Repellency of Novel Catnip Oils Against the Bed Bug (Hemiptera: Cimicidae).

The common bed bug, Cimex lectularius L., resurged as an important urban pest in the last 20 yr. Yet, there are no commercial repellent products labeled for bed bugs available in the United States. We evaluated the repellency of two catnip oils from newly developed cultivars, CR3 and CR9, and compared each to 10 and 25% N,N-diethyl-meta-toluamide (DEET). CR3 contains 63.4% E,Z-nepatalactone and 27.5% Z,E-nepatalactone, and CR9 contains 94.9% Z,E-nepatalactone. Arena studies showed that CR3 and CR9 oils were more effective than DEET within a 24-h period. At 10% concentration, both CR3 and CR9 oils exhibited a repellency of over 94% during the first 8 h. At 25% concentration, the repellency of CR3 and CR9 oils increased to 100%, and repellency of DEET was 92% during the first 24 h. Repellency of 25% CR3 and CR9 oils became lower than 25% DEET after being aged for 3 d. After 28-d aging, repellency of 25% CR3, CR9, and DEET reduced to 25, 64, and 92%, respectively. Soiled socks were placed above repellent treated bands to determine if the repellent can protect soiled socks from being infested. The 20% CR3 oil prevented 100% of bed bugs from infesting soiled socks showing that it was more effective than DEET. These results indicate that catnip oils from CR3 and CR9 cultivars are more repellent than DEET over a 24-h period following application, but their longevity is shorter than DEET after 72 h.

Calling and Mating Behavior of Diaphania angustalis (Lepidoptera: Crambidae).

Diaphania angustalis Snellen (Lepidoptera: Crambidae) has emerged as a very important pest of blackboard tree, Alstonia scholaris (L.) R. Br. (Apocynaceae), in China during the last two decades. Understanding its biology and behavior is crucial for designing effective and environmentally friendly pest management strategies. Under laboratory conditions [25-28°C, 12:12 (L:D) h, 75-80% RH], adults emerged during both light and dark hours with peak emergence occurring between the first and fifth hours of scotophase, and unmated males and females lived for a mean (±SE) 5.4 ± 0.4 and 5.3 ± 0.7 d, respectively. Female calling behavior was observed only during scotophase (peaking in the fifth hour) by 1- to 5-d-old females, and mating activities occurred 2-5 d after emergence, peaking on day 3. These behavioral characteristics could inform control programs targeting adults.

Does Soil Treated with Conidial Formulations of Trichoderma spp. Attract or Repel Subterranean Termites?

Previous studies showed that many wood-rotting fungi were attractive to termites; however, little attention has been paid to the relationship between termites and soil fungus. In the present study, different designs of two-choice tests were conducted to investigate the behaviors of two subterranean termites, Coptotermes formosanus Shiraki (wood-feeding lower termites) and Odontotermes formosanus (Shiraki) (fungus-growing higher termites), in response to soil (or sand) treated with the commercial conidial formulations of Trichoderma harzianum Rifai (BioWorks) and Trichoderma viride Pers. ex Fries (Shuiguxin). The short-term (1 d) choice tests showed no significant difference in termite aggregation (C. formosanus and O. formosanus) between treated and untreated soil, regardless of Trichoderma species and concentrations. However, in the long-term choice tests, C. formosanus consumed significantly more wood in the chambers containing soil treated with the conidial formulation of T. viride (1 × 108 conidia/g) than that containing untreated soil. The tunneling choice tests showed that sand treated with T. viride (1 × 106 or 1 × 108 conidia/g) or T. harzianum (1 × 106 conidia/g) significantly increased the tunneling activities of C. formosanus. However, sand treated with T. viride (1 × 106 or 1 × 108 conidia/g) had a repellent effect on O. formosanus. Our study showed that the two subterranean termites behaved differently when responding to the conidial formulations of Trichoderma.

Field Evaluation of Commercial Attractants and Trap Placement for Monitoring Pine Sawyer Beetle, Monochamus alternatus (Coleoptera: Cerambycidae) in Guangdong, China.

The pine sawyer beetle, Monochamus alternatus Hope (Coleoptera: Cerambycidae) is a serious insect pest of pine trees by vectoring the pine wood nematode, Bursaphelenchus xylophilus (Steiner and Buhrer) Nickle (Nematoda: Aphelenchoididae). Field studies were carried out during 2013-2015 in Guangdong (China) to evaluate the effectiveness of commercial attractants, effect of trap placement for monitoring M. alternatus, and temporal patterns of trap catch. Four commercial attractants, three trap placements (0, 1.5, and 3 m above ground) and different trapping distances (50, 200, 400, 600, and 900 m) from forest edge were evaluated for monitoring M. alternatus. Traps baited with a mixture of monochamol and plant volatiles captured significantly more beetles than traps baited with monochamol alone or plant volatiles alone. Traps set up at 1.5 m above the ground captured significantly more M. alternatus than those at 0 m and 3 m height. Based on 2,687 beetles trapped from two locations in 2013 and 2014, the female:male ratio was 2.9-4.1:1. The beetles' natural dispersal distance was approximately 100 m based on traps set at different distances from edge of the forest. Continuous monitoring over 38-wk period indicates the peak of adult M. alternatus emergence was between May and June within a year.

Production, identification, and field evaluation of sex pheromone from calling females in Diaphania angustalis (Lepidoptera: Crambidae).

Insect sex pheromones play a crucial role in the mate finding and calling behavior of Lepidoptera pests. Currently, little is known about the chemical ecology of Diaphania angustalis Snellen (Lepidoptera: Crambidae), a severe and important defoliator attacking the medicinal plant, Alstonia scholaris. In the present study, the pheromone components of D. angustalis females were investigated using electrophysiological and behavioral methods. Distilled hexane extracts of female pheromone glands were analyzed through electroantennogram (EAG) and gas chromatography-electroantennogram detector (GC-EAD), and the active compounds were identified through gas chromatography-mass spectrometry (GC-MS). Production peak of female sex pheromone occurred on the third day of age at 5 h into the scotophase with the EAG test, and the hexane extracts were attractive to males in the wind tunnel test. GC-EAD analysis of virgin males to gland extracts that were subsequently evaluated showed two active compounds, (E,E)-10,12-hexadecadienal (E10E12-16:Ald) and (E,E)-10,12-hexadecadien-1-ol (E10E12-16:OH), based on comparison of retention time and mass spectrum, with suitable synthetic compounds. Under laboratory conditions, the blend of E10E12-16:Ald and E10E12-16:OH in a ratio of 9:1 elicited a stronger EAG response than other treatments or a single component. In the field, more male moths were captured by traps baited with the mixture of E10E2-16:Ald and E10E2-16:OH in a ratio of 9:1, whereas a mixture of 8:1 and 10:1 also caught males. Accordingly, E10E2-16:Ald and E10E2-16:OH were regarded as the major sex pheromone components in D. angustalis females.

[Litter decomposition of dominant plantations in Guangxi and its effects on leachate quality].

To understand the decomposition characteristics of the litters in different forest plantations and the effects of released substances during litter decomposition on the leachate quality, litter samples (leaf, shoot, and cortices) were collected from five forest plantations (1 year-old Eucalyptus urophylla x E. grandis, EU1; 4 year-old Eucalyptus urophylla x E. grandis, EU4; 7 year-old Acacia mangium x A. auriculaef, AM; 13 year-old Pinus massoniana Lamb, PL; and mixed broad-leaved softwood, BL), and incubated at 28 degrees C, using water leached for 255 days. In the first 105 days, the litter leachates of EU1 and EU4 had significantly higher coloration and N and P contents and lower pH than those of AM, PL, and BL. On the 255th day, the cumulative chemical oxygen demand (COD) in the leaf litters leachates of EU1 and EU4 was 193.9 and 212.8 g x kg(-1), being 4.2, 4.0, and 4.3 times and 5.3, 4.4, and 4.7 times higher than that of AM, PL, and BL, respectively. The mass loss rate and the N and P leaching rate of the leaf litter of EU1 were significantly higher than those of AM, PL, and BL. The mass loss rate of cortices of EU1 was significantly higher than that of PL. No significant difference was observed for the leaching rate of the shoot litters between AM, PL, and BL. Among the litter samples, leaf litter was easiest to be decomposed, while shoot litter was most difficult to be decomposed. The pH value of the litter leachates of Eucalyptus plantations was significantly negatively correlated with leachate chroma and COD, and the COD had significant positive correlations with the concentrations of total N and P in the leachates.