James E. Carpenter

PARASITOIDS AND PARASITES OF SPODOPTERA FRUGIPERDA (LEPIDOPTERA: NOCTUIDAE) IN THE AMERICAS AND CARIBBEAN BASIN: AN INVENTORY

Abstract An inventory of parasitoids and parasites of fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), was conducted using references describing parasitized FAW eggs, larvae, pupae and adults collected from different crops or habitats throughout the Americas and the Caribbean Basin. The crops and countries where these parasites were reported occurring in the Americas is also inventoried. Maize was the crop where the FAW was more frequently collected followed by rice. Overall, Chelonus insularis (Cresson) had the broadest natural distribution in the Americas. For the North American region C. insulares, Chelonus sp., and Euplectrus platyhypenae (Howard) were the most relevant parasitoids. In Central America, C. insularis was the most prevalent parasitoid, and in the South American region the most prevalent parasites were Archytas incertus (Macq.), A. marmoratus (Tns.), C. insularis, and Meteorus laphygmae (Viereck). Diapetimorpha introita (Cresson) is the most important pupal parasitoid of FAW occurring mainly in North America. An acugutturid, Noctuidonema guyanense (Remillet & Silvain), is the most important ectoparasitic nematode attacking adults of FAW and other noctuid moths in South and Southeastern US, and Mexico in North America, Caribbean Basin, Central America, and Northern South America.

Applications of F1 sterility for research and management of Cactoblastis cactorum (Lepidoptera: Pyralidae)

The unintentional arrival of the cactus moth, Cactoblastis cactorum (Berg), in Florida has raised concerns for the safety of native and rare Opuntia species in the Florida Keys and the potential spread of C. cactorum to the Opuntia-rich areas of the western United States and Mexico. In addition to threatening the biodiversity of these native ecosystems, such non-target effects would generate negative publicity that could heighten public concern over the use of exotic natural enemies and jeopardize future biological control programs against weeds. In this paper we discuss the use of inherited (F1) sterility in Lepidoptera to study, predict, and manage the expanding populations of C. cactorum. Research areas in which the use of F1 sterility would be most applicable include (1) elucidation of the host range of C. cactorum for key native Opuntia species from across the U.S., (2) prediction of the geographic range of C. cactorum in the U.S. and Mexico, and (3) delineation of the impact of native natural enemies on the spread of C. cactorum. The use of F1 sterility for control of C. cactorum would be most appropriate for (1) eradication of C. cactorum from areas of new introductions, or from isolated and/or environmentally sensitive areas such as the Florida Keys, (2) establishment of a barrier by means of release of irradiated moths along the leading edge of the C. cactorum geographical range, and (3) provisioning sterile C. cactorum in the field as hosts for released natural enemies to increase their initial survival and establishment.

NATURAL DISTRIBUTION OF HYMENOPTERAN PARASITOIDS OF SPODOPTERA FRUGIPERDA (LEPIDOPTERA: NOCTUIDAE) LARVAE IN MEXICO

Abstract A survey of parasitoids of fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), larvae was conducted in six Mexican states during August and September 2000. Thirteen genera of hymenopteran parasitoids were recovered representing the following 3 families, Braconidae: Aleoides, Chelonus, Cotesia, Glyptapanteles, Homolobus, and Meteorus; Ichneumonidae: Campoletis, Eiphosoma, Ophion, and Pristomerus; and Eulophidae: Aprostocetus, Euplectrus, and Horismenus. Out of 5591 FAW larvae collected, 772 produced parasitoids, for a parasitism rate of 13.8%. The highest rate of parasitism from a single collection was 42.2%, representing three species of parasitoids in Michoacán. Chelonus insularis Cresson was the most widely distributed species occurring in 45.3% of the locations. Pristomerus spinator (F.), and Meteorus laphygmae (Viereck), exhibited the highest rates of parasitism for a single collection with 22.2% and 22.1%, in Sinaloa, and Michoacán, respectively. The results supported the hypothesis that natural distribution and rates of parasitism of FAW larvae may be related to more diverse habitats with more forests, orchards, and pastures near to cornfields.

Flight Phenology of Male Cactoblastis cactorum (Lepidoptera: Pyralidae) at Different Latitudes in the Southeastern United States

ABSTRACT Long term trapping studies of the invasive moth Cactoblastis cactorum (Berg) were conducted at various latitudes from Puerto Rico to South Carolina. Three flight periods per year were identified at the 5 temperate sites studied, which covered the majority of the infested range on mainland United States. In general, the 3 flight periods across a latitudinal gradient from south Florida to central, coastal South Carolina were a spring flight during Feb–-May, a summer flight during Jun–Aug, and a fall flight during Sep–Nov. At any 1 site, each flight period lasted about 2 months. In the tropical areas of the Florida Keys and a Caribbean Island, the insect exhibited overlapping generations. Previous studies of this insect (as a biological control agent) report 2 flight periods per year in its native range of Argentina and its introduced range of Australia and South Africa. A synthetic pheromone-baited trap was a good indicator of generational time, and we suggest that trapping assays in these areas will likely identify 3 generations rather than 2. Initiation and timing of the 3 generational flights has importance in the current United States and Mexico monitoring program for presence and expansion of this invasive pest, development of mapping programs to identify monitoring windows and management efforts with the Sterile Insect Technique.

Cytological Attributes of Sperm Bundles Unique to F1 Progeny of Irradiated Male Lepidoptera: Relevance to Sterile Insect Technique Programs

ABSTRACT n The unique genetic phenomena responsible for inherited F1 sterility in Lepidoptera and some other arthropods provide advantages for the use of inherited sterility in a sterile insect technique (SIT) program. Lepidopteran females generally can be completely sterilized at a dose of radiation that only partially sterilizes males of the same species. When these partially sterile males mate with fertile females, many of the radiation-induced deleterious effects are inherited by the F1 generation. At the appropriate dose of radiation, egg hatch of females mated with irradiated males is reduced and the resulting (F1) offspring are both highly sterile and predominantly male. Lower doses of radiation used to induce F1 sterility increase the quality and competitiveness of the released insects. However, during a SIT program it is possible that traps used to monitor wild moth populations and over-flooding ratios (marked released males vs unmarked wild males) may capture unmarked F1 sterile males that cannot be distinguished from wild fertile males. In this study we developed a cytological technique with orcein and Giemsa stains to distinguish adult F1 progeny of irradiated males and fertile males. Our observations on 6 pest species in 5 families of Lepidoptera indicate that F1 males (sterile) from irradiated fathers can be distinguished from fertile males by the nuclei cluster in the eupyrene sperm bundles. The nuclei cluster in the fertile males exhibited a regular and organized arrangement of the sperm and was homogeneously stained, whereas in F1 males the nuclei cluster of sperm was disorganized, irregular and unevenly stained. Supplementary Material: color illustrations are available online at http://www.fcla.edu/FlaEnt/fe921.htm

Influence of Radiation Dose on the Level of F1 Sterility in the Cactus Moth, Cactoblastis cactorum (Lepidoptera: Pyralidae)

Abstract We examined inherited sterility effects on the F1 and F2 generations of the cactus moth, Cactoblastis cactorum (Berg) after gamma sterilization. Our objectives were to identify the dose of gamma radiation that would fully sterilize F1-generation moths and result in no viable offspring when F1 males were inbred- or out-crossed to fertile females, and that would allow maximum production of F1 sterile C. cactorum adults by irradiated males. Newly emerged adults of C. cactorum were exposed to increasing doses of gamma radiation and inbred or out-crossed to fertile counterparts. Inherited effects resulting from irradiation of males and females were expressed in the F1 generation as reduced egg hatch, increased developmental time for the F1 egg, and increased F1 larval to adult mortality. These effects were most pronounced when parental adults were irradiated at 200 Gy. Survival of F1-generation offspring originating from irradiated male × fertile female crosses was greatest at 200 Gy. In addition, inbred- and out-crosses of surviving F1 adults, with 1 parent irradiated at 200 Gy, resulted in no F2 adults. Maximum production of sterile F1 adults at 200 Gy suggests this dose is the most appropriate dose for implementing the sterile insect technique (SIT)-F1 sterility for control of C. cactorum in North America and for testing host suitability and potential geographical range in the field.

PRESENTATION OF ARTIFICIAL DIET: EFFECTS OF COMPOSITION AND SIZE OF PREY AND DIET DOMES ON EGG PRODUCTION BY ORIUS INSIDIOSUS (HETEROPTERA: ANTHOCORIDAE)

Abstract The size of prey is critical to the feeding success of any given predator, but the effects of diet packet size have not been studied. We examined the effects of size of packets (Parafilm® domes) of artificial diet and the size of prey eggs on oviposition and mortality rates of Orius insidiosus (Say). Artificial diet was presented to adult female O. insidiosus in 10-, 25- and 50-μL domes for 6 d and rate of oviposition was measured for 24 h. Oviposition was highest after feeding on the 10-μL domes, decreased slightly on the 25-μL domes, and was significantly reduced on the 50-μL domes. The effect of capsule size was negated on the 25-μL and 50-μL diet domes when the diet was supplemented with E. kuehniella egg protein. Predators were also fed eggs of 4 species of Lepidoptera, Ephestia kuehniella Zeller, Plodia interpunctella (Hübner), Helicoverpa zea (Boddie), Spodoptera frugiperda (J. E. Smith), and Heliothis virescens (Fabricius), ranging in volume from 19 ± 1.7 nL (mean ± SD) for P. interpunctella to 108 ± 21.3 nL for H. virescens eggs. Oviposition was highest and comparable on the E. kuehniella, P. interpunctella and H. virescens eggs and significantly less on S. frugiperda and H. virescens eggs. Oviposition positively correlated and mortality negatively correlated with weight-specific protein contents of the eggs, but neither correlated with egg volume. When all species of eggs were extracted and combined with diet in domes of constant size and constant protein content, only extracts of E. kuehniella and P. interpunctella eggs were more active than diet alone.

CACTOBLASTIS CACTORUM (Lepidoptera: pyralidae): Observations of Courtship and Mating Behaviors at Two Locations on the Gulf Coast of Florida

Abstract Cactoblastis cactorum (Berg) has become an invasive pest of Opuntia spp. along the coastal areas of southeastern United States from the panhandle of Florida to South Carolina. Spread of this insect into cactus dominated natural areas of the United States and Mexico and into agricultural opuntia fields of Mexico is raising concerns within international governments and conservation organizations. Interest is growing in using the Sterile Insect Technique (SIT) to manage C. cactorum populations. Information on courtship and mating behaviors of this insect is important in the development and application of SIT. We conducted mating table studies and determined that this moth exhibits simple rather than elaborate mating behaviors and that courtship and mating take place briefly during morning twilight. Typically, females initiate calling, males respond to females, and copulation are complete before sunrise. Successfully mated females attract males within a short period (mean of 5.2 min), while unsuccessful females continue calling for about 40 minutes. Mating pairs remain in copula for a mean of 31.8 min. Generally, mated females are busy ovipositing the first few nights after mating, not exhibiting additional mating behaviors. A release of marked males revealed that males stay near the release site and can be recovered and identified for subsequent population estimate studies. This study on courtship/mating behavior is helpful to the ongoing C. cactorum research to develop a successful SIT program, identify the female calling pheromone, improve monitoring traps, and develop a technique to estimate adult moth population abundance.

DEVELOPMENT OF THE MOST EFFECTIVE TRAP TO MONITOR THE PRESENCE OF THE CACTUS MOTH CACTOBLASTIS CACTORUM (LEPIDOPTERA: PYRALIDAE)

Abstract Various trap specifications were evaluated to identify the most effective trap for capturing wild male Cactoblastis cactorum (Berg). All traps were baited with virgin female C. cactorum and, except for the first comparison of trap type, a standard wing trap was used in all experiments. Although wing traps captured more males than did the other trap types (delta or bucket), the differences were not significant. However, significantly higher numbers of males were captured in wing traps placed 2 m above ground than traps at 1 m or 0.5 m, and wing traps baited with four virgin females caught significantly more males than wing traps baited with a single female. Differences in number of males captured by young and old females were not significant, but more than twice as many males were captured in traps baited with one-day-old females than traps baited with four day old females. In addition, there were no significant differences in number of males caught in unpainted, white, wing traps and wing traps painted one of eight different colors (flat white, black, dark green, fluorescent green, yellow, fluorescent yellow, orange, or blue), although, more males were captured in the unpainted wing traps. The results presented here suggest that the best trap currently available to monitor C. cactorum is a standard (unpainted) wing trap, placed at a height of 2.0 m aboveground, and baited with four newly emerged females.

LABORATORY EVALUATION OF INSECTICIDES FOR CONTROL OF THE INVASIVE CACTOBLASTIS CACTORUM (LEPIDOPTERA: PYRALIDAE)

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 Cactoblastis 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 dipping, 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.