Delphastus Pusillus Raymond A
Total Page:16
File Type:pdf, Size:1020Kb
Floriculture Indiana Vol. 8 No. 4 Fall 1994 Page 4 Delphastus pusillus Raymond A. Cloyd Entomology Department, Purdue University Whiteflies are major greenhouse pests, are longer than they are wide. The fourth instar and the two most commonly encountered are: the eventually crawls down a plant stalk and pupates greenhouse whitefly, Trialeurodes vaporariorum, inside driedup leaves. Newly emerged adults are and the silver-leaf whitefly, Bemisia argentifolii pale-brown to almost white, but they eventually (formerly known as strain 'B' ofthe sweet potato turn black. Development from egg to adult takes whitefly, Bemisia tabaci). One method ofwhite about 3 weeks at 80° F. Females live for about 50 fly control is reliance on chemical insecticides. daysandcanlay approximately3to4 eggs perday. Though chemical insecticides have been some Bothlarvaeand adults areactive predators that can what effective in controlling whiteflies they are consume over 300 eggs or 100nymphsofsilverleaf becoming more difficult to use because of strin whitefly per day. Adults and larvae feed by gent rules and regulations. An alternative control piercingthe insect integument (covering) and ex method is the use ofbeneficial organisms or bio tractingout the contents. Release ofD. pusillus is logical control. Control of greenhouse whitefly compatible with other biological control organ has been very successful with the parasitoid, isms becauseitavoidsparasitizedwhiteflies. Some Encarsia formosa. This parasitoid,however, is not thing to be aware ofwhen using D. pusillus is that as effective in controlling silverleaf whitefly. In trichomes (hairs)on plantleaves can deter feeding contrast, Delphastus pusillus, a predatory beetle and egg laying. shows more potential for controlling this pest. Considerations for Use Biology Releases must be concentrated near areas Delphastus pusillus is a native lady bird ofhighwhitefly populations. D. pusillus performs beetle that attacks all species and stages ofwhite best when the temperature is between 65 and 90 flies, with a preference foreggs andnymphs. The F and when the relative humidity is above 75%. adults are small (1/16 inch), shiny, black beetles. Remember that releases ofD. pusillus must occur They are strong fliers that usually migrate into before whitefly populations in the entire green areas which contain high densities of whiteflies. house are out of control. Predators should be Femalebeetles tend to lay theireggs within white released as soon as possible, release in the early fly egg clusters to make it easier for the young morningorevening(dusk). ThecostforD.pusillus larvae to find a food source. ranges from $25.00 to $60.00 per 100 adults. For Delphastus pusillus undergoes complete more information on release rates and costs con metamorphosis and consists of an egg stage, 4 sult supplier catalogs. larval instars, a pupae stage, and an adult. The eggs are clear and approximately twice as long as * The authorwishestothankDr. CliffordSadoffor they arewide. Larval stages arepale-yellow, and his comments and suggestions. Floriculture Indiana Vol. 8 No. 4 Fall 1994 Page 5 DeiPUMrm pvtiLUsA ; Development Time, Zl Day* Af 7/>jF Aa/d 95% Relative H-jniotry :ApvlT Longevityl 30 +PA YS Female Fgcunqity, 50 fc&$ &££& LiFgr/Aiz , 5.ALE: ^ Imm (1000m ) U ^i L_ O.t'mm (100*) ?vPA' P*rlf-2l Vaj. -. , 4th [MM Larva • Pax ILK l£jnm , PalE Yeliaw- Green 2up Invar LARVA: Pay 1-8 Pale Yellow- Gb&sN CLe'ar.