choice-no-choice-bioassays-to-study-pupation-preference-emergence

Choice and No-Choice Bioassays to Study the Pupation Preference and Emergence Success of <em>Ectropis grisescens</em>

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 ...

South China Agricultural University

Ectropis grisescens Warren (Lepidoptera: Geometridae) is one of the most severe pests of tea plants in China. This species commonly pupates in soil; however, little is known about its pupation ecology. In the present study, choice and no-choice tests were conducted to investigate the pupation behaviors and emergence success of E. grisescens in response to different substrates (sand, sandy loam 1, sandy loam 2, and silt loam) and moisture contents (5, 20, 35, 50, 65, and 80%). Moisture-choice bioassays showed that significantly more E. grisescens individuals pupated in or on soil (sandy loam 1 and 2 and silt loam) that was at the intermediate moisture levels, whereas 5%- and 35%-moisture sand was significantly more preferred over 80%-moisture sand for pupating. Substrate-choice bioassays showed that sand was most preferred by E. grisescens individuals at 20%- and 80%-moisture levels, but no preference was detected among the four substrates at 50%-moisture content. No-choice tests showed that the percentage of burrowed E. grisescens individuals and pupation depth were significantly lower when soil was dry (20% moisture) or wet (80% moisture). In addition, 20%-moisture sandy loam 2 and silt loam significantly decreased the body water content of pupae and emergence success of adults compared to 50%-moisture content. However, each measurement (percentage of burrowed individuals, pupation depth, body water content, or emergence success) was similar when compared among different moisture levels of sand. Interestingly, pupae buried with 80%-moisture soil exhibited significantly lower emergence success than that were unburied.

Pupation Behaviors and Emergence Successes of Ectropis grisescens (Lepidoptera: Geometridae) in Response to Different Substrate Types and Moisture Contents.

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.

Huifang Wang

Guangdong Key Laboratory for Innovation Development and Utilization of Forest Plant Germplasm,
College of Forestry and Landscape Architecture,
Guangdong Key Laboratory for Innovation Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture

South China Agricultural University

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

Huifang Wang

Guangdong Key Laboratory for Innovation Development and Utilization of Forest Plant Germplasm,College of Forestry and Landscape Architecture,Guangdong Key Laboratory for Innovation Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture

South China Agricultural University

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

Guangdong Key Laboratory for Innovation Development and Utilization of Forest Plant Germplasm,
College of Forestry and Landscape Architecture,
Guangdong Key Laboratory for Innovation Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture