Insecticide Efficacy and Timing for Control of Western Bean Cutworm (Lepidoptera: Noctuidae) in Dry and Snap Beans.

The western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), is a recent pest of corn, dry,and snap beans, in the Great Lakes region, and best practices for its management in beans need to be established.Insecticide efficacy and application timing field studies, conducted in 2011­2013, determined that lambda-cyhalothrin and chlorantraniliprole were capable of reducing western bean cutworm feeding damage in dry beans from 2.3 to 0.4% in preharvest samples, and in snap beans from 4.8 to 0.1% of marketable pods, respectively. The best application timing in dry beans was determined to be 4­18 d after 50% egg hatch. No economic benefit was found when products were applied to dry beans, and despite high artificial inoculation rates, damage to marketable yield was relatively low. Thiamethoxam, methoxyfenozide, and spinetoram were also found to be effective at reducing western bean cutworm damage in dry bean to as low as 0.3% compared to an untreated control with 2.5% damaged pods. In snap beans, increased return on investment between CAD$400 and CAD$600 was seen with multiple applications of lambda-cyhalothrin, and with chlorantraniliprole applied 4 d after egg mass infestation.

Predation by Coccinella septempunctata and Harmonia axyridis (Coleoptera: Coccinellidae) on Aphis glycines (Homoptera: Aphididae).

Coccinella septempunctata L. and Harmonia axyridis Pallas are key natural enemies of soybean aphid, Aphis glycines Matsumura, in North America. Third instars, adult females, and adult males of both C. septempunctata and H. axyridis exhibited a type II functional response for predation toward adult soybean aphids at 26 +/- 1 degrees C. In C. septempunctata, the functional response curve of adult males differed from those of third instars and adult females, but there was no difference between third instars and adult females. In H. axyridis, the functional response curves of larvae, adult females, and adult males all differed significantly. Third instars and adult females consumed significantly more soybean aphids than did adult males at prey densities of 150 and 180 aphids per arena for C. septempunctata and at prey densities of 60, 90, 120, 150, and 180 aphids per arena for H. axyridis. The theoretical maximum daily predation rate of adult aphids by C. septempunctata was predicted to be 204 per third instar, 277 per adult female, and 166 per adult male, and 244, 156, and 73, respectively, for H. axyridis. Third instars and adult females of both species consumed significantly more aphids than did adult males on soybean plants with the recommended action threshold of 250 soybean aphids per plant. Both C. septempunctata and H. axyridis have high predation capacities and are important in suppressing soybean aphid populations.

Role of visual and olfactory cues from agricultural hedgerows in the orientation behavior of multicolored Asian lady beetle (Coleoptera: Coccinellidae).

Harmonia axyridis Pallas is an introduced lady beetle common in eastern North American agroecosystems. Two-choice behavioral bioassays were performed to determine whether visual and olfactory stimuli from prey and host habitats could elicit taxis in wild-collected H. axyridis adults and whether beetles exhibit a preference among stimuli. Soybean aphid (Aphis glycines Matsumura) spends much of the year in agricultural hedgerows residing on buckthorn (Rhamnus cathartica L), and H. axyridis is frequently observed feeding on aphids in this habitat. Olfactory bioassays were performed in a Y-tube olfactometer and tested the response of beetles to the odor of buckthorn leaves, apple leaves (Malus domestica Borkh.), and buckthorn leaves both naturally and artificially infested with A. glycines. No differences were observed between the numbers of beetles moving toward the odor of buckthorn artificially infested with A. glycines and uninfested buckthorn, but more beetles preferred naturally infested buckthorn over uninfested buckthorn. Visual bioassays were performed in an acrylic tube arena,and tested beetle response to silhouettes and to apple and buckhorn leaves. Beetles were significantly more likely to choose silhouettes over blank space in visual trials. Significantly more beetles moved toward buckthorn leaves than blank space, but beetles did not discern between apple and buckthorn until olfactory cues were also included. This study lays the foundation for future work examining the response of H. axyridis to visual and olfactory cues in Ontario agroecosystems, which could help enhance effectiveness of H. axyridis as a biological control and mitigate its impacts as a pest species.

Polymerase chain reaction-restriction fragment-length polymorphism method to distinguish Liriomyza huidobrensis from L. Langei (Diptera: Agromyzidae) applied to three recent leafminer invasions.

A molecular method is presented for differentiating the morphologically cryptic leafminers Liriomyza langei Frick and L. huidobrensis (Blanchard). This method requires polymerase chain reaction (PCR) amplification of a 1031-bp region of mitochondrial cytochrome oxidase DNA followed by restriction fragment analysis using the restriction enzymes SpeI and EcoRV. Spel cuts the mitochondrial fragment of L. langei into two fragments, but does not cut the L. huidobrensis fragment. EcoRV cuts the L. huidobrensis fragment into two fragments, but does not cut the L. langei fragment. This PCR-restriction fragment-length polymorphism (RFLP) method is faster and less costly than DNA sequencing,which is currently the only other way to differentiate these two species. We apply the method to samples from recently introduced leafminer populations in Sri Lanka, Canada, and South Africa and find that the invasive leafminer in all three locations is L. huidobrensis.

Modeling distribution and abundance of soybean aphid in soybean fields using measurements from the surrounding landscape.

Soybean aphid (Aphis glycines Matsumura) is a severe pest of soybean in central North America. Outbreaks of the aphid in Ontario are often spotty in distribution, with some geographical areas affected severely and others with few or no aphid populations occurring in soybean for the duration of the season. A. glycines spend summers on soybean and overwinter on buckthorn, a shrub that is widespread in southern Ontario and is commonly found in agricultural hedgerows and at the margins of woodlots. A. glycines likely use both short distance migratory flights from buckthorn and longer distance dispersal flights in the search for acceptable summer hosts. This study aims to model colonization of soybean fields by A. glycines engaged in early-season migration from overwintering hosts. Akaike's information criterion (AIC) was used to rank numerous competing linear and probit models using field parameters to predict aphid presence, colonization, and density. The variable that best modeled aphid density in soybean fields in the early season was the ratio of buckthorn density to field area, although dramatic differences in relationships between the parameters were observed between study years. This study has important applications in predicting areas that are at elevated risk of developing economically damaging populations of soybean aphid and which may act as sources for further infestation.

Pheromone chirality of asian palm weevils,Rhynchophorus ferrugineus (Oliv.) andR. vulneratus (Panz.) (Coleoptera: Curculionidae).

Production of 4-methyl-5-nonanol, and 4-methyl-5-nonanone by two sympatric Asian palm weevils,Rhynchophorus ferrugineus (Oliv.) andR. vulneratus (Panz.) suggested that enantiospecificity of either compound could impart species specificity of pheromone communication. Weevil-produced, racemic 4-methyl-5-nonanol and 4-methyl-5-nonanone and their stereoselectively synthesized optical isomers were subjected to gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometry (MS) on a chiral Cyclodex-B column. Only theS,S stereoisomer of 4-methyl-5-nonanol was EAD active and was produced by bothR. ferrugineus andR. vulneratus. Production and EAD activity of (S)-4-methyl-5-nonanone exceeded that of its antipode in both weevils. In field experiments in Java. (4S, 5S)-4-methyl-5-nonanol and the stereoisomeric mixture were equally attractive. The 4R,5R stereoisomer was inactive. The corresponding ketone enantiomers neither enhanced nor reduced attraction to (4S,5S)-4-methyl-5-nonanol. Lack of apparent differences betweenR. ferrugineus andR. vulneratus pheromones suggests that synonomy of both weevils should be considered unless other pre- or postzygotic reproductive isolating mechanisms are disclosed in future studies.

Aggregation pheromone of coconut rhinoceros beetle,Oryctes rhinoceros (L.) (coleoptera: Scarabaeidae).

Male coconut rhinoceros beetles,Oryctes rhinoceros (L.), produce three sex-specific compounds, ethyl 4-methyloctanoate, ethyl 4-methylheptanoate, and 4-methyloctanoic acid, the first of which is an aggregation pheromone. Synthesis of these compounds involving conjugate addition of organocuprates to ethyl acrylate is reported. In field trapping experiments, (4S)-ethyl 4-methyloctanoate and the racemic mixture were equally attractive and 10 times more effective in attracting beetles than ethyl chrysanthemumate, a previously recommended attractant. Ethyl 4-methylheptanoate was as attractive as ethyl chrysanthemumate and more attractive than 4-methyloctanoic acid, but further studies are required before it can be classed as an aggregation pheromone. Compared to ethyl 4-methyloctanoate alone, combinations of the three male-produced compounds did not increase attraction, whereas addition of freshly rotting oil palm fruit bunches to pheromone-baited traps significantly enhanced attraction. With increasing dose, captures ofO. rhinoceros increased, but doses of 6, 9, and 18 mg/day were competitive with 30 mg/day lures. Newly designed vane traps were more effective in capturing beetles than were barrier or pitfall traps. Results of this study indicate that there is potential for using ethyl 4-methyloctanoate in operational programs to controlO. rhinoceros in oil palm plantations.