TY - JOUR
AU - Wang,, Cai
AB - Abstract 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. Camellia sinensis, Ectropis grisescens, emergence, preference, pupation The tea looper, Ectropis grisescens Warren (Lepidoptera: Geometridae), is one of the most significant chewing pests of tea plants (Camellia sinensis L.) in China (Zhang 2004, Zhang et al. 2016), but little was known about the biological characteristics of this species until recent years. The lack of E. grisescens studies is due to the mistaken identification of this species as Ectropis obliqua (Prout) (Lepidoptera: Geometridae) during the past decades (Jiang et al. 2014, Xi et al. 2014). Although these sibling species are morphologically and behaviorally similar, they are different in many aspects (Jiang et al. 2014; Zhang et al. 2014, 2016; Ge et al. 2016; Ma et al. 2016). Based on molecular identification methods, Jiang et al. (2014) reported that E. grisescens has a much wider geographic distribution compared to E. obliqua, and therefore could cause greater economic losses in tea growing areas over south and east China, which have largely been ignored so far. Traditionally, diverse groups of chemical pesticides have been used for the control of E. grisescens as well as other tea pests (Zhang 2004). However, pesticide residues have received increasing attention (Chang et al. 2016, Chen et al. 2017). The EU Pesticides database (http://ec.europa.eu/sanco_pesticides/public/index.cfm) listed the maximum residue limits of 448 pesticides for tea (Cajka et al. 2012). Unfortunately, several surveys showed that the concentration of pesticide residues in some tea products was above these limits (Feng et al. 2015, Zhou 2017), which not only poses health risks for customers but also hurts the reputation of tea industries. Therefore, it would be important to develop novel and environmental friendly methods for the control of E. grisescens, which largely depend on the full understanding of the biology of this tea pest. E. grisescens normally pupates in soil under field conditions (Ge et al. 2016). Our preliminary studies showed that although E. grisescens larvae could successfully pupate in substrate-free containers, they showed a strong tendency to burrow into soil or sand, if available, for pupating. To our best knowledge, the pupation behavior of E. grisescens has not yet been investigated in detail. Here, we focus on how soil type and moisture content influence pupation behaviors and emergence success of E. grisescens under laboratory conditions. The results will contribute to develop soil management tactics for E. grisescens control. Materials and Methods Insect Rearing A laboratory colony of E. grisescens was provided by the Tea Research Institute, Chinese Academy of Agricultural Sciences (Hangzhou, China), in August 2016. This colony was previously established from E. grisescens larvae collected from Xingchang, Zhejiang, China (Ge et al. 2016). The fresh tea shoots were collected from the tea plantation in the arboretum of South China Agricultural University (Guangzhou, China) and used to feed E. grisescens in this study. The method provided by Ge et al. (2016) was used to obtain several generations of E. grisescens under laboratory conditions (26 ± 2°C, 60–90% RH, and a photoperiod of 14:10 [L:D] h). Our preliminary observation indicated that the mature E. grisescens larvae fell from leaves and actively ‘wandered’ on the bottom of the container to search the proper pupation sites (the immature larvae would move upward to search the food after falling and therefore can be distinguished from the mature ones). Hundreds to thousands of wandering late-instar larvae were obtained for each generation, and larvae tested in each experiment were collected from the same generation. Substrate Preparation Four substrates (sand and three types of soil) were collected from the arboretum of South China Agricultural University. Only the top layer (<5 cm in depth) of substrate was collected. A sample of each substrate was analyzed by the Laboratory of Forestry and Soil Ecology (College of Forestry and Landscape Architecture, South China Agricultural University) to determine textural classes and characteristics (Table 1). Results showed that the three soil samples represent common soil types in south China and are suitable for growing tea plants (Ma et al. 2000, Yu et al. 2003). To prepare the experiments, substrates were dried in an oven at 50°C for several weeks and sterilized at 80°C for >3 d. Dried substrates were then ground with wooden pestles and mortars, sifted through a 3-mm sieve, and stored in Zip lock bags (CleanWrap, Shanghai, China). The moisture content of each substrate was calculated with the equation provided by Chen and Shelton (2007) as follows: moisture content (%) = [weight of distilled water added into soil/(weight of saturated soil − weight of dried soil)] × 100%. Before experiments, the required amount of distilled water was added and thoroughly mixed with sand or soil to make the 5%-, 20%-, 35%-, 50%-, 65%-, and 80%-moisture substrate. Table 1. Textural classes and characteristics of substrates used in the present study Substrate texture . Particle size distribution (%) . Organic matter (%) . pH . Saturated water content (%) . Sand . Silt . Clay . Sand 95.0 3.6 1.4 0.10 7.76 20.6 Sandy loam 1 78.6 10.4 11.0 3.98 4.23 35.2 Sandy loam 2 71.4 16.6 12.0 7.63 5.55 53.4 Silt loam 45.4 52.8 1.8 0.55 4.67 44.7 Substrate texture . Particle size distribution (%) . Organic matter (%) . pH . Saturated water content (%) . Sand . Silt . Clay . Sand 95.0 3.6 1.4 0.10 7.76 20.6 Sandy loam 1 78.6 10.4 11.0 3.98 4.23 35.2 Sandy loam 2 71.4 16.6 12.0 7.63 5.55 53.4 Silt loam 45.4 52.8 1.8 0.55 4.67 44.7 Open in new tab Table 1. Textural classes and characteristics of substrates used in the present study Substrate texture . Particle size distribution (%) . Organic matter (%) . pH . Saturated water content (%) . Sand . Silt . Clay . Sand 95.0 3.6 1.4 0.10 7.76 20.6 Sandy loam 1 78.6 10.4 11.0 3.98 4.23 35.2 Sandy loam 2 71.4 16.6 12.0 7.63 5.55 53.4 Silt loam 45.4 52.8 1.8 0.55 4.67 44.7 Substrate texture . Particle size distribution (%) . Organic matter (%) . pH . Saturated water content (%) . Sand . Silt . Clay . Sand 95.0 3.6 1.4 0.10 7.76 20.6 Sandy loam 1 78.6 10.4 11.0 3.98 4.23 35.2 Sandy loam 2 71.4 16.6 12.0 7.63 5.55 53.4 Silt loam 45.4 52.8 1.8 0.55 4.67 44.7 Open in new tab Moisture-Choice Bioassays Six-choice tests conducted to study the pupation-site preferences of E. grisescens in response to the six moisture levels (5, 20, 35, 50, 65, and 80%) of each substrate (sand, sandy loam 1, sandy loam 2, or silt loam). The bioassays were conducted from August to October 2016. The protocol provided by Wen et al. (2016) was modified to set the experiment. In brief, the bioassay arenas were polypropylene containers (upper side: 20.0 cm [L] × 13.5 cm [W], bottom side: 17.0 cm [L] × 10.0 cm [W], height: 6.5 cm) with fresh tea leaves pasted on the inner side of lids (Fig. 1A). Waterproof polyvinyl chloride (PVC) sheets (height = 3.5 cm) were used to equally divide each container into six chambers, and hot glue was used to fix PVC sheets and seal any cracks to prevent water permeation. For the test of each substrate, chambers were filled with the substrate at different moisture levels with the randomly assigned order (Fig. 1B). Each test was repeated eight times. Thirty wandering E. grisescens larvae were released onto the leaves pasted on the lids, and the container was then sealed. All released larvae actively wandered after they dropped from leaves, so they could move freely on different substrate types and search for the proper pupation site. On day 5, the number of live pupae in each chamber was counted. All bioassays of this and following experiments were kept in incubators setting at 26°C and 90% RH. Fig. 1. Open in new tabDownload slide Bioassay arenas of the choice tests: fresh tea leaves were pasted on the inner side of lids where mature Ectropis grisescens larvae were released (A). For the six-choice test, waterproof PVC sheets were used to equally divide each container into six chambers, which were filled with the substrate at different moisture levels (B). For the four-choice test, the containers were equally divided into four chambers, which were filled with the four types of substrate that were at the same moisture level (C). Fig. 1. Open in new tabDownload slide Bioassay arenas of the choice tests: fresh tea leaves were pasted on the inner side of lids where mature Ectropis grisescens larvae were released (A). For the six-choice test, waterproof PVC sheets were used to equally divide each container into six chambers, which were filled with the substrate at different moisture levels (B). For the four-choice test, the containers were equally divided into four chambers, which were filled with the four types of substrate that were at the same moisture level (C). Substrate-Choice Bioassays Four-choice tests were conducted to study the pupation-site preferences of E. grisescens in response to the four substrates at 20%-, 50%-, or 80%-moisture levels. The experiments were conducted from November to December 2016. The bioassay arenas were similar to the moisture-choice bioassays, but the container was equally divided into four chambers with PCR sheets. For each moisture level, four substrates were carefully added until filling of the chamber (Fig. 1C). Each test was repeated eight times, and 30 larvae were released into each replicate. On day 5, the live pupae in each chamber was counted. Pupation Bioassays Pupation bioassays were conducted to study the effect of substrate type and moisture content on pupation behaviors and pupal physiology of E. grisescens. The experiments were conducted from March to April 2017. Bioassay arenas were plastic cups (upper side: 11.5 cm in diameter; bottom side: 8.5 cm in diameter; height: 6.5 cm) filled with the substrate in the depth of 5.0 cm. In each treatment, a combination of one substrate type (sand, sandy loam 1, sandy loam 2, or silt loam) and one moisture level (20, 50, or 80%) was tested. Each treatment was repeated eight times. For each replicate, six E. grisescens larvae were released onto the surface of the substrate. The lids were then placed to prevent insect escape but were not tightly covered to let airflow. On day 5, the soil was carefully removed with a small spoon until the pupa was exposed. This pupa was carefully transferred to a 2-ml Eppendorf tube. A toothpick was vertically inserted into the pupal chamber until reaching the bottom, and the pupation depth (the length of the inserted section of the toothpick) of E. grisescens individuals was measured using a digital caliper (Vogel, IP54, Germany). If the pupae laid on the surface of the substrate, the pupation depth was recorded as 0. A digital caliper was used to measure the length and width of each pupa (considered as a prolate spheroid) for calculating surface area and volume. The fresh weight of each pupa was measured using a 0.1-mg electronic balance. The surface-to-volume and surface-to-mass ratios were calculated. The pupa was then oven dried at 50°C for 3 d for dry weight measuring. The body water content of each pupa was calculated as follows: body water content (%) = [(fresh weight − dry weight)/fresh weight] × 100%. Only live pupae were tested. In total, 39–48 pupae were measured in each treatment. Emergence Bioassays Emergence bioassays were conducted to study the effect of substrate type and moisture content on the pupal development time and emergence success of E. grisescens. The experiments were conducted from April to May 2017. The bioassays contained 12 treatments (the combinations of the four substrate types and three moisture levels as described in the pupation bioassays), and seven replicates in each treatment were conducted. For each replicate, the substrate was added into the container (plastic cup as mentioned above) to a depth of 3 cm. Fifteen wandering larvae were released into each cup. Because there was air for prepupae and pupae breathing, the lids were tightly covered to reduce moisture changes of the substrate. On day 3, the number of pupae and any dead larvae on surface of the substrate was recorded, and the percentage of E. grisescens individuals burrowed into the substrate was calculated as follows: percentage of burrowed individuals (%) = [(15 − number of individuals on the surface)/15] × 100%. The number of emerging adults was recoded daily until no more adult emerged for 15 d, and the emergence success was calculated. The percentage of wing-deformed adults was calculated by dividing the number of wing-deformed individuals (Supp Fig. S1 [online only]) by the number of emerging adults. Three emergence parameters, including days to first emergence, emergence peak, and emergence duration, were also recoded as described in Chen and Shelton (2007). Burying Bioassays Our study showed that E. grisescens individuals tended to pupate on the surface of soil under 20%- and 80%-moisture conditions (see Results). Therefore, we decided to conduct burying bioassays to test the emergence success of E. grisescens pupae if they were passively buried. The experiments were conducted from April to May 2017. Soil (sandy loam 1) at each of the three moisture levels (20, 50, or 80%) was added into the container (plastic cup) to a depth of 2 cm, and fifteen 1-d-old E. grisescens pupae (previously pupated in a substrate-free container) were evenly placed on the surface of soil. These pupae were then either unburied or buried into 1-cm soil (the moisture of burying soil was the same to that initially added in each container). In total, there were six treatments, and each treatment was repeated seven times. The number of emerging adults was recorded daily, and the emergence success, percentage of wing-deformed adults, and emergence parameters were recorded as described in Emergence Bioassays. Data Analyses For the choice tests, the percentage of E. grisescens individuals pupated in each chamber was calculated. Because of the sum constraint of the percentage data (i.e., the sum of the percentage of live pupae in all chambers equals 1), the ln-ratio transformation was conducted to make the transformed variables independent (Aitchison 1986, Kucera and Malmgren 1998, Wen et al. 2016, Veen et al. 2017). The transformed data were then compared among moisture levels (six-choice tests) or substrate types (four-choice tests) using one-way analysis of variance (ANOVA, SAS 9.4, SAS Institute, Cary, NC). For the pupation and emergence bioassays, data (pupation depth, body water content, surface-to-volume ratio, surface-to-mass ratio, percentage of burrowed individuals, emergence success, percentage of wing-deformed adults, or each emergence parameter) were compared among treatments using one-way ANOVAs. Tukey’s honestly significant difference tests were conducted for means comparison after each ANOVA. For the burying bioassays, the two-sample t-test (SAS 9.4) was conducted to compare the emergence success, percentage of wing-deformed adults, and each emergence parameter among pupae that were buried and unburied within each moisture content. In all tests, the significance levels were determined at α = 0.05. Results Moisture-Choice Bioassays The percentage of pupae in the chambers containing 5%- and 35%-moisture sand was significantly higher than that in the chambers containing 80%-moisture sand, but they were not significantly different from other moisture levels (Fig. 2A). For sandy loam (1 and 2) and silt loam, 35%- and 50%-moisture levels were most preferred by E. grisescens individuals for pupating, and dry (5% moisture) and wet (80% moisture) soil was significantly less preferred (Fig. 2B–D). Fig. 2. Open in new tabDownload slide Percentage (mean ± SE) of live Ectropis grisescens pupae in the chambers containing different moisture levels of sand (A), sandy loam 1 (B), sandy loam 2 (C), or silt loam (D). Different letters indicate significant differences (P < 0.05). Fig. 2. Open in new tabDownload slide Percentage (mean ± SE) of live Ectropis grisescens pupae in the chambers containing different moisture levels of sand (A), sandy loam 1 (B), sandy loam 2 (C), or silt loam (D). Different letters indicate significant differences (P < 0.05). Substrate-Choice Bioassays At 20%-moisture content, significantly more E. grisescens individuals pupated in the chambers containing sand compared to sandy loam (1 and 2), but they were not significantly different from silt loam (Fig. 3A). At 50%-moisture content, the percentage of live pupae was similar when compared among the four substrates (Fig. 3B). At 80%-moisture content, sand was significantly more preferred over other substrates (Fig. 3C). Fig. 3. Open in new tabDownload slide Percentage (mean ± SE) of live Ectropis grisescens pupae in the chambers containing the four substrates that were at 20%- (A), 50%- (B), or 80%-moisture content (C). Different letters indicate significant differences (P < 0.05). Fig. 3. Open in new tabDownload slide Percentage (mean ± SE) of live Ectropis grisescens pupae in the chambers containing the four substrates that were at 20%- (A), 50%- (B), or 80%-moisture content (C). Different letters indicate significant differences (P < 0.05). Pupation Bioassays The pupation depth of E. grisescens was not significantly different among different moisture levels of sand (Fig. 4A). However, for sandy loam (1 and 2) and silt loam, pupation depth was significantly higher at 50%-moisture content compared to 20%- and 80%-moisture levels (Fig. 4A). In sandy loam 2 and silt loam, the body water content of E. grisescens pupae was significantly lower at 20%-moisture content compared to 50%-moisture content (Fig. 4B). The pupae collected from 20%-moisture silt loam and 80%-moisture sandy loam 1 exhibited significantly higher surface-to-volume ratio compared to 80%-moisture silt loam, but they were not significantly different from other treatments (Fig. 4C). The surface-to-mass ratio of pupae in 20%-moisture silt loam was significantly higher than all remaining treatments (Fig. 4D). Fig. 4. Open in new tabDownload slide Pupation depth (A), body water content (B), surface-to-volume ratio (C), and surface-to-mass ratio (D) of Ectropis grisescens pupae in or on each substrate (sand, sandy loam 1, sandy loam 2, or silt loam) at each moisture level (20, 50, or 80%). Data are presented as mean ± SE, and different letters indicate significant differences (P < 0.05). Fig. 4. Open in new tabDownload slide Pupation depth (A), body water content (B), surface-to-volume ratio (C), and surface-to-mass ratio (D) of Ectropis grisescens pupae in or on each substrate (sand, sandy loam 1, sandy loam 2, or silt loam) at each moisture level (20, 50, or 80%). Data are presented as mean ± SE, and different letters indicate significant differences (P < 0.05). Emergence Bioassays Significantly fewer E. grisescens individuals burrowed into soil (sandy loam 1 and 2 and silt loam) at 20%- and 80%-moisture levels compared to 50%-moisture content (Fig. 5A). In sandy loam 2 and silt loam, the emergence successes were significantly lower at 20%-moisture content than at 50%-moisture content (Fig. 5B). However, the percentage of wing-deformed adults (Fig. 5C) and emergence parameters (days to first emergence, emergence peak, and emergence duration; Supp Fig. S2 [online only]) were not significantly different when compared among the treatments. Fig. 5. Open in new tabDownload slide Percentage of burrowed individuals (A), emergence success (B), and percentage of wing-deformed adults (C) of Ectropis grisescens that pupated in or on each substrate (sand, sandy loam 1, sandy loam 2, or silt loam) at each moisture content (20, 50, or 80%). Data are presented as mean ± SE, and different letters indicate significant differences (P < 0.05). Fig. 5. Open in new tabDownload slide Percentage of burrowed individuals (A), emergence success (B), and percentage of wing-deformed adults (C) of Ectropis grisescens that pupated in or on each substrate (sand, sandy loam 1, sandy loam 2, or silt loam) at each moisture content (20, 50, or 80%). Data are presented as mean ± SE, and different letters indicate significant differences (P < 0.05). Burying Bioassays Burying in 80%-moisture soil (sandy loam 1) significantly decreased the emergence success compared to the pupae that were placed on the surface of 80%-moisture soil (Fig. 6A). However, there was no significant difference in the emergence success between buried and unburied pupae at 20%- and 50%-moisture levels. The percentage of wing-deformed adults (Fig. 6B) and emergence parameters (Supp Fig. S2 [online only]) were similar when compared among the pupae that were buried and unburied within each moisture content. Fig. 6. Open in new tabDownload slide Emergence success (A) and percentage of wing-deformed adults (B) of Ectropis grisescens that were unburied or buried with soil (sandy loam 1) at each of the three moisture levels (20, 50, or 80%). Data are presented as mean ± SE. The asterisk (*) indicates significant difference (P < 0.05), and NS indicates no significant difference (P > 0.05). Fig. 6. Open in new tabDownload slide Emergence success (A) and percentage of wing-deformed adults (B) of Ectropis grisescens that were unburied or buried with soil (sandy loam 1) at each of the three moisture levels (20, 50, or 80%). Data are presented as mean ± SE. The asterisk (*) indicates significant difference (P < 0.05), and NS indicates no significant difference (P > 0.05). Discussion Although soil-pupation behaviors of true flies and beetles have been studied intensively (e.g., Hulthen and Clarke 2006; Chen and Shelton 2007; Montoya et al. 2008; Renkema et al. 2011, 2012; Meikle and Diaz 2012; Holmes et al. 2013; Bernier et al. 2014; Woltz and Lee 2017), little attention has been paid on lepidopterans that pupate in soil. For example, Sprague and Woods (2015) reported that the tobacco hornworm, Manduca sexta (L.) (Lepidoptera: Sphingidae), spent a lot of energy to construct large underground pupal chambers, which were about eight times larger than the pupae itself. Wen et al. (2017) also reported that Heortia vitessoides Moore (Lepidoptera: Crambidae) exhibited complex pupal-chamber construction behaviors in soil. Moreover, soil burrowing was associated with the long-lasting diapause process for the pine processionary moth, Thaumetopoea pityocampa (Denis & Schiffermuller) (Lepidoptera: Notodontidae) (Torres-Muros et al. 2017). For these species, pupating in the substrate is essential to complete metamorphosis otherwise they would die at the prepupal stage (Sprague and Woods 2015; Wen et al. 2016, 2017; Torres-Muros et al. 2017). E. grisescens represents another type of soil-pupating lepidopterans as it could successfully pupate and emerge either on or in the substrate, or even when the substrate is unavailable. Previous studies showed that high moisture could greatly suppress emergence success and extend the development time of soil-pupating insects. For example, Hou et al. (2006) reported that pupae of the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), could not survive when the moisture content of soil was above 80%; also, the 70%-moisture content of soil could significantly delay the emerging time. Similarly, Zheng et al. (2013) found that the pupal survivorship of the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), decreased drastically in saturated or near-saturated soil, which also caused a hysteretic effect on the development of prepupae. Our studies (burying bioassays) showed that significantly fewer adults emerged after pupae were buried with the 80%-moisture soil, which indicates that the near-saturated soil adversely affected E. grisescens during the pupal stage. However, when wandering last-instar larvae were released onto the 80%-moisture soil (emergence bioassays), they pupated on surfaces, and neither decrease in emergence success nor hysteretic effect on pupal development was observed. Due to this flexible pupating strategy, E. grisescens might be more adaptable than rigidly soil-pupating species such as B. dorsalis and S. exigua. However, the wild E. grisescens pupae may suffer higher predation when they are exposed on the soil surface. It would be valuable to conduct field studies to evaluate the trade-off between predation hazards and on-ground pupating in response to adverse soil conditions. The emergence bioassays also showed that the low moisture level (20%) of soil significantly decreased the emergence success of E. grisescens as compared to the intermediate moisture level (50%). Although more than half of individuals could emerge from 20%-moisture soil, they exhibited a significantly lower body water content during the pupal stage as shown in the pupation bioassays. The sublethal dehydration could adversely affect many biological processes for insects (Edney 1977). It would be valuable to test if low soil moisture could influence the longevity and fertility of emerged E. grisescens adults in future studies. In addition, pupae collected from 20%-moisture silt loam exhibited highest surface-to-volume and surface-to-mass ratios, which may cause a high rate of water loss through respiration and cuticular water evaporation (Gibbs and Rajpurohit 2010). Likewise, Wen et al. (2017) reported that H. vitessoides pupae in dry soil were smaller and had significantly higher surface-to-volume ratio than those in wet soil. These results showed that when the soil was dry, both species (E. grisescens and H. vitessoides) exhibited unfavorable morphological traits that may exacerbate the risk of desiccation. Unlike soil, the three moisture levels of sand did not significantly affect the percentage of burrowed individuals, pupation depth, body water content, surface-to-volume and surface-to-mass ratios, and emergence success of E. grisescens in the pupation and emergence bioassays. It is probably because sand has lower water holding capacity and higher air capacity than soil (Obia et al. 2016). Therefore, relatively dry sand could still release some free water to maintain a favorable microhabitat for E. grisescens pupating. Moreover, the small cracks between coarse particles of sand might storage enough oxygen and let air exchange so that E. grisescens pupae could breathe even under the near-saturated conditions. Interestingly, in the four-choice tests, sand was most preferred by E. grisescens individuals under dry (20% moisture) or wet (80% moisture) conditions but was not preferred over other substrates at 50%-moisture content. These results indicated that E. grisescens individuals could discriminate the proper conditions for pupating, and the preference was determined by both substrate type and moisture content. Our study might provide insights to develop novel methods for E. grisescens control. For example, applying root canal irrigation techniques and reducing surface irrigation may decrease the moisture of top soil and therefore reduce the emergence success of E. grisescens. Burying E. grisescens pupae with near-saturated soil by ploughing after raining or irrigating may also contribute to decrease emerging adults. Moreover, placing sand around tea plants may attract pupating E. grisescens individuals especially when the top soil is dry or wet, and pupae in the sand can be concentrated for elimination. Future studies would be valuable to evaluate the effectiveness of these soil management tactics in the field. Supplementary Data Supplementary data are available at Environmental Entomology online. Acknowledgments This work was funded by the National Natural Science Foundation of China (Grant 31600516), the Guangdong Natural Science Foundation (Grant 2016A030310445), and the Young Investigator Research Grant of College of Forestry and Landscape Architecture, South China Agricultural University. References Cited Aitchison , J . 1986 . The statistical analysis of compositional data . Chapman & Hall , London, United Kingdom . Google Scholar Crossref Search ADS Google Scholar Google Preview WorldCat COPAC Bernier , M. , Fournier V., and Giovenazzo P.. 2014 . Pupal development of Aethina tumida (Coleoptera: Nitidulidae) in thermo-hygrometric soil conditions encountered in temperate climates . J. Econ. Entomol . 107 : 531 – 537 . Google Scholar Crossref Search ADS PubMed WorldCat Cajka , T. , Sandy C., Bachanova V., Drabova L., Kalachova K., Pulkrabova J., and Hajslova J.. 2012 . Streamlining sample preparation and gas chromatography–tandem mass spectrometry analysis of multiple pesticide residues in tea . Anal. Chim. Acta 743 : 51 – 60 . Google Scholar Crossref Search ADS PubMed WorldCat Chang , Q. Y. , Pang G. F., Fan C. L., Chen H., Yang F., Li J., and Wen B. F.. 2016 . High-throughput analytical techniques for the determination of the residues of 653 multiclass pesticides and chemical pollutants in tea, Part VII: A GC-MS, GC-MS/MS, and LC-MS/MS study of the degradation profiles of pesticide residues in green tea . J. AOAC Int . 99 : 1619 – 1627 . Google Scholar Crossref Search ADS PubMed WorldCat Chen , M. S. , and Shelton A. M.. 2007 . Impact of soil type, moisture, and depth on swede midge (Diptera: Cecidomyiidae) pupation and emergence . Environ. Entomol . 36 : 1349 – 1355 . Google Scholar Crossref Search ADS PubMed WorldCat Chen , H. , Pan M., Liu X., and Lu C.. 2017 . Evaluation of transfer rates of multiple pesticides from green tea into infusion using water as pressurized liquid extraction solvent and ultra-performance liquid chromatography tandem mass spectrometry . Food Chem . 216 : 1 – 9 . Google Scholar Crossref Search ADS PubMed WorldCat Edney , E. B . 1977 . Water balance in land arthropods , vol. 9 . Springer-Verlag , New York . Google Scholar Crossref Search ADS Google Scholar Google Preview WorldCat COPAC Feng , J. , Tang H., Chen D., and Li L.. 2015 . Monitoring and risk assessment of pesticide residues in tea samples from China . Hum. Ecol. Risk Assess . 21 : 169 – 183 . Google Scholar Crossref Search ADS WorldCat Ge , C. M. , Yin K. S., Tang M. J., and Xiao Q.. 2016 . Biological characteristics of Ectropis grisescens Warren . Acta Agr. Zhejiangensis 28 : 464 – 468 . OpenURL Placeholder Text WorldCat Gibbs , A. G. , and Rajpurohit S.. 2010 . Cuticular lipids and water balance , pp. 100 – 120 . In G. J. Blomquist and A. G. Bagnères (eds.), Insect hydrocarbons . Cambridge University Press , Cambridge, United Kingdom . Google Scholar Crossref Search ADS Google Scholar Google Preview WorldCat COPAC Holmes , L. A. , Vanlaerhoven S. L., and Tomberlin J. K.. 2013 . Substrate effects on pupation and adult emergence of Hermetia illucens (Diptera: Stratiomyidae) . Environ. Entomol . 42 : 370 – 374 . Google Scholar Crossref Search ADS PubMed WorldCat Hou , B. , Xie Q., and Zhang R.. 2006 . Depth of pupation and survival of the oriental fruit fly, Bactrocera dorsalis (Diptera: Tephritidae) pupae at selected soil moistures . Appl. Entomol. Zool . 41 : 515 – 520 . Google Scholar Crossref Search ADS WorldCat Hulthen , A. D. , and Clarke A. R.. 2006 . The influence of soil type and moisture on pupal survival of Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) . Aus. J. Entomol . 45 : 16 – 19 . Google Scholar Crossref Search ADS WorldCat Jiang , N. , Liu S. X., Xue D. Y., Tang M. J., Xiao Q., and Han H. X.. 2014 . External morphology and molecular identification of two tea geometrid moth from southern China . Chin. J. Appl. Entomol . 51 : 987 – 1002 . OpenURL Placeholder Text WorldCat Kucera , M. , and Malmgren B. A.. 1998 . Logratio transformation of compositional data: a resolution of the constant sum constraint . Mar. Micropaleontol . 34 : 117 – 120 . Google Scholar Crossref Search ADS WorldCat Ma , L. , Shi Y., and Lu J.. 2000 . Soil pHs in the tea gardens in Jiangsu, Zhejiang, and Anhui provinces and changes of soil pH in the past decade . Chin. J. Soil Sci . 31 : 205 – 207 . OpenURL Placeholder Text WorldCat Ma , T. , Xiao Q., Yu Y. G., Wang C., Zhu C. Q., Sun Z. H., Chen X. Y., and Wen X. J.. 2016 . Analysis of tea geometrid (Ectropis grisescens) pheromone gland extracts using GC-EAD and GC× GC/TOFMS . J. Agr. Food Chem . 64 : 3161 – 3166 . Google Scholar Crossref Search ADS WorldCat Meikle , W. G. , and Diaz R.. 2012 . Factors affecting pupation success of the small hive beetle, Aethina tumida . J. Insect Sci . 12 : 1 – 9 . Google Scholar Crossref Search ADS WorldCat Montoya , P. , Flores S., and Toledo J.. 2008 . Effect of rainfall and soil moisture on survival of adults and immature stages of Anastrepha ludens and A. obliqua (Diptera: Tephritidae) under semi-field conditions . Fla Entomol . 91 : 643 – 650 . OpenURL Placeholder Text WorldCat Obia , A. , Mulder J., Martinsen V., Cornelissen G., and Børresen T.. 2016 . In situ effects of biochar on aggregation, water retention and porosity in light-textured tropical soils . Soil Till. Res . 155 : 35 – 44 . Google Scholar Crossref Search ADS WorldCat Renkema , J. M. , Cutler G. C., Lynch D. H., Mackenzie K., and Walde S. J.. 2011 . Mulch type and moisture level affect pupation depth of Rhagoletis mendax Curran (Diptera: Tephritidae) in the laboratory . J. Pest Sci . 84 : 281 – 287 . Google Scholar Crossref Search ADS WorldCat Renkema , J. M. , Lynch D. H., Cutler G. C., Mackenzie K., and Walde S. J.. 2012 . Emergence of blueberry maggot flies (Diptera: Tephritidae) from mulches and soil at various depths . Environ. Entomol . 41 : 370 – 376 . Google Scholar Crossref Search ADS PubMed WorldCat Sprague , J. C. , and Woods H. A.. 2015 . Costs and benefits of underground pupal chambers constructed by insects: a test using Manduca sexta . Physiol. Biochem. Zool . 88 : 521 – 534 . Google Scholar Crossref Search ADS PubMed WorldCat Torres-Muros , L. , Hódar J. A., and Zamora R.. 2017 . Effect of habitat type and soil moisture on pupal stage of a Mediterranean forest pest (Thaumetopoea pityocampa) . Agr. Forest Entomol . 19 : 130 – 138 . Google Scholar Crossref Search ADS WorldCat Veen , T. , Brock C., Rennison D., and Bolnick D.. 2017 . Plasticity contributes to a fine-scale depth gradient in sticklebacks’ visual system . Mol. Ecol . 26 : 4339 – 4350 . Google Scholar Crossref Search ADS PubMed WorldCat Wen , Y. , Jin X., Zhu C., Chen X., Ma T., Zhang S., Zhang Y., Zeng S., Chen X., Sun Z., Wen X., and Wang C.. 2016 . Effect of substrate type and moisture on pupation and emergence of Heortia vitessoides (Lepidoptera: Crambidae): choice and no-choice studies . J. Insect Behav . 29 : 473 – 489 . Google Scholar Crossref Search ADS WorldCat Wen , Y. , Qin W., Chen X., Wen X., Ma T., Dong X., Lin S., Sun Z., Zeng S., and Wang C.. 2017 . Soil moisture effects on pupation behavior, physiology, and morphology of Heortia vitessoides (Lepidoptera: Crambidae) . J. Entomol. Sci . 52 : 229 – 238 . Google Scholar Crossref Search ADS WorldCat Woltz , J. M. , and Lee J. C.. 2017 . Pupation behavior and larval and pupal biocontrol of Drosophila suzukii in the field . Biol. Control 110 : 62 – 69 . Google Scholar Crossref Search ADS WorldCat Xi , Y. , Yin K.-S., Tang M.-J., and Xiao Q.. 2014 . Geographic populations of the tea geometrid, Ectropis obliqua (Lepidoptera: Geometridae) in Zhejiang, eastern China have differentiated into different species . Acta Entomol. Sin . 57 : 1117 – 1122 . OpenURL Placeholder Text WorldCat Yu , S. , He Z., Zhang R., Chen G., Huang C., and Zhu B.. 2003 . Soil basal respiration and enzyme activities in the root layer soil of tea bushes in a red soil . Chin. J. Appl. Ecol . 14 : 179 – 183 . OpenURL Placeholder Text WorldCat Zhang , J. W . 2004 . The occurrence and control of Ectropis grisescens in Hunan . J. Tea Commun . 31 : 18 – 20 . OpenURL Placeholder Text WorldCat Zhang , G. H. , Yuan Z. J., Zhang C. X., Yin K. S., Tang M. J., Guo H. W., Fu J. Y., and Xiao Q.. 2014 . Detecting deep divergence in seventeen populations of tea geometrid (Ectropis obliqua Prout) in China by COI mtDNA and cross-breeding . PLoS ONE 9 : e99373 . Google Scholar Crossref Search ADS PubMed WorldCat Zhang , G. H. , Yuan Z. J., Yin K. S., Fu J. Y., Tang M. J., and Xiao Q.. 2016 . Asymmetrical reproductive interference between two sibling species of tea looper: Ectropis grisescens and Ectropis obliqua . Bull. Entomol. Res . 11 : 1 – 8 . doi: 10.1017/S0007485316000602 . Google Scholar Crossref Search ADS WorldCat Zheng , X. L. , Wang P., Lei C. L., Lu W., Xian Z. H., and Wang X. P.. 2013 . Effect of soil moisture on overwintering pupae in Spodoptera exigua (Lepidoptera: Noctuidae) . Appl. Entomol. Zool . 48 : 365 – 371 . Google Scholar Crossref Search ADS WorldCat Zhou , G . 2017 . Segmented food safety standard setting , pp. 141 – 167 . In Carroll T., Cammack P., Gerard K. and Jarvis D. S. L. (eds.), The regulatory regime of food safety in China . Springer International Publishing , Gewerbestrasse, Switzerland . Google Scholar Crossref Search ADS Google Scholar Google Preview WorldCat COPAC Author notes " These authors contributed equally to this work. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
TI - Pupation Behaviors and Emergence Successes of Ectropis grisescens (Lepidoptera: Geometridae) in Response to Different Substrate Types and Moisture Contents
JF - Environmental Entomology
DO - 10.1093/ee/nvx168
DA - 2017-12-08
UR - https://www.deepdyve.com/lp/oxford-university-press/pupation-behaviors-and-emergence-successes-of-ectropis-grisescens-kfhOMDGakd
SP - 1365
VL - 46
IS - 6
DP - DeepDyve
ER -