Potential of contact insecticides to control Xyleborus glabratus (Coleoptera: Curculionidae), a vector of laurel wilt disease in avocados.

Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae) is an invasive ambrosia beetle that vectors laurel wilt, a new disease that threatens avocado and other species in the Lauraceae Family. The lethal concentrations (LC50 & 90) of nine commercial insecticides to X. glabratus were determined by using a bolt-dip bioassay. Different formulations of bifenthrin, permethrin, fenpropathrin, z-cypermethrin + bifenthrin, 1-cyhalothrin + thiamethoxam, malathion, chlorpyrifos, carbaryl, and methomyl were tested. Four concentrations of each insecticide were tested (0.5, 0.1, 0.03, and 0.01 of the label rate) and with water as a control. Beetles were exposed to treated bolts and mortality registered 48 h later. After 2 wk, bolts were destructively sampled to determine the number of beetles that constructed galleries and were alive inside the wood. Probit analysis was used to determine the LC50 & 90. Six pesticides were applied directly to the trunk and limbs of avocado trees in a commercial grove. Limbs of treated trees were cut weekly after the application and exposed to X. glabratus to determine the number of beetles boring into the logs. The toxicity of pesticides to X. glabratus was greatly reduced 2 wk after application. Among the tested pesticides, malathion and z-cypermethrin + bifenthrin provided the best suppression of X. glabratus. Among the insecticides registered for use in avocado, fenpropathrin and malathion were the most effective in protecting trees from attack by X. glabratus. Other pesticides that are currently not registered for use in avocados could be useful for managing this ambrosia beetle.

Occurrence of Xyleborus bispinatus (Coleoptera: Curculionidae: Scolytinae) Eichhoff in southern Florida.

Xyleborus bispinatus Eichhoff is reported from Florida for the first time. It was previously unrecognized and not distinguished from Xyleborusferrugineus (F.). There is no reason to believe at this point that it represents an introduction. Rather it is one of a group of widely distributed Neotropical species that are also found in southern Florida. Characters are discussed to allow it to be distinguished from X. ferrugineus and X. impressus Eichhoff.

Prey-stage preferences and functional and numerical responses of Amblyseius largoensis (Acari: Phytoseiidae) to Raoiella indica (Acari: Tenuipalpidae).

Raoiella indica Hirst (Acari: Tenuipalpidae) is a phytophagous mite that recently invaded the Western Hemisphere. This mite is a multivoltine and gregarious species that can reach very high population densities and cause significant damage to various palm species (Arecaceae). The predatory mite Amblyseius largoensis (Muma) (Acari: Phytoseiidae) has been found associated with R. indica in Florida. This study evaluated A. largoensis for potential to control R. indica by (1) determining predator preferences among developmental stages of R. indica, and (2) estimating predator functional and numerical responses to varying densities of its most preferred prey-stage. Under no-choice conditions A. largoensis consumed significantly more eggs than other stages of R. indica. In choice tests A. largoensis showed a significant preference for R. indica eggs over all other prey stages. Amblyseius largoensis displayed a type II functional response showing an increase in number of prey killed with an increase in prey population density. Consumption of prey stabilized at approximately 45 eggs/day, the level at which oviposition by the predator was maximized (2.36 ± 0.11 eggs/day; mean ± SEM). Results of this study suggest that A. largoensis can play a role in controlling R. indica populations, particularly when prey densities are low.

A review of the natural enemies of the red palm mite, Raoiella indica (Acari: Tenuipalpidae).

A review of all the available information about the natural enemies reported in association with the red palm mite, Raoiella indica is presented. Twenty-eight species of predatory arthropods, including mites and insects, have been reported in association with R. indica in Asia, Africa and the Neotropics. In addition, pathogenic fungi associated with R. indica in the Caribbean have been reported. The available literature indicates that each site has a different natural enemy complex with only one predator species, Amblyseius largoensis (Acari: Phytoseiidae), present in all the geographical areas. The phytoseiids, Amblyseius caudatus Berlese, Amblyseius channabasavanni Gupta and A. largoensis, were regarded as important natural enemies of R. indica, and their predatory efficiency was studied in some detail. Among the predatory insects the coccinellids Stethorus keralicus Kapur and Telsimia ephippiger Chapin were reported as major predators of R. indica. The known distribution, abundance and relative importance of each species reported in association with R. indica are discussed.

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.

Attraction of the redbay ambrosia beetle, Xyleborus glabratus, to avocado, lychee, and essential oil Lures.

The redbay ambrosia beetle, Xyleborus glabratus Eichhoff, is an exotic wood-boring insect that vectors the mycopathogen responsible for laurel wilt, a lethal vascular disease of trees in the Lauraceae. High mortality has occurred in native Persea species in the southeastern U.S., and the vector-pathogen complex poses an imminent threat to the production of commercial avocado, P. americana, in south Florida. There is a critical need for effective attractants to detect, monitor, and control this invasive pest. This study combined field tests and laboratory bioassays to evaluate the response of female X. glabratus to host-based volatiles from wood of avocado (cultivars of West Indian, Guatemalan, and Mexican races); from wood of lychee (Litchi chinensis, a presumed non-host that is high in the sesquiterpene α-copaene, a putative attractant); and to commercial lures containing manuka and phoebe oils, two reported attractive baits. Volatile collections and GC-MS analyses were performed to quantify the sesquiterpene content of test substrates. In the field, traps baited with lychee wood captured more beetles than those with wood from avocado cultivars; traps baited with phoebe oil lures captured more beetles than those with manuka oil lures (the current monitoring tool). In field and laboratory tests, X. glabratus did not show a preference among avocado races in either attraction or host acceptance (initiation of boring). In choice tests, lychee was more attractive than avocado initially, but a higher percentage of beetles bored into avocado, suggesting that lychee emits more powerful olfactory/visual cues, but that avocado contains more of the secondary cues necessary for host recognition. Emissions of α-copaene, ß-caryophyllene, and α-humulene were correlated with field captures, and lychee wood may be a source of additional semiochemicals for X. glabratus.

Mechanisms underlying photosynthetic acclimation to high temperature are different between Vitis vinifera cv. Syrah and Grenache.

Photosynthesis acclimation to high temperature differs among and within species. Grapevine intra-specific variation in photosynthetic acclimation to elevated temperature has been scarcely assessed. Our objectives were to (i) evaluate the mechanisms underlying long-term acclimation of photosynthesis to elevated temperature in grapevine, and (ii) determine whether these responses are similar among two varieties. A warming experiment with well irrigated Grenache and Syrah field-grown plants was performed during two growing seasons comparing plants exposed at ambient temperature (control) with plants in open-top chambers (heating) that increased mean air temperature between 1.5 and 3.6°C. Photosynthetic acclimation was assessed through the response of net assimilation (An), Rubisco carboxylation rate (Vcmax) and electron transport rate (Jmax), at leaf temperatures from 20 to 40°C. Our results evidenced different mechanisms for photosynthetic acclimation to elevated temperature. Compared with control, Grenache heated increased An, maintaining higher Vcmax and Jmax at temperatures above 35°C. By contrast, Syrah heated and control presented similar values of An, Vcmax and Jmax, evidencing an adjustment of photosynthesis without increasing C assimilation. Both varieties increased the optimum temperature for An, but to a lesser extent when growth temperature was higher. Our study provides evidence that grapevine varieties present different acclimation mechanisms to expected warming.

Development and reproduction of Amblyseius largoensis (Acari: Phytoseiidae) feeding on pollen, Raoiella indica (Acari: Tenuipalpidae), and other microarthropods inhabiting coconuts in Florida, USA.

The red palm mite, Raoiella indica (Acari: Tenuipalpidae), is an important pest of palms (Arecaceae) and other species within the Zingiberaceae, Musaceae and Strelitziaceae families. Raoiella indica was discovered in the USA (Palm Beach and Broward counties, Florida) late in 2007, and it subsequently spread to other Florida counties. The predatory mite Amblyseius largoensis (Acari: Phytoseiidae) has been found associated with R. indica in Florida. In order to verify whether A. largoensis can develop and reproduce when feeding exclusively on R. indica, the biology of this predator was evaluated on various food sources, including R. indica. Five diets [R. indica, Tetranychus gloveri Aonidiella orientalis, Nipaecocus nipae, oak (Quercus virginiana) pollen] and a no-food control were tested to determine the predators' development, survivorship, oviposition rate, sex ratio and longevity at 26.5 +/- 1 degrees C, 70 +/- 5% RH and a 12:12 L:D photophase. Amblyseius largoensis was able to complete its life cycle and reproduce when fed exclusively on R. indica. The development of immature stages of A. largoensis was faster and fecundity and survivorship were higher when fed on R. indica or T. gloveri compared to the other food sources. The intrinsic rate of natural increase of A. largoensis was significantly higher when fed on R. indica than on other diets. These results suggest that, despite earlier assessments, A. largoensis can play a role in controlling R. indica.

Effectiveness of Hot-Water Immersion Against Brevipalpus yothersi (Acari: Tenuipalpidae) as a Postharvest Treatment for Lemons.

Citrus leprosis is a destructive disease of citrus caused by several viruses (CiLVs) that are quarantine pests in the United States. Brevipalpus yothersi Baker (Acari: Tenuipalpidae) vectors the most virulent strain of CiLV. This mite is present in the United States and could facilitate the spread of the disease if CiLV reaches the country. Postharvest treatments could mitigate B. yothersi on imported commodities from areas where CiLV exists. The current study explores the effectiveness of hot-water immersion as a postharvest treatment against B. yothersi. Lemons were immersed in water at 21, 48, 53, or 63°C for 5, 10, and 15 min. Immersions at 53 and 63°C for all time schedules dislodged over 99% of adult mites. Lemon fruit quality and B. yothersi egg viability after hot-water immersion were also evaluated. Fruit quality significantly decreased in lemons treated at 63°C resulting in decay (grade 3, rejection), while at 53°C there was a quality reduction (grade 2, minimum acceptable market level) compared to lemons immersed at 21°C or nontreated controls (grade 1). None of the eggs hatched when the lemons were immersed in water at 63°C and an average of 1.5% hatched at 53°C for all time schedules. Immersion in water at 53°C for 5 min dislodged 99.71% and 57.14% of adult and immature mites, respectively, and resulted in 98.11% unhatched eggs without significant fruit quality reduction. Hot-water immersion could be a key component in a systems approach to control B. yothersi on imported citrus fruits from countries where citrus leprosis is present.

Relative susceptibility of Haeckeliania sperata (Hymenoptera: Trichogrammatidae) to pesticides used in citrus and ornamental systems in Florida.

Haeckeliania sperata Pinto is an egg-endoparasitoid of Diaprepes abbreviatus L. (Coleoptera: Curculionidae). We evaluated the relative susceptibility of H. sperata adults to commercially relevant pesticides used in citrus and ornamental production systems. Parasitoids were exposed to pesticide residues on leaf surfaces. Four concentrations of seven pesticides were tested; concentrations for each pesticide consisted of a dilution series using the label rate for field applications as the starting concentration. Lethal concentrations (LC50s and LC90s) were calculated 12 and 24 h after exposure to the pesticides. Lethal times (LT50s and LT90S) were estimated for each pesticide concentration. All tested pesticides had a negative effect on Haeckeliania's survivorship. However, some pesticides were significantly less harmful to this parasitoid. LC50s and LC90s of organophospate, carbamate, and pyrethroid pesticides were less than one eighth of the label rates. LT50s and LT90s of these insecticides were < 12 h even at the most diluted concentrations. Thus, applications of these pesticides might have a strong negative impact on the natural control of D. abbreviatus by H. sperata. Commercial formulations of imidacloprid, abamectin, petroleum oil, and a phosphonate fungicide allowed H. sperata to live longer compared with the previous pesticides, suggesting a certain degree of selectivity. Moreover, adults exposed to diluted concentrations of imidacloprid, abamectin, petroleum oil, and a phosphonate fungicide had a greater survival than those exposed to label concentrations. These findings suggest that the use of products that have less toxic effects on the introduced parasitoid will increase its chances to parasitize D. abbreviatus eggs.

Effect of host plants on successful parasitism by Haeckeliania sperata (Hymenoptera: Trichogrammatidae) on Diaprepes abbreviatus (Coleoptera: Curculionidae) eggs.

Diaprepes abbreviatus L. is a highly polyphagous root weevil that causes damage to several fruit crops, ornamental plants, and other naturally occurring plants in Florida. Haeckeliania sperata Pinto is a gregarious endoparasitoid that attacks D. abbreviatus eggs. We hypothesized that the reproductive success of H. sperata is affected by the host plant of D. abbreviatus. Six host plants with varying degrees of pubescence were used to determine the effect of leaf trichomes on the searching behavior and success of parasitism by H. sperata. No-choice tests showed that H. sperata was able to parasitize Diaprepes eggs laid on the six host plants. However, the plants with a high trichome density on their leaves had a lower percent of parasitism than the plants with smoother leaves. Removing trichomes from a host plant showed that the presence of some leaf trichomes had a negative effect on the overall searching efficiency of H. sperata. The presence of trichomes decreased the total distance traveled and increased the total search time of H. sperata females, resulting in a lower searching speed. Multiple regression analysis was used to establish the relationship between percent parasitism and leaf trichome density, leaf thickness, and the searching speed of H. sperata. Searching speed was the best predictor of percent parasitism; this parameter could be used to predict the suitability of host plants for the establishment of H. sperata. Our findings suggest that the reproductive success of H. sperata is affected by the host plant of D. abbreviatus.

Correction: The Influence of Host Plant Extrafloral Nectaries on Multitrophic Interactions: An Experimental Investigation.

[This corrects the article DOI: 10.1371/journal.pone.0138157.].

Reproductive biology of Fidiobia dominica (Hymenoptera: Platygastridae), an egg parasitoid of Diaprepes abbreviatus (Coleoptera: Curculionidae).

The reproductive biology of Fidiobia dominica Evans (Hymenoptera: Platygastridae) was studied in the laboratory (25.6 +/- 1 degrees C) using host eggs of Diaprepes abbreviatus L. (Coleoptera: Curculionidae). F. dominica readily parasitized D. abbreviatus eggs on both host plant and wax paper substrates. The number of egg masses parasitized and the number of offspring produced were higher when females were offered more than one host egg mass but did not differ when either two or three egg masses were offered. Female parasitoids that were provided with host eggs and a honey food source lived significantly longer than those that were not provided a food source; however, they did not parasitize more D. abbreviatus eggs. Oviposition occurred in host eggs from 0 to 7 d old, and host mortality was relatively consistent for eggs 0-5 d old and lower for eggs 6-7 d old. Successful parasitoid emergence seldom occurred after host eggs were 4 d old, and by 7 d, no adults successfully emerged. Developmental time from egg to adult was 19.3 +/- 0.2 d for males, significantly more rapid than the females (20.4 +/- 0.1 d). The mean longevity of adult females was 8.0 +/- 0.4 d, with a mean oviposition period of 2.7 +/- 0.3 d; males survived 8.1 +/- 0.4 d. The demographic parameters including intrinsic rate of increase (r(m)), generation time (T), and net reproduction (R(o)) were 0.142/d, 22 d, and 22.4 female eggs/d, respectively.

The Influence of Host Plant Extrafloral Nectaries on Multitrophic Interactions: An Experimental Investigation.

A field experiment was conducted with outplantings of the native perennial shrub Senna mexicana var. chapmanii in a semi-natural area adjacent to native pine rockland habitat in southern Florida. The presence of ants and the availability of extrafloral nectar were manipulated in a stratified random design. Insect communities were monitored and recorded over a period of six months with a view to addressing three main questions. Do ants provide biotic defense against key herbivores on S. chapmanii? Is the presence of ants on S. chapmanii mediated by EFN? Finally, are there ecological costs associated with the presence of ants on S. chapmanii, such as a reduction in alternative predator or parasitoid numbers? Herbivores on S. chapmanii included immature stages of three pierid butterflies, and adult weevils. Eight species of ants were associated with the plants, and other predators included spiders, ladybugs, wasps, and hemipterans. Parasitic, haemolymph-sucking midges (Ceratopogonidae) and parasitoid flies were also associated with the caterpillar herbivores, and possibly the extrafloral nectaries of the plants. The presence of ants did not appear to influence oviposition by butterflies, as numbers of lepidopterans of all developmental stages did not differ among treatments. Significantly more late instar caterpillars, however, were observed on plants with ants excluded, indicating that ants remove small caterpillars from plants. Substantially more alternative predators (spiders, ladybugs, and wasps) were observed on plants with ants excluded. Rates of parasitization did not differ among the treatments, but there were substantially fewer caterpillars succumbing to virus among those collected from control plants. We provide a rare look at facultative ant-plant mutualisms in the context of the many other interactions with which they overlap. We conclude that ants provide some biotic defense against herbivores on S. chapmanii, and plants benefit overall from the presence of ants, despite negative impacts on non-ant predators.

Life history and larval morphology of Eurhinus magnificus Gyllenhal (Coleoptera: Curculionidae), a new weevil to the United States.

Eurhinus magnificus Gyllenhal has been collected in south Florida, presumably introduced through trade with countries in its native range. Very little information has been published on the biology or taxonomy of this insect. We conducted studies to investigate various aspects of its life history and host plant associations. The pre-imaginal life stages of E. magnificus are described for the first time. Dimensions of the adult, egg, larval, and pupal stages are also provided; head capsule measurement revealed five larval instars. All life stages of E. magnificus were collected at several sites in Broward and Miami-Dade counties from the host plant Cissus verticillata (L.) Nicolson & Jarvis (Vitaceae). Eggs were laid singly within the succulent, young subterminal portion of the host plant stem, one or two occurring between two nodes. Gall formation was apparent by the first to third instar and continued to increase in size until pupation which occurred within the gall. Predators and pathogens appeared to be responsible for considerable mortality in the field; there was no evidence of parasitism of any of the life stages. Greenhouse studies were undertaken to determine E. magnificus development time and host specificity. Adult weevils attacked grape cultivars (Vitis spp.) and feeding opened the stems to fungal agents but no physical evidence of larval development was apparent on grapes.

Life history and larval morphology of Eurhinus magnificus Gyllenhal (Coleoptera: Curculionidae), a new weevil to the United States

Eurhinus magnificus Gyllenhal has been collected in south Florida, presumably introduced through trade with countries in its native range. Very little information has been published on the biology or taxonomy of this insect. We conducted studies to investigate various aspects of its life history and host plant associations. The pre-imaginal life stages of E. magnificus are described for the first time. Dimensions of the adult, egg, larval, and pupal stages are also provided; head capsule measurement revealed five larval instars. All life stages of E. magnificus were collected at several sites in Broward and Miami-Dade counties from the host plant Cissus verticillata (L.) Nicolson & Jarvis (Vitaceae). Eggs were laid singly within the succulent, young subterminal portion of the host plant stem, one or two occurring between two nodes. Gall formation was apparent by the first to third instar and continued to increase in size until pupation which occurred within the gall. Predators and pathogens appeared to be responsible for considerable mortality in the field; there was no evidence of parasitism of any of the life stages. Greenhouse studies were undertaken to determine E. magnificus development time and host specificity. Adult weevils attacked grape cultivars (Vitis spp.) and feeding opened the stems to fungal agents but no physical evidence of larval development was apparent on grapes.

Se ha recolectado, en el sur de Florida, a Eurhinus magnificus Gyllenhal. Se efectuaron estudios de investigación sobre varios aspectos del ciclo biológico, y asociaciones entre el picudo y plantas hospederas. Se describen aquí por primera vez los estados inmaduros de E. magnificus. Se dan a conocer las dimensiones de los estados de adulto, huevo, larva y pupa. Las medidas de la cápsula cefálica revelaron que hay cinco estadios en esta especie. Todos los estados de E. magnificus fueron colectados en la planta hospedera Cissus verticillata (L.) Nicholson y C.E. Jarvis (Vitaceae) en varios lugares localizados en los condados de Broward y Miami-Dade. Los picudos depositan un o dos huevos dentro de la parte más tierna del tallo que se encuentra entre dos yemas laterales localizadas en la región subterminal de la planta hospedera. En esta región, aparece una agalla, la cual es más visible cuando la larva esta entre el primer y tercer estadios. La agalla crece en tamaño hasta empupamiento, el cual ocurre dentro de esta. Los depredadores y patógenos parecen ser responsables por una gran mortalidad de estados inmaduros en el campo; En el campo, no se observó ningun indice de parasitismo en esta especie. Se llevaron a cabo estudios en casa de malla con el fin de determinar el tiempo de desarrollo y especificidad de hospederos de E. magnificus. Los picudos atacaron cultivares de uva (Vitis spp. - Vitaceae). No se observó el desarrollo larvario de E. magnificus en Vitis L.