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INSECT PESTS OF PIGEONPEA AND THEIR MANAGEMENT (1999)

Shanower, T. G. ; Romeis, J. ; Minja, E. M.

Palo Alto, Calif. : Annual Reviews

Annual Review of Entomology 44 (1999), S. 77-96

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ISSN: 0066-4170

Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff

Topics: Biology

Notes: Abstract Pigeonpea (Cajanus cajan) is an important crop in semi-arid tropical and subtropical farming systems, providing high quality vegetable protein, animal feed, and firewood. Insect pests feeding on flowers, pods, and seeds are the most important biotic constraint affecting pigeonpea yields. This review summarizes the biology and ecology of the three most important groups of pests: flower- and pod-feeding Lepidoptera, pod-sucking Hemiptera, and seed-feeding Diptera and Hymenoptera. Recent research investigating the complex interactions among pigeonpea, its key pests, and their natural enemies is also reviewed. These relationships have implications on the pest status of individual species and on possible control strategies. Pigeonpea pest management research has focused until recently on the identification and development of resistant cultivars and on chemical control. Future research must focus on environmentally sound pest management strategies that are compatible with the needs and limitations of pigeonpea farmers. Several priority areas for research are suggested.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1146/annurev.ento.44.1.77

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Physical and chemical plant characters inhibiting the searching behaviour of shape Trichogramma chilonis (1998)

Romeis, J. ; Shanower, T.G. ; Zebitz, C.P.W.

Springer

Entomologia experimentalis et applicata 87 (1998), S. 275-284

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ISSN: 1570-7458

Keywords: filter paper bioassay ; Cajanus spp. ; Helicoverpa armigera ; infochemicals ; olfactometer ; pigeonpea ; surface chemicals ; Trichogramma chilonis ; trichomes ; trichome exudates ; walking speed

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Several plant characters are known to affect the searching behaviour and parasitization efficiency of Trichogramma spp. (Hymenoptera: Trichogrammatidae). In this study, plant characters contributing to the low Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) egg parasitism levels on pigeonpea (Cajanus cajan (L.) Millspaugh) were investigated. The efficiency of T. chilonis on pigeonpea was dependent on the plant structure on which the host eggs were found. In a cage experiment, more than 55% of eggs placed on leaves were parasitized, while 1% of eggs on calyxes and no eggs on pods were parasitized. In a filter paper bioassay, parasitoids were deterred by acetone and hexane surface extracts from pigeonpea pods but showed no response to water extract. The searching behaviour of the parasitoids was not affected by different solvent extracts from the surface of pigeonpea leaves. In a four-armed airflow olfactometer, T. chilonis was repelled by volatiles from pigeonpea pods but showed no response to volatiles derived from hexane extract of pod surfaces. Volatile infochemicals and hexane surface extracts from pods of two wild Cajanus species, C. scarabaeoides (L.) Thours and C. platycarpus (Bentham) van der Maesen, were similarly deterrent to T. chilonis. The movement of the parasitoids on pigeonpea pods and calyxes was inhibited by long trichomes and wasps were trapped by sticky trichome exudates. Parasitoids walked significantly faster on leaves than on pods. The walking speed on both pods and leaves increased significantly after washing with hexane. The results presented in this paper show that the plant growth stage and the plant structures preferred by H. armigera for oviposition are the least suitable for T. chilonis, contributing to the low parasitoid efficiency on pigeonpea.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1003275419997

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Response of Trichogramma egg parasitoids to colored sticky traps (1998)

Romeis, J. ; Shanower, T.G. ; Zebitz, C.P.W.

Springer

BioControl 43 (1998), S. 17-27

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ISSN: 1573-8248

Keywords: color preference ; habitat location ; parasitoids ; sticky traps ; Trichogramma spp.

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract The response of Trichogramma spp. egg parasitoids to colored sticky traps was evaluated in the field during two seasons (1995/1996, 1996/1997). Traps consisted of a glass tube coated with Bird-Tanglefoot® into which colored paper was inserted or clear traps without paper. Colors tested were white, green, blue, yellow and red in the first season and white, green, yellow and black in the second season. The proportion of both female and male parasitoids caught on the sticky traps was significantly different among colors, indicating that the parasitoids actively move between plants and are not solely carried along passively by wind. White was the color most preferred by female parasitoids, followed by clear and green traps. Yellow was preferred over black but was less attractive than green. Visual cues may be used by Trichogramma spp. during the habitat location process. The color preference of male Trichogramma spp. differed significantly from females with yellow and green being more attractive than white. For all colors, more female Trichogramma spp. were caught on the sticky traps (〉85% of all wasps caught), indicating a lower activity level and/or shorter lifespan for males. The use of white cylindrical sticky traps for monitoring Trichogramma spp. populations in the field is recommended.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1009905722193

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Trichogramma egg parasitism of Helicoverpa armigera on pigeonpea and sorghum in southern India (1999)

Romeis, J. ; Shanower, T.G. ; Zebitz, C.P.W.

Springer

Entomologia experimentalis et applicata 90 (1999), S. 69-81

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ISSN: 1570-7458

Keywords: clutch size ; Helicoverpa armigera ; intercropping ; mass-release ; pigeonpea ; sex ratio ; sorghum ; sticky traps ; Trichogramma spp.

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Trichogramma spp. (Hymenoptera: Trichogrammatidae) only rarely parasitize eggs of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) on pigeonpea (Cajanus cajan (L.) Millspaugh), while on other plants including sorghum (Sorghum bicolor (L.)) high parasitism levels of this host are found. In this study two strategies designed to increase the parasitoid activity on pigeonpea were tested in the field: intercropping pigeonpea with sorghum and mass-releasing T. chilonis Ishii. Neither strategy led to an increase in parasitism. On pigeonpea, H. armigera oviposited 〉74.8% of its eggs on calyxes and pods. Parasitism levels in host eggs collected from different plant structures varied significantly with 3.6, 0.3, and 40.7% of eggs on calyxes, pods, and leaves parasitized. Earlier studies have shown that calyxes and pods possess long glandular and non-glandular trichomes, and are covered by sticky trichome exudates which inhibit parasitoid searching behaviour. Parasitism levels between 27.9 and 100% were recorded from host eggs on the intercropped sorghum. Trichogramma chilonis was the dominant parasitoid species. The mean clutch size was 2.03, but up to six parasitoids emerged per egg. Progeny sex ratio (% females) decreased with clutch size, from 63.1% at a clutch size of one to 46.0% at a clutch size of five. Sticky trap catches showed that while the parasitoid population in sorghum increased when H. armigera started ovipositing, the population within pigeonpea did not benefit from either a high parasitoid population in sorghum or a high host egg density on pigeonpea. During one of five seasons studied, however, high parasitism levels (up to 73%) were recorded on pigeonpea. During this season, H. armigera oviposited on pigeonpea plants in the vegetative growth stage and a high proportion of eggs were collected from leaves. Parasitism levels were positively correlated with the percentage of eggs collected from leaves. This study shows that the parasitization efficiency of Trichogramma spp. on pigeonpea depends mainly on the location of the host eggs. This explains why parasitism levels of H. armigera eggs on pigeonpea did not increase when intercropped with sorghum or after mass-releasing T. chilonis.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1003502331350

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Searching behaviour of Encarsia formosa as mediated by colour and honeydew (1997)

Romeis;, J. ; Zebitz, C.P.W.

Springer

Entomologia experimentalis et applicata 82 (1997), S. 299-309

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ISSN: 1570-7458

Keywords: Bemisia tabaci ; searching behaviour ; Encarsia formosa ; filter paper bioassay ; honeydew ; kairomones ; olfactometer ; Trialeurodes vaporariorum

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract The habitat- and host-searching behaviour of female Encarsia formosa Gahan (Hymenoptera: Aphelinidae) was assessed using an airflow olfactometer and a filter paper test. Responses to different odour cues, colours, host-produced honeydew, non-host honeydew and single carbohydrates were determined. The parasitoid was not attracted to or arrested by odours emanating from clean tobacco leaves, tobacco leaves heavily infested with the host Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae) and covered with honeydew, or honeydew alone. However, E. formosa females showed a significant response to green light transmitted through a tobacco leaf. The yellow part of the spectrum was partly responsible for this response. Thus, the long-range orientation is random with respect to the presence of hosts. Filter paper tests showed that the short-range searching behaviour is influenced by water soluble, non-volatile contact-kairomones contained in the host-produced honeydew. Contact with honeydew excreted by L3/L4 T. vaporariorum resulted in longer searching times than honeydew from adult T. vaporariorum or L3/L4 Bemisia tabaci Gennadius (Homoptera: Aleyrodidae). No difference was found between the response to honeydew excreted by adult and L3/L4 B. tabaci. The parasitoids' response to honeydew was unaffected by the host plant on which the whiteflies had fed. Non-host honeydew and single carbohydrates also affected the searching behaviour of E. formosa but to a lower extent than host honeydew. The possible differences in the carbohydrate and amino acid composition of the honeydew excreted by different life-stages of T. vaporariorum and B. tabaci are discussed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1002907627178

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Trichomes on Pigeonpea [Cajanus cajan (L.) Millsp.] and Two Wild Cajanus spp. (1999)

Romeis, J. ; Shanower, T.G. ; Peter, A.J.

Springer

Crop science 39 (1999), S. 564-569

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ISSN: 1435-0653

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Cajanus cajan (L.) Millsp., is often heavily damaged by insect pests, and trichomes provide a potential insect resistance mechanism. The following study was conducted to identify and characterize the distribution of trichomes on pigeonpea and two wild species, C. platycarpus (Bentham) van der Maesen and C. scarabaeoides (L.) Thours. Three glandular (Types A, B, and E) and two nonglandular (Types C and D) trichome types were identified with light and electron microscopy. Types A, B, C, and D were found on leaves, pods, and calyxes of all three Cajanus spp., except for Type A, which was not found on pods and calyxes of most C. scarabaeoides accessions examine. Because of their small size and rarity, Type E trichomes were not considered in this study. Pods of C. scarabaeoides were the most densely pubescent, followed by pods of C. cajan and C. platycarpus. Trichome density on pods varied significantly among pigeonpea genotypes and different accessions of C. scarabaeoides. Differences across seasons and in greenhouse versus field-grown plants were also significant. Leave of C. platycarpus possessed the fewest trichomes, while C. cajan and C. scarabaeoides had highly pubescent leaves. The resistance of C. scarabaeoides pods to Helicoverpa armigera (Hübner) larvae reported in an earlier study is due to the high density of nonglandular trichomes. This wild species may thus be an important source for developing insect resistant pigeonpea.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/

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