Divina M. Amalin

Effects of Host Age, Female Parasitoid Age, and Host Plant on Parasitism of Ceratogramma etiennei (Hymenoptera: Trichogrammatidae)

Abstract Parasitism of Diaprepes abbreviatus (L.) eggs by Ceratogramma etiennei Delvare as influenced by host age, age of the female parasitoid, and host plant preference was evaluated under laboratory or greenhouse tests. Percent parasitism of D. abbreviatus eggs by C. etiennei decreased as eggs matured. The optimal age of C. etiennei for successful parasitism ranged from 1-2-d old. Host plant leaf thickness, leaf pubescence, and plant strata probably played a role on the parasitism by C. etiennei. This parasitoid is diurnal and spent approximately 5 min searching for eggs laid in cryptic locations, 46 min parasitizing an egg mass and 24 min resting. This biological information is relevant in evaluating the potential of C. etiennei in the classical biological control of D. abbreviatus.

Host plant range of Raoiella indica (Acari: Tenuipalpidae) in areas of invasion of the New World

Raoiella indica has spread rapidly through the Neotropical region where the mite damages economically and ecologically important plants. Three studies were conducted to determine the host plant range of R. indica, using the presence of colonies containing all life stages as an indicator of reproductive suitability. Periodic surveys at the Fairchild Tropical Botanic Garden (Miami Dade County, FL, USA) and the Royal Botanical Gardens (Port of Spain, Trinidad and Tobago) identified 27 new reproductive host plants. The reproductive suitability of two dicotyledonous species and three native Florida palm species was examined. An updated list of reproductive host plants of R. indica is presented. All reported reproductive hosts (91 plant species) of R. indica are monocots from the orders Arecales (Arecaceae), Zingiberales (Heliconiaceae, Musaceae, Strelitziaceae, Zingiberaceae) and Pandanales (Pandanaceae). Most are palms of the family Arecaceae that originated in areas of the Eastern Hemisphere; about one fourth of the reported hosts are native to the New World and could be considered new host associations of R. indica. Six years after the initial detection in the Caribbean, R. indica has expanded its host plant range. Here we report 27 new reproductive host of R. indica that represent 30% of increase on previous host plant records. As this mite continues spreading in the Neotropical region a great diversity of plants is potentially affected.

Comparison of Different Sampling Methods and Effect of Pesticide Application on Spider Populations in Lime Orchards in South Florida

Abstract A survey of predatory arthropods in lime orchards at Homestead, FL, showed that spiders significantly outnumbered the other predatory arthropods (the green lacewing Chrysoperla rufilabris, coccinellid Harmonia sp., and the ant Myrmelachista sp.). The spider community consisted of nine families, 25 genera, and 15 species. The abundance and diversity of the predatory spiders in lime orchards suggests their possible role in regulating the increase of arthropod pest populations. In general, comparison of three sampling methods revealed that the visual sampling method provided the highest number of spiders collected followed by the shake-cloth method and the DVAC suction method collected the least. However, our data showed that the choice of sampling method depends on the species of interest. For instance, spider species in the hunting group were collected frequently using the visual method followed by the shake-cloth method; whereas, most of the species in the web-building group were collected by the three sampling methods with similar frequencies. The difference in the efficiency of the sampling methods may be explained by the retreating habits of the different spider species. The data gathered in sampling the predatory arthropods in sprayed and nonsprayed lime orchards demonstrated the probable nontarget effect of the different pesticides used in the orchards.

PREDATORY BEHAVIOR OF THREE SPECIES OF SAC SPIDERS ATTACKING CITRUS LEAFMINER

Abstract The predatory habit of three species of sac spiders, Chiracanthium inclusum, Hibana velox, and Trachelas volutus, on citrus leafminer, Phyllocnistis citrella, was investigated. Observation of spider activities during the photophase and the scotophase confirmed that these three species of sac spiders are nocturnal. They detect their prey by sensing vibrations of the substrate induced by the concealed prey. Movements of P. citrella larvae and prepupae appear to create vibrations of the leaf substrate, which then serve as cues for the spiders to locate them. The searching and prey capture behaviors of these spiders are discussed. Two methods of prey attack were exhibited. In one method, the spider punctures the mine, immobilizes the larva and then bites it and sucks the larval body fluid. In the second behavioral pattern, the spider makes a slit in the mine, uses its forelegs to pull the larva or prepupa out of the mine, holds the prey securely, and finally bites it and regurgitates digestive juices into the prey and ingests the pre-digested liquid tissue. The three species of sac spiders were found to start feeding on P. citrella larvae during the 2nd instar stage. Consumption increased as they developed to later instars. Maximum consumption for all species was recorded at the 4th instar. Although C. inclusum and T. volutus can complete their life cycle with P. citrella as their only food, H. velox was not able to develop to the adult stage. Results obtained from this study provide useful data to better understand the role of sac spiders in the overall management of P. citrella.

COMPARISON OF THE SURVIVAL OF THREE SPECIES OF SAC SPIDERS ON NATURAL AND ARTIFICIAL DIETS

Abstract Three species of sac spiders were reared under laboratory conditions to investigate their survival and development. First, the effects of three artificial diets, milk + egg yolk, soybean liquid, and a combination of them, on the survival and development of Hibana velox were evaluated. Results over a 10 wk rearing period showed that the percentages of survival of H. velox reared on soybean liquid and combination diets did not differ significantly. However, the survival of H. velox on the milk + egg yolk diet was significantly lower than on the other two artificial diets. More molts and instars occurred in spiders raised on milk + egg yolk and on the combination diet than on the soybean liquid diet. Second, the development and percent survival of three sac spiders (Chiracanthium inclusum, H. velox, and Trachelas volutus) on artificial diet (i.e., the combination diet) and natural diets (i.e., citrus leafminer larvae and Drosophila adults) were compared. The three sac spiders developed into the adult stage on the combination diet. Similarly, all three sac spiders reared on Drosophila adults were able to develop to the adult stage. Chiracanthium inclusum and T. volutus reared on citrus leafminer larvae developed to the adult stage, whereas H. velox did not. Females of these three species that matured using combination diet and were fertilized in captivity produced 1–3 egg masses. Oviposition took place 2–7 days after mating. Chiracanthium inclusum had an average of 57 eggs per egg mass, whereas H. velox and T. volutus had an average of 110 and 56 eggs per egg mass, respectively.

Life Table Analysis and Development of Singhiella simplex (Hemiptera: Aleyrodidae) under Different Constant Temperatures

ABSTRACT Singhiella simplex (Singh) (Hemiptera: Aleyrodidae) is a newly invasive pest of several species of Ficus plants in the United States. Very little is known about its biology and life history. Here, we studied its development and reproduction at 15, 20, 25, 27, 30, and 35°C. No immatures survived the 35°C treatment. Stage-specific duration times are presented for the other temperatures. Total duration of immature stages varied from 97.1 d at 15°C to 25.2 d at 30°C. Linear functions were used to describe development rates for eggs, instars and pupal stages. Total immature development also was modeled using a nonlinear Briere-1 function: r(T) = aT(T -T0) where r(T) is developmental rate at temperature (T), a = 0.0000146, T0 = 7.3120084 and TL = 45.9512202 (constant, lower developmental threshold, and lethal temperature, respectively). The thermal requirement for development from eggs to pupae was estimated to be 487.8 degree-days. S. simplex reproduction was highest at 27°C, where R0, GRR, T, r, &lgr;, and DT were 23.114 ♀ / ♀, 24.25 ♀/♀, 31.413 d, 0.099 ♀ / ♀ /d, 1.105 ♀ / ♀ /d, and 6.93 d, respectively. The combined effect of temperature and female adult age on daily oviposition rate was modeled using the Enkegaard equation: eggmean = (p + qT) d exp(-wTd), where T is temperature. Parameter estimates were p = -30.21, q = 2.62, and w = 0.034. Duration of female adulthood was 8 d at 15°C, significantly longer than 2.5–4.2 d at the higher temperatures. At 25 and 27°C, lifetime fecundity per female averaged 37.9 and 46.2, respectively.

Predation by Hunting Spiders on Citrus Leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae)

Feeding efficiency of the three species of hunting spiders, Chiracanthium inclusum Hentz, Hibana velox (Becker), and Trachelas volutus (Gertsch), was investigated in laboratory, greenhouse, and fie...

Egg Distribution and Sampling of Diaprepes abbreviatus (Coleoptera: Curculionidae) on Silver Buttonwood

Abstract Taylor’s power law and Iwao’s patchiness regression were used to analyze spatial distribution of eggs of the Diaprepes root weevil, Diaprepes abbreviatus (L.), on silver buttonwood trees, Conocarpus erectus, during 1997 and 1998. Taylor’s power law and Iwao’s patchiness regression provided similar descriptions of variance-mean relationship for egg distribution within trees. Sample size requirements were determined. Information presented in this paper should help to improve accuracy and efficiency in sampling of the weevil eggs in the future.

TEMPORAL AND SPATIAL CHARACTERIZATION OF AN INFESTATION OF PARATACHARDINA LOBATA LOBATA (HEMIPTERA: KERRIIDAE), A NEW INVASIVE PEST IN FLORIDA

Abstract The lobate lac scale, Paratachardina lobata lobata (Chamberlin) was first found in south Florida in 1999. Reported hosts are present in the germplasm collection located at the USDA/ARS Subtropical Horticulture Research Station in Miami, and the scale was first found there in the summer of 2002. A study was initiated to determine the spatio-temporal dynamics of a lobate lac scale infestation at SHRS from Jul 2003 to Jul 2005. Numbers and percentages of viable adults, and reproductive success as indicated by ratio of nymphs to viable adults (<2 cm diam and 30 cm long branch sample) were recorded. There were 55 plants evaluated over the ∼80 hectares study site. Infestation increased from 42% of sampled plants at the start of the study to 75% at the end, and most of the plants had low or moderate levels of infestation (between 0 and 100 adults per 30 cm branch) over the course of the study. Percentage of non-viable adults dropped from ∼27% at the start of the study to ∼7% by the end of the study, and ratio of nymphs to viable adults dropped from ∼9% to ∼2%. Spatial analysis showed that initial infestations were along the eastern edge of the sampled area, with populations declining over the first half of the study but then increasing during the second half. Over the course of the study, heavy infestations (≥100 scales per 30 cm branch) were found on only seven host plants. Among plants located in areas of high infestation probabilities, individual host susceptibility appeared to be the primary factor regulating infestation level.