

Host

Larvae feed on a wide variety of stored products and dried foods. They prefer whole grain and cereal products such as Triticum aestivum (wheat), Hordeum vulgare (barley), and Oryza sativa(rice), but larvae have been recorded on the following: Avena spp. (oats), Secale spp. (rye), Zea mays (corn), dried blood, dried milk, fishmeal, Arachis hypogea (groundnut), flour, bran, malt, Linum usitatissimum (flax seed), Medicago sativa (alfalfa seed), Lycopersicum esculantus (tomato seed), Phaseolus vulgaris (pinto beans), Vigna unguiculata (blackeyed cowpeas), Sorghum bicolor (sorghum seed) and many other food products (Lindgren and Vincent 1959; Lindgren et al. 1955).

Geographic distribution

The distribution of khapra beetle extends from Mayanmar (Burma) to West Africa and is limited by the 35° parallel to the north and the equator to the south. It has been introduced by commerce into some areas of similar climatic conditions (Anonymous 1981). The khapra beetle is found in all continents where grain and grain products are stored.

Biology and transmission

The adults are oblong-oval beetles, approximately 1.6 to 3.0 mm long and 0.9 to 1.7 mm wide. Males are brown to black with indistinct reddish brown markings on elytra. Females are slightly larger than males and lighter in color. The head is small and deflexed with a short 11-segmented antenna. The antennae have a club of three to five segments, which fit into a groove in the side of the pronotum. The adults are covered with hairs. The eggs are milky white, turning pale yellowish with age, cylindrical, 0.7 ´ 0.25 mm, one end rounded, the other pointed and bearing spine-like projections. Larvae are uniformly yellowish white, except head and body hairs are brown. As the larvae increase in size, their body color changes to a golden or reddish brown, more body hairs develop, and the tail becomes proportionally shorter. Mature larvae are approximately 6 mm long and 1.5 mm wide. Adult khapra beetles have wings, but apparently do not fly and feed very little. Mated females live from four to seven days, unmated females from 20 to 30 days, and males from seven to12 days. Mating occurs about five days after emergence, and egg laying begins almost immediately at 40°C. Egg laying may begin at one to three days at cooler temperatures, but no eggs are produced at 20°C. Eggs hatch in three to 14 days after the female lays an average of 50 to 90 eggs that are loosely scattered in the host material. Complete development from egg to adult can occur from 26 to 220 days, depending upon temperature. Optimum temperature for development is 35°C. If the temperature falls below 25°C for a period of time or if larvae are very crowded, they may enter diapauses. They can survive temperatures below -8°C. In diapauses, the larvae can molt but are inactive and may remain in this condition for many years (Anonymous 1981).

Detection/indexing methods at ICRISAT

Treatment/control

Procedures followed in case of positive test at ICRISAT

References and further reading

Anonymous. 1981. Data sheets on quarantine organisms. Trogoderma granarium Everts. European and Mediterranean Plant Protection Organization Bulletin 11 (1) Set 4, List A2, 1-6 pp.

Lindgren DL, Vincent LE. 1959. Biology and control of Trogoderma granarium Everts. Journal of Economic Entomology 52: 312-319.

Lindgren DL, Vincent LE and Krohne HE. 1955. The khapra beetle, Trogoderma granarium Everts. Hilgardia 24: 1-36.

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The Genebanks

The 11 CGIAR genebanks currently conserve 730,000 of cereals and grain legumes, forage crops, tree species, root and tuber crops, bananas and crop wild relatives.

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