Read Chapter 5 Groups Used as Agents for Biological Control of Weeds
Classical Biocontrol of Weeds Requires Agents with Narrow Host Ranges 1. Insects 2. Mites 3. Nematodes 4. Fungi
Coleoptera Families used in weed biocontrol to date (red = families of greatest importance) Chrysomelidae Curculionidae Cerambycidae Apionidae Bruchidae (now part of Curculionidae) Buprestidae Anthribidae
Coleoptera: Chrysomelidae Agasicles hygrophila- for alligator weed, Alternanthera philoxeroides
Agasicles hygrophila (Chrysomelidae) Eggs and larvae Weed stand in invaded habitat
Longitarsus jacobaeae for control of tansy ragwort in the western United States Larvae of L. jacobaeae feeds inside plant roots
Tansy ragwort, Senecio jacobaea, is an invader of western grasslands
Appearance of tansy ragweed (Senecio jacobaea) infestations before biological control introductions
Appearance of same area after control of tansy ragweed (Senecio jacobaea) with biological control introductions
Coleoptera: Chrysomelidae Chrysolina quadrigemina, introduced to OR and CA in 1940s for control of St. Johnswort, Hypericum perforatum
Chrysolina quadrigemina, Chrysomelidae Larva of C. quadrigemina (top) and its host plant, Hypericum perforatum
Effect of Chrysolina quadrigemina on St. Johnswort, Hypericum perforatum Native grasslands of CA invaded by H. perforatum, as seen in the 1950s Above, yellow flowers of H. perforatum BEFORE project Right, restored grassland after BC of weed
Chrysomelidae: Apthona species Apthona laceratosa Apthona cyparissiae Used in western US for leafy spurge, Euphorbia escula
Leafy spurge (Euphorbia escula) Apthona larvae feed on roots Apthona larva
Before: 1991 After: 1998 Control of leafy spurge (Euphorbia escula) by Apthona spp. beetles in the western United States
Coleoptera: Chrysomelidae Neochetina larva in stem of waterhyacinth Neochetina eichhornia, a control agent for waterhyacinth
Waterhyacinth, Eichhornia crassipes The world s worst water weed
Healthy stand of waterhyacinth
Stand of waterhyacinth damaged by Neochetina weevils
Curculionidae: Oxyops vitiosa Released in Florida against invasive tree in Everglades
Curculionidae:Rhinocyllus conicus Carduus nutans R. conicus Released US against nodding thistle, Carduus nutans
Rhinocyllus conicus- a thistle seed head feeder 1. eggs 3. pupae 2. larva Lifecylce of R. conicus: -Eggs laid in thistle receptacle -Larvae fed on seed embryos -Pupae form in seed head
Rhinocyllus conicus has had nontarget effects on native thistles such as Platte thistle in Nebraska Habitat of Platte thistle is the sandhills of Nebraska, which are outside the range of the target non native thistles
Curculionidae: Cyrtobagous salvinae Released in many countries for control of giant salvinia
Salvinia molesta, a South America floating fern spread by the aquarium trade Green mat is S. molesta on lake in Australia Add photos of more species
After Successful Biological Control same location as two slides previous, after the introduction of C. salviniae Green mat is S. molesta on lake in Australia Add photos of more species
Lepidoptera Families used in weed biocontrol to date (red = families of greatest importance) Pyralidae Noctuidae Tortricidae Gelechiidae Arctiidae Gracillariidae Fifteen other families
Pyralidae: Cactoblastis cactorum An Opuntia feeder, released both against invasive spp. (e.g., Australia, S. Afr.) and in the Caribbean against native Opuntia
Arctiidae:Tyria jacobaeae Tyria jacobaeae was introduced to Oregon and played a minor role in control of tansy ragwort
Hemiptera (including Homoptera) Families used in weed biocontrol to date (red = families of greatest importance) Dactylopiidae Tingidae Coreidae Five other families
Dactylopiidae: Dactylopius sp. Cochineal insects are cactus specialists and have been used to control invasive Opuntia spp. in many locations
Cochineal insects are cactus specialists
Diptera Families used in weed biocontrol to date (red = families of greatest importance) Tephritidae Cecidomyiidae Four other families
Diptera: Tephritidae, Urophora affinis Note banding on wing and long ovipositor Introduced into the western United States as part of complex for control of diffuse knapweed, Centaurea diffusa
Tephritidae, Urophora affinis larvae Note banding on wing and long ovipositor Larvae develop in seed head of diffuse knapweed, Centaurea diffusa
Diptera: Cecidomyiidae, skeletonweed gall midge, Cystiphora schmidti Adult fly Galls on target weed, sketonweed, Chondrilla juncea
1. Thysanoptera 2. Hymenoptera 3. Orthoptera 4. Acarina (mites) Other orders
Thysanoptera: Alligator weed thrips, Amynothrips andersoni (Phlaeothripidae) Note banding on wing and long ovipositor
Arundo scale (Rhizaspidiotus donacis) has been released against the invasive giant Arundo reed
The Arundo gall wasp, Tetramesa romana, Hymenoptera: Eurytomidae
Hymenoptera: Pteromalidae Galls of a gall-making wasp, Trichilogaster acaciaelongifoliae, on Acacia longifolia in South Africa
Acarina: Tetranychidae-gorse spider mite Tetranychus lintearius, introduced to NZ for control of gorse, Ulex europaeus
Tetranychidae-gorse spider mite Note banding on wing and long ovipositor See yellow color of affect plants
Eriophyid mite (Eriophyes chondrillae), a gall forming mite on skeletonweed (Chondrilla juncea) Mite gall on target weed Micrograph of mite Gall mite introduced in Australia against skeletonweed, Chondrilla juncea
Weed biocontrol via specialized plant pathogens 1. Rusts 2. Smuts
Puccinia chondrillina, a rust fungus on a seedling of skeletonweed (Chondrilla juncea) Red dots on foliage are rust bodies
Rubus fruticosus, an introduced horticultural blackberry, has become a major environmental weed in Australia and the target of biological control via a rust fungus introduction
Virulent strains of the rust fungi Phragmidium violaceum were sought and introduced to Australia Rust lesions on leaf
Eruptions on leaf of the blackberry rust fungi Phragmidium violaceum and its teleospores (inset)
Non-selective Suppression of Whole Plant Communities has been Sought by Use of Generalist Herbivores 1. Fish
Many generalist herbivorous fish have been introduced ostensibly for control of nuisance weeds Grass carp (Ctenopharyngodon idella)
Grass carp (Ctenopharyngodon idella) have been released to suppress both native plants and invaders such as Hydrilla verticillata
But is weed control the real motive? Happy anglers with big grass carp
Introductions like this are irresponsible Although some say the flavor of the flesh of the grass carp has a strong algal flavor, the market for the fish as food is high in some areas. Grass carp are known to compete for food with invertebrates such as crayfish, and other fish species, and causes significant changes in phytoplankton, invertebrate communities, interfere with reproduction of other fish, modify habitat by destroying vegetation and water quality, and much more. Grass carp can grow to be about 4 ft. and 40-50 pounds (from US Fish and Wildlife website)