Bloem et al.: Insecticides for Control of Cactoblastis cactorum 395 LABORATORY EVALUATION OF INSECTICIDES FOR CONTROL OF THE INVASIVE CACTOBLASTIS CACTORUM (LEPIDOPTERA: PYRALIDAE) STEPHANIE BLOEM1, RUSSELL F. MIZELL III2, KENNETH A. BLOEM3, STEPHEN D. HIGHT4 AND JAMES E. CARPENTER5 1Center for Biological Control, Florida A&M University, Tallahassee, FL 32308 2University of Florida, North Florida Research and Education Center, Quincy, FL 32351 3USDA-APHIS-PPQ-CPHST, at Center for Biological Control, Florida A&M University, Tallahassee, FL 32307 4USDA-ARS-CMAVE, at Center for Biological Control, Florida A&M University, Tallahassee, FL 32308 5USDA-ARS-CPMRU, Tifton, GA 31794 ABSTRACT We conducted laboratory assays of nine products registered for use on ornamental plants in Florida for their ovicidal and larvicidal activity against the invasive cactus moth Cactoblas- tis cactorum. One-hundred percent mortality (or 0% survival) of 1-day-old eggs was obtained when eggstick sections were treated with cypermethrin, spinosad, or imidacloprid. These products were equally as effective when assayed against eggs that were fully embryonated (28 days old), when cladodes of Opuntia stricta were exposed to neonates 24 hours after dip- ping, or to cladodes that were dipped and stored for 30 days before exposure. When Bacillus thuringiensis (Dipel®) was used to prevent neonate penetration into treated cladodes of O. stricta, 100% mortality (or 0% survival) was recorded in the laboratory. Key Words: insecticides, invasives, Cactoblastis cactorum, Lepidoptera, Pyralidae, cyper- methrin, emamectin benzoate, abamectin, spinosad, azadirachtin, fenoxycarb, imidacloprid, acephate, Bacillus thuringiensis RESUMEN Nosotros realizamos unos ensayos del laboratorio de nueve productos registrados para el uso sobre plantas ornamentales en Florida para su actividad ovicida y larvacida contra la polilla invasora de cactus Cactoblastis cactorum. Una mortalidad de cien por ciento (o 0% sobrevi- viencia) de huevos de 1 dia de edad fue obtenida en secciones de grupos de huevos tratados con cypermethrin, spinosad, o imidacloprid. Estos productos fueron igualmente efectivos en ensayos contra huevos con embriones completemente desarrollados (de 28 dias de edad), cuando los cladodios de nopal de Opuntia stricta fueron expuestas a neonatas (larvas recien nacidas) 24 horas después ser emergidos, o a los cladodios que fueron emergidos en insecti- cida y almacenados por 30 dias antes de ser expuestos. Cuando Bacillus thuringiensis (Di- pel®) fue usado para prevenir la penetración de las neonatas dentro los cladadios de O. stricta tratados, un mortalidad de 100% (o 0% sobrevivencia) fue registrada en el laboratorio. Cactoblastis cactorum (Berg) successfully con- southern United States and in Mexico (Zimmer- trolled several species of invasive prickly pear mann et al. 2000). Stiling (2002) suggested that cacti (Cactaceae: Opuntioideae—Opuntia) in the geographical range of C. cactorum in Florida Australia (Dodd 1940), South Africa (Pettey was expanding at an approximate rate of 50-75 1948), and in many other parts of the world (Mo- km per year. However, unpublished data collected ran & Zimmermann 1984). In 1989 C. cactorum by our group suggests that the spread rate along was detected in the Florida Keys (Habeck & Ben- coastal locations in the Gulf of Mexico was closer nett 1990; Dickel 1991). The cactus moth may to 160 km per year during 2000-2003 (S. D. Hight, have arrived through natural dispersal from the unpublished data). Given this rapid rate of geo- Caribbean Islands, where it was intentionally in- graphical expansion, C. cactorum could arrive in troduced in the 1950s (Simmonds & Bennett Texas by the year 2007. Invasion and establish- 1990), or it may have been accidentally intro- ment of the cactus moth in the southwestern duced by the nursery trade (Pemberton 1995). United States and in Mexico will have serious Nevertheless, its rapid spread along the Atlantic detrimental effects on biodiversity and stability of and Gulf Coasts has raised concerns about its un- native desert ecosystems and on vegetable, fruit, avoidable impact on native Opuntia cacti in the and forage Opuntia industries in these areas 396 Florida Entomologist 88(4) December 2005 (Soberón et al. 2001; Zimmermann et al. 2000). be employed in culturally managed plantings of Even though C. cactorum was deliberately intro- Opuntia (nurseries, backyards, landscaped public duced into South Africa to control invasive cacti, lands) either alone or in combination with other spineless Opuntia is still used as fodder for cattle suppression tactics. Furthermore, insecticides and other livestock during times of drought. As could be used to treat ornamental Opuntia in such, livestock farmers manage their Opuntia nursery settings to ensure that no infested plants plantations in order to minimize losses due to in- are being sold to the public. In this paper we re- sect damage. port results of laboratory assays of several insec- The biology of C. cactorum is well documented ticides that are registered for use on ornamental (Dodd 1940; Pettey 1948; Zimmermann et al. plants in Florida. Ovicidal and larvicidal proper- 2000). Mating occurs one hour before sunrise ties of the products were examined and results (Hight et al. 2003) and eggs are laid to form spine- obtained are discussed in context of the area-wide like eggsticks, each with 60-100 eggs. Neonates management of this invasive insect. burrow collectively into cactus cladodes (pads or stems) where larvae feed gregariously and move MATERIALS AND METHODS to new pads as old ones are destroyed. Pupation occurs in plant litter or soil. The moth completes Test Insects three full generations in Florida, with peak adult flights taking place in April, July, and October Eggsticks used in these experiments came (Zimmermann et al. 2004). from a laboratory colony of C. cactorum main- Burger (1972) was the first to report on the use tained at the USDA-ARS Crop Protection and of cover sprays of methidathion and carbaryl to Management Research Unit, Tifton, Tift Co., GA. protect Opuntia plantations in South Africa The insects are reared on cladodes of O. stricta in- against attack by both C. cactorum and Dacty- side rectangular plastic boxes (25 by 17 by 8 cm) lopius opuntiae (Cockerell) (Homoptera: Dacty- that are held in environmental chambers at 26 ± lopiidae). Subsequently, Pretorius et al. (1986) and 1°C, a 14:10 (L:D) photoperiod, and 70% RH dur- Pretorius & Van Ark (1992) assayed additional ing larval and pupal development. Cocoons are products applied either as cover sprays or stem in- collected twice per week, de-silked in a dilute jections to prevent cladode penetration by first in- bleach solution, and pupae are sorted by gender. star C. cactorum. Pretorius et al. (1986) indicated Groups of 30-50 newly emerged adults of each that cover sprays of cypermethrin gave excellent gender are placed together in aluminum screen results. However, they found that stem injections cages (35 by 35 by 35 cm) containing 1-3 cladodes of monocrotophos gave inadequate control and of O. stricta for mating and oviposition. Eggsticks were expensive and impractical to use against the are collected from the cages once per day, placed insect. Pretorius & Van Ark (1992) evaluated addi- in small plastic cups (60 ml), and maintained at tional products (mevinphos and dimethoate) as 26 ± 1°C, a 14:10 (L:D), and 70% RH until needed. both stem injections and cover sprays and discov- Under these conditions eggsticks take approxi- ered that these materials applied as sprays trans- mately 30 d to complete their development. located effectively through the plants and provided good protection against larval attack. According to Products Assayed Nel et al. (2002), the insecticides currently regis- tered for use against C. cactorum in South Africa Studies were conducted during 2004 at the UF/ include a carbamate (carbaryl), an organophos- IFAS North Florida Research and Education Cen- phate (methidathion), and two pyrethroid insecti- ter (NFREC), Quincy, Gadsden Co., FL. Nine dif- cides (deltamethrin and tralomethrin). ferent commercially available products were The current infestation of C. cactorum in Flor- tested in the laboratory for their ovicidal and lar- ida is affecting native Opuntia species distributed vicidal activity against C. cactorum. The products throughout large expanses of natural areas were cypermethrin (Ammo® 2.5 E, FMC Corpora- (O. stricta (Haworth) Haworth, O. humifusa (Raf.) tion, Philadelphia, PA), emamectin benzoate Raffinesque, and O. pusilla (Haworth) Nutall), as (Proclaim® 5 SG, Syngenta Crop Protection Inc., well as ornamental cactus plants (O. ficus-indica Greensboro, NC), abamectin (Avid® 1.5 EC, Syn- (L.) Miller and O. stricta) in urban settings (Hight genta Crop Protection, Inc., Greensboro, NC), spi- et al. 2002). Even though chemical control is not a nosad (SpinTor® 2 SC, DowAgro Sciences LLC, practical or environmentally responsible tactic to Indianapolis, IN), azadirachtin (Azatin® EC, protect the millions of hectares of natural Opun- AgriDyne Technologies Inc., Salt Lake City, UT), tia vegetation (Mahr 2001), insecticide controls fenoxycarb (Distance® IGR, Valent U.S.A. Corpo- should be evaluated for their potential use in ur- ration, Walnut Creek, CA), imidacloprid (Ad- ban settings. Leibee & Osborne (2001) summa- mire® 2 F, Bayer Corporation Crop Protection, rized information on new insecticides to be as- Kansas City, MO), and acephate (Orthene® 75 sayed for use against