Choice and No-Choice Bioassays to Study the Pupation Preference and Emergence Success of Ectropis grisescens.

Many insects live above the ground as larvae and adults and as pupate below the ground. Compared to the above-ground stages of their life cycles, less attention has been paid on how environmental factors affect these insects when they pupate within the soil. The tea looper, Ectropis grisescens Warren (Lepidoptera: Geometridae), is a severe pest of tea plants and has caused huge economic losses in South China. The protocols described here aim to investigate, through multiple-choice bioassays, whether mature last-instar E. grisescens larvae can discriminate soil variables such as the substrate type and moisture content, and determine, through no-choice bioassays, the impact of the substrate type and moisture content on pupation behaviors and the emergence success of E. grisescens. The results would enhance the understanding of the pupation ecology of E. grisescens and may bring insights into soil-management tactics for suppressing E. grisescens populations. In addition, these bioassays can be modified to study the influences of various factors on the pupation behaviors and survivorship of soil-pupating pests.

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.

Essential Balm: A Strong Repellent Against Foraging and Defending Red Imported Fire Ants (Hymenoptera: Formicidae).

In the present study, the repellent effects of essential balm, a traditional medicine product in China, was tested against foraging and defending red imported fire ants, Solenopsis invicta Buren, under laboratory and field conditions. The laboratory study showed that both band- (width = 1 cm) and patch-smearing of essential balm at each concentration (0.5, 1, or 2 µl/cm(2)) significantly decreased the number of S. invicta foragers within the 6-h observation period. Moreover, band-smearing of 2 µl/cm(2) essential balm and patch-smearing of 0.5, 1, and 2 µl/cm(2) essential balm inhibited most S. invicta foraging activity at 3, 6, 6, and 24 h into the experiment, respectively. The field study showed that after a disturbance was created on the S. invicta mound, there were significantly less defending ants on the substance treated (patch-smeared) with 0.5, 1, and 2 µl/cm(2) essential balm than the controls, but the number of ants on the substance of these three concentrations was similar. Our study suggested that essential balm is a strong repellent against foraging and defending S. invicta and could be applied when temporary protection from S. invicta is needed.