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Aprostocetus fukutai (Miwa & Sonan) (Hymenoptera: Eulophidae) is the only known egg parasitoid of the citrus longhorned beetle Anoplophora chinensis Forster (Coleoptera: Cerambycidae), a high-risk invasive pest of hardwood trees. Native to East Asia, A. fukutai has been accidentally introduced in northern Italy, where it has 1–2 generations per year, overwinters as diapausing mature larvae within host eggs, and adults emerge in early summer in synchrony with the egg deposition of its host. As part of the efforts to develop a biological control program using this specialist parasitoid, this study investigated some of its key reproductive traits, including egg maturation dynamics, host egg age preference, clutch size, and lifetime fecundity under quarantine laboratory conditions. Newly emerged adult females after winter diapause had a substantial proportion (43.7%) of their lifetime complement of mature eggs and matured additional eggs rapidly, reaching a peak 4–8 days post-emergence. The parasitoid preferred to attack 1–3 day old over 4–7 or 7–10 day old host eggs. Adults of the first (overwintering) generation were more fecund than those of the second (summer) generation. Females of the first and second generations parasitized 3.6 and 2.8 hosts, produced 11.2 and 9.6 offspring per parasitized host for a total of 37.5 and 24.7 offspring with sex ratio of 85.3 and 82.8% females over their lifetime, respectively. These results provide novel information that may help improve protocols for future rearing, study, or field-release of this parasitoid against A. chinensis.

The tawny crazy ant

Bagrada hilaris (Burmeister) is an invasive pest of economically important crops in the United States. During physiological investigations of B. hilaris, a flagellated protozoan was discovered in the alimentary canal of many specimens. This manuscript characterizes the morphology and molecular identification of the trypanosomatid, which appears similar to trypanosomatids identified in other stink bug species. It has been identified as a species in the Blastocrithidia genus based on morphological characteristics and molecular analyses.

Monoecious and dioecious forms of the submerged aquatic plant hydrilla, Hydrilla verticillata (Linn. f.) Royle (Hydrocharitaceae) are invasive weeds in the US. Surveys for biological control agents of hydrilla throughout its native range have been conducted since the 1970s. Surveys between 1996 and 2013 focused on China, Southeast Asia and Australia, with 425 collections of hydrilla made in seven countries. Most of the herbivores collected were typical of previous surveys and included three main feeding guilds and taxonomic groups: stem-boring Bagous weevils, leaf-mining Ephydridae flies and defoliating Crambidae moths. Preliminary testing of prioritized agents collected from 1996 to 2013 did not reveal candidates for use as biological control agents with those tested being polyphagous. Further surveys are currently in China and South Korea, where hydrilla forms/genotypes exist that match those found in the US.

Monoecious and dioecious biotypes of Hydrilla verticillata were introduced from Asia into the United States (U.S.). Although biological control agent development has been ongoing for many years to combat this invasive aquatic weed, the focus has now shifted towards the monoecious biotype because of apparent incompatibilities between previously introduced agents and this lineage. To facilitate collection of natural enemies, we surveyed eastern areas of China and all of South Korea (592 samples from 129 sites) to locate geographic source areas with the introduced monoecious biotype. We used both chloroplast and nuclear microsatellite markers to identify genotypes. Eastern China had high genetic diversity and significant genetic structure across river basins, including three previously described chloroplast clades (B, C, D), one of which (B) includes both biotypes that were introduced into the U.S. South Korea had the monoecious biotype from clade B and clade C. South Korea had a subset of the genetic diversity in China, consistent with China being the ancestral region for hydrilla. U.S. introduced monoecious hydrilla had significantly lower diversity than this genotype in China and South Korea. U.S. monoecious microsatellite profiles cluster with samples from both China and South Korea, failing to resolve a clear region of origin. Reproductive strategies for clade B are more variable than in the introduced range with both monoecious and dioecious individuals sharing the same chloroplast haplotypes and microsatellite clusters. The introduced monoecious biotype of hydrilla is becoming a major problem in the U.S., but in the native range it is rare, patchily distributed, and often mixed with individuals from clade C. Current exploration for biological control agents will need to determine the genetic identity of the plants from which potential biological control agents are collected.

The morphology of the female reproductive system in Megamelus scutellaris Berg (Hemiptera: Delphacidae), a biocontrol agent of Eichhornia crassipes (Mart.) Solms, was examined using standard light microscopy techniques. Ovaries extracted from individuals dissected in phosphate buffered saline were examined using both stereo and compound microscopy. These were typical of other Delphacid planthoppers in that the reproductive system was composed of two ovaries with each consisting of 11 to 13 tubular ovarioles. The ovarioles within each ovary connected via a lateral oviduct and ultimately to the other ovary via a common oviduct. Ovaries were of the telotrophic meroistic type wherein nurse cells contained within the distal germarium did not descend individually with each maturing follicle. An enlarged sac-like bursa copulatrix opened into the common oviduct just posterior to the spermatheca. The bursa copulatrix contained globular structures which we interpreted to be spermatophores. Individual follicles consisted of an inner yolk-filled oocyte (in more mature follicles) with a distinct germinal vesicle or enlarged nucleus present in the proximal region of the follicle. Each oocyte was surrounded by a single layer of cells, termed the follicular epithelium, and the entire ovariole was surrounded by a thin membranous layer, the ovariole sheath. A unique structure surrounding the most distal portion of the lateral oviduct and appearing as a loose grouping of cells which opened proximally was visible at the base of each ovariole in reproductive females. This structure, which we termed the collar, did not appear to be attached to the ovarioles or the lateral oviduct tissues and has not previously been reported in other planthopper or insect species. The continuum of ovarian development was divided into three nulliparous and three parous stages based on ovariole differentiation, presence and appearance of follicular relics, and collar length, which increased linearly with increasing numbers of ovulations. Taken together these characteristics can be used to estimate reproductive condition and number of ovulations of this biological control agent. Key Words: Eichhornia crassipes ; ovary; ovariole; follicular relics Resumen Se examino la morfologia del sistema reproductor femenino en Megamelus scutellaris Berg (Hemiptera: Delphacidae), un agente de biocontrol de Eichhornia crassipes (Mart.) Solms (Pontederiaceae), con tecnicas de microscopia optica estandar. Se examinaron los ovarios extraidos de individuos disecados en solucion salina tamponada con fosfato con microscopia estereoscopica y compuesta. Estos fueron tipicos de otros plantofilos delphacid en que el sistema reproductor estaba compuesto de 2 ovarios con cada uno consistente de 11 a 13 ovarioles tubulares. El oviducto lateral de cada ovario condujo a un oviducto comun. Los ovarios eran del tipo meroista telotrofico donde las celulas enfermeras estaban dentro del germario distal. Un bursa copulatrix de tipo saco ampliado se abre al oviducto comun justo posterior a la espermateca. La bursa copulatrix contenia estructuras globulares que interpretamos como espermatoforos. Los foliculos mas maduros contenian un ovocito lleno de yema de huevo con una vesicula germinal distinta o un nucleo ampliado presente en la region distal del foliculo. Cada ovocito estaba rodeado por una sola capa de celulas, denominada epitelio folicular, y el ovariole entero estaba rodeado por una fina capa membranosa, la vaina ovariole. Una estructura unica que rodeaba la porcion mas distal del oviducto lateral y que aparecia como un grupo suelto de celulas que se abrian proximalmente era visible en la base de cada ovariole en hembras reproductivas. Esta estructura, que denominamos el cuello, no parecia estar unida a los ovarioles ni a los tejidos laterales del oviducto y no ha sido reportada previamente en otras especies de saltamontes o insectos. Se dividio el continuo del desarrollo ovarico en 3 estadios nuliparos y 3 parosos, basados en la diferenciacion ovariole, la presencia y aparicion de reliquias foliculares y la longitud del collar, que aumento linealmente con el aumento del numero de ovulaciones. En conjunto, estas caracteristicas se pueden utilizar para estimar la condicion reproductiva y el numero de ovulaciones. Palabras Clave: Eichhornia crassipes ; ovario; ovariole; reliquias foliculares View this article in BioOne

Olfaction plays a dominant role in insect communication. Alarm pheromones, which alert other insects of the same species of impending danger, are a major class of releaser pheromones. The major components of alarm pheromones in red imported fire ants, honeybees and aphids have been identified as 2-ethyl-3,6-dimethylpyrazine (2E-3,6-DP), isopentyl acetate (IPA), and E-&beta, farnesene (E&beta, F), respectively. In this study, electroantennography (EAG) responses to EDP (a mixture of 2-ethyl-3,6-dimethylpyrazine and 2-ethyl-3,5-dimethylpyrazine), IPA and E&beta, F were investigated in a wide range of insect species. Beside imported fire ants, the EDP (2-ethyl-3,6(5)-dimethylpyrazine) elicited significant EAG response from all other tested insects, including six ant species and one hybrid ant, honeybee, bagrada bug, lady beetle, housefly, small hive beetle, yellow fever mosquito, termite, bedbug, water hyacinth weevil, southern green stink bug and two aphid species. In contrast, IPA elicited significant EAG response only in the honeybee, red imported fire ant, an Aphaenogaster ant, and the water hyacinth weevil. The E&beta, F only elicited EAG responses in two aphids, small hive beetle and housefly. The results clearly indicate that EDP can be detected by widespread insect species that did not coevolve with S. invicta and further suggested alkylpyrazine may activate multiple generally tuned olfactory receptors (ORs) across a wide number of insect species.

An adventive aphid and novel host-parasitoid association from cultivated strawberry (Fragaria × ananessa Duch. cv. Chandler; Fragaria × ananessa Duch. cv. Camarosa) in Mississippi, USA are reported herein. The aphid, first detected in high tunnel cultivation, was found predominately on newly emerged, not fully developed leaflets of daughter plants in the Fall of 2016. By 2017, aphids and their associated mummies were observed on fully developed leaflets on mother plants of both cultivars. The aphid was identified as Aphis ruborum (Borner & Schilder) using morphology and DNA barcoding studies. In addition, DNA barcoding identified parasitoid adults emerging from aphid mummies as two cryptic species, Aphelinus varipes (Foerster) and Aphelinus albipodus Hayat and Fatima. Occurrence of A. ruborum in Mississippi represents a new state record and the eastern-most established record in the United States. The A. ruborum - A. varipes or A. albipodus host-parasitoid association is reported for the first time anywhere in the world.

In this paper, we describe the morphology of the female Bagrada hilaris (Burmeister) reproductive system and develop a physiological age-grading system related to egg production. The female reproductive system is composed of two meroistic and telotrophic ovaries each containing 5–6 tubular ovarioles. The ovarioles unite into the lateral oviduct which combine to form the common oviduct. The ovarioles are composed of two regions; the distal germarium and the tubular vitellarium which contains maturing follicles. Each follicle is surrounded by a layer of cells; the follicular epithelium. As the follicle passes from the ovariole to the lateral oviducts the follicular epithelial cells slough off and accumulate in the base of the ovarioles and are known as follicular relics. The continuum of ovarian development is divided into two categories: nulliparous (‘nonreproducing’) and parous (‘reproducing’). The nulliparous category is characterized by the absence of follicular relics or eggs in the oviducts as opposed to the parous category where follicular relics and, in many cases, eggs occurred in the oviducts. The nulliparous category is divided further into two stages; N1 and N2 based on ovariole differentiation. The parous category is divided into three stages; P1, P2, and P3, based on the quantity and appearance of follicular relics. Females characterized as P3 produced three times more eggs (79.2 eggs ± 5.7) than females characterized as P1 (27.1 eggs ± 6.0).

Summary Here, we report on the first state and county record of Euschistus quadrator Rolston (Hemiptera: Pentatomidae) in Washington County, Mississippi. The species has been documented from Honduras to Virginia primarily on soybean, cotton, various row crops, fruit, and non-crop hosts. The local impact on agricultural crops in the area is unknown. The lack of E. quadrator sightings in Mississippi compared with the frequency of occurrence in literature from Louisiana is of interest. Weather patterns may have contributed to the range expansion. Future efforts to educate growers and consultants on identifying key characteristics of the various Euschistus species common in the southeastern United States may reveal an even larger distribution of E. quadrator in the state and region.

Life fertility tables were constructed for Phymastichus coffea LaSalle, the only known endoparasitoid wasp that attacks the adult female of the coffee berry borer (CBB) Hypothenemus hampei Ferrari. No preoviposition period was observed, and the parasitoid female attacked the CBB females immediately after emergence. The reproductive period was 20.33 (±0.87 SE) h and the postreproductive period of 14.78 (±0.99 SE) h. Mean generation time was 37 d. Median longevity for female and male fed on honey-water solution (50:50) was 35.22 (±1.18 SE) and 17.16 (±0.96 SE) h, respectively. The highest oviposition values were observed during the first 4 h after emergence. The sex ratio (F:M) was 1.11 (±0.31 SE): 1.04 (±0.32 SE) with a finite rate of increase [λ] of 1.06 (±0.002 SE) wasp per days and a rm value of 0.067 (±0.002 SE). Gross fecundity [Mx] and net fecundity [mx] were 19.87 (±1.57 SE) males and females per female and 10.9 (±0.88 SE) females per female, respectively. The net reproductive rate [R0] was 9.49 (±0.75 SE) female per wasp. This study was designed to quantify reproductive rates of P. coffea in CBB females reared on artificial diets and used to improve a mass rearing system for this parasitoid.

Although insecticidal properties of certain benzoates have been investigated for pest insects and mites, toxicity of benzoates to the red imported fire ants, Solenopsis invicta Buren, has never been reported. In this study, 15 commercially available benzoates were assessed for their contact and fumigation toxicity to S. invicta workers and their chemical structure-activity relationships. Among tested benzoates, benzylbenzoate, n-pentybenzoate, and n-hexylbenzoate were three most potent contact toxins against S. invicta workers (mean LD50 value = 23.31, 35.26, 35.99 µg per ant, respectively) and methyl-3-methoxybenzoate, methyl-3-methylbenzoate, and methylbenzoate were the three most potent fumigants (mean LC50 value = 0.61, 0.62, 0.75 µg/ml, respectively). For nonsubstituted alkyl benzoates (esters of benzoic acid and C1-C6 linear alcohols), the contact toxicity was positively correlated to the alkyl chain length (r = 0.89), while the fumigation toxicity was negatively correlated (r = 0.90). Presence of a methoxyl group at either the ortho or meta position of methylbenzoate significantly increased its contact toxicity, so did a methyl group at meta position. However, presence of a methyl group at ortho position reduced the contact toxicity. Presence of methyl or methoxyl group at the meta position did not have significant effect on the fumigation toxicity; however, methyl, methoxyl, chloro, or nitro groups at the ortho position significantly reduced fumigation toxicity. Hexylbenzoate has neither known Occupational Safety and Health Administration hazards nor aquatic toxicity, and methyl 3-methoxybenzoate is not considered a hazardous substance, indicating a great potential for their application in fire ant management.

AIMS AND SCOPE: The aim of this special collection is to highlight the importance of reproduction (ie, oviposition) in the life history, population dynamics, survival, and fitness of beneficial insects, broadly defined. Specific areas of interest include the (1) identification of natural products to boost oviposition; (2) importance of chemical cues in oviposition site selection; (3) influence of host plant defenses on oviposition success; (4) reproductive physiology and the frequency of egg laying; (5) trade-offs between maternal size and egg size; (6) foraging behavior, host selection, and oviposition in parasitoids; and (7) oviposition decisions in the face of intraguild predators.

The morphology of the female Cyrtobagous salviniae Calder and Sands reproductive system is similar to other weevil species being meroistic and telotrophic. The reproductive system is composed of 2 ovaries each containing 2 ovarioles where the follicles mature. A physiological age grading system was developed where the continuum of ovarium development was divided into 2 nulliparous and 3 parous classes. This was based on the differentiation of the ovarioles, presence, and appearance of follicular relics, cuticle hardness/coloration, and fat body quantity/appearance. High correlation occurred between the parous classes and number of eggs produced where the P3 class had over 9-fold higher number of eggs in comparison with the P1 class. Mean number of eggs produced for each parous class was significantly different, however, overlap occurred. Such a system enables a determination of the past, present, and future reproductive status of field populations and mass-rearing colonies.

Biological aspects and demographic parameters of Cephalonomia stephanoderis Betrem (Hymenoptera: Bethylidae) and Prorops nasuta Waterston (Hymenoptera: Bethylidae) parasitoids of the coffee berry borer (CBB), Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae) were investigated using diet-reared CBB hosts. Developmental time from eggs to adults, oviposition, and postoviposition period were comparable for both parasitoids. However, P. nasuta had a considerably longer preoviposition and longevity period averaging 17.3 and 63.1 d, respectively. The reproductive rate for C. stephanoderis was 46.1 daughters per female with a mean generation time of 47.4 d, whereas P. nasuta had a reproductive rate of 18.3 daughters per female in a mean time of 58.6 d. Oviposition behavior was also different with C. stephanoderis typically ovipositing on CBB prepupae and pupae, while P. nasuta preferred prepupae and second-instar CBB larvae. An abridged cohort life table for both parasitoids was constructed for growth rates estimations.

Aflatoxin is a carcinogenic contaminant of many commodities that are infected by Aspergillus flavus . Nonaflatoxigenic strains of A. flavus have been utilized as biological control agents. Here, we report the genome sequences from three biocontrol strains. This information will be useful in developing markers for postrelease monitoring of these fungi.

PURPOSE: Information from unpublished reports, field, and greenhouse observations suggests that temperatures exceeding 29 deg C can cause reduced development and increased mortality of Megamelus scutellaris Berg (waterhyacinth planthopper), a biological control agent released for the management of Eichhornia crassipes (Mart. Solms). This document reports the results of an experiment conducted under greenhouse conditions designed to gauge temperature impacts to M. scutellaris survival and reproduction under fluctuating temperatures regimes.

The biology and population dynamics of Trichopria columbiana, a native semi-aquatic parasitoid of ephydrid flies of the genus Hydrellia, were investigated in Florida and Texas, USA. Hydrellia pakistanae and Hydrellia balciunasi were introduced for classical biological control of the invasive aquatic weed Hydrilla verticillata in the 1980s and acquired T. columbiana post-release. Several life history parameters of T. columbiana were investigated in the laboratory, including fecundity, egg shape and size, number and location of egg(s) deposited per host, preferred host age, description and number of instars, mode of respiration and host-selection behaviour. Field studies included seasonal abundance of T. columbiana and the introduced Hydrellia spp., parasitism levels, overwintering stage and adult winter sex ratio. T. columbiana is a synovigenic solitary endoparasitoid that developed from egg to adult in 21.9 ± 0.2 days under laboratory conditions. Eggs of T. columbiana are hydropic, hymenopteriform in shap...

Salvinia molesta D. S. Mitchell (Salviniales: Salviniaceae), a small floating fern introduced from South America, is causing an increasing number of problems in the US. Increased reliance on the biocontrol agent, Cyrtobagous salviniae, in the US is becoming more commonplace and several mass-rearing facilities have been developed. Because of differences in sampling protocols including sample size, reporting parameters, and numbers released, an investigation into sampling efficiency was initiated. A small pond in southern Louisiana was sampled in an effort to understand what constitutes an adequate sample size and methodologies needed to estimate numbers of weevils. A clumped distribution in the pond was identified, which required a large number of samples to be taken to minimize differences in means and variation. When randomly selecting 10 sets of samples where n = 5 for Sep, means varied from a high of 280 weevils/m2 to a low of only 50 weevils /m2, a difference of nearly 6-fold. However, when r...

Biological control is considered the best management option against the aquatic weed Hydrilla verticillata, one of the most damaging invasive plants in the United States. The search for natural enemies is ongoing. Larval flies from two families (Ephydridae and Chironomidae) were collected feeding on H. verticillata during recent surveys across China and Korea (the possible origin of both the monoecious and dioecious forms of this weed found in the United States). DNA barcoding was used to provide initial identifications, using the Barcode of Life database. In addition, we assessed the genetic structuring and geographic distribution of each provisionally identified species. Four distinct Hydrellia (Ephydridae) clades were identified. The species identity of these clades could not be confirmed, although two form part of the Hydrellia pakistanae species group. Significant genetic structuring was observed within the most widespread clade, suggesting it may comprise several species, although further investigation is required. Fourteen distinct chironomid clades were identified, nine of which correspond to previously described species. Genetic diversity within the chironomid species was low, even across a broad spatial scale, though some genetic structuring was observed in Cricotopus sylvestris. The results of this study provide direction for additional sampling of H. verticillata across China and Korea. Specifically, we recommend further surveys in Zhouzhuang (China), Yeonpori, Yangsancheon, and Deokeuwonri (all Korea). These surveys should be complemented with structured population genetics screening of both plant and insect material; this will help resolve the species status and host associations of the discrete mitochondrial lineages identified in this study.

Bagrada hilaris is a polyphagous herbivore reported as an invasive pest in the United States. During the course of dissecting Burmeister hilaris unique crystals were observed in both the midgut and oviducts. Crystals were identified using X-ray diffraction techniques. Both acicular (i.e., needle-like, slender, and/or tapered) and cubic (i.e., cube shaped) crystals were observed in six of 75 individuals examined (8.0%). The crystals were mainly observed in females (6.7%), followed by males (1.3%) with no crystals observed in the minimal number of nymphs examined (0%). Crystals of both types were detected in the midgut and lateral oviducts of the females and midgut in males. The acicular crystals often appeared as distinct bundles when present in the midgut and oviducts. Crystals varied in size with the acicular crystals ranging from 0.12 mm to 0.5 mm in length although the cubic crystals ranged in length from 0.25 mm to over 1.0 mm with widths of ∼0.25 mm. The cubic crystals were identified as allantoin although the acicular crystals were most likely dl-allantoin in combination with halite. While allantoin in a soluble form is often found in insect tissues and excreta; being present as a crystal, especially in such a large form, is curious and raises some interesting questions. More research is warranted to further understand mechanisms associated with such crystal formation in B. hilaris and can lead to a better understanding of the excretory process in this species and the role allantoin plays in the elimination of excess nitrogen.

Alkaloids, including 2,5-dialkylpyrrolidines and 2,5-dialkylpyrrolines, have been reported to be components in the venom of little black ants, Monomorium minimum (Buckley). Two fatty amines were recently reported as minor compounds. By analyzing the discharge collected from the stinger apparatus (milking), this study revealed the presence of an additional seven compounds in the defensive secretion of this ant species. Compounds identified were 9-decenyl-1-amine, N-methylenedecan-1-amine, N-methylenedodecan-1-amine, 2-(1-non-8-enyl)-5-(1-hex-5-enyl)-1-pyrroline, N-methyl-2-(hex-5-enyl)-5-nonanyl-1-pyrrolidine, β-springene ((E,E)-7,11,15-trimethyl-3-methylene-1,6,10,14-hexadecatetraene) and neocembrene ((E,E,E)-1-isopropenyl-4,8,12-trimethylcyclotetradeca-3,7,11-triene). β-springene and neocembrene were found only in the defensive secretion of queens. Analyses of the contents of isolated poison and Dufour's glands of the queen indicated that all amines and alkaloids were from the poison gland and that β-springene and neocembrene were from the Dufour's gland. This demonstrated that the defensive secretion in M. minimum queens consists of components from both glands. This is also the first report on the natural occurrence of 9-decenyl-1-amine, N-methylenedecan-1-amine, and N-methyllenedodecan-1-amine.

The wetland plant Ludwigia peploides (floating primrose-willow) often is problematic in the southern USA, as well as elsewhere in its introduced range. Surveys to identify potential herbivorous insects to use as biological controls have focused on South America, but implementing a management program with foreign insects in the USA is difficult and can take years of testing in quarantine. During 2006–2008, populations of floating primrose-willow were surveyed in the southern USA to determine presence and extent of native herbivorous insects. At least nine species were identified, represented mainly by weevils (Curculionidae) and leaf beetles (Chrysomelidae). Of these, two were undescribed species of weevils (Auleutes), and six species, including Tyloderma sphaerocarpae and Chaetocnema, have never been associated with floating primrose-willow.

The objective of this research was to describe the anal plates of the larval stages of the ephydrid fly, Hydrellia pakistanae Deonier, a biological control agent of hydrilla (Hydrilla verticillata (L.f.) Royle). This was accomplished using light microscopy coupled with a specialized staining technique; and scanning electron microscopy (SEM). AU 3 instars of H. pakistanae were collected from hydrilla cultured in outdoor concrete-lined ponds. To ascribe a function to the anal plates, a modified staining technique was employed that uses a 5% silver nitrate solution, which, upon ionization, binds with chloride ions suggesting an osmoregulatory function. Under light microscopy the two anal plates appeared smooth, flat crescent moon-shaped structures that encircled the anus of the larva. SEM revealed the anal plates to be relatively smooth with an undulating surface pattern possibly an artifact of the high vacuum conditions associated with the SEM. This may therefore indicate a difference in cuticle th...

We examined insect herbivores associated with Heteranthera dubia from surveys conducted from 2006 to 2009. Plants were collected, invertebrates were removed, and signs of feeding damage were noted. Herbivores were quantified, and geographic regions were compared based on herbivore density, taxa richness, evenness, and diversity. The greatest density of herbivores occurred at Parker Pond, Washington, which was largely influenced by an abundance of aphids (Rhopalosiphum spp.). Density, richness, and evenness were not significantly different among regions. At least 23 potential insect herbivores were recorded from 15 sites in Texas, Washington, Minnesota, Wisconsin, Vermont, and New York. Of these, five taxa were collected from the order Lepidoptera, one from Coleoptera, six from Diptera, and at least 11 from Trichoptera. The majority of the herbivores were generalists; several had unknown diets. Damage observed to H. dubia included extensive tunneling in the stems of the plant and, in some cases, substantia...

The invasive tree Melaleuca quinquenervia (Cavanilles) Blake (Myrtaceae) is widely distributed throughout peninsular Florida, U.S.A. and poses a threat to species diversity in the wetland systems of the Florida Everglades. Biological control research targeting the weed resulted in the introduction of Oxyops vitiosa Pascoe, 1870 to Florida. Approximately three years following its release, adult weevils were collected over 12 consecutive months across six study sites, resulting in a 52:48 F:M sex ratio that did not vary among sites or over time. All female weevils were dissected and their reproductive anatomy was investigated, particularly in relation to the fluctuation of host plant suitability. The continuum of reproductive development was divided into three distinct stages: nulliparous, parous, or degenerative. The general anatomy of each stage is described. In contrast to other systems, fat body abundance provided little insight into the weevil's reproductive status, as 99.5% of all females possessed fat bodies that filled >2/3 of the abdominal cavity. Nulliparous weevils possessed the softest elytra and were lighter in color, parous weevils had the hardest and darkest elytra, while females with degenerative reproductive systems were intermediate to the other two reproductive classes. The proportion of parous O. vitiosa females in a population was strongly influenced by resource availability, as the number of actively ovipositing females increased concomitantly with increasing suitable foliage in the host's canopy.

This study examined the interaction and main-effect impacts of herbivory by the leaf-mining fly Hydrellia pakistanae and plant competition from Vallisneria americana on the growth, expansion and tuber formation of Hydrilla verticillata in a 2 × 2 factorial design experiment. The study was conducted in 14,000-L tanks, over two growing seasons. Each tank represented a single experimental unit and contained 32 1-L pots. At the beginning of the experiment half of these were planted with H. verticillata while the other half were either left empty or planted with V. americana (the competitor). H. pakistanae fly larvae (the herbivore) were added to tanks as appropriate. No significant interactions were identified between herbivory and competition on any parameter of H. verticillata growth analyzed (i.e., total tank biomass accumulation, total number of rooting stems, total tuber number, total tuber mass, and tuber size), indicating that the factors were operating independently and neither antagonism nor synergism was occurring. Both competition and herbivory impacted the growth of H. verticillata. H. verticillata plants grown in the presence of V. americana developed less total biomass, had fewer total basal stems, had fewer tubers and less tuber mass per tank, and produced significantly smaller tubers relative to control plants. Herbivory also suppressed H. verticillata biomass accumulation and tended to suppress the number and total mass of tubers produced in each tank. Both factors showed 30–40% reduction of total H. verticillata biomass, although the mechanism of impact was different. Competition suppressed expansion of H. verticillata into adjoining pots but had little impact on its growth in pots where it was originally planted. Herbivory resulted in a general suppression of growth of H. verticillata in all pots. Although herbivory significantly impacted H. verticillata biomass, it did not result in competitive release for V. americana under the current experimental conditions. We conclude that management activities that promote competition or herbivory will impact the growth and expansion of H. verticillata. Furthermore, since these factors operated independently, the combined use of both factors should be beneficial for suppression of H. verticillata dominance.

The submersed macrophyte, Hydrilla verticillata, was grown using different nutritional regimes under greenhouse conditions to obtain plants that were significantly different in percent nitrogen-free extract, crude fiber, ether-extractable compounds, crude protein, and ash in shoot tissue. Shoots were then challenged by the biological control fungal pathogen, Mycoleptodiscus terrestris, to determine the effects of plant nutritional status on disease severity, growth, and reproduction. Fourteen days post-inoculation, shoots from plants grown in high-fertility sediment had significantly greater disease severity ratings than shoots from plants grown in low-fertility sediment. The nutritional status of the plants also impacted asexual reproduction of the pathogen by thin-walled conidia and melanized survival structures called microsclerotia. At 14 days post-inoculation, significantly higher numbers of conidia were produced in flasks containing hydrilla plants grown in high-fertility sediment. In contrast, microsclerotia increased almost fourfold in leaf tissues of hydrilla grown in low-fertility sediment. It appears from these studies that the nutritional condition of target plants cannot be excluded as an important factor in efficacy of pathogens used as biological control agents. The nutritional status of the host tissues influences M. terrestris ingress into host tissues, vegetative growth, production of secondary inoculum in the form of disseminative spores or conidia, and production of survival structures, the microsclerotia.

The morphology of the female Cyrtobagous salviniae Calder and Sands reproductive system is similar to other weevil species being meroistic and telotrophic. The reproductive system is composed of 2 ovaries each containing 2 ovarioles where the follicles mature. A physiological age grading system was developed where the continuum of ovarium development was divided into 2 nulliparous and 3 parous classes. This was based on the differentiation of the ovarioles, presence, and appearance of follicular relics, cuticle hardness/coloration, and fat body quantity/appearance. High correlation occurred between the parous classes and number of eggs produced where the P3 class had over 9-fold higher number of eggs in comparison with the P1 class. Mean number of eggs produced for each parous class was significantly different, however, overlap occurred. Such a system enables a determination of the past, present, and future reproductive status of field populations and mass-rearing colonies.

The impacts of varying levels of herbivory by Hydrellia pakistanae on the dioecious ecotype of Hydrilla verticillata were evaluated by conducting a 10-week growth experiment within mesocosm tanks. The observed leaf damage to H. verticillata stems was highly correlated with the total number of immature H. pakistanae in H. verticillata tissue at the time of harvest (P 0.80). Increasing levels of insect herbivory significantly impacted biomass and growth morphology of H. verticillata. Relative to control tanks, plants under intermediate or high levels of herbivory produced progressively less biomass. Insect herbivory also significantly impacted investment of energy in sexual and asexual reproduction. Plants under an intermediate or high level of herbivory produced fewer than 15% of the number of pistillate flowers produced by plants in control tanks. Furthermore, plants subject to high insect herbivory produced fewer and smaller tubers than control tanks. Finally, herbivory had a strong impact on the photosynthetic potential of stems. With 10–30% leaf damage, the maximum rate of light-saturated photosynthesis was reduced 30–40% relative to undamaged controls. Total daily photosynthetic production in these stems was estimated to balance, just barely, the daily respiratory needs of stems. Photosynthetic rate was reduced by about 60% in stems showing 70–90% leaf damage. This level of photosynthetic reduction would make continued survival of the plants unlikely since they would be unable to meet daily respiratory demands.

/ We hypothesized that repeated herbicidal (maintenance) control of water hyacinth infestations in Florida suppressed biological control agent populations, especially the weevils Neochetina eichhorniae and N. bruchi. We therefore sampled water hyacinth and weevil populations at 54 sites distributed statewide. Half were under maintenance control, half were not treated with herbicides. General site conditions were assessed, demographic data were collected on weevil and plant populations, the reproductive condition of the weevils was determined, and plant nutrient and proximate composition of water hyacinth leaves were analyzed. Water hyacinth infestations under maintenance control were minimal when compared to unmanaged sites. Likewise, on a population basis, all weevil cohorts were much lower due to the paucity of plants. Plants at unmanaged sites, where weevil intensities were much higher, suffered high levels of stress and showed low growth potential. Lower percentages of the female weevils were reproductive at unmanaged sites when compared to managed sites, so densities of reproductives and immatures were similar at both site types. Reproductive status of the weevils improved with increased plant quality. Plant quality, in turn, declined as stresses arising from weevil feeding increased. Plant quality was positively correlated with plant growth potential and flower production. Thus, maintenance control improved plant nutritive quality thereby inducing reproductive vigor of the weevils, but ensuring plant regrowth and the need for future control. This suggests that biological and herbicidal controls should be integrated, using herbicides to maintain water hyacinth infestations below management thresholds but in a manner that conserves biological control agent populations. This approach would lead to improved plant nutritional quality that would, in turn, stimulate reproduction in biological control agent populations. KEY WORDS: Eichhornia crassipes; Neochetina eichhorniae; Neochetina bruchi; Phytophagy; Integrated control; Aquatic weeds

Neochetina eichhorniaehas a meroistic reproductive system composed of a pair of ovaries each subdivided into two tube-like ovarioles. The ovarioles consist of two main regions, the distal germarium and the proximal vitellarium. The vitellarium houses the developing follicles, which mature sequentially. The two ovarioles in each pair connect proximally via the lateral oviducts. The paired ovaries join one another via the common oviduct. Ovarian development involves two distinct phases: a nulliparous (meaning “no eggs”) phase and a parous (meaning “with eggs”) phase. Each phase undergoes three sequential stages, named N1, N2, and N3 and P1, P2, and P3 for the nulliparous and parous categories, respectively. The degree of maturity of the proximate follicles and the extent of follicular differentiation distinguish the nulliparous stages. The quantity and quality of follicular relics (and, by association, the number of egg ovulations) distinguishes the parous phases. The overall condition of the ovaries can be characterized from the number of developing follicles in the ovarioles as well as the integrity of the follicular cellular material. Samples from field populations in Texas revealed distinct seasonal changes in physiological age structure and condition of the reproductive system. This physiological age-grading system can be an important tool for assessing age structure and relative reproductive health ofN. eichhorniaepopulations or other weed biological control agents with similar reproductive systems.

The Australian leaf-mining fly,Hydrellia balciunasi,was first released as a biological control agent for the management of the submersed aquatic plant,Hydrilla verticillatain August 1989 in southern Florida. Since then, 284,684 individuals have been released at seven Florida and four Texas sites. Despite this effort, populations have persisted at just two Texas sites: Sheldon Reservoir near Houston and Lake Raven in Huntsville State Park.H. balciunasilevels have remained relatively low at these sites, averaging, at best, less than 1000 immatures/kg wet plant weight. All other collections were substantially lower. Reasons for poor establishment are unknown but probably relate to a complex of factors, including competition with another introduced leaf-mining species, parasitism by native wasps, poor host quality, genetic differences between Australian and United States hydrilla resulting in mismatched physiological strains of agent and host plant, and possibly inbreeding depression in laboratory colonies used for releases.

The Indian leaf-mining fly Hydrellia pakistanae Deonier was released in the United States during October 1987 as a potential agent for the biological control of the submersed aquatic plant,Hydrilla verticillata(L.f.) Royle. Since then, nearly 3 million individuals have been released in four states at over 25 separate locations. Hydrellia pakistanae is now permanently established at many locations in Florida as well as other portions of the southeastern United States. Despite early failures, populations established from at least 70% of the release attempts. Modifications of rearing and release procedures that considered the biology of the agent in relation to various habitat characteristics facilitatedsuccessfulestablishment. r 1997 Academic Press

This study summarizes how a relatively simple model can be used to predict invasion potential by an aquatic nuisance species. The spread and subsequent unlikely eradication of alien species from recently invaded ecosystems reinforces the need for predictive tools to help management personnel evaluate associated detrimental impacts. It is estimated that in most countries 102-104 nonindigenous species have been documented, and numbers should increase with expanding global trade and travel (Lodge 1993). Although only a small percent (usually < 10 percent) are invasive (Williamson and Fitter 1996), some have enormous economic and ecological impacts (Office of Technology Assessments (OTA) 1993; Ricciardi and Rasmussen 1998). For these reasons a need exists to determine which species will be introduced and which will cause impacts in order to allocate resources for prevention, detection, management, and control efforts (Grosholz and Ruiz 1996; Ricciardi and Rasmussen 1998; Colnar and Landis 2007). Many models, simple and complex, have been developed to predict invasions of nonindigenous species over large regional areas. For example, invasive species attributes combined with transfer vectors and climate matching were used to predict potential distribution of common carp (Cyprinus carpio L.) in Australia (Koehn 2004). Attributes that were examined included: invasion history, environmental tolerances, genetic variability, sexual maturity, generation time, growth rate, reproductive capacity, diet, gregariousness, dispersal mechanisms, and use by humans. Vectors were either natural movement within watersheds or more frequently via accidental or deliberate release by anglers or through importation and release of ornamental "Koi" carp (Koehn 2004). Finally the authors found climatic conditions that exist in Australia matched other regions of the world where common carp have established, thus increasing the likelihood that the species would become established and widespread.