Biocontrol: Bioinsecticides, Bioherbicides and Biofungicides, Defined as use of one organisms to reduce or eliminate the population of another organism. An old concept that can be seen in early history and various cultures: Early recognition that some animals controlled population of others. Cats could control rodents attracted to fields of crops. Led to domestication of cats by Egyptians. Perhaps why cats were revered by Egyptians An old concept that can be seen in early history and various cultures: In 900 A.D., China introduced ants to orange groves to prevent worms in the fruit. In 1762 - introduction of Mynah Birds to Mauritius to control locust. By 19 th. Century, in Europe, variety of insects and arachnids used to control various pests. An old concept that can be seen in early history and various cultures: One of the means attempted to control Phylloxera (aphid), in vineyard of France was introduction of mites from America. Understanding of biocontrol came about due to these efforts, in Europe. By early 20 th. Century, first use of biocontrol, in North America, was in California. Cotton Cushion Scale introduced from Australia was devastating citrus crops. Entomologist sent to Australia to find natural predator to insect. Predator beetle found. Introduction significantly reduced scale insect on citrus. 1
History of Herbicides Parallel to the development of biocontrol was chemical control of weeds and insects. Earliest herbicides were inorganic. Ancient time, herbicide composed of ashes, salt and bittern (seawater) In 1896, Bordeaux mixture found to effective in controlling certain weeds. Other herbicides, included iron sulfate, copper nitrate, various sodium and potassium salts, etc, by 1900. History of Herbicides Parallel to the development of biocontrol was chemical control of weeds and insects. Inorganic herbicides used as recently as 1960 Organic herbicides (containing carbon compounds) developed in 1932, with dinitrophenol compounds. 1942 development of 2,4 D, a synthetic plant hormone occurred, highly selective for broad leaf plants. History of Herbicides Parallel to the development of biocontrol was chemical control of weeds and insects. Other organic herbicides would follow. In 1960 s and 70 s combination of 2,4 D and 2,4,5 T widely used in Vietnam = Agent Orange. Ecological and health issues curtailed their uses. Use of compound was prohibited by U.S. in 1984. History of Herbicides Parallel to the development of biocontrol was chemical control of weeds and insects. Other organic herbicides have taken their place, e.g. Roundup now very popular. Very economically important area of research. History of Insecticides History of insecticides also parallel that of biocontrol and herbicides. Use of insecticides reliably documented by Pliny The Elder(19-73 AD). Burning of brimstone (sulfur) as a fumigant. Recorded the various types of insecticides in his Natural History. Included, lye, pepper and nicotine extracts, turpentine, fish oil, etc. History of Insecticides History of insecticides also parallel that of biocontrol and herbicides. Number of insecticides escalated from there. Biggest breakthrough was in discovery of DDT. Dr. Paul Muller, entomologist, awarded Nobel Price for its discovery, in medicine, in 1939. For many years DDT thought to be magic bullet of insecticides. 2
History of Insecticides History of insecticides also parallel that of biocontrol and herbicides. Environmental and health hazard discovered much later. In 1973, EPA banned use of DDT. Many insecticides developed that were also toxic. Biocontrol Why was biocontrol not popular like herbicides and insecticides, in 20 th Century. More economical than biocontrol. More easily obtained and applied. With discovery of toxicity of effective herbicides and insecticides, biocontrol by 1980 s, considered as an alternative. However, development of less toxic herbicides and insecticides continues. Fungi as Bioinsecticides Insect does not have to ingest any material. Thus, does not go up food chain Fungi that parasitize insects can penetrate the cuticle by various means. Numerous species of fungi are parasitic on insects. Few studied carried out and few species used for pest control. Effects are variable of those studied. Fungi as Bioinsecticides Most species that have been studied are members of the Zygomycota, (Entomphthorales). Three categories of treatment used in biocontrol of insects. Permanent Introduction (still involves periodic reintroduction) Inoculative Augmentation: Must reinoculate area annually. Conservation or Environmental Manipulation: modification of environment. Fungi as Bioinsecticides Use of spores is most effective means of using fungi for biocontrol of insects. Also can mass produce fungus, lyophilize fungus, and break into pieces. Specific examples of bioinsecticides: Permanent Introduction: Control of Gypsy Moth by Entomophaga maimaiga Control of Gypsy Moth by Entomophaga maimaiga Introduced into United States in 1869 and became major pest. By 1889, Gypsy Moth caterpillar was causing severe damage to trees. Entomophaga maimaiga introduced into northeaster United States, in 1910 and 1911. No apparent effects! Not hear from, again, until 1989, during revival of biocontrol interest, by Anne Hajek, Cornell. 3
Control of Gypsy Moth by Entomophaga maimaiga Hajek did observe major die off of Gypsy Moth, due to E. maimaiga. However, there was no doubt that fungus was responsible for die off. Hajek concluded that periodic die offs were due to inoculations from 1910-11. Hajek carried out inoculation experiments, in 1991 and 1992 that caused major dieoff of Gypsy Moth. Control of Pine Moth by Beauveria bassiana Inoculative augmentation. Largest program of biocontrol, in People s Republic of China. One million hectares (2.47 acres/hectare) sprayed with fungus. Was effective, but must be resprayed every 3 years. Control of Alfalfa Beetle by Erynia Environmental manipulation By cutting alfalfa early and leaving it in piles for several days, moisture develops. Encourages growth of Erynia (Zygomycota). Light spray with insecticide also weakens beetle. Other Potential Insect Biocontrol Agents Entomophthora muscae, parasite on flies. Entomophthora muscae, parasitic on fly. 4
The genus Cordyceps is a well known parasites of insects and arachnids Entomophthora muscae, parasitic on fly. Beauvaria bassiana infection of Clover Worm. Beauvaria bassiana infection of worm within woody substrate. Cordyceps melolonthae is a parasite on beetles Cordyceps militaris, The Caterpillar Fungus is also used as a herbal medicine. 5
Another Cordyceps species parasitic on caterpillar of moth. Cordyceps species, parasitic on ant. Cordyceps species, parasitic on fly. Cordyceps, parasitic on dragonfly. Cordyceps, parasitic on unknown, insect, larval stage. Cordyceps sinensis fruiting bodies. 6
Arthrobotrys, a genus that forms constricting rings to trap nematodes Arthrobotrys with constricted rings and trapped nematode. Adhesive knob Dactylaria candida, parasite on nematodes. Dactylaria candida, parasite on nematodes. Catenaria, an aquatic fungus, and internal parasite of nematodes. Coelomomyces, an aquatic fungus, and parasite to malaria mosquito. Laboratory tests have indicated that it can be potentially successful. 7
Unknown fungus parasitized and killed insect. Bioherbicides Almost a natural tool for control of weedy plants since many fungi are plant pathogens. Utilization of insects for this purpose has long been used. Use of fungi is much more recent. Use of fungi more effective and can be more host specific than insects. Bioherbicides One example that has been somewhat successful in Hawaii. Some weeds that have been controlled by fungi include: Clidemia hirta (Kostner s Curse) controlled by Collectotrichum gloeosporioides f. sp. clidemiae Ageratina riparia (Hamakua) controlled by Entyloma compositarum Bioherbicides Clidemia hirta Ageratina riparia Clidemia hirta Bioherbicides Entyloma compositarum Biofungicides Bioherbicides and bioinsecticides have not met with commercial success. However, a number of biofungicides are sold commercially. Most have in them Trichoderma harzianum, a species genetically engineered at Cornell Other species also been used: AQ10 has Ampelomyces quisqualis and is used to treat powdery mildew 8
Biofungicides However, a number of biofungicides are sold commercially. Other species also been used: Fusaclean has Fusarium oxysporum and is used to treat wilt caused by other species of Fusarium Rotstop has Peniophora gigantea and is used to control butt rot caused by Heterobasidion annosum 9