Back To BNI Home
Back to BNI News


December 2001, Volume 22 No. 4

 

General News

   

Biocontrol of Diamondback Moth in St Helena

The diamondback moth (DBM), Plutella xylostella, is a serious pest of crucifer crops on the island of St Helena, a small British island in the South Atlantic Ocean. Farmers were heavily dependent on chemical pesticides, often overdosing and mixing several pesticides when recommended dosages were not effective. Surveys in cabbage fields revealed that the only parasitoid of DBM on St Helena was the ichneumonid larval-pupal parasitoid Diadegma mollipla, which also occurs in several countries on the African mainland. As most supplies to St Helena, including fresh produce, are shipped from Cape Town, it was assumed that DBM as well as D. mollipla have been introduced into the island with cabbages from South Africa. Because D. mollipla was not able to reduce DBM populations on St Helena to below economic damage levels, a biological control project managed by the IPM Project on St Helena, NRInternational, UK and funded by DFID (the UK Department for International Development) was initiated. The Plant Protection Research Institute (PPRI) in Pretoria, South Africa was contracted to supply parasitoids of DBM to St Helena and train personnel of the IPM Project in mass rearing the moth and its parasitoids, parasitoid release methods and the follow up of parasitoid dispersal and establishment.

During May 1999, a consignment of the braconid Cotesia plutellae, a larval parasit-oid, and the ichneumonid Diadromus collaris, a pupal parasitoid, was shipped to St Helena. It was assumed that if these parasitoids became established they would not compete with the local larval-pupal parasitoid Diadegma mollipla. St Helena does not have an airport, and the consign-ment was flown from Pretoria to Cape Town and then undertook a 6-day sea voyage on board the RMS St Helena to the island.

The consignment contained all developmental stages of the parasitoids, i.e. adult wasps, parasitoid cocoons and parasitized DBM larvae and pupae. Daily on board the ship, adult wasps were fed with honey and water, and the parasitized DBM larvae were provided with fresh cabbage leaves until parasitoid cocoons formed or the larvae pupated.

On St Helena a rearing facility was established in which a DBM culture was maintained on potted cabbage plants and the two parasitoids were mass reared in separate wooden cages. In order to boost the genetic material of the parasitoid cultures in St Helena, an additional consignment of C. plutellae and Diadromus collaris was sent from PPRI in Pretoria in December 1999.

Before the releases of the parasitoids, extension officers of the IPM Project visited many farms and recommended that in order to give the introduced parasitoids a chance to establish, farmers replace chemical insecticides with Bt sprays to combat DBM outbreaks.

The two parasitoids were released into the field continually from May 1999 to September 2000. A total of 17,500 C. plutellae and 23,500 D. collaris were released in ten different farms across the island.

During January to March 2000, a preliminary survey was conducted in the ten release sites and in an additional nine farms (a total of 19 farms) to monitor the dispersal and establishment of the introduced parasitoids.

As expected in this early stage of the project, Diadegma mollipla was the most abundant and widely distributed parasitoid found in the survey. It emerged from DBM samples taken from 17 farms.

Samples of DBM larvae were collected in 16 farms and C. plutellae was present in samples from 15 farms. In eight of these farms parasitoids have never been released. The proportion of DBM larvae parasitized by C. plutellae was relatively high. For example, in Briars 34 C. plutellae emerged from 104 collected larvae (32.7% parasitism), in Mulberry Gut 19 C. plutellae emerged from 70 larvae (27.7% parasitism) and in Pouncey's (not a release site) 24 C. plutellae emerged from 30 DBM larvae (80% parasitism).

DBM pupae were sampled in 14 farms and samples from five farms, of which one has not been a release site, yielded Diadromus collaris. The proportion of parasitized pupae ranged between 0% and 55%. In one site, Nr Half Way, 11 D. collaris emerged from 20 collected pupae (55% parasitism). The results from this early survey indicated that the two parasitoids had survived in the release sites, had found and parasitized the pest and were dispersing.

As the insect rearing facility of the IPM Project on St Helena was needed for other projects, the rearing of DBM and its parasitoids was terminated shortly after the last parasitoid release in September 2000.

The IPM Project personnel conducted another field survey early in 2001 but it was called off because of extremely low infestation levels by DBM. However, cocoons of C. plutellae were present in most farms, which is an indication that the parasitoid could have been the cause for the decline in DBM population levels. Spring (September-October) is normally when DBM outbreaks occur on St Helena but local farmers have commented that DBM infestations have not been recorded this year and no chemical or Bt treatments have been requested by farmers since March 2001.

By: Rami Kfir,
Plant Protection Research Institute,
Pretoria 0001, South Africa
Email: rietrk@plant2.agric.za
and
Jason Thomas,
Agriculture & Natural Resources Department,
St Helena Island, South Atlantic Ocean

This article also appears in the ARC-PPRI Bulletin, Plant Protection News No. 59 (Spring/Summer 2001), with agreement of the author and PPRI.

Coconut Mite in India: Biopesticide Breakthrough

Aceria guerreronis, the only eriophyid mite considered to be serious on coconuts, has been a big problem to coconut cultivation in Central and South America, the Caribbean and West Africa. The mite was first reported from Mexico in 1960 and was described by Keifer in 1965. Recently, the pest has assumed serious proportions in India and Sri Lanka and experts have not ruled out its further spread to other coconut economies in the east. [See also: Moore, D. (2000) BNI 21(3) (September), 83N-88N. Non-chemical control of Aceria guerre-ronis on coconuts.]

In India, A. guerreronis was first observed to be causing severe damage to coconuts in the southern state of Kerala in the late 1990s. The pest has now spread to almost all the districts of Kerala and the major coconut-growing districts of its neighbouring states including Tamil Nadu, Karnataka, Andhra Pradesh, Pondicherry and Goa in mainland India and the Lakshadweep Islands in the Arabian Sea. Losses of 25-30% in copra yield have been recorded. With its high reproductive rate, the mite is increasing in great numbers and spreading fast as well.

The first symptoms of mite infestation are white streaks, which originate from the perianth and go downwards along the nut surface. Later, white to cream-coloured triangular patches are formed along the edge of the perianth. As the fruit increases in size, the older patches turn brown and acquire a corky appearance. And at the same time, new patches start appearing owing to the shifting or formation of new colonies of the mite. Because of the formation of cracks, the exocarp splits and the fissures can reach deep into the mesocarp.

Until the advent of the mite, probably no other pest in India created such an unprecedented panic among farmers, agricultural scientists, politicians and bureaucrats alike. Even ordinary people, who have one to a few trees around their residence, became panicky when they first realised that mites were attacking their coconuts.

The ensuing hue and cry resulted in the prescription of a variety of chemicals by scientists and officers of central institutes, universities and the departments of agriculture in different states. The chemicals that found favour with the farmers during the initial years were monocrotophos (root feeding or stem injection), dicofol, endosulfan and ethion. Later triazophos and carbosulfan entered the list of recommended chemicals. In addition, micronized wettable powder formulation of sulphur at 0.4 % and azadirachtin at 0.004% concentration are also recom-mended for spraying. A homemade 2% neem oil-garlic soap mixture has also been very popular among Kerala farmers. Nevertheless, none of the methods could bring the pest under sufficient control. Environment and health have been the ultimate casualties.

The results from experiments in many countries indicate that chemical control is possible, but the many treatments and the quantities of chemicals required make it not only uneconomical but also dangerous to the environment and various life forms. Resistance to chemicals is also feared. With the passing of time the problem has been becoming a political issue as many of the farmers and politicians have come to the conclusion that there is no effective control measure in sight.

A recent study in Kerala is an eye-opener. In the Alappuzha district of Kerala, more than 70% of coconut growers expressed their reservations about the extensive use of chemicals against the mite, citing the inimical nature of pesticides to natural enemies. They preferred the use of biopesticides to toxic chemicals. And surprisingly, many coconut farmers that we came across in the affected states were unanimous in their view that chemicals bring about havoc in the long term. Yet in spite of the growing alertness of the public, when it comes to the ground reality, chemicals still have a large customer base.

Concentrated surveys since early 1999 for pathogens of the coconut mite in the southern states had indicated the natural regulatory role played by many entomopathogens, especially Hirsutella thompsonii, the well-known eriophyid mite-specific fungus. We isolated and investigated the potential of many strains of the fungus against the mite and uncovered the immense potential of the pathogen. That resulted in the development of a mycoacaricide named 'Mycohit' based exclusively on H. thompsonii, the first Indian mycoacaricide based exclusively on this species.

The product is based on the strain MF(Ag)5 [ITCC 4962; IMI 385470] originating from Tamil Nadu. The product has a potency of 2.5 × 108 CFU/g (colony-forming units/g) with a moisture content of about 12%. Mycohit is generally recommended for use as a spray when the weather is dry. It should be used at 1% concentration and about 2 litres of the spray solution is needed per tree. Up to 50 trees (about 1 acre/~0.4 ha) can be treated with 1 kg of the product. In certain situations such as after a heavy rain, just dusting of the product on the bunches is enough because of the wet microclimate within the crown.

Field investigations have been conducted in more than 15 locations to evaluate the performance of Mycohit. In several places, by the 70th day of the experiment more than 70% and 90% mortality of the mite was observed in nuts sprayed once and twice (at 2-week intervals), respectively.

Then our immediate concern was to make available the required quantity of the mycoacaricide, which runs into several thousand tonnes, to the affected planters. Therefore, towards the objective of commercializing Mycohit, help has been sought from the Research & Development Division of the Hindustan Antibiotics Limited (HAL), Pimpri, Pune. We have given the fungal culture and know-how to HAL for pilot-scale production of the mycoacaricide. HAL in turn produced two different variants of Mycohit, namely, Formulation-T (talc-based and similar to the original) and Formulation-W (wettable powder), using our strain and know-how for preliminary bioefficacy investigations. The field trials conducted by us indicated that the former preformed the better and so we chose the talc-based formulation for further work. Subsequently-produced batches of the talc-based formulation ('Mycohit-T') performed consistently well in the field and produced results on a par with our original version of the myco-acaricide.

In an ongoing trial (started in June 2001, at the beginning of the southwest monsoon), both versions of Mycohit showed highest mortality of 98.80% (ours) and 96.62% (HAL's) by the end of the third week, i.e. a week after the second application of the product.

The Government of India has recently (February 2001) included Hirsutella in the Schedule to the Insecticides Act (1968) because of our efforts. This has enabled the registration of products based on the fungus with the Central Insecticides Board (CIB). HAL has been testing the biosafety of H. thompsonii and the product separately for us thus paving the way for registration of Mycohit in the coming months.

The mite has recently been found to be infesting the palmyrah palm (Borassus flabellifer) in Tamil Nadu State, where the tree is an important source of toddy. Farmers are also apprehensive of its spread to the arecanut (Areca catechu), which has become one of the most remunerative plantation crops in the south, especially in Karnataka. Therefore, H. thompsonii has a very significant role to play through its natural presence as well as in the form of a product.

We have also isolated Sporothrix fungorum, which is also widely found associated with the coconut mite in south India. Preliminary trials with the fungus have given encouraging results. Similarly, we have also tried Verticillium lecanii with considerable success.

By: P. Sreerama Kumar & S. P. Singh, Project Directorate of Biological Control (ICAR),
P. B. No. 2491, H. A. Farm Post,
Hebbal, Bellary Road,
Bangalore 560 024,
Karnataka, India
Email: pdblc@kar.nic.in
Fax: +91 80 341 1961

Building Stem Borer Management Capacity

Some 20 moth species constitute the most important cereal pests in many parts of Africa. Their caterpillars, commonly known as stem or stalk borers, bore into the stems of maize, sorghum, millet and rice, often killing the plant. The cereals attacked are grown on small farms to feed the farmers and their families and are of great importance as the staple food for the population in most parts of Africa. Complex control measures, including the use of chemicals, are often inappropriate, and the development of specific regional strategies for environmentally sustainable stem borer management is therefore a priority.

A 2-year collaborative cereal stem borer management initiative in southern Africa plans to bring this goal closer. Funded by USAID (US Agency for International Development), this venture involves ICIPE (International Centre for Insect Physiology and Ecology), Kenya and two South African ARC (Agricultural Research Council) institutions, PPRI (Plant Protection Research Institute) and GCI (Grain Crops Institute). The aim is to increase the capacity of national institutions in southern Africa to manage maize and sorghum stem borers using environmentally sustainable methods. To this end, the project is engaging national programme scientists in Mozambique, Angola, Swaziland, Lesotho, Malawi and Botswana.

The project began with a planning workshop and training course, held in South Africa in September 2000. The training course for 15 participants developed skills in stem borer and natural enemy identification, their collection and rearing (including mass rearing) and host plant resistance screening. Participants also learnt techniques for biological control and habitat management, and were given an introduction to biological and transgenic plant resistance. The planning workshop developed work plans for country-wide surveys of stem borers and their natural enemies.

In July 2001, progress was discussed during a special symposium held during the 13th Congress of the Entomological Society of Southern Africa. Representatives from the participating countries reported on the progress of their work, and proposed activities for the future. The proceedings of the workshop are being compiled and will be published shortly.

Much baseline information on the biology, natural enemies and control of cereal stem borers in Africa can be found in:
Polaszek, A. (ed) (1998) African cereal stem borers: economic importance, taxonomy, natural enemies and control. Wallingford, UK, CABI Publishing, 556 pp. ISBN 0 85199 175 0

Source: Breytenbach, E. (2001) Collaborative cereal stem borer management initiative.
ARC-PPRI Bulletin, Plant Protection News, No. 58 (Autumn/Winter 2001), pp. 2-4.

For project information contact: Rami Kfir, Insect Ecology Division,
ARC-Plant Protection Research Institute, Private Bag X134,
Pretoria 0001, South Africa
Email: rietrk@plant2.agric.za
Fax: +27 12 329 3278
Or: Bill Overholt,
International Centre of Insect Physiology and Ecology,
P.O. Box 30772,
Nairobi, Kenya
Email: woverholt@icipe.org

Biocontrol Progress in India

Once again, the Project Directorate of Biological Control (PDBC) based in Bangalore has been a hive of biocontrol activity. Major highlights of work in the last year1 included the introduction of two parasitoids of the coffee berry borer (Hypothenemus hampei; CBB). Prorops nasuta and Phymastichus coffea were imported from Colombia and were established in the field, thus contributing two new country records.

The maintenance and supply of host insects and natural enemies from PDBC, together with the basic research that supports this, continues to be a priority activity to which much energy and expertise is devoted. Biosystematic studies were conducted on Indian predatory coccinellids, with Diomus recorded from India for the first time. Rearing techniques were standardized for a number of natural enemies, and biological and behavioural studies were conducted. Artificial diets were devised for host insects including Spodoptera litura and a number of natural enemies. More progress was made in the development of temperature- and multiple pesticide-resistant strains of trichogrammatid parasitoid wasps. Advances were also made on the production and use of insect viruses and fungi, fungal and bacterial antagonists, entomopathogenic nematodes, and fungal biocontrol agents of plant parasitic nematodes and weed pathogens.

On the information side, a CD version of the expert system BIORICE is now available, and a system for pest control in oilseeds and pulses is in preparation.

The success of PDBC in conducting necessary basic research, and developing this through lab studies and field trials to effective pest control solutions for farmers is illustrated by the many and varied field tests of modules they are developing for the biological management of pests in many crops. In the past year a vast number of field trials have been conducted in sugarcane, cotton, tobacco, pulses, rice, coconut, fruit and vegetable crops and potatoes in different states. A striking success this year has been the development of a biopesticide for coconut mite (Aceria guerreronis) [see 'Coconut mite in India: biopesticide breakthrough', General News, this issue]. Monitoring and evaluation of weed control agents against water hyacinth (Eichhornia crassipes) is also highlighted.

The Annual Report2 provides details of these and other research efforts by PDBC in Bangalore and in its coordinating centres spread over different parts of India. The work at PDBC included biosystematic studies on Indian predatory Coccinellidae. Progress in rearing work included multiplication of Harmonia octomaculata on Ferrisia virgata and Aphis craccivora in the lab. It was also shown that higher parasitization rates of Helicoverpa armigera eggs by Trichogramma chilonis could be achieved with the aid of synomones (herbivore-induced plant chemicals). Artificial diets were syn-thesized for rearing Cheilomenes sexmaculata, Coccinella septempunctata, Chilocorus nigrita and Cryptolaemus montrouzieri. Endosulfan-resistant T. chilonis was utilized for developing a multiple-resistant pesticide strain. Fungal pathogens were isolated from Helicoverpa armigera, Plutella xylostella, and Chilo partellus. Nomuraea rileyi was cultured and a water dispersible powder formulation of Bacillus thuringiensis (Pusa Bt) developed and bioassayed. Trichoderma harzianum PDBCTH10 and T. viride PDBCTV23 as powder formulation were tested for control of fusarial wilt and Rhizoctonia wet root rot of chickpea. The entomopathogenic nematodes (EPNs) Steinernema carpocapsae, S. bicornutum and Heterorhabditis indica isolates were successfully used for control of Leucinodes orbonalis on brinjal [aubergine] in field trials. A talc-base formulation of EPN isolates showed a shelf-life of more than 3 months. The mycoherbicidal potential of Lasiodiplodia theobromae, Nigrospora oryzae, Phoma chrysanthemicola and P. eupyrena was tested against Parthenium hysterophorus.

In Punjab, a BIPM (biocontrol-based IPM) module proved effective for cotton pest control. In Gujarat, Andhra Pradesh, Tamil Nadu, Maharashtra and Punjab, cotton bud and boll damage and populations of sucking pests were lower with the BIPM module than with insecticide treatments. Bt products gave effective control in cotton in Gujarat. In Andhra Pradesh, the use of the EPN Steinernema carpocapsae was found superior to SlNPV against Spodoptera litura in tobacco nurseries. In Tamil Nadu, the pod borer (H. armigera) complex in pigeon pea was controlled with Bt-HaNPV application. In Andhra Pradesh, Heter-orhabditis indica sprays were successful against Helicoverpa armigera in pigeon pea. In Assam, Punjab, Gujarat and Tamil Nadu, integrated use of biocontrol agents and Bt was effective in reducing rice stem borer (Scirpophaga incertulas) popu-lations. BIPM modules at different crop stages were useful in management of rice stem borer and leaf folder (Cnaphalocrocis medinalis) in Kerala and Punjab. In Karnataka, as noted above, control of coconut mite was successfully achieved with the mycoacaricide formulation 'Mycohit' containing Hirsutella thompsonii. In Himachal Pradesh and Karnataka, fruit damage due to pomegranate fruit borer (Deudorix isocrates) was controlled with parasitoid (Trichogramma chilotraeae) releases. In Kerala and Assam, the weevils Neochetina eichhorniae, N. bruchi and the mite Orthogalumna terebrantis gave successful control of water hyacinth.

By: Dr. S. P. Singh

1Singh, S.P.; Rao, N.S.; Ramani, S.; Poorani, J. (eds) (2001) Research highlights - 2000-01. Bangalore, India; PDBC, 21 pp.

2Singh, S.P.; Rao, N.S.; Ramani, S.; Poorani, J. (eds) (2001) Annual Report 2000-01, Project Directorate of Biological Control, Bangalore. Bangalore, India; PDBC, 218 pp.

Copies can be obtained from:
Project Directorate of Biological Control (ICAR),
P.B. No. 2491, H. A. Farm Post,
Hebbal, Bellary Road,
Bangalore 560 024,
Karnataka, India
Email: pdblc@kar.nic.in / drspsingh@valise.com
Fax: +91 80 3411961

IOBC-Africa: Helm Changes Hands

This year saw the retirement from the Presidency of the International Organ-ization For Biological Control of Noxious Animals and Plants - Afro-Tropical Regional Section (IOBC-ATRS) of one of the great figures in weed biological control, Dr Helmuth Zimmermann. As Division Manager of the Weeds Division at PPRI, he oversees the integrated and biological control of invading alien plant species in South Africa in four laboratories spread through South Africa. His own main research focus is the biological control of cacti, and he is currently involved in numerous projects throughout the world on the biological and integrated control of cacti, and their utilization.

Helmuth had been President of IOBC-ATRS since 1996, and his most enduring legacy is the IOBC Global Working Group on Biological and Integrated Control of Water Hyacinth. This was set up in 1997 and held its first workshop in Harare, Zimbabwe in 1998. It is fitting, then, that a key figure in the well-publicized success of biological control against water hyacinth (Eichhornia crassipes) in Lake Victoria is succeeding him The Global IOBC Executive Committee appointed James Ogwang as President of IOBC-ATRS following Helmuth's recommendation.

James Ogwang was born in Uganda, and obtained his BSc Degree (Botany and Zoology) from Makerere University in 1979. He continued his studies in the UK, where he gained an MSc. and a DIC (Diploma of Imperial College) from Imperial College, University of London in 1984. Moving back to Africa, he was awarded a PhD from Rivers State University of Science and Technology, Nigeria in 1991. He was employed as a Scientific Officer at Uganda's Ministry of Agriculture before a spell (1991-1992) at ICIPE (International Centre for Insect Physiology and Ecology) in Nairobi as a Post-Doctoral Fellow. Upon his return to Uganda from ICIPE in 1992, he was employed as Senior Research Officer in the National Agricultural Research Organ-ization (NARO), and was assigned to develop a Biological Control Unit to integrate use of natural enemies in Uganda's crop protection policy.

James has worked mainly in the field of biological control and he was instrumental in promoting its adoption in Uganda, where it has been used successfully to combat such devastating pests as the cassava mealybug (Phenacoccus manihoti) and, more recently, in the successful biological control of water hyacinth in Uganda. He is currently the Head of Biological Control Unit of NARO.

James brings experience, enthusiasm and energy to meet the challenge of following in Helmuth's footsteps. One of his first initiatives is to organize (together with Martin Hill, PPRI) the next water hyacinth Global Working Group meeting (see Announcements section, this issue).

All About Biocontrol

Trawling the Internet for news and background information occasionally throws up a real gem. This quarter it led to the University of California, Riverside website, which hosts a biocontrol goldmine in Professor Legner's Faculty Homepage at:
http://www.faculty.ucr.edu/~legneref/

Innocuously called 'Discoveries in Natural History & Exploration', the site includes a biocontrol database, and this incorporates lecture notes and a biocontrol text developed over many years as teaching materials for courses at UC Riverside. The database, which is for educational purposes only, is almost a 'one-stop shop' for the student of biological control, and especially the history and theory of classical biological control. The Biocontrol Database has a long and distinguished history. It began as a course taught by the founder of the Department of Biocontrol, Harry Scott Smith. Later Paul DeBach, Charles Fleschner and Ernest Bay developed the course further, with Fred Legner teaching the final version, which comprises most of the Database on the Internet today. Now retired from the University of California at Riverside, Prof. Legner is devoting time to developing an unparalleled Internet resource.

Exhaustive coverage of the theory and practice of biocontrol - everything from ecological theory to implementation and evaluation methods, is backed up by sections covering biocontrol on a group-by-group basis, and also on a regional basis. Some 'new' topics, such as nontarget effects are not yet given up-to-date coverage, but as Prof. Legner makes clear below, the database is very much in development, and is building on its solid base. The extensive coverage afforded by a database allows inclusion of many topics often given scant space in printed texts, and for which summarized information can be hard to find. There is, for example, an in-depth discussion in the section, 'Economic gains from biological control' of not only the measurable monetary costs and benefits of biological control, but also less-easily quantifiable economic gains from increased food security and reduced pesticide use. Prof Legner has considerably enlarged the database, too, to include peripheral aspects of biocontrol, such as insect morphology, taxonomy and integrated control. Other links developed naturally from the numerous travels that he made to secure natural enemies of insects from many lands.

There is a depressing endnote, though. The University of California, Riverside used to have a Department of Biological Control of international renown. In 1962, when Fred Legner joined the Department, there were about 45 full-time faculty and staff devoted to the deployment of natural biological control (a branch of the Department resided at Albany, California). Most efforts involved the importation of natural enemies to combat alien pest insects and mites. There cannot be many readers of this journal who have not benefited either directly or indirectly from the work and research of this department, yet today only remnants remain.

An enduring legacy of the people who worked there, though will be this authoritative Biocontrol Database. There are no restrictions on the use and dissemination of information, as long as it is for nonprofit educational purposes. Fred Legner says he is still developing the site, and is in the process of obtaining feedback from colleagues; parts of it are in a prog-ressive state of change, with new or revised material appearing often daily.

It is impossible to give more than a flavour of what the site contains here, so readers are encouraged to take a look for themselves.

Contact: Professor Fred Legner
Email: legneref@hotmail.co

Back To BNI Home
Back to BNI News