Ian C. Stocks

Phylogenetic analysis reveals positive correlations between adaptations to diverse hosts in a group of pathogen-like herbivores

A jack of all trades can be master of none—this intuitive idea underlies most theoretical models of host‐use evolution in plant‐feeding insects, yet empirical support for trade‐offs in performance on distinct host plants is weak. Trade‐offs may influence the long‐term evolution of host use while being difficult to detect in extant populations, but host‐use evolution may also be driven by adaptations for generalism. Here we used host‐use data from insect collection records to parameterize a phylogenetic model of host‐use evolution in armored scale insects, a large family of plant‐feeding insects with a simple, pathogen‐like life history. We found that a model incorporating positive correlations between evolutionary changes in host performance best fit the observed patterns of diaspidid presence and absence on nearly all focal host taxa, suggesting that adaptations to particular hosts also enhance performance on other hosts. In contrast to the widely invoked trade‐off model, we advocate a “toolbox” model of host‐use evolution in which armored scale insects accumulate a set of independent genetic tools, each of which is under selection for a single function but may be useful on multiple hosts.

The Phloem-Sap Feeding Mealybug (Ferrisia virgata) Carries 'Candidatus Liberibacter asiaticus' Populations That Do Not Cause Disease in Host Plants

‘Candidatus Liberibacter asiaticus’ (Las) is the primary causal agent of huanglongbing (HLB), the most devastating disease of citrus worldwide. There are three known insect vectors of the HLB-associated bacteria, and all are members of the Hemiptera: Diaphorina citri (Psyllidae), Trioza erytreae (Triozidae), and Cacopsylla (Psylla) citrisuga (Psyllidae). In this study, we found that another hemipteran, the striped mealybug Ferrisia virgata (Cockerell) (Hemiptera: Pseudococcidae), was able to acquire and retain Las bacteria. The bacterial titers were positively correlated with the feeding acquisition time on Las-infected leaf discs, with a two-weeks feeding period resulting in Ct values ranging from 23.1 to 36.1 (8.24×107 to 1.07×104 Las cells per mealybug). We further discovered that the prophage/phage populations of Las in the mealybugs were different from those of Las in psyllids based on Las prophage-specific molecular markers: infected psyllids harbored the Las populations with prophage/phage FP1 and FP2, while infected mealybugs carried the Las populations with the iFP3 being the dominant prophage/phage. As in the psyllids, Las bacteria were shown to move through the insect gut wall to the salivary glands after being ingested by the mealybug based on a time-course quantitative polymerase chain reaction (qPCR) assay of the dissected digestive systems. However, Las populations transmitted by the mealybugs did not cause disease in host plants. This is the first evidence of genetic difference among Las populations harbored by different insect vectors and difference among Las populations with respect to whether or not they cause disease in host plants.

Host plants and natural enemies of rugose spiraling whitefly (Hemiptera: Aleyrodidae) in Florida

Summary The rugose spiraling whitefly, Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae), is a polyphagous pest that has caused significant damage in the Florida landscape. Various plants have been identified as primary hosts in affected areas. Rugose spiraling whitefly was confirmed in 22 counties, and surveys for biological control agents have found several important natural enemies and other species that collectively provide appreciable control of this whitefly pest.

Developing Detection and Monitoring Strategies for Planococcus minor (Hemiptera: Pseudococcidae)

ABSTRACT A pheromone-based system to locate and monitor Planococcus minor (Maskell), a pest of over 250 plants including citrus, grape, and cacao, was tested. The difficulty in distinguishing P. minor from the citrus mealybug, P. citri, makes finding and evaluating the impact of the pest challenging. Studies conducted in Puerto Rico determined that synthetic P. minor pheromone lures preaged 120 d in the field caught similar number of males as lures not aged (fresh). Molecular analysis of trapped mealybug males using mitochondrial cytochrome oxidase-1, the internal transcriber space two locus, and 28S-D2 gene showed the pheromone traps to be species specific. Traps baited with P. minor pheromone were used to monitor the pest in south Florida and to locate potential infestations. P. minor males were found at all locations studied in South Florida and were present in low numbers (1.03 ± 0.69 mean ± SE/trap/14 d). Over 14,000 terminals, fruit, and flowers were visually inspected over a 6 mo period of peak trap catches before the first adult P. minor female was found. The synthetic pheromone lures proved to be an effective tool to locate and monitor this pest new to the continental United States.

New Record of Hypogeococcus pungens (Hemiptera: Pseudococcidae) in the Dominican Republic with Comments on Specific Characters

The mealybug Hypogeococcus pungens Granara de Willink (Hemiptera: Pseudococcidae) is a new record for the Dominican Republic, based on specimens collected on 21 May 2010 from the ornamental plant Gomphrena globosa L. (Caryophyllales: Amaranthaceae), in Santo Domingo. La especie Hypogeococcus pungens Granara de Willink (Hemiptera: Pseudococcidae) fue encontrada el 21 de mayo del 2010 como un nuevo record para la Republica Dominicana, especimenes fueron colectados en Santo Domingo sobre la planta ornamental Gomphrena globosa L. (Caryophyllales: Amaranthaceae). View this article in BioOne

First Report of Economic Injury Due to the Spiraling Whitefly (Hemiptera: Aleyrodidae) on Pepper in Indonesia

Summary A pest survey and subsequent identification confirmed the presence of the spiraling whitefly, Aleurodicus dispersus Russell (Hemiptera: Aleyrodidae), in Pinrang District, South Sulawesi Province of Indonesia. This is the first report of the insect in the province and population outbreaks resulting in serious damage to pepper, Capsicum annuum L. (Solanaceae), in Indonesia. In our subsequent survey, A. dispersus was found on pepper in 2 other districts of the province, Pangkep and Wajo. Given its wide host range and dispersal capability, the insect poses a serious threat to pepper in Indonesia. Pepper growers at the survey site applied mixtures of insecticides 2–3 times per week to suppress the pest. Their insecticide choices and application frequencies were based on their own experience in controlling other pests. They urgently need information on effective measures to control this new pest. Therefore, a study on field and laboratory evaluations of selected insecticides against the spiraling whitefly has been completed recently and the results will be published in a separate paper. Surveys for potential biological control agents, such as parasitoid wasps and entomopathogenic fungi, are also underway. Furthermore, given the following phenomena: the presence of high population of A. dispersus concomitant with the high incidence of PepYLCIV, a Begomovirus; low population of its known vector, B. tabaci; and the ability of A. dispersus to transmit a Begomovirus, CBSV in Africa; it is imperative to conduct a study to determine the capability of the spiraling whitefly in transmitting the PepYLCIV in South Sulawesi.

Occurrence of Boisduval Scale, Diaspis boisduvalii (Hemiptera: Diaspididae), on Native Epiphytic Orchids in Collier Co., Florida, Including Fakahatchee Strand State Preserve

ABSTRACT We present the results of a field study conducted in 2011 to assess native epiphytic orchids in South Florida for infestations of armored scales (Hemiptera: Coccoidea: Diaspididae). A total of 1,726 orchids spanning 10 taxa were surveyed at 7 locations at 3 sites. Boisduval scale, Diaspis boisduvalii Signoret, was detected on 2.3% of the orchids from 6 of the 10 orchid species, and was present at all 3 primary sites surveyed. Prosthechea cochleata and Epidendrum amphistomum (Asparagales: Orchidaceae) appeared to be most vulnerable to this scale, with infection totals of 5.8% and 2.1%, respectively. Of 44 scales from the 39 orchids, 27% hosted hymenopteran parasitoids in various stages of development. The presence of D. boisduvalii adds an additional burden to state-endangered orchid populations and indicates that resource managers may need to expand management approaches to include plant-parasitic insect control.

DNA Barcode Development for Three Recent Exotic Whitefly (Hemiptera: Aleyrodidae) Invaders in Florida

Abstract Several new whitefly (Hemiptera: Aleyrodidae) species have become established in Florida in the past decade. Three of these, fig whitefly (FW), rugose spiraling whitefly (RSW), and Bondars nesting whitefly (BNW), have caused noticeable damage to residential plants in the landscape including ficus hedges, palms, and bird of paradise. Whiteflies are difficult to identify and 4th instar nymphs are needed for morphological identification making whiteflies good candidates for identification via DNA barcoding. A DNA barcoding cocktail to amplify the 5′ end of the coxI mitochondrial gene from these species was developed. Subsequently, primers were developed for each species, validated with multiple populations collected throughout Florida, and a phylogenetic tree was constructed for placement of the 3 species in the whitefly tree of life. Besides FW, RSW, and BNW, 2 additional species of whiteflies were detected in collections, namely Paraleyrodes pseudonaranjae Martin (Hemiptera: Aleyrodidae) and a species provisionally designated Aleurodicinae sp1. RSW and BNW clustered with congeners within the phylogeny, and FW was resolved as a possible sister taxa to the genus Bemisia. The barcoding cocktail should allow sequencing of 5′ coxI from multiple genera and both sub-families of whiteflies, and the primers developed for each species will facilitate rapid identification of these 3 invasive whiteflies.

Armored Scales (Hemiptera: Diaspididae) Infesting Hass Avocado Intercepted in Florida and a New Parasitoid-Host Association for Davidsonaspis aguacatae

Summary A new parasitoid-host association between Davidsonaspis aguacatae (Evans, Watson & Miller) (Hemiptera: Diaspididae) and Encarsia lounsburyi (Berlese & Paoli) (Hymenoptera: Aphelinidae) is documented, and an overview of armored scales infesting Hass avocados intercepted in Florida is given. An observation of the occurrence of crawler scales developing inside a parasitized female scale is discussed.

Armored Scale (Hemiptera: Diaspididae) Pests on Abies fraseri (Pinaceae) Christmas Trees Imported into Florida

Summary Adventive and potentially pestiferous species are a constant threat to the agriculture of Florida. Fiorinia externa Ferris (Hemiptera: Diaspididae), the elongate hemlock scale, is a recent but persistently intercepted pest of Fraser fir and related species grown out-of-state and imported annually into Florida as cut Christmas trees. Although this and a second species, Hemiberlesia ithacae (Ferris) (Hemiptera: Diaspididae), the hemlock scale, may not become established in Florida on native or cultivated hosts, the risk remains and illustrates the importance of continued vigilance against pest species incursion.