Optimization of the sex pheromone of the rice leaffolder moth Cnaphalocrocis medinalis as a monitoring tool in China

The crude extract from Cnaphalocrocis medinalis (Lepidoptera, Pyralidae) has been identified to be (Z)‐11‐octadecenal (Z11‐18:Ald), (Z)‐13‐octadecenal (Z13‐18:Ald), (Z)‐11‐octadecen‐1‐ol (Z11‐18:OH) and (Z)‐13‐octadecen‐1‐ol (Z13‐18:OH) in the GC‐MS, confirming the results reported previously in Japan. Field evaluation in China showed that the optimal blend is Z11‐18:Ald, Z13‐18:Ald, Z11‐18:OH and Z13‐18:OH at a ratio of 3 : 25 : 3 : 3. The optimal dosage is 500 μg Z13‐18:Ald per PVC tubing lure. In August, trap catches were highest between 3:00 and 4:00 a.m., and no moths were caught before 12:00 a.m. or after 6:00 a.m. The impact of trap design and trap height placement was also evaluated in the paddy field. The sticky wing trap was better than the water pan trap. The number of moths captured by the electric grid trap was 1.7 times greater than caught by the sticky wing trap. The optimal trap height was 20 cm below the top of the rice plants (80 cm high). Pheromone lure formulated from 60 μg Z11‐18:Ald, 500 μg Z13‐18:Ald, 60 μg Z11‐18:OH and 60 μg Z13‐18:OH was effective for population monitoring in trial sites in Zhejiang, Shanghai, Jiangxi, Hunan, Hubei, Guangxi, Guizhou, Chongqing and Hainan Provinces, encompassing both subtropical and temperate regions. Use of this synthetic pheromone blend provides a promising alternative to the currently used disturb and count method (DCM) for monitoring the population of C. medinalis in China.     

Behavioural effects of minor sex pheromone components in Brazilian apple leafroller Bonagota cranaodes (Lep., Tortricidae)

Abstract:  The behavioural response of Brazilian apple leafroller males, Bonagota cranaodes (Meyrick), to natural and synthetic sex pheromone was studied in a wind tunnel. Calling females elicited upwind flights followed by landing and wingfanning at the source in 72% of the males tested. Female gland extracts, with the main compound ( E , Z )3,5dodecadienyl acetate released at 100 pg/min, attracted 57% of the males to the source. Few males (1%) were attracted to the main compound alone, released at the same rate. Even a synthetic blend of all five gland compounds eliciting an antennal response, formulated according to their proportion in female gland extracts, was barely attractive (7%). Comparison of this synthetic blend and female gland extracts indicates a behavioural role of other gland compounds. Male attraction was significantly increased (34%) in response to a 100 : 5 : 5 : 5-blend of the main compound and three minor gland compounds, ( Z )-5-dodecenyl acetate, ( E , Z )-3,5-tetradecadienyl acetate, and ( Z )-9-hexadecenyl acetate.     

Reproductive allocation in multinest colonies of the ponerine ant Pachycondyla goeldii

Abstract.  1.  Pachycondyla goeldii constitutes the only recorded case of a monogynous (i.e. one queen per colony) polydomous (i.e. several nests per colony) species in the Ponerinae subfamily. This study examines the impact of polydomy on reproductive allocation between nests (also called 'calies' in polydomous society) in Pachycondyla goeldii Forel, by: (i) recording the number of workers and sexuals in 67 nests belonging to 21 colonies; (ii) dissection of workers in nine nests containing a queen (QR nests), nine nests without a queen but associated to a QR nest (QL nests) and five nests belonging to colonies that permanently lost the queen (OR nests); and (iii) measuring the length of all eggs present in the nests (our laboratory study shows that queen-laid eggs were significantly longer than worker-laid eggs).
2. The number of workers was significantly higher in QR nests than in QL nests, while the number of virgin queens was significantly higher in QL nests compared with QR nests.
3. Worker ovarian activity is inversely related to queen proximity: highest in OR nests, intermediate in QL nests, and lowest in QR nests.
4. Egg length was highest in QR nests, where the queen was most likely the primary egg-layer, intermediate in QL nests, where eggs could have originated from both the queen and workers, and lowest in OR nests, where workers were the sole egg-layers.
5. We postulate that the proximal mechanism explaining differences between QR and QL nests is the pheromonal absence of the queen from QL nests and that the evolutionary reasons of these divergences between nest types are likely to originate from the different conflicts occurring in ant colonies.     

Investigation of the optimal carbon-nitrogen ratio and carbohydrate-nutrient blend for mixed-acid batch fermentations

To determine the optimal scenario for mixed-acid fermentations, an array of batch fermentations were performed that independently varied the C/N ratio (adjusted using urea) and the blend of carbohydrate (office paper) and nutrient (wet chicken manure (CM)). A blend of 93% paper and 7% wet CM (dry basis) with a C/N ratio of 37 g C_NA/g N had the highest culture yield (0.21 g acid_produced/g NAVS_initial), total acid productivity (0.84 g acid_produced/(L_liq d)), and conversion (0.43 g NAVS_consumed/g NAVS_initial). Compared to a control blend of 80% paper and 20% wet CM (dry basis, no urea) the culture yield, productivity, and conversion improved 53%, 44%, and 70%, respectively. Selectivity was a strong function of C/N ratio and varied from 0.167 to 0.667 acid_produced/g NAVS_consumed. Nitrogen supplementation with urea improves performance and reduces costs of (1) capital, (2) nutrients, and (3) downstream processing by reducing impurities from nutrient-rich wastes (e.g., manures, sewage sludge).     

Wind tunnel behavioural response and field trapping of the blowfly Calliphora vicina

The attraction of the blowfly Calliphora vicina Robineau‐Desvoidy, 1830 (Diptera: Calliphoridae) to single synthetic compounds, blends and authentic odours was investigated in a wind tunnel. A total of 1850 C. vicina (1750 females and 100 males) were tested. A comparison of male and female responses showed significant differences in attraction between the sexes. Females were more attracted than males to liver odour. The attraction of females lay in the ranges of 0–22% for single compounds, 26–64% for synthetic blends and 58–88% for authentic odours. Dimethyl trisulphide was the most attractive single compound. Significant improvement in attraction was achieved with blends and a three‐component lure, consisting of dimethyl trisulphide, mercaptoethanol and o‐cresol, was found to be the best solution for field trapping of C. vicina. Authentic odours from dead fish and mice were significantly more attractive than liver and the three‐component blend, and the blend and liver were similarly effective as attractants. Field tests support the results of the wind tunnel study and a high number of C. vicina were caught in funnel traps. Overall, 99.1% of the specimens caught were females.     

Disruption of pheromone communication in moths: is the natural blend really most efficacious?

It is widely assumed that a blend of pheromone components, that is qualitatively and quantitatively similar to the natural sex attractant, is the most effective mating disruptant for moths. However, the literature contains only limited evidence supporting this assumption. The authors discuss the importance of comparing the relative effectiveness of complete and incomplete pheromone blends when evaluating the potential of mating disruption for controlling pest moths.     

Optimal pheromone trap density for mass trapping cacao mirids

Sahlbergella singularis Haglund and Distantiella theobroma (Distant) (Heteroptera: Miridae) are the key insect pests of cacao in Ghana and elsewhere in West Africa. Since 1954, spraying with synthetic insecticides has been the principal means of controlling these pests. In West Africa, environmental concerns, economic stimuli, and unreliable access to insecticides have stimulated interest in ecologically more benign mirid control strategies as an alternative to a total reliance on insecticides. Males of both mirid species, and those of the less damaging Bryocoropsis laticollis Schumacher, respond to the same synthetic sex pheromone blend, so pheromone‐based strategies may provide control as well as monitoring opportunities. Pheromone traps were deployed for 3 months at nine densities between two and 30 traps per 0.1 ha plot (20–300 traps ha^?1) plus an untreated control treatment in a replicated large‐scale field experiment on mature mixed Upper Amazon hybrid cacao in Ghana, in order to determine the optimal dispenser density for mass trapping, lure‐and‐kill, and/or lure‐and‐infect. At the end of the trapping period, mirid populations in the various treatments were assessed by insecticide knockdown on 400 trees and by searches to hand height on 1 200 trees, together with an assessment of mirid damage. In total 781 S. singularis and 235 D. theobroma were captured in the pheromone traps. The optimal dispenser density for S. singularis was 150 traps ha^?1. Over 300 traps ha^?1 was probably optimal for D. theobroma as a smaller proportion of the population was captured, and numbers caught per trap displayed no decline with increasing trap density. From insecticide knockdowns, mirid population density was estimated at 220–230 ha^?1, 63% of which were D. theobroma. Too few pods and orthotropic shoots were damaged by mirids to establish the efficacy of pheromone trapping for mirid control.