June 1997, Volume 18 No. 2

General News

David Rosen (1936-1997)

David Rosen, The Vigevani Professor of Agriculture and Professor of Entomology at the Faculty of Agriculture of the Hebrew University of Jerusalem, and World leader in chalcidoid taxonomy and biological control of insect pests, died on 8 January 1997 after a brave struggle with cancer. David was born in Tel Aviv, Israel in 1936. He pursued his scientific studies at the Hebrew University where he obtained his M.Sc. degree summa cum laude in 1959 and his Ph.D. in agricultural entomology in 1965. David remained a permanent staff member of the Faculty of Agriculture, rising quickly from the rank of lecturer in 1967 to Full Professor in 1978. In 1990 he became the first appointee of the Vigevani Chair in Agriculture. He chaired the Department of Entomology, first as acting chairman (1974) and then as elected chairman, from 1977 to 1980 and from 1992 on, resigning from his second term after discovering his illness in 1995. In addition to his duties as chairman, David was very involved in University life. He was active on numerous committees as well as being Director of the Research Center for Integrated Pest Managment from 1988 on. He was also deeply involved in teaching, both at the administrative level, where he contributed measurably to the shaping of future teaching curricula in plant protection, and at the personal level where he was known as an excellent teacher and lecturer at home and abroad. His death came only a few days before he would have been awarded the M. Millikan Prize for Distinction in Teaching in recognition of his excellence.

Throughout his career, David devoted a large part of his time to improving Israeli agriculture. He contributed measurably to the introduction and improvement of biological and integrated pest control methodology. His awareness of environmental problems culminated in his heading a committee appointed by the chief scientist for the Ministry of Agriculture, to examine the possibilities of reducing the use of poisonous pesticides in agriculture. For this purpose, he assembled a committee comprising leading scientists and extension service, plant protection and inspection service officers together with producers of plant protection products. The committee's report that was published in 1990 after almost two years of deliberations, reflected his leadership, excellent ideas and superb penmanship, and served as an important landmark in plant protection in Israel.

David was an active member of the Entomological Society of Israel since its establishment and served on its committees till the last day of his life. He was also a member of the editorial board of the Society Journal: The Israel Journal of Entomology.

On the international level, David was well known as one of the proponents and leaders in biological pest control. He was an active member of the IOBC and a member of the IOBC\WPRS Council, leaving his mark on many of its decisions. He also served as a member of the FAO\UNEP Inter-national Panel of Experts on Integrated Pest Control. His active participation in the International Plant Protection Congresses led the organizing com-mittee to elect him chairman for the next (14th) meeting in 1999, to be held in Israel. His international contributions included editorial duties in numerous professional publications including: Annual Review of Entomology, Biological Control, Entomophaga, Integrated Pest Management Reviews, and The Journal of Hymenoptera Research. David took also an important part in the International Congresses of Entomology, in which, for the last 20 years, he organized symposia and participated as an invited speaker in numerous forums. During the 20th Congress, held last summer in Firenze, Italy, he was elected to replace Professor R. Galun as a member of the organizing committee for the 21st Congress.

He travelled extensively in the Americas, Europe, the CIS, the Far East and Australia and fulfilled many international appointments. These included visiting Professorships of Entomology at the University of California in Berkeley and Riverside, the Universities of Ankara and Adana in Turkey, the University of Maryland in College Park, Texas A&M Univer-sity in College Station, and the University of Florida in Gainesville.

David has published widely in Hebrew and English. His scientific contributions include 164 refereed articles, and seven books that are listed at the end of this article. The latter include two books that he co-authored with Paul DeBach, and five books that he edited.

David was a well known taxonomist of parasitic Hymenoptera, and was known both as a specialist of Encyr-tidae and Aphelinidae, and as a strong proponent of recognizing the im-portance of taxonomy for biological sciences in general and biological control in particular. His taxonomic contributions culminated in 1979 in the publication of a revisionary book on the genus Aphytis co-authored with Professor Paul DeBach. This work gained the authors the prestigious Filippo Silvestri Foundation prize from the University of Naples.

David was a proud Israeli, believing in the right of all peoples to live freely in their homeland. He will also be remembered as speaking up, on many occasions, in favour of separating science from politics. He was a family man, a good husband and proud father to his three children. During the last few years he could often be seen in the company of his wife, Mazal, at many professional meetings. The many students and scientists whom he supervised for both M.Sc. and Ph.D. degrees, as well as his colleagues in Israel and abroad, will always remember David as an exemplary family man, a true friend and a brilliant colleague who was always ready to contribute and help with his wisdom, humour and scientific insight. Together with his family and the scientists' community we shall sorely miss him.

Books authored or edited by Professor D. Rosen:

Rosen, D.; DeBach, P. (1979) The species of Aphytis of the World, Hymenoptera, Aphelinidae. Jerusalem; Israel Universities Press and The Hague, Netherlands; W. Junk, 801 pp.

DeBach, P.; Rosen, D. (1991) Biological control by natural enemies. Cambridge, UK; Cambridge University Press, 440 pp.

Rosen, D. (1990) (ed) Report of the steering committee of reducing use of pesticides in agriculture. Rehovot, Israel; Chief Scientist, Faculty of Agriculture, 148 pp. [in Hebrew]

Rosen, D. (ed) 1990 Armored scale insects their biology, natural enemies and control. World Crop Pests. Amsterdam, Oxford, New York, Tokyo; Elsevier, Volume A, 384 pp. and Volume B, 688 pp.

Rosen, D.; Bennet, F.D.; Capinera, J.L. (eds) (1994) Pest management in the subtropics: biological control - a Florida perspective. Andover, UK; Intercept Ltd, Volume I, 737 pp.

Rosen, D.; Bennet, F.D.; Capinera J.L. (eds) (1996) Pest management in the subtropics: integrated pest management - a Florida perspective. Andover, UK; Intercept Ltd,
Volume II, 578 pp.

Rosen, D.; DeBach, P. (eds) (1994) Advances in the study of Aphytis (Hymenoptera: Aphelinidae). Andover, UK; Intercept Ltd, 362 pp.

By: Dan Gerling and Manes Wysoki

Ken Hagen

The biological control world lost another well-known and respected figure with the death of Kenneth Hagen earlier this year. Ken Hagen, from the University of California at Berkeley, was a pioneer of IPM by enhancement of action of native natural enemies. A full appreciation will be published in the next issue.

Locust Control Goes Green

Once upon a time they sprayed dieldrin from the back of Landrovers to control locusts in Africa. But mounting concern over the environmental impact of this and subsequent chemically based control strategies, together with their diminishing efficacy and escalating costs, led to a quest for alternative methods. During seven years' research, the LUBILOSA (LUtte BIologique contre les LOcustes et les SAuteriaux) programme has developed the mycopesticide `Green Muscle'®, based on an oil formulation of the aerial conidia of the fungal pathogen Metarhizium. Metarhizium has recently been recommended by the Food and Agriculture Organization of the UN (FAO) for use in environmentally sensitive areas. The programme has now entered an implementation phase and registration is being sought.

The cornerstone to the development of Green Muscle® was an inspiration by Chris Prior. He demonstrated that fungal conidia formulated in oil worked quicker and more effectively than water-based suspensions, and this difference was more pronounced at low humidity. This discovery allowed the development of a product which is effective in the field in Africa. The mycopesticide is mixed from a dry spore powder and vegetable or mineral oils to give a suspension for ultra-low volume (ULV) application; an oil-miscible flowable concentrate is also being developed.

Fungal infection can occur directly from spray droplets, or indirectly from spray residues or infected individuals. The conidia initially attach to the insect cuticle and, on germination, penetrate and invade the body tissues with hyphae and blastospores. It takes six days or more for the pathogen to kill its host, and although this is on a different time-scale to knock-down chemicals, there are many situations where speed of kill is not critical. Field performance trials have demonstrated the efficacy of Green Muscle® against a wide range of African acridids.

For further information see: Bateman, R. L. (1997) The development of a mycoinsecticide for the control of locusts and grasshoppers. Outlook on Agriculture 26 (March issue).

Cypress Aphid Parasitoid Established in Malawi

The cypress aphid, Cinara cupressi, which was first recorded in Africa in Malawi in 1986, is a major forestry pest now present in most of southern, eastern and central Africa. A regional biological control project involving IIBC and national forestry programmes has been funded by the Canadian International Development Agency (CIDA), and by the Overseas Development Administration, UK (ODA) through their Malawi pro-gramme, since 1991 for the control of this and other devastating forestry pests. A parasitoid from Europe, Pauesia juniperorum, was released in Malawi at Zomba, Dedza and Mt. Mulanji, all in the central/southern part of the country, in August-December, 1995. The Forest Research Institute of Malawi (FRIM) reported successful initial establishment in 1995 at all three sites on both Mexican cypress (Cupressus lusitanica) and indigenous Mulanje cedar (Widdringtonia cupressoides). Then in June 1996, parasitized aphids were found at Zomba, and surveys during 1996 have shown that the parasitoid has dispersed up to 25 km away from the release sites at Zomba and Mt. Mulanje. Pauesia juniperorum has been recorded on all the ornamental cypresses and hedges inspected in and around Zomba, and widespread parasitism was also found at Dedza at the end of 1996.

Phorids Meet Fire Ants Head-on

The relentless 40-year advance of the imported fire ant, Solenopsis invicta, across the southern USA may soon be limited by parasitic phorid flies from South America. Originally discounted because they caused such low (1-3%) mortality in fire ants, recent work has demonstrated that some Brazilian Pseudacteon species have significant behavioural effects on S. invicta that may allow indigenous American ant species to compete more effectively. This spring will see Pseudacteon released in Texas and Florida.

Research on biological control of fire ants has its origins in ecological studies of ant/phorid relationships in the USA. In Texas, for instance, a research group at the University of Texas at Austin, led by Professor Larry Gilbert, began in the 1980s to study fire ant ecology and the curious biology of phorids which lay their eggs in the head capsules of these ants. Inspired by Don Feener's earlier demonstration there that phorid flies alter the ability of a Pheidole sp. to compete for food, the group re-examined the potential of phorids to control fire ants. In 1989 Sanford Porter, originally from the Austin team and now working on fire ant biological control with the US Department of Agriculture (USDA) in Florida, took these studies further to Brazil. He found that densities of S. invicta in the USA were five times greater than they were in South America where fire ants are generally not viewed as a pest. Up to seven species of Pseudacteon were found attacking it in different areas. Since 1994 University of Texas scientists in collaboration with the Universities of Campinas (Brazil) and Buenos Aires have also been studying the phorids in South America and assessing their suitability as biocontrol agents for S. invicta. Screening studies on 13 genera of ants demonstrated Pseudacteon to be highly specific to Solenopsis, and three species have been found with high specificity to S. invicta.

A USDA APHIS permit to release three species in Texas was obtained in May 1995. Several release attempts were made between November 1995 and August 1996. Unfortunately, that period corresponded with the most severe drought the region has seen in a century, lasting from mid November to June with temperatures ranging from -10 to 37deg.C in February, and then in August the latest releases of the flies were followed by near-hurricane levels of wind and rain. Further releases are planned this spring, both in Texas where the weather has been more propitious this year, and in Florida where granting of release permits is anticipated. USDA and University of Texas scientists are collecting the first phorids this season from field sites in Jaguariuna and Campinas, Brazil for release in the USA.

However, mass-rearing for release is not yet a viable proposition and release depends on using field-collected Pseudacteon brought from South America and exposing to them S. invicta workers subsequently released back into mounds in the field. Adults may have a brief life span, and most of the life cycle may be spent inside the fire ant hosts, so establishing them this way may be particularly difficult. Work at USDA is continuing on rearing methods where they now have a laboratory colony of several thousand flies that has cycled through six generations. In Texas they are constructing a 475 m2 tropical greenhouse over fire ant habitat for incipient phorid populations, and to provide an `outdoor' release site for bad weather. It is also planned to use it as a breeding facility for the phorids.

The prospect of biological control of fire ants is a refreshing development in a longstanding saga of difficulties with this pest. In the early 1970s, an unsuccessful and highly political eradication campaign in the southern USA led to the application of the pesticide Mirex over large areas, which was associated with widespread mortality of birds and aquatic life as residues washed into rivers and the Gulf of Mexico.

Chocolate-lovers' Nightmare

There is growing concern in the chocolate industry that the World's demand for cocoa will outstrip supply over the next five to 10 years. The major constraint to production is disease, and particularly witches' broom disease caused by the agaric fungus Crinipellis perniciosa. Since 1989 when the disease first arrived in the Brazilian state of Bahia, the principal cocoa-growing region of the Americas, annual cocoa production there has been halved from over 400,000 t to less than 200,000 t. The big fear is that not only will the disease continue to decimate cocoa in Brazil, but it may eventually spread to West Africa.

A meeting of the World's major chocolate industries had identified the fungus as the main threat to global cocoa production, with a real possibility of chocolate shortages in the short-term future if the disease is not contained, and the International Office of Cocoa, Chocolate and Confectionery (IOCCC) has been forced to take an initiative. At a workshop in Miami (USA) in February, funded by the IOCCC, representatives of the World's foremost chocolate manufacturers met with leading scientists from Brazil, Ecuador, the UK and the USA to develop a management strategy for the disease.

Biological control is being considered as a viable management option and several projects have been initiated recently in order to assess the potential of fungal antagonists. IIBC, in collaboration with the Universidade Nacional Agraria de la Selva, are working in Peru to search for and evaluate coevolved natural enemies of C. perniciosa; amongst these is the mycoparasite Cladobotryum amazonense. In contrast, US Department of Agriculture scientists from ARS-Beltsville are planning to screen a number of generalist mycofungicides already established on the market, for example Soil Gard® (based on Gliocladium virens) and Aspire® (based on Candida oleophila)

A Witches' Broom Working Group was formed to prioritize research on resistance breeding and biological control. Biotechnology was also considered to be a potentially important component, particularly the possibility of incorporating the fungitoxic gene from C. amazonense into the cocoa genebank.

But witches' broom is not the only pest problem facing the cocoa industry in South America: Moniliophthora pod rot is also a serious threat and could deliver the killer blow to the industry in Brazil and particularly in Bahia. Thus, a coherent crop protection strategy for cocoa is urgently needed.

Prosopis to Turn Turtle on Ascension

The nesting sites of green turtles on the beaches around Ascension Island are under threat from invasion by mesquite, Prosopis juliflora, and the large colony of sooty terns there will also be at risk if the spread of the plant continues. At present, bulldozing is used to prevent the trees becoming established at several of the key turtle beaches.

Concern over the current and future impact of the invasive alien tree on Ascension Island has been growing. It is now present over about 75% of the island and in some areas has formed impenetrable thickets. There is a small, but interesting, endemic invertebrate fauna which could be eliminated by invading Prosopis, either by direct effects or because the presence of the tree will encourage a range of other exotic animal species to invade. Euphorbia origanoides is the only endemic higher plant in the regions Prosopis is invading, but it will also be threatened if Prosopis comes to dominate substantial areas of the lava.

As well as being a threat to the indigenous biodiversity on the island, Prosopis causes substantial amenity problems. Its fast growth habit means that it rapidly impedes tracks and paths, and along roadsides it can obstruct visibility. The large, robust Prosopis spines cause punctures to vehicles, bicycles and even footballs. There is also the issue of aesthetics and landscape: although much of Ascension Island is apparently barren lava/ash, there are areas which are scenically spectacular and these could be drastically altered by continued Prosopis invasion. Furthermore, the island is justly well-known among geologists for the many volcanic features of its landscape, and these would be obscured and inaccessible if they were covered by thickets of Prosopis. Finally, the tree burns readily, and there are houses and other buildings close to infested areas.

Mechanical and chemical control are used to a limited extent, but these methods are only feasible and environmentally appropriate on a small scale. Fortunately, extensive research into the biological control of Prosopis spp. has been carried out around the World because the plant has become invasive in many of the areas where it was introduced as a useful agroforestry tree. In particular, the Plant Protection Research Institute (PPRI) in South Africa has studied and screened a range of potential bio-control agents, and released several seed-feeding bruchid beetles originat-ing from the native range of Prosopis in the New World. The Ascension Island authorities have thus been able to make use of previous research on biological control of Prosopis, and such programmes using `off-the-shelf' agents do not have the high initial research costs of biological control programmes against novel weed targets.

There are very few plants on Ascension Island that could conceivably be at risk from the introduction of such agents. Although there are no indigenous Fabaceae, the family to which Prosopis belongs, there are several closely related plants that have been intro-duced to Ascension, including several other members of the subfamily Mimosoideae grown as ornamentals or naturalized and valued aesthetically (e.g. Leucaena leucocephala and Acacia spp.). The majority of crops or potential crops within the Fabaceae are mem-bers of the subfamily Papilionoideae.

The Foreign and Commonwealth Office of the UK Government has recently approved funding for a project to introduce two bruchid species to Ascension Island. These beetles, Algarobius prosopis and Neltumius arizonensis are being supplied by PPRI, and are currently in culture at the IIBC quarantine facility at Silwood Park (UK). Shipments to Ascension Island are expected to begin in May. It is anticipated that the beetles will destroy a large proportion of the seed pro-duced by Prosopis on the island. This should slow the rate of spread of the weed, but further agents may be required to control existing stands. The programme will be integrated with mechanical and chemical control in selected areas, and overall will need to be considered as a component of the broad-ranging conservation plans for the island being developed by the Administrator and his staff.