Steven R. Alm

Trapping Phyllophaga spp. (Coleoptera: Scarabaeidae: Melolonthinae) in the United States and Canada using sex attractants.

Abstract The sex pheromone of the scarab beetle, Phyllophaga anxia, is a blend of the methyl esters of two amino acids, L-valine and L-isoleucine. A field trapping study was conducted, deploying different blends of the two compounds at 59 locations in the United States and Canada. More than 57,000 males of 61 Phyllophaga species (Coleoptera: Scarabaeidae: Melolonthinae) were captured and identified. Three major findings included: (1) widespread use of the two compounds [of the 147Phyllophaga (sensu stricto) species found in the United States and Canada, males of nearly 40% were captured]; (2) in most species intraspecific male response to the pheromone blends was stable between years and over geography; and (3) an unusual pheromone polymorphism was described from P. anxia. Populations at some locations were captured with L-valine methyl ester alone, whereas populations at other locations were captured with L-isoleucine methyl ester alone. At additional locations, the L-valine methyl ester-responding populations and the L-isoleucine methyl ester-responding populations were both present, producing a bimodal capture curve. In southeastern Massachusetts and in Rhode Island, in the United States, P. anxia males were captured with blends of L-valine methyl ester and L-isoleucine methyl ester. Resumen La feromona sexual del escarabajo, Phyllophaga anxia, es una mezcla de los ésteres metílicos de dos aminoácidos, L-valina y L-isoleucina. Se condujo un estudio de campo usando diferentes mezclas de los dos componentes en 59 sitios de Estados Unidos y Canada. Más de 57,000 machos de 61 especies dePhyllophaga fueron capturados e identificados. Tres de los resultados más importantes incluyen: (1) el extenso uso de los dos componentes [de las 147 especies de Phyllophaga (sensu stricto), en Estados Unidos y Canada, fueron capturados machos de cerca del 40% de ellas.]; (2) para la mayoría de las especies, la respuesta intraespecífica de los machos a las combinaciones de los dos aminoácidos fue consistente entre años diferentes, y en todos los sitios geográficos; y (3) un inusual polymorfismo de la feromona fue descrito para P. anxia. Poblaciones de algunos sitios fueron atrapados sólo con valina, mientras que poblaciones de otros sitios fueron atrapados sólo con isoleucina. También se encontraron sitios donde las poblaciones responden a ambos componentes, valina e isoleucina, produciendo una curva de captura bimodal. En el sureste del estado de Massachusetts y en Rhode Island, en Estados Unidos, machos de P. anxia fueron atrapados en trampas con mezclas de valina e isoleucina.

Pyrethroid resistance in populations of Listronotus maculicollis (Coleoptera: Curculionidae) from southern New England golf courses.

ABSTRACT Topical application bioassays of bifenthrin and &lgr;-cyhalothrin were conducted on field-collected populations of Listronotus maculicollis Kirby (Coleoptera: Curculionidae) from eight southern New England golf courses, six in Connecticut, one in Massachusetts, and one in Rhode Island. Concentrations versus mortality regression lines were estimated to compare the LD50 values and resistance ratios for each insecticide and each population. The LD50 ranges for bifenthrin and &lgr;-cyhalothrin were 1.80–244.67 ng per insect and 0.52–159.53 ng per insect, respectively. The field-collected strains showed low to high levels of resistance to bifenthrin (6.1–135.9-fold) and &lgr;-cyhalothrin (28.7–306.8-fold). This is the first report of insecticide resistance in this species. The loss of pyrethroid efficacy is making control of Listronotus maculicollis more challenging.

Use of Early Ripening Cultivars to Avoid Infestation and Mass Trapping to Manage Drosophila suzukii (Diptera: Drosophilidae) in Vaccinium corymbosum (Ericales: Ericaceae)

ABSTRACT Use of early ripening highbush blueberry cultivars to avoid infestation and mass trapping were evaluated for managing spotted wing drosophila, Drosophila suzukii (Matsumura). Fourteen highbush blueberry cultivars were sampled for spotted wing drosophila infestation. Most ‘Earliblue’, ‘Bluetta’, and ‘Collins’ fruit were harvested before spotted wing drosophila oviposition commenced, and so escaped injury. Most fruit from ‘Bluejay’, ‘Blueray’, and ‘Bluehaven’ were also harvested before the first week of August, after which spotted wing drosophila activity led to high levels of blueberry infestation. In a separate experiment, damage to cultivars was related to the week in which fruit were harvested, with greater damage to fruit observed as the season progressed. Attractant traps placed within blueberry bushes increased nearby berry infestation by 5%, irrespective of cultivar and harvest date. The significant linear reduction in infestation with increasing distance from the attractant trap suggests that traps are influencing fly behavior to at least 5.5 m. Insecticides applied to the exterior of traps, compared with untreated traps, revealed that only 10–30% of flies visiting traps enter the traps and drown. Low trap efficiency may jeopardize surrounding fruits by increasing local spotted wing drosophila activity. To protect crops, traps for mass trapping should be placed in a perimeter outside fruit fields and insecticides need to be applied to the surface of traps or on nearby fruit to function as an attract-and-kill strategy.

Susceptibility of Four Species of Turfgrass-Infesting Scarabs (Coleoptera: Scarabaeidae) to Bacillus thuringiensis Serovar japonensis Strain Buibui

Abstract Bacillus thuringiensis serovar japonensis strain Buibui experimental formulations containing Cry8Ca1 δ-endotoxin were evaluated in the field for the control of oriental beetle, Anomala orientalis Waterhouse; Japanese beetle, Popillia japonica Newman; Asiatic garden beetle, Maladera castanea (Arrow); and European chafer, Rhizotrogus majalis (Razoumowsky) larvae infesting turfgrasses. In 17 fall applications, control of A. orientalis and P. japonica was achieved at rates as low as 100 g of toxin per ha; however, rates of 301 or 593 g/ha were consistently more effective. A. orientalis larvae were the most susceptible followed by P. japonica, R. majalis, and M. castanea. Two spring applications of 120 g of toxin per ha were not effective against oriental or Japanese beetles.

Pyrethroid Resistance Mediated by Enzyme Detoxification in Listronotus maculicollis (Coleoptera: Curculionidae) From Connecticut

ABSTRACT In 2009, pyrethroid resistance was confirmed for seven “annual bluegrass weevil” Listronotus maculicollis Kirby (Coleoptera: Curculionidae) adult populations from southern New England. The mechanisms responsible for conferring this resistance were unknown. In this study, topical application bioassays with bifenthrin and bifenthrin combined with synergists affecting three detoxification systems were conducted on four field-collected adult populations of L. maculicollis from Connecticut to determined whether cytochrome P450 monooxgenases (P450s), glutathione S-trans-ferases (GSTs), and/or carboxyl-esterases (COEs) mediated metabolic detoxification. Because a susceptible L. maculicollis laboratory strain does not exist, the most susceptible field-collected population (New Haven) provided a baseline against which all other populations were compared. In the population with the lowest resistance (Norwich), only detoxification by P450s was significant. Detoxification in the population with the second highest level of resistance (Stamford) involved both P450s and GSTs. Detoxification in the population with the highest level of resistance (Hartford) involved P450s, GSTs, and COEs. This study suggests that enzyme-mediated metabolic detoxification plays an important role in annual bluegrass weevil pyrethroid resistance.

Synergism between demethylation inhibitor fungicides or gibberellin inhibitor plant growth regulators and bifenthrin in a pyrethroid-resistant population of Listronotus maculicollis (Coleoptera: Curculionidae).

ABSTRACT In 2007–2008, the “annual bluegrass weevil,” Listronotus maculicollis Kirby (Coleoptera: Curculionidae), a serious pest of Poa annua L. (Poales: Poaceae) on U.S. golf courses, was shown to be resistant to two pyrethroids, bifenthrin and lambda-cyhalothrin. In 2008, we showed that bifenthrin resistance was principally mediated by oxidase detoxification (cytochrome P450 [P450]). P450s can be inhibited by demethylation inhibitor fungicides and gibberellin inhibitor plant growth regulators, both of which are commonly used on golf courses. We tested these compounds for synergistic activity with bifenthin against a pyrethroid-resistant population of L. maculicollis. The LD50 value for bifenthrin was significantly reduced from 87 ng per insect (without synergists) to 9.6–40 ng per insect after exposure to the fungicides fenarimol, fenpropimorph, prochloraz, propiconazole, and pyrifenox and the plant growth regulators flurprimidol, paclobutrazol, and trinexapac-ethyl. Simulated field exposure with formulated products registered for use on turf revealed enhanced mortality when adult weevils were exposed to bifenthrin (25% mortality, presented alone) combined with field dosages of propiconizole, fenarimol, flurprimidol, or trinexapac-ethyl (range, 49–70% mortality).

Enhanced Toxicity of Bacillus Thuringiensis Japonensis Strain Buibui Toxin to Oriental Beetle and Northern Masked Chafer (Coleoptera: Scarabaeidae) Larvae with Bacillus sp. NFD2

ABSTRACT Bacillus thuringiensis japonensis strain Buibui (Btj) has the potential to be an important control agent for pest scarabs. Bioassays using autoclaved and nonautoclaved soil showed there were always lower LC50 values associated with nonautoclaved soil. We identified five other bacteria found in the hemolymph of insects killed by Btj and used them in bioassays to see whether we could enhance the control achieved with Btj alone. One bacterium, designated NFD2 and later identified as a Bacillus sp., showed the greatest enhancement of Btj in preliminary experiments and was used in bioassays with Btj versus oriental beetle, Anomala orientalis (Waterhouse), and northern masked chafer, Cyclocephala borealis Arrow (Coleoptera: Scarabaeidae), larvae. This bacterium alone was nontoxic to grubs in bioassays. A combination of this bacterium with Btj in nonautoclaved soil resulted in a significantly lower LC50 value (0.23 µg toxin per g soil) from all other treatments for A. orientalis with one exception; the LC50 where NFD2 was added back into autoclaved soil (0.29 µg toxin per g soil). A combination of this bacterium with Btj in nonautoclaved soil resulted in a significantly lower LC50 value (48.29 µg toxin per g soil) from all other treatments for C. borealis with the exception of the treatment where Bacillus sp. NFD2 was added back to autoclaved soil (96.87 µg toxin per g soil) with Btj. This research shows that other soil bacteria can be used to enhance the toxicity of Btj and possibly other Bts.

Field performance of Metarhizium anisopliae against Popillia japonica (Coleoptera: Scarabaeidae) and Listronotus maculicollis (Coleoptera: Curculionidae) larvae in turfgrass

Japanese beetle, Popillia japonica Newman, and annual bluegrass weevil, Listronotus maculicollis Kirby, larvae damage turfgrasses in the northeastern U.S. from April to October. Insecticides from several classes are extensively used to manage both species; however, inappropriate use has led to the development of insecticide resistance in both species and has negatively impacted nontarget predators of P. japonica, thus warranting research on alternative insect control options. We studied the effects of liquid and granular formulations of Metarhizium anisopliae (Metschnikoff) Sorokin strain F52 against P. japonica and L. maculicollis larvae under field conditions. The liquid formulation provided 31 - 46% control of L. maculicollis larvae, but did not control P. japonica larvae. The granular formulation provided 49% control of P. japonica larvae on aerated turf, but did not control these larvae in nonaerated turf nor did it control L. maculicollis larvae. Whereas the overall effectiveness of M. anisopliae F52 for controlling turfgrass–infesting larvae of P. japonica and L. maculicollis ranged from none to moderate, it may be useful in areas where insecticide use is restricted.

LC and LD50 Values of Bacillus thuringiensis Serovar japonensis Strain Buibui Toxin to Oriental Beetle and Northern Masked Chafer Larvae (Coleoptera: Scarabaeidae)

ABSTRACT Bacillus thuringiensis serovar japonensis strain Buibui has the potential to be an important control agent for pest scarabs. Bioassays were designed to test B. t. japonensis against two of the major turf and ornamental scarab pests infesting turfgrasses and ornamentals and to serve as a basis for further tests against other scarab pests. LC and LD50 values of B. t. serovar japonensis strain Buibui toxin and spores were determined by four different bioassays for the oriental beetle, Anomala orientalis (Waterhouse), and northern masked chafer, Cyclocephala borealis Arrow. Oriental beetle larvae were bioassayed in autoclaved and nonautoclaved soil from where they were collected (Kingston, RI [native]), in nonautoclaved soil from where the northern masked chafer larvae were collected (Groton, CT [foreign]), and per os. Northern masked chafer larvae were bioassayed in autoclaved and nonautoclaved soil from where they were collected (Groton, CT [native]), in nonautoclaved soil from where the oriental beetle larvae were collected (Kingston, RI [foreign]) and per os. LC50 values of 3.93 µg toxin/g autoclaved native soil, 1.80 µg toxin/g nonautoclaved native soil, and 0.42 µg toxin/g nonautoclaved foreign soil and an LD50 value of 0.41 µg per os were determined at 14 d for A. orientalis. LC50 values of 588.28 µg toxin/g autoclaved native soil, 155.10 µg toxin/g nonautoclaved native soil, 265.32 µg toxin/g nonautoclaved foreign soil, and LD50 of 5.21 µg per os were determined at 14 d (soils) and 10 d (per os) for C. borealis. There were significant differences in LC50 values for oriental beetles in autoclaved, nonautoclaved native soil and nonautoclaved foreign soil. There were significant differences in LC50 values for northern masked chafers in autoclaved and nonautoclaved native soil. B. t. japonensis can be applied now for control of oriental beetles at rates that are economically competitive with synthetic chemicals. If we can determine the component of nonautoclaved soil that enhances the activity of toxin, it may be possible to lower the rates of toxin needed for control to more economical levels for more difficult to control species such as the northern masked chafer.

Native Bee Diversity and Pollen Foraging Specificity in Cultivated Highbush Blueberry (Ericaceae: Vaccinium corymbosum) in Rhode Island

Abstract We identified 41 species of native bees from a total of 1,083 specimens collected at cultivated highbush blueberry plantings throughout Rhode Island in 2014 and 2015. Andrena spp., Bombus spp., and Xylocopa virginica (L.) were collected most often. Bombus griseocollis (DeGeer), B. impatiens Cresson, B. bimaculatus Cresson, B. perplexus Cresson, and Andrena vicina Smith collected the largest mean numbers of blueberry pollen tetrads. The largest mean percent blueberry pollen loads were carried by the miner bees Andrena bradleyi Viereck (91%), A. carolina Viereck (90%), and Colletes validus Cresson (87%). The largest mean total pollen grain loads were carried by B. griseocollis (549,844), B. impatiens (389,558), X. virginica (233,500), and B. bimaculatus (193,132). Xylocopa virginica was the fourth and fifth most commonly collected bee species in 2014 and 2015, respectively. They exhibit nectar robbing and females carried relatively low blueberry pollen loads (mean 33%). Overall, we found 10 species of bees to be the primary pollinators of blueberries in Rhode Island.