Catharine M. Mannion

Life History of the Mealybug, Maconellicoccus hirsutus (Hemiptera: Pseudococcidae), at Constant Temperatures

Abstract Important life history parameters of the mealybug, Maconellicoccus hirsutus (Green), were characterized on hibiscus (Hibiscus rosa-sinensis L.) cuttings at six constant temperatures between 15 and 35°C. The development of M. hirsutus was the fastest at 27°C, where the mealybugs completed development in ≈29 d. The lower (Tmin) and upper (Tmax) developmental thresholds and the optimal developmental temperature (Topt) for the development of female mealybugs were estimated as 14.5, 35, and 29°C, respectively. The thermal constant (K), which is the number of temperature-day or degree-day units required for development, of the females was 347 DD. The original distribution range prediction (based on Tmin = 17.5°C and K = 300 DD) indicated that M. hirsutus could complete at least one generation in all of the continental United States. However, results of this study suggested that the distribution range of M. hirsutus may expand northward because of the lower Tmin, and the predicted number of generations in a year may be lower because of the higher K required to complete each generation. The average cumulative survival rate of M. hirsutus at 25 and 27°C was 72%, which was significantly higher than 51 and 62% at 20 and 30°C, respectively. M. hirsutus reproduced sexually, with each mated female producing 260–300 eggs between 20 and 27°C but only ≈100 eggs at 30°C. Female longevity was reduced from 28 d at 20°C to 19–21 d at 25–30°C. At 27°C, the net reproductive rate (Ro) was estimated at 165 ♀/♀, the intrinsic rate of population increase (rm) was 0.119 (♀/♀/d), the generation time (TG) was 43 d, and the doubling time (DT) was 5.8 d. The life table statistics suggested that the currently released biological control agents, which have higher rm than M. hirsutus, will be able to complete more generations than the mealybug within the tested temperature range; thus, they are effective against M. hirsutus.

Management of Early-Instar Japanese Beetle (Coleoptera: Scarabaeidae) in Field-Grown Nursery Crops

Abstract Numerous field studies were conducted in commercial nurseries in Tennessee from 1996 through 1999 to evaluate chemical and biological treatments, application timing and rates, and method of application for control of early instars of Japanese beetle, Popillia japonica Newman. Insecticide treatments included bifenthrin, bendiocarb, chlorpyrifos, carbaryl, fipronil, halofenozide, imidacloprid, permethrin, tefluthrin, thiamethoxam, and trichlorfon. Biological treatments included entomopathogenic nematodes (Heterorhabditis bacteriophora HP88 or H. marelatus), Bacillus thuringiensis Berliner subspecies japonensis Buibui strain, and Beauveria bassiana (Balsamo) Vuillemin. All treatments were applied on the soil surface or injected into the soil around the base of each tree. Tree type and size varied among and within tests, however, the sampling unit (61-cm-diameter root ball) remained the same throughout all tests. The biological treatments provided poor-to-moderate control (0–75%) of Japanese beetle larvae. Imidacloprid was the most frequently evaluated insecticide and achieved 91–100, 87–100, 83–100, and 41–100% control with applications in May, June, July, and August, respectively. Halofenozide treatments were not significantly different from imidacloprid treatments with one exception. Halofenozide provided 60–87, 85–100, and 82–92 control with applications made in June, July, and August, respectively. Fipronil and thiamethoxam were evaluated to a lesser extent but both performed similarly to imidacloprid. Most other insecticide treatments were less successful in reducing numbers of Japanese beetle larvae and with few exceptions achieved <50% control.

Effect of Temperature on the Life History of the Mealybug Paracoccus marginatus (Hemiptera: Pseudococcidae)

Abstract Effect of temperature on the life history of the mealybug Paracoccus marginatus Williams & Granara de Willink (Hemiptera: Pseudococcidae) was investigated in the laboratory. P. marginatus was able to develop and complete its life cycle at 18, 20, 25, and 30 ± 1°C. At 15, 34, and 35°C, the eggs hatched after 27.5, 5.9, and 5.5 d of incubation, respectively, but further development of the first-instar nymphs was arrested. No eggs hatched at 37°C. The developmental time for egg to adult was the longest at 18°C for both males and females. Approximately 80–90% of the eggs survived between 20 and 30°C. The highest fecundity was at 25°C with each female producing an average of 300 eggs. Adult longevity, and preoviposition and oviposition periods increased with decreasing temperature up to 25°C. The proportion of females was ≈42% at 25°C and was between 70 and 80% at 18, 20, and 30°C. Adult males and females required 303.0 and 294.1 degree-days (DD), respectively, to complete their development. The estimated minimum temperature thresholds for the adult males and females were 14.5 and 13.9°C, respectively. For adult males, the estimated optimum and maximum temperature thresholds were 28.7 and 31.9°C; and for adult females, they were 28.4 and 32.1°C, respectively. The ability of P. marginatus to develop, survive, and reproduce successfully between 18 and 30°C suggests that it has the capability to develop and establish in areas within this temperature range.

Life History of Paracoccus marginatus (Hemiptera: Pseudococcidae) on Four Host Plant Species Under Laboratory Conditions

Abstract Life history of the mealybug, Paracoccus marginatus Williams and Granara de Willink, on three ornamental plants [Hibiscus rosa-sinensis L., Acalypha wilkesiana (Muell.-Arg.), and Plumeria rubra L.] and one weed species (Parthenium hysterophorus L.) was studied under laboratory conditions. Mealybugs were able to develop, survive, and reproduce on all four hosts; however, there were differences in the life history parameters. Adult females that developed on acalypha and parthenium emerged ≈1 d earlier than those that developed on hibiscus and plumeria. Adult males had a longer developmental time on plumeria than on the other hosts. Survival of first- and second-instar nymphs and cumulative adult survival were lowest on plumeria. Longevity was not affected by hosts for males and females and averaged 2.3 ± 0.1 and 21.2 ± 0.1 d, respectively. On plumeria, 58.9 ± 1.7% of the adults were females, which was a higher female percentage than on the other hosts. No egg production occurred in virgin females. Prereproductive and reproductive periods of the females were not affected by hosts and averaged 6.3 ± 0.1 and 11.2 ± 0.1 d, respectively. Mean fecundity of 186.3 ± 1.8 eggs on plumeria was lower than on the other three plant species. Life history parameters of P. marginatus on hibiscus, acalypha, plumeria, and parthenium show its ability to develop, survive, and reproduce on a wide variety of plant species.

OVIPOSITION AND LARVAL SURVIVAL OF DIAPREPES ABBREVIATUS (COLEOPTERA: CURCULIONIDAE) ON SELECT HOST PLANTS

Abstract In a preliminary survey in four commercial ornamental nurseries in south Florida (1998), Diaprepes abbreviatus (L.) (Coleoptera: Curculionidae) egg masses, feeding damage, or adults occurred on numerous field-grown ornamental plant species. Live oak (Quercus virginiana Mill.), silver buttonwood (Conocarpus erectus L. variety sericeus Fors. Ex DC), and black olive (Bucida buseras L.) had the highest percentage of plants with egg masses. Adult feeding damage was found on all examined plants of dahoon holly (Ilex cassine L.), cocoplum (Chrysobalanus icaco L.), black olive, live oak, Bauhinia sp., and Cassia sp. Oviposition of D. abbreviatus was evaluated in no-choice, two-choice, three-choice and multiple-choice caged tests. In no-choice tests, silver buttonwood had the highest mean number of egg masses. In two-choice tests, egg masses were laid on all plant species tested but there were significantly more egg masses on silver buttonwood than the alternate choice. The number of egg masses in the three-choice tests was low and there were no significant differences among the plant species tested. As in the no-choice and two-choice tests, significantly more egg masses were found on silver buttonwood in multiple-choice tests. Survival of larvae and their effect on plant growth was examined on several commonly grown plant species in southern Florida. Larval survival was highest on silver buttonwood and Sorghum sudanense Pers (sorghum-sudan) compared with other plant species. Root and/or total biomass was significantly reduced on green bean (Phaseolus vulgaris), silver buttonwood, Tahiti lime (Citrus aurantifolia), and sorghum-sudan.

Density and Natural Enemies of the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Psyllidae), in the Residential Landscape of Southern Florida

Abstract This study was conducted to determine the density, the incidence of parasitism, and the generalist predator assemblage of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), on orange jasmine plants [Murraya paniculata (L.) Jack] in the residential landscape of Miami-Dade County, Florida. Flush shoots (10 cm) were collected from ten orange jasmine hedges in each of the four communities (Doral, Coral Gables, Palmetto Bay, and Homestead). We did not detect any consistent pattern in the fluctuation of psyllid density over time in the four communities. The greatest densities of eggs (65.5 ± 36.3 eggs/shoot), early instars (first to third) (87.2 ± 47.8 nymphs/shoot), and late instars (fourth and fifth) (16.9 ± 9.3 nymphs/shoot) were detected on 24 May 2006 in Palmetto Bay (egg) and Doral (early and late instars). The density of adult psyllids remained below two individuals per flush shoot at all locations for the entire sampling period. There were no consistent correlations between environmental factors (temperature, relative humidity, precipitation, and wind speed) and the densities of nymphs and eggs. Percent parasitism by Tamarixia radiata (Waterston) averaged 18.5% in 2006, and no consistent patterns were observed among communities and sampling dates. Ladybeetles, syrphid flies, and spiders were the most common generalist predators observed on the psyllid-infested flush shoots.

Comparison of Sex Pheromone Traps for Monitoring Pink Hibiscus Mealybug (Hemiptera: Pseudococcidae)

Abstract The pink hibiscus mealybug, Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae), is a highly polyphagous pest that invaded Florida in 2002 and has recently been reported from several locations in Louisiana. Although identification of its sex pheromone in 2004 improved monitoring capabilities tremendously, the effectiveness and efficiency of different pheromone trap designs for capturing males has not been evaluated. We deployed green Delta, Pherocon IIB, Pherocon V, Jackson, and Storgard Thinline traps in Homestead, FL, and compared the number of male M. hirsutus captured per trap, the number captured per unit of trapping surface area, the amount of extraneous material captured, and the time taken to count trapped mealybugs. Pheromone-baited traps with larger trapping surfaces (green Delta, Pherocon IIB, and Pherocon V) captured more males per trap than those with smaller surfaces (Jackson and Storgard Thinline), and fewest males were captured by Storgard Thinline traps. However, Jackson traps captured as many or more males per square centimeter of trapping surface as those with larger surfaces, and the time required to count males in Jackson traps was significantly less than in green Delta, Pherocon IIB, and Pherocon V traps. Although all trap designs accumulated some debris and nontarget insects, it was rated as light to moderate for all designs. Based on our measures of effectiveness and efficiency, the Jackson trap is most suitable for monitoring M. hirsutus populations. Additionally, unlike the other traps evaluated, which must be replaced entirely or inspected in the field and then redeployed, only the sticky liners of Jackson traps require replacement, enhancing the efficiency of trap servicing.

Expression of Feeding Symptoms from Pink Hibiscus Mealybug (Hemiptera: Pseudococcidae) by Commercially Important Cultivars of Hibiscus

ABSTRACT The pink hibiscus mealybug, Maconellicoccus hirsutus (Green), is a highly polyphagous pest that invaded southern Florida in 2002 and is now widely established throughout most of the state. Although Hibiscus rosa-sinensis L. is a preferred and economically important host of M. hirsutus, the susceptibility and expression of feeding symptoms by different cultivars have not been evaluated. Cultivars of H. rosa-sinensis were infested with M. hirsutus and evaluated daily for 40 d for the onset and percentage of terminals expressing feeding symptoms. Under different initial densities of M. hirsutus, the cultivar ‘President’ showed no difference in the latency to expression of feeding symptoms, which occurred between 7 and 15 d after infestation, but did show significant differences between initial density and percentage of terminals expressing feeding symptoms from 10 d onward. When infested with 20 females, 80% of ‘President’ terminals exhibited symptoms 30 d after infestation. Four other cultivars initially infested with 10 female M. hirsutus showed significant differences in the onset and severity of feeding symptoms. All plants of the cultivars ‘Florida Sunset’ and ‘Joanne’ expressed damage symptoms at 12 ± 2 SE d and 10 ± 1 d, respectively, following infestation. Only a single plant of the cultivars ‘Double Red’ and ‘Snow Queen’ showed such symptoms at 19 and 30 d after infestation, respectively. Significant differences between cultivar and the percentage of terminals expressing feeding symptoms were observed from 20 d onward. Terminals sampled from all plants after 40 d revealed that egg, nymph, and adult female M. hirsutus were found on all plants, including those that did not exhibit feeding symptoms. These data have shown that hibiscus cultivars differ in their expression of M. hirsutus feeding symptoms, that M. hirsutus can reproduce on cultivars of hibiscus that do not express feeding symptoms, and that feeding symptoms are not a reliable indicator of infestation by M. hirsutus, highlighting the need for further investigation of the mechanisms underlying differences among cultivars.

Chlorpyrifos Immersion to Eliminate Third Instars of Japanese Beetle (Coleoptera: Scarabaeidae) in Balled and Burlapped Trees and Subsequent Treatment Effects on Red Maple

Abstract This study examined chlorpyrifos immersion of balled and burlapped (B&B) nursery trees for elimination of third instars of Japanese beetle, Popillia japonica Newman (Coleoptera: Scarabaeidae), and for phytotoxicity on red maple, Acer rubrum L. Trees were harvested as 45- and 60-cm-diameter B&B and immersed in chlorpyrifos at U.S. Domestic Japanese Beetle Harmonization Plan rate (0.24 kg active ingredient [AI]/100 liters) or lower rates of 0.015, 0.03, 0.06, and 0.12 kg (AI)/100 liters. The 0.03, 0.06, and 0.24 kg (AI) rates provided 100% control of Japanese beetle grubs in both 45- and 60-cm B&B. The 0.015 and 0.12 kg (AI) chlorpyrifos rates were 100% effective in three tests. However, in another test, 0.015 and 0.12 kg (AI) chlorpyrifos treatments had four (93% control) and one (98% control) grubs recovered, respectively. Root ball soils consisted of loam, silt loam, or clay loam texture classifications. Trunk diameter and internode growth of red maple harvested as 45-cm B&B decreased linearly with increasing chlorpyrifos dip rate during the first year, but effects were unapparent in the second year. Chlorpyrifos rates had no measurable impact on growth of red maples harvested as 60-cm B&B. No visual phytotoxicity symptoms were detected for chlorpyrifos rate or root ball size treatments. In conclusion, results support lowering the U.S. Domestic Japanese Beetle Harmonization Plan chlorpyrifos dip rate for category 2 states to at least 0.03 kg (AI) for B&B diameters ≤60 cm. Chlorpyrifos rates <0.24 kg (AI) will lower cost, reduce worker exposure, and lessen potential environmental contamination.

Life History of an Exotic Soft Scale Insect Phalacrococcus howertoni (Hemiptera: Coccidae) Found in Florida

ABSTRACT We investigated the life history of an exotic soft scale insect, Phalacrococcus howertoni Hodges and Hodgson that damages croton and several other economically important ornamental and fruit plants in Florida. There was no difference in the development, survival, and reproduction of this scale insect species when reared either on croton or on buttonwood at 27 ± 1°C, 12:12 (L:D) h and 65% R. H. The scale insect practiced ovoviviparity. We observed that eggs that came out from vulva hatched to first instars immediately. Newly hatched nymphs had a tendency stay underneath the female body for somewhat less than approximately 24 h and then disperse throughout the leaf area for feeding. Females went through 3 immature stages (first, second, and third-instar) prior to becoming adults, while males had 4 immature stages (first, second, third (‘pre-pupa’), and fourth instar (‘pupa’)). Survival in the first instars was the lowest (50.0–50.9%), while the survivorship of the other instars was as follows: second instars (88.9–90.0%), third instar males (92.9–93.7%), third instar females (92.9–94.8%) and fourth-instar males (96.0–97.6%).Thus, approximately 40% of the first instars survived to adults. The pre-oviposition period was 17.6–19.1 d and the oviposition period was 13.9–15.5 d. Lifetime fertility was in the range of 382.4–394.7 live first instars per female. Intrinsic rate of increase (rm) was 0.091–0.095. The lifespan of adult males was very short (less than 1 d) at 27 ± 1°C compared to that of adult females (60.3–61.5 d).