**4.8** *Cerotoma trifurcata* **(Forster) (Coleoptera: Chrysomelidae)**

**Identification:** The bean leaf beetle adult is 5 mm long, with or without four black spots (parallelogram shaped) on the wing covers. Adults can vary in color but are most often yellow-green, tan or red. A small, black triangle is visible at the base of the wing covers the prothorax - behind the head. The margins of the wing covers have a black border. Eggs are orange colored and lemon shaped (OMAFRA, 2011).

**Life cycle and damage**: Females lay eggs in small clusters in the soil at the base of the soybean plants. Newly hatched larvae feed on roots and other underground plant parts for about 30 days before pupating. Adults second generation emerges, feeds on the pods until the plants senesce. They then migrate to alfalfa fields if available or move to their over wintering sites. *C. trifurcate* overwinters in the adult stage in woodlots, leaf litter and soil debris. Defoliation injury by this pest is generally not serious and the exception is damage caused by over wintering adults to young soybean plants. Adult feeding appears as small round holes between the major leaflet veins. Cotyledons and seedling plants can be clipped off by heavier populations. They also feed on the surface of the pod, leaving only a thin film of tissue to protect the seeds within the pod. These pod lesions increase the pod's susceptibility to secondary pod diseases such as alternaria. The bean leaf beetle is a vector of bean pod mottle virus (BPMV) which causes the plant and seed to become wrinkled and mottled, reducing the quality of the seed (OMAFRA, 2011).

**Monitoring:** monitor from seedling stage to dry edible bean pod-fill stages. Fumigation cage, sweep net, pitfall trap and shaking over the ground cloth are the methods used for sampling. For sweep net sampling take 20-sweep samples at each sample location. Sweep as you walk down the row and calculate an average number of beetles per sweep. In the case of shaking over the ground cloth; place a two foot wide strip of cloth on the ground between the rows and shake the plants over them. Then quickly count the number of beetles. In the "seedling stage" see underside of the leaves and calculate the average number of beetles per meter of row; in the soybean "R5-R6 Stage", assess the number of pods with feeding injury or clipping; in the "prior to the dry edible bean pod-fill Stages" determine the percent defoliation that has occurred; and in the case of "dry edible bean pod-fill Stages" determine the percent of pods with feeding damage. For pod sampling collect five plant samples from each sampling location and calculate an average number of pods with holes in the pod wall per five plants (OMAFRA, 2011).

**Economic and action thresholds:** Thresholds for bean leaf beetle are 16 adult beetles per foot of row in early seedling stages. In V3-R4 stage of soybean; the economic threshold is when defoliation exceeds 30% and for R5-R6 stage if 10% of the pods on the plants have feeding injury and the beetles are still active in the field (OMAFRA, 2011).

**Control**: Seed treatment using thimethoxam and late planting date, may result in low initial population of beetles. Tachinid species, *Calatoria diabroticae* (Shimer) and *Medina* sp. can control *C. trifurcata*. Application of foliar insecticide between emergence and first trifoliate using pyrethroid has been shown to reduce beetles incidence, by protecting soybean from

Oilseed Pests 149

has four or five generations per year and pupae overwinter in the stem. The infestation significantly reduced the plant height, number of branches per plant, number of trifoliate leaves, leaf area per plant and dry matter accumulation. The infestation rate ranges from 85 to 100% due to the planting dates and being higher on the late sown crop (Savajji, 2006).

**Monitoring:** Stem flies reached their peak in the 5th–8th weeks after planting and declined towards the end of the season. Observe percent seedling mortality, percent stem tunneling and areas of poor stand. Also, dig up some seed and examine for the presence of insects and

**Economic and action thresholds:** economic threshold level is 5% plant infestation (Rao et al., 2007). However, according to (Johnson et al., 2009) there is no rescue treatment for this pest. Estimate area and amount of stand reduction for reporting in Comments. This

**Control**: deep summer ploughing; proper crop rotation with dissimilar crops; removing and destroying the damaged plant parts can reduce the population. However, if the threshold is exceeded application of insecticides is essential. Spray monocrotophos 36 WSC twice, at the crop age of one and three weeks. In case of severe infestation, apply phorate or lindane in the soil 10 kg/ha before sowing. Soil application of phorate 10 G, 10 kg/ha or carbofuran 3 G, 30 kg/ha at the time of sowing will prevent early infestation by stem fly. One or two sprays of endosulfan 35 EC or dimethoate 30 EC or quinalphos 25 EC can stop the damage

**Identification:** Soybean pod gall midge is described from Japan and at least five named and 13 undetermined species of *Asphondylia* are found in Japan. Most of the undescribed species are morphologically very similar to one another. Yukawa et al., (2003) studied the morphological characteristics of soybean pod gall midge and DNA sequencing of several *Asphondylia* gall midges. They prove that *A. yushimai* is a distinct species of the genus

**Life cycle and damage**: females lay eggs inside young pods of soybean and cause yield losses with malformation of pods by larval infestations. Soybean pod gall midge is one of the major pests of soybean in Japan, Indonesia and China. In summer and autumn, the soybean pod gall midge has two or more generations in the pods of soybean, *G. max* or wild fabaceous and caesalpiniaceous plants (Yukawa et al., 2003). *Asphondylia* sp. cannot overwinter on soybean because the host dies back in winter; whether the soybean species

**Monitoring:** collect the galls and count number of larvae. Color traps present a potential

**Control**: Controlling weeds beneath or around the plants and removing fallen fruit from fields (bury at least 15 cm deep or burn them) may reduce the infestation of gall midge. If a field is of no further economic use, destroy completely or remove all reproductive structures at least twice weekly (RADA, 2010). Contact county Cooperative Service Extension agent or

tactic for monitoring soybean pod gall midge or mating disruption (RADA, 2010). **Economic and action thresholds:** No action threshold has been set for *A. yushimai*.

*Asphondylia*, identify its winter host, and outline host alternation by this gall midge.

information will be useful when making a decision on replanting.

**4.11** *Asphondylia yushimai* **sp. n. (Diptera: Cecidomyiidae)** 

overwinters on another legume or host (Gagne & Woods, 1988).

or damage (Savajji, 2006).

(Pande et al., 2000; TNAU, n.d.-c).

office for latest applicable insecticides.

overwintering beetles. Additional application of foliar insecticide (around blooming) was shown to further suppress of population. A mid-season foliar insecticide application is aimed at controlling the first generation of bean leaf beetle (Bennett et al.).

#### **4.9** *Epilachna varivestis* **(Mulsant) (Coleoptera: Coccinellidae)**

**Identification:** Mexican bean beetles are copper to yellow, rounded with 16 black spots on their backs. Males can be distinguished from females by having a small notch on the ventral side of the last abdominal segment. The eggs are yellow about 1.3 mm long and elliptical. Larvae are yellow, oval, soft-bodied, grub like with darker, branched spines. The pupae are yellow and about 6 mm long. It moves very little, has fewer spines than the larva, and is most commonly found on the lower half of the soybean plant (Sanchez-Arroyo, 2009).

**Life cycle and damage**: females lay eggs in clusters of 40-75 on the undersides of bean leaves. They hatch in a week during warm weather or after at least two weeks under unfavorable conditions. The larvae are gregarious and feed voraciously for two to five weeks. The larva has five instars and attaches itself by the posterior end of the body to the underside of leaves, stems, or pods of the bean plants and often to parts of nearby plants and pupates. The pupal stage lasts 5-10 days. Adults and larvae feed on the underside of leaves and eat the softer leaf tissues. Damaged leaves appear netlike (Sanchez-Arroyo, 2009).

**Monitoring:** monitoring should be done weekly with directly observing the plant during early stages of growth. As the plant growth use sweep net or shaking the plants over the ground cloth for sampling *E. varivestis.* After shaking the plants quickly count number of the present adults and larvae (Sanchez-Arroyo, 2009).

**Economic and action thresholds:** economic threshold level ranges from 1 to 1.5 larvae per plant on beans or when 30–35% defoliation is observed prior to full bloom and 15% during pod-set and podfill (Sanchez-Arroyo, 2009).

**Control**: destruction of overwintering locations; late planting of the soybean crop; planting trap crops and resistant varieties are techniques that may reduce population build up. Releasing biological control agents such as tachinid fly, *Paradexodes epilachnae* (Aldrich) and the eulophid wasp, *Pediobius foveolatus* (Crawford) can control the number of *E. varivestis* beetles. If the threshold is exceeded application of systemic insecticides at planting has become a standard practice (Sanchez-Arroyo, 2009).

#### **4.10** *Melanagromyza sojae* **(Zehntner) (Diptera: Agromyzidae)**

**Identification:** adults of stem fly are shining black and about 2 mm long. The larva which is named maggot is white in color and remains inside the stem. The egg measures about 0.34 mm in length and 0.15 mm in width. It is whitish, partly transparent and the yolk occupies one third of the central part of the egg (TNAU, n.d.-c).

**Life cycle and damage**: The females lay eggs on or in the leaves. Maggots bore the nearest vein of the leaf and subsequently reach the stem through petiole and bore down the stem. If the infected stem is opened by splitting, zigzag reddish tunnel can be seen with maggot or pupae inside it. The maggots feed on stem cortical, may extend to tap root, killing of the plant. The third larval instar, mine a hole to the epidermis to assist in the emergence of the adult and pupates in the stem. The pupal period lasted 6-12 days (TNAU, n.d.-c). *M. sojae*

overwintering beetles. Additional application of foliar insecticide (around blooming) was shown to further suppress of population. A mid-season foliar insecticide application is

**Identification:** Mexican bean beetles are copper to yellow, rounded with 16 black spots on their backs. Males can be distinguished from females by having a small notch on the ventral side of the last abdominal segment. The eggs are yellow about 1.3 mm long and elliptical. Larvae are yellow, oval, soft-bodied, grub like with darker, branched spines. The pupae are yellow and about 6 mm long. It moves very little, has fewer spines than the larva, and is most commonly found on the lower half of the soybean plant (Sanchez-Arroyo, 2009).

**Life cycle and damage**: females lay eggs in clusters of 40-75 on the undersides of bean leaves. They hatch in a week during warm weather or after at least two weeks under unfavorable conditions. The larvae are gregarious and feed voraciously for two to five weeks. The larva has five instars and attaches itself by the posterior end of the body to the underside of leaves, stems, or pods of the bean plants and often to parts of nearby plants and pupates. The pupal stage lasts 5-10 days. Adults and larvae feed on the underside of leaves and eat the softer leaf tissues. Damaged leaves appear netlike (Sanchez-Arroyo, 2009). **Monitoring:** monitoring should be done weekly with directly observing the plant during early stages of growth. As the plant growth use sweep net or shaking the plants over the ground cloth for sampling *E. varivestis.* After shaking the plants quickly count number of the

**Economic and action thresholds:** economic threshold level ranges from 1 to 1.5 larvae per plant on beans or when 30–35% defoliation is observed prior to full bloom and 15% during

**Control**: destruction of overwintering locations; late planting of the soybean crop; planting trap crops and resistant varieties are techniques that may reduce population build up. Releasing biological control agents such as tachinid fly, *Paradexodes epilachnae* (Aldrich) and the eulophid wasp, *Pediobius foveolatus* (Crawford) can control the number of *E. varivestis* beetles. If the threshold is exceeded application of systemic insecticides at planting has

**Identification:** adults of stem fly are shining black and about 2 mm long. The larva which is named maggot is white in color and remains inside the stem. The egg measures about 0.34 mm in length and 0.15 mm in width. It is whitish, partly transparent and the yolk occupies

**Life cycle and damage**: The females lay eggs on or in the leaves. Maggots bore the nearest vein of the leaf and subsequently reach the stem through petiole and bore down the stem. If the infected stem is opened by splitting, zigzag reddish tunnel can be seen with maggot or pupae inside it. The maggots feed on stem cortical, may extend to tap root, killing of the plant. The third larval instar, mine a hole to the epidermis to assist in the emergence of the adult and pupates in the stem. The pupal period lasted 6-12 days (TNAU, n.d.-c). *M. sojae*

aimed at controlling the first generation of bean leaf beetle (Bennett et al.).

**4.9** *Epilachna varivestis* **(Mulsant) (Coleoptera: Coccinellidae)** 

present adults and larvae (Sanchez-Arroyo, 2009).

become a standard practice (Sanchez-Arroyo, 2009).

one third of the central part of the egg (TNAU, n.d.-c).

**4.10** *Melanagromyza sojae* **(Zehntner) (Diptera: Agromyzidae)**

pod-set and podfill (Sanchez-Arroyo, 2009).

has four or five generations per year and pupae overwinter in the stem. The infestation significantly reduced the plant height, number of branches per plant, number of trifoliate leaves, leaf area per plant and dry matter accumulation. The infestation rate ranges from 85 to 100% due to the planting dates and being higher on the late sown crop (Savajji, 2006).

**Monitoring:** Stem flies reached their peak in the 5th–8th weeks after planting and declined towards the end of the season. Observe percent seedling mortality, percent stem tunneling and areas of poor stand. Also, dig up some seed and examine for the presence of insects and or damage (Savajji, 2006).

**Economic and action thresholds:** economic threshold level is 5% plant infestation (Rao et al., 2007). However, according to (Johnson et al., 2009) there is no rescue treatment for this pest. Estimate area and amount of stand reduction for reporting in Comments. This information will be useful when making a decision on replanting.

**Control**: deep summer ploughing; proper crop rotation with dissimilar crops; removing and destroying the damaged plant parts can reduce the population. However, if the threshold is exceeded application of insecticides is essential. Spray monocrotophos 36 WSC twice, at the crop age of one and three weeks. In case of severe infestation, apply phorate or lindane in the soil 10 kg/ha before sowing. Soil application of phorate 10 G, 10 kg/ha or carbofuran 3 G, 30 kg/ha at the time of sowing will prevent early infestation by stem fly. One or two sprays of endosulfan 35 EC or dimethoate 30 EC or quinalphos 25 EC can stop the damage (Pande et al., 2000; TNAU, n.d.-c).
