Surendra K. Dara

Performance of the tobacco aphid (Homoptera: Aphididae) on various host plants.

The tobacco aphid, Myzus nicotianae Blackman, is a major pest of tobacco in the United States. It was separated from the green peach aphid, M. persicae (Sulzer), and described as a new species in 1987. Information on its host range is limited because the two species are so similar. Therefore, the performance of the tobacco aphid was studied on 28 potential host plants in six families. Numbers of offspring, age at first reproduction, longevity, weight, and percentage reproducing were compared. Tests were conducted on excised leaves or leaf disks maintained in Petri dishes in an environmentally-controlled chamber. Myzus nicotianae reproduced on hosts in the families Asteraceae, Convolvulaceae, Cruciferae, Malvaceae, and Solanaceae, but not on Spinacia in Chenopodiaceae. Myzus nicotianae generally reproduced most quickly, was heaviest, and produced the most nymphs on tobacco, Nicotiana tabacum L., and American black nightshade, Solanum americanum (Solanaceae). Performance also was good on Capsicum and S. dul...

Endophytic colonization and pest management potential of Beauveria bassiana in strawberries

BACKGROUND: Chemical pesticides are predominantly used for managing various pests on strawberries in California. Biological control is limited to the release of predatory mites against spider mites. Predominant use of chemical pesticides does not provide complete and satisfactory control of certain pests and interferes with biological control. Microbial control is an unexplored area in California strawberries. Limited pest control with current practices, risk of pesticide resistance, and concern for environmental safety associated with excessive use of chemical pesticides prompt the search for safer and effective alternatives. Entomopathogenic fungus, Beauveria bassiana (Balsamo) Vuillemin and a botanical pesticide, azadirachtin are active against most of the strawberry pests. Additionally, B. bassiana is known to endophytically colonize some plant species and provide protection against herbivore damage. Identifying non-chemical alternatives is a critical area in strawberry pest management. OBJECTIVE: Explore the potential of B. bassiana against strawberry pests and the ability to colonize strawberry plants. METHODS: Efficacy of reduced rates of chemical pesticides, B. bassiana, and azadirachtin against adult lygus bug, Lygus hesperus Knight were determined in laboratory assays. Greenhouse and laboratory studies were conducted to determine endophytic colonization potential of B. bassiana in strawberry plants. Efficacy of B. bassiana against L. hesperus was determined in small plot field trial in strawberries and against other pests in greenhouse strawberries was also studied. RESULTS: Certain combinations of chemical pesticides and B. bassiana at reduced rates improved L. hesperus mortality. Beauveria bassiana colonized and persisted in various strawberry tissues for up to 9 weeks after inoculation. No impact of the B. bassiana on L. hesperus numbers was seen in the field study, but was found effective, along with azadirachtin, against some pests in the greenhouse study. CONCLUSION: Non-chemical alternatives such as B. bassiana and azadirachtin have a good potential for strawberry pest management.

Incidence of Pandora neoaphidis (Remaudière and Hennebert) Humber (Zygomycetes: Entomophthorales) in the Myzus persicae (Sulzer) complex (Homoptera: Aphididae) on three species of Brassica in the fall and winter.

The incidence of the aphid pathogen, Pandora neoaphidis (Remaudiere & Hennebert) Humber, was monitored in populations of the Myzus persicae (Sulzer) complex (green peach aphid, M. persicae, and the...

Mite Pathogens and Their Use in Biological Control

An overview of infectious microorganisms associated with pest mites is presented. Many mites are major impediments to the production of food crops either in open fields or under protected environments such as greenhouses and plastic tunnels. Reliance on chemical acaricides for management of these mites is of serious concern due to the development of resistance in mite populations, environmental disturbance and effect on human health. Several pathogens play an important role in the regulation of pest mite populations through natural epizootics. The majority of these are fungi, but other pathogens include viruses, bacteria, protozoa, and nematodes. Several successful examples of pathogens that have been produced in vitro for the control of pest mites are presented. Interaction of the pathogens with beneficial arthropods such as predatory mites is also important for implementing biological control. Prospects for the application of acaropathogens in the management of mites in various agricultural systems are discussed.

Isolation and Evaluation of Beauveria bassiana (Deuteromycotina: Hyphomycetes) for the Suppression of the Glassy-winged Sharpshooter, Homalodisca coagulata (Homoptera: Cicadellidae)

The glassy-winged sharpshooter, Homalodisca coagulata (Say) (Homoptera: Cicadellidae), is a significant threat to California agriculture as a vector of the bacterium, Xylella fastidiosa Wells, caus...

Managing Strawberry Pests with Chemical Pesticides and Non-Chemical Alternatives

ABSTRACT Western tarnished bug or lygus bug (Lygus hesperus) is a major pest of California strawberries causing significant yield reduction. Other common insect pests include aphids (Chaetosiphon fragaefolii and Myzus persicae), greenhouse whitefly (Trialeurodes vaporariorum), and western flower thrips (Frankliniella occidentalis). Growers mainly depend on chemical pesticides for managing these pests. Limited control with some of the available chemical pesticides and the risk of resistance development due to their repeated use warrant a strong integrated pest management program where multiple tools can be utilized. Field studies conducted in commercial strawberry fields from 2012–14 in Santa Maria with an emphasis on managing L. hesperus demonstrated the potential of botanical and microbial pesticides. Replacing one or more applications of chemical pesticides with botanical and microbial alternatives and using them in different combinations can make a significant contribution to a sustainable management strategy.

Evaluation and Molecular Characterization of Beauveria bassiana for the Control of the Glassy-winged Sharpshooter (Homoptera: Cicadellidae) in California

The glassy-winged sharpshooter, Homalodisca coagulata (Say), is an important pest on grapes, citrus, almonds and other commercial crops in California as it is a vector of Xylella fastidiosa Wells, a bacterium that causes Pierces disease in grapes, citrus variegated chlorosis, almond leaf scorch and other plant diseases. Various entomopathogenic fungi isolated from natural infections of H. coagulata, its habitats and other insect hosts were evaluated against this insect vector. Based on these studies, 3 isolates of the hyphomycetous fungus, Beauveria bassiana (Balsamo) Vuillemin, were selected for further evaluation. Two of these were California isolates, one each from the three-cornered alfalfa hopper, Spissistilus festinus (Say), and soil from H. coagulata habitat, and the third was a Texas isolate from natural infections of H. coagulata. All three were similar in their virulence to H. coagulata under laboratory conditions. The genetic relatedness of the B. bassiana isolates also was compared using single sequence repeat (SSR) markers which showed genetic diversity of this species based on the source of the isolate. Some isolates were 4x more infectious than others demonstrating that virulence of B. bassiana is not necessarily associated with their genetic relatedness.

Distribution, Cultivar Susceptibility, and Epidemiology of Apium virus Y on Celery in Coastal California

Apium virus Y (ApVY) is a potyvirus that was recently found to cause crop loss to celery (Apium graveolens) in California. Symptoms on leaves exhibit varying forms of chlorosis and necrosis. Depending on the cultivar, celery petioles could also exhibit extensive necrotic, sunken, elongated lesions. Severely affected plants were unmarketable. Disease incidence surveys found that a susceptible celery (cv. 414) showed 55% (2007) and 71% (2008) disease. Because it was noted that the Apiaceae weed poison hemlock (Conium maculatum) was present in almost all areas where ApVY affected celery, a 4-year survey collected overwintered hemlock from six coastal county regions and tested composite samples for ApVY using reverse transcription-polymerase chain reaction (RT-PCR) and ApVY-specific primers. These plants were consistently positive for ApVY. Seeds collected from these plants were also positive when tested with the same RTPCR method. However, when ApVY-positive hemlock seeds were germinated and the resulting seedlings tested, all results were negative. The failure of ApVY to be transmitted from hemlock seeds to seedlings was further documented by collecting newly germinated hemlock seedlings from the field and testing them with RT-PCR. All such seedlings were negative for ApVY even though large, adjacent, overwintered hemlock plants tested positive. Two crops of celery seed were produced from ApVY-positive mother plants; celery seed from these infected plants likewise tested positive for ApVY, but seedlings grown from the seed lots were negative for ApVY. Twenty-one celery and celeriac cultivars were inoculated with ApVY using viruliferous aphids, planted in a replicated field trial, and then grown to maturity. Seven cultivars remained symptomless, tested negative for ApVY, and showed signs of possible resistance. The epidemiology of disease caused by ApVY in California evidently involves poison hemlock as a common overwintering host with subsequent vectoring of the virus from hemlock to celery via aphids. ApVY was not seedborne in this weed host or in celery in our experiments. Our data suggest that growers can manage this disease by controlling poison hemlock weed populations and by planting celery cultivars that are not susceptible to ApVY.

Microbial biopesticides for insect pest management in India: Current status and future prospects

The biopesticide industry in India is undergoing rapid change, reflecting increased global trade in agricultural commodities, a changing regulatory environment and evolving consumer preferences. Currently biopesticides comprise ≈ 5% of the Indian pesticide market, with at least 15 microbial species and 970 microbial formulations registered through the Central Insecticides Board and Registration Committee (CIBRC). As of 2017, over 200 products based on entomopathogenic fungi (Beauveria bassiana, B. brongniartii, Metarhizium anisopliae s.l., Lecanicillium lecanii and Hirsutella thompsonii) and nematicidal fungi (Purpureocillium lilacinum and Pochonia chlamydosporia) are registered for use against various arthropods and plant parasitic nematodes. Regarding bacteria, over 30 products based on Bacillus thuringiensis (Bt) subsp. kurstaki are registered against bollworms, loopers and other lepidopterans, while 12 based on Bt subsp. israelensis and three with Bt subsp. sphaericus have been used against mosquitoes. Two viruses are registered, namely Helicoverpa armigera nucleopolyhedrovirus (22 products) and Spodoptera litura nucleopolyhedrovirus (5 products) for use against bollworms and armyworms. Four entomopathogenic nematode species are sold in Indian market. These include long-lasting wettable powder formulations of Heterorhabditis indica developed by the ICAR-National Bureau of Agricultural Insect Resources, Bengaluru which have been distributed on a large scale to control white grubs and other sugarcane pests. Biopesticide research on the subcontinent is at a relatively early stage, but evolving rapidly, and focusing on indigenous entomopathogens. Despite onerous regulation, quality-control issues and limited large-scale production facilities, investment in domestic fermentation technologies, improved delivery systems, and promotion of biological control through private and public initiative will increase the share of microbial biopesticides in the country.

Evaluating Correlations and Development of Meteorology Based Yield Forecasting Model for Strawberry

California state is among the leading producers of strawberries in the world. The value of the California strawberry crop is approximately