**3.1 The pest insects**

An estimated 200 insect pests that belong to 48 families in Coleoptera, Diptera, Hemiptera, Hymenoptera, Isoptera, Lepidoptera, Orthoptera, Thysanoptera, and 7 mites of the order Acarina are known to infest green gram and black gram. Under severe cases stem fly may alone cause more than 90 per cent damage with a yield loss of 20 per cent (Talekar, 1990). The galerucid beetle, *Madurasia obscurella* causes damage up to 20 – 60 per cent. Whitefly, a

tender pods or flowers at different population densities (1, 2, 3 and 4 larvae per plant or in a geometrical progression as 2, 4, 8 and 16). A no-larval release control should also be taken side by side on the pot plants. The plants should be caged properly and the treatments replicated. Observations on the number of healthy and damaged pods, and grain weight per plant should be recorded. Taking the reduction in yield due to different levels of larval density release, the regression analysis can be worked out to quantify the damage. The economic injury level for the pod borer on green gram can be determined by using the

ManagementCost(Rs/ha) Gain threshold(G.T.)= =kg/ha Marketed valueof Mungbean(Rs/kg)

Gain threshold(kg/ha) Economicinjurylevel(EIL) =insect/ha Lossperinsect(kg/insect)

The economic threshold level can be calculated by the method suggested by Johnston and Bishop (1987). They established economic threshold level as the population of economic injury level minus the increase in population of the pest concerned per day. The increasing rate of larval population under natural field conditions can be determined by recording the weekly population of the pod borer during larval activity. The rate of increase in population

Early flowering marigold variety must be sown in well prepared, raised nursery beds at least 45 days before transplanting. Niger crop has to be directly sown 28 to 30 days before sowing the main crop of green gram. In short, sowing should be adjusted in such a manner that flowering of niger/marigold and green gram should coincide so that nectar/pollen feeding natural enemies would be attracted to the farmscape plants. The sowing operations

1. In the green gram and niger farmscaping (3: 1 ratio), niger sowing is done first and

2. In the green gram and marigold farmscaping (3: 1 ratio), transplanting of marigold on

The row to row distance and plant to plant spacing for green gram can be 60cm and 10cm, respectively or 45cm and 10cm, respectively; whereas, mature seedlings of marigold are to

An estimated 200 insect pests that belong to 48 families in Coleoptera, Diptera, Hemiptera, Hymenoptera, Isoptera, Lepidoptera, Orthoptera, Thysanoptera, and 7 mites of the order Acarina are known to infest green gram and black gram. Under severe cases stem fly may alone cause more than 90 per cent damage with a yield loss of 20 per cent (Talekar, 1990). The galerucid beetle, *Madurasia obscurella* causes damage up to 20 – 60 per cent. Whitefly, a

method suggested by Hammond and Pedigo (1982).

**2.4 Farmscaping in green gram with annual marigold and niger** 

for green gram and the different farmscape plants should be as:

ridges should be carried out 45 days after sowing green gram.

be transplanted in between two rows of green gram at a distance of 30cm.

followed by sowing of green gram a month later.

can be calculated arithmetically.

**3. Pest management strategies** 

**3.1 The pest insects** 

potential vector of mungbean yellow mosaic virus (MYMV), can cause losses ranging from 30–70 per cent. The major insect pests, particularly those often cited, have been enlisted in Table - 1.

The insect pests that infest green gram are better classified according to their appearance based on crop phenology. Accordingly, they can be: (1) stem feeders, (2) foliage feeders, (3) pod feeders, and (4) pests of stored grains; which are also convenient to access their economic importance so as to devise suitable management measures.

At the seedling stage are the agromyzid flies, also known as bean flies (possibly few species), *Melanagromyza* (*Ophiomyia*) *phaseoli* (Tryon) being of more common occurrence. *Ophiomyia phaseoli* larva is a cortex feeder and pupates in the cortex mostly at the root-shoot junction. Sometimes pupae can be seen sticking under the membranous epidermis. In India the girdle beetle, *Oberiopsis brevis* (Swedenbord), a major pest of soybean, sometimes infests mungbean locally (Talekar, 1990).

(*M*. *s*. = *M*. *sojae*, *O*. *p*. = *O*. *phaseoli*, *0*. *c*. = *O*. *centrosematis*; please note, *O*. *phaseoli* does not lay eggs in the cotyledons of green gram) [Ref.: Talekar, 1990]

Fig. 1. Location of ovipositional and larval feeding sites in soybean plant

Insect Pests of Green Gram *Vigna radiata* (L.) Wilczek and Their Management 209

Farmscaping is an ecological approach to pest management; comprising the use of hedgerows, insectary plants, cover crops, and water reservoirs to attract and support populations of beneficial organisms such as insects, bats, and birds of prey. Such minilivestock requires adequate supplies of nectar, pollen, and herbivorous insects and mites as food to sustain and increase their populations. The best source of these foods is flowering plants. Flowering plants are particularly important to adults of the wasp and fly families, which require nectar and pollen sources in order to reproduce the immature larval stages that parasitize or prey on insect pests. However, using a *random* selection of flowering plants to increase the biodiversity of a farm may favor pest populations over beneficial organisms. It is important to identify those plants, planting situations, and management practices that

There are many approaches to farmscaping: some farmers, after observing a cover crop harboring beneficial insects, plant strips of it in or around their crop fields. The advantages of this kind of approach are that it is simple to implement, is often very effective and the farmer can modify the system after observing the results. Problems arise when the beneficial insect habitat, without the knowledge of the cultivator, also harbors pest species. In other instances the beneficials may not exist in numbers sufficient to control pest populations, *especially during the time when pest populations generally increase*. Predator/prey population balances are influenced by the *timing* of availability of nectar, pollen and alternate prey/hosts for the beneficials; therefore, essentially efforts must be made to for have yearround beneficial organism habitat and food sources. The beneficial habitat season may be extended by adding plants that bloom sequentially throughout the growing season or the

The mechanisms by which insectary plantings can help natural enemies of crop pests and other beneficial arthropods are complex, and their effectiveness can vary greatly from site to site depending on the specific situation. For this reason, it is especially important that insectary plantings are planned and assessed on a case-by-case basis, and integrated into whole-farm plans for pest management and other farm operations. Insectary plantings that are well thought out can maximize the benefits to natural enemies and minimize the benefits

The goal of farmscaping is to prevent pest populations from becoming economically damaging. This is accomplished primarily by providing habitat to beneficial organisms that increase ecological pressures against pest populations. Farmscaping requires a greater investment in knowledge, observation, and management skill than conventional pest management tactics, while returning multiple benefits to a farm's ecology and economy. However, farmscaping alone may not provide adequate pest control. It is important to monitor pest and beneficial populations so that quick action can be taken if beneficials are not able to keep pest populations in check. Measures such as maintaining healthy soils and rotating crops are complementary to farmscaping and should be integrated with farmscaping efforts. Bio-intensive Integrated Pest Management (IPM) measures, such as the release of commercially-reared beneficials (applied biological control) and the application of soft pesticides (soaps, oils, botanicals) can be used to

to pest species (Pfiffner and Wyss 2004, Quarles and Grossman 2002).

best support populations of beneficial organisms.

whole year (Rex Dufor, 2000).

augment farmscaping efforts.

The foliage feeders, especially defoliators that belong to Lepidoptera and Coleoptera include: the leaf folder, *Lamprosema indica* (F.); caterpillars of *Spodoptera exigua* (Hubner), *Anticarsia irrorata* (F.) the tobacco caterpillar, *Spodoptera litura* (F.), the hornworms, *Agris convolvuli* (L.) and *Acherontia styx* (Westwood); the Bihar hairy caterpillar, *Spilosoma obliqua*  (Walker), the tussock caterpillars, *Euproctis fraterna* (Moore), *Dasychira mendosa*; the weevils, *Cyrtozemia dispar* Pascoe, *Myllocerus undecimpustulatus maculosus* Desbr., *Myllocerus discolor* Boheman, *Myllocerus viridanus* Boheman, *Episomus lacerata* Fabr.; the hada beetle, *Henosepilachna* spp., chrysomelid (leaf) beetles, *Monolepta signata*, and the grasshopper, *Attractomorpha crenulata crenulata*.

Among the sap feeding insects the more common are aphids, especially black bean aphids, *Aphis craccivora* Koch; jassids, *Empoasca kerri* Pruthi; white flies, *Bemisia tabaci* Gennadius, thrips belonging to genus *Megalurothrips* and *Caliothrips indicus* Bagnall; the plant bugs, *Riptortus* spp., *Nezara viridula* L., *Plautia fimbriata* (Fabricius) and the pod bug, *Clavigralla* spp. They cause significant damage to green gram foliage and pods; besides causing damage to other related legumes. It was observed that green gram cultivated in the vicinity of pigeon pea was heavily infested and rather preferred by the pigeon pea pod bug, *Clavigralla* spp. (Swaminathan, *et al*., 2007). A linear relationship was observed between pod feeder infestation and seed loss, with the rate of seed loss being greater for *Riptortus linearis* and *Nezara viridula* than for *Maruca testulalis* (Hussain and Saharia, 1994).

The blister beetles (species of *Mylabris*) cause serious damage to the flowers, especially to the second and third flush during August – September months in most green gram cultivation areas in India.

The key pod borers include the lepidopteran caterpillars – the spotted pod borer, *Maruca testulalis* (Geyer) [*Maruca vitrata*] and the spiny pod borer, *Etiella zinckenella* Tretsche; however, the blue butterflies, *Lampides boeticus* Linnaeus and *Catechrysops cnejus* Fabricius; the gram caterpillar, *Helicoverpa armigera* (Hubner) have also been reported among the major pests.

The primary insect pests of stored green gram include species of bruchids belonging to the genus *Callosobruchus*. The annual yield loss is estimated to be 20 per cent in pigeonpea, 15 per cent in chickpea and 30 per cent in black gram and green gram. On an average 2.5 to 3.0 million tonnes of pulses are lost annually due to pests (Ali, 1998). Damage due to bruchids, *Callosobruchus chinensis* (L.) begins right from the field; adults emerging from the stored seeds lay eggs on healthy grains. The field infestation ranges from 7.8–9.9 per cent (Banto and Sanchez, 1972) and 100 per cent destruction of seeds occurred at 9.9 per cent field infestation.

#### **3.2 Pest management strategies**

#### **3.2.1 Organic approach**

Of late, use of various cultural practices and framscaping for the management of insect pests of green gram seems to gain importance. Adjusting the sowing dates, use of resistant varieties and growing inter or trap crops can be followed depending on the availability and effectiveness in a particular location. Since use of bio-control agents has not been successful in these crops although it is a viable alternative despite the record of several natural enemies in the field, their augmentation through farmscaping is a viable option.

The foliage feeders, especially defoliators that belong to Lepidoptera and Coleoptera include: the leaf folder, *Lamprosema indica* (F.); caterpillars of *Spodoptera exigua* (Hubner), *Anticarsia irrorata* (F.) the tobacco caterpillar, *Spodoptera litura* (F.), the hornworms, *Agris convolvuli* (L.) and *Acherontia styx* (Westwood); the Bihar hairy caterpillar, *Spilosoma obliqua*  (Walker), the tussock caterpillars, *Euproctis fraterna* (Moore), *Dasychira mendosa*; the weevils, *Cyrtozemia dispar* Pascoe, *Myllocerus undecimpustulatus maculosus* Desbr., *Myllocerus discolor* Boheman, *Myllocerus viridanus* Boheman, *Episomus lacerata* Fabr.; the hada beetle, *Henosepilachna* spp., chrysomelid (leaf) beetles, *Monolepta signata*, and the grasshopper,

Among the sap feeding insects the more common are aphids, especially black bean aphids, *Aphis craccivora* Koch; jassids, *Empoasca kerri* Pruthi; white flies, *Bemisia tabaci* Gennadius, thrips belonging to genus *Megalurothrips* and *Caliothrips indicus* Bagnall; the plant bugs, *Riptortus* spp., *Nezara viridula* L., *Plautia fimbriata* (Fabricius) and the pod bug, *Clavigralla* spp. They cause significant damage to green gram foliage and pods; besides causing damage to other related legumes. It was observed that green gram cultivated in the vicinity of pigeon pea was heavily infested and rather preferred by the pigeon pea pod bug, *Clavigralla* spp. (Swaminathan, *et al*., 2007). A linear relationship was observed between pod feeder infestation and seed loss, with the rate of seed loss being greater for *Riptortus linearis*

The blister beetles (species of *Mylabris*) cause serious damage to the flowers, especially to the second and third flush during August – September months in most green gram cultivation

The key pod borers include the lepidopteran caterpillars – the spotted pod borer, *Maruca testulalis* (Geyer) [*Maruca vitrata*] and the spiny pod borer, *Etiella zinckenella* Tretsche; however, the blue butterflies, *Lampides boeticus* Linnaeus and *Catechrysops cnejus* Fabricius; the gram caterpillar, *Helicoverpa armigera* (Hubner) have also been reported among the major pests.

The primary insect pests of stored green gram include species of bruchids belonging to the genus *Callosobruchus*. The annual yield loss is estimated to be 20 per cent in pigeonpea, 15 per cent in chickpea and 30 per cent in black gram and green gram. On an average 2.5 to 3.0 million tonnes of pulses are lost annually due to pests (Ali, 1998). Damage due to bruchids, *Callosobruchus chinensis* (L.) begins right from the field; adults emerging from the stored seeds lay eggs on healthy grains. The field infestation ranges from 7.8–9.9 per cent (Banto and Sanchez, 1972) and 100 per cent destruction of seeds occurred at 9.9 per cent field

Of late, use of various cultural practices and framscaping for the management of insect pests of green gram seems to gain importance. Adjusting the sowing dates, use of resistant varieties and growing inter or trap crops can be followed depending on the availability and effectiveness in a particular location. Since use of bio-control agents has not been successful in these crops although it is a viable alternative despite the record of several natural enemies

in the field, their augmentation through farmscaping is a viable option.

and *Nezara viridula* than for *Maruca testulalis* (Hussain and Saharia, 1994).

*Attractomorpha crenulata crenulata*.

areas in India.

infestation.

**3.2 Pest management strategies** 

**3.2.1 Organic approach** 

Farmscaping is an ecological approach to pest management; comprising the use of hedgerows, insectary plants, cover crops, and water reservoirs to attract and support populations of beneficial organisms such as insects, bats, and birds of prey. Such minilivestock requires adequate supplies of nectar, pollen, and herbivorous insects and mites as food to sustain and increase their populations. The best source of these foods is flowering plants. Flowering plants are particularly important to adults of the wasp and fly families, which require nectar and pollen sources in order to reproduce the immature larval stages that parasitize or prey on insect pests. However, using a *random* selection of flowering plants to increase the biodiversity of a farm may favor pest populations over beneficial organisms. It is important to identify those plants, planting situations, and management practices that best support populations of beneficial organisms.

There are many approaches to farmscaping: some farmers, after observing a cover crop harboring beneficial insects, plant strips of it in or around their crop fields. The advantages of this kind of approach are that it is simple to implement, is often very effective and the farmer can modify the system after observing the results. Problems arise when the beneficial insect habitat, without the knowledge of the cultivator, also harbors pest species. In other instances the beneficials may not exist in numbers sufficient to control pest populations, *especially during the time when pest populations generally increase*. Predator/prey population balances are influenced by the *timing* of availability of nectar, pollen and alternate prey/hosts for the beneficials; therefore, essentially efforts must be made to for have yearround beneficial organism habitat and food sources. The beneficial habitat season may be extended by adding plants that bloom sequentially throughout the growing season or the whole year (Rex Dufor, 2000).

The mechanisms by which insectary plantings can help natural enemies of crop pests and other beneficial arthropods are complex, and their effectiveness can vary greatly from site to site depending on the specific situation. For this reason, it is especially important that insectary plantings are planned and assessed on a case-by-case basis, and integrated into whole-farm plans for pest management and other farm operations. Insectary plantings that are well thought out can maximize the benefits to natural enemies and minimize the benefits to pest species (Pfiffner and Wyss 2004, Quarles and Grossman 2002).

The goal of farmscaping is to prevent pest populations from becoming economically damaging. This is accomplished primarily by providing habitat to beneficial organisms that increase ecological pressures against pest populations. Farmscaping requires a greater investment in knowledge, observation, and management skill than conventional pest management tactics, while returning multiple benefits to a farm's ecology and economy. However, farmscaping alone may not provide adequate pest control. It is important to monitor pest and beneficial populations so that quick action can be taken if beneficials are not able to keep pest populations in check. Measures such as maintaining healthy soils and rotating crops are complementary to farmscaping and should be integrated with farmscaping efforts. Bio-intensive Integrated Pest Management (IPM) measures, such as the release of commercially-reared beneficials (applied biological control) and the application of soft pesticides (soaps, oils, botanicals) can be used to augment farmscaping efforts.

Insect Pests of Green Gram *Vigna radiata* (L.) Wilczek and Their Management 211

populations mainly occurred after most squares had become less vulnerable bolls. Weed

Some of the more recent literature on the impact of intercropping on insect pest situation has been reviewed herein. Populations of *O*. *phaseoli* on *V*. *mungo* and *B*. *tabaci* on cowpea increased when these crops were intercropped with maize. The incidence of yellow mosaic was lower in intercrops of *V*. *radiata* with maize and sorghum than in monocultures. Conversely, pod borer damage to *V*. *radiata* was lower in monocultures than in intercrops. There was no significant difference in populations of *A*. *soccata* and *C*. *partellus* on pure and intercrops (Natarajan *et al*., 1991). Rekha Das Dutta (1996) observed that intercropping *V*igna *radiata* with maize resulted in reduced populations of the pests *viz*., *Monolepta signata*, *Aphis craccivora*, *Nacolea vulgaris*, *Nezara viridula* and *Riptortus linearis* on *V*. *radiata* than when intercropped with other legumes like *Vigna umbellata* (rice bean), *Glycine max* (soybean), *Vigna mungo* (black gram) and *Arachis hypogea* (groundnut). Intercropping maize and sorghum along the periphery significantly reduced the whitefly (*Bemisia tabaci*) population and the damage caused by the pod borers (*Maruca testulalis* [*M*. *vitrata*] and *Lampides boeticus*). All intercrops resulted in increased yields over the sole crops; however, maize and

competition resulted in lower lint yields of 89 and 32 per cent in 2 years.

sorghum intercropped along the periphery was more promising (Dar *et al*., 2003).

to hoverfly (Diptera: Syrphidae) larvae (Chaney, 2004).

species.

Various forms of farmscaping in the form of permanent hedgerows or temporary insectary strips in vegetable fields to increase the activity of beneficial insects have shown that data on the effectiveness of these practices is sparse at best, as is information on the best plant species to use. The primary pest target is often aphids. The use of sweet alyssum (*Lobularia maritima*) provides long periods of flowering and fits into most grower operations, yet was chosen originally for its ability to attract and provide resources to hymenopteran aphid parasitoids. Now that the aphid species of concern has shifted from green peach aphid (*Myzus persicae*) to lettuce aphid, the natural enemy of greatest importance has also shifted

Higher numbers of arthropod pests were observed in onion plants 30 m from the marigold strip, while higher numbers of predators and parasitoids were found at 5 m distance. Species richness and Shannon's diversity index were higher at 5 m from marigold. Therefore, marigold rows next to onion fields resulted in higher number of entomophagous

Evaluating the suitability of some farmscaping plants as nectar sources for the parasitoid wasp, *Microplitis croceipes* (Hymenoptera: Braconidae), Nafziger and Fadamiro (2011) observed that the greatest longevity (~16 days) was recorded for honey-fed wasps (positive control). Buckwheat significantly increased the lifespan of female and male wasps by at least two-fold as compared to wasps provided water only (longevity=3-4 days). Licorice mint significantly increased female longevity and numerically increased male longevity. Sweet alyssum slightly increased longevity of both sexes though was not significantly different from the water only control. Females had a significantly longer longevity than males on all the diet treatments. The greatest carbohydrate nutrient levels (sugar content and glycogen) were recorded in honey-fed wasps followed by wasps fed buckwheat, whereas very little nutrients were detected in wasps provided sweet alyssum, licorice mint or water only. However, female wasps were observed to attempt to feed on all three flowering plant

species, potentially enhancing the natural control of onion pests (Silveira et al., 2009).

In a case study on the impact of farmscaping in greengram on the major insect pests and their natural enemy complex at the College farm, Udaipur, India, a comparison of the seasonal mean abundance of the major foliage feeding and pod damaging insect pests showed a significant difference among the treatments. The Shanon Weiner diversity index was the maximum under green gram + marigold weeded and unweeded farmscape conditions being 0.7936 and 0.7790. The sole crop of green gram had the lowest diversity index of 0.6622 for weeded and 0.6863 for unweeded conditions. Comparisons made for the associated natural enemy complex in the different treatments showed that the farmscape treatment green gram + niger under unweeded conditions had the highest Shanon Weiner diversity index of 1.5932 followed by that for green gram + marigold under unweeded conditions with an index of 1.5716. Green gram sole crop had the lowest diversity indices being 1.2882 and 1.3854 under weeded and unweeded conditions, respectively. Niger, by virtue of being taller than green gram, acts as a physical barrier to blister beetle infestation on green gram floral parts. Some blister beetles may happen to alight on niger flowers and cause some damage, thereby safeguarding damage to green gram. Marigold is preferred by *Helicoverpa armigera* (Hubner) for laying eggs; thereby, the main crop of mung bean/green gram significantly escapes the pest infestation (Unpublished data – Swaminathan, 2011).
