{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T16:57:59Z","timestamp":1785430679539,"version":"3.56.0"},"reference-count":28,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T00:00:00Z","timestamp":1785283200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"State University Santa Elena Peninsula, Ecuador","award":["CUP: 91870000.0000.390381"],"award-info":[{"award-number":["CUP: 91870000.0000.390381"]}]},{"award":["CUP: 91870000.0000.390381"],"award-info":[{"award-number":["CUP: 91870000.0000.390381"]}],"id":[{"id":"https:\/\/ror.org\/01k410495","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Insects"],"abstract":"<jats:p>The Egyptian cotton leafworm Spodoptera littoralis (Boisduval) is a major polyphagous pest in vegetable and cotton crops. Accurate forecasting of its field generations is essential for effective integrated pest management (IPM). Forecasting its generations in the field is traditionally based on the trapping of males, but the use of temperature sums (degree-days, DD) could offer a robust alternative for triggering pest control interventions. The aim of this study was to monitor the flight activity and calculate the summations of degree-days, as well as to compare expected generation peaks and the reliability of S. littoralis males in predicting generations over three successive growing seasons. The study was carried out over three consecutive growing seasons (2017, 2018, and 2019) at Abnob district in Assiut Governorate, Egypt, comparing twice-weekly male captures using pheromone traps and emergence dates predicted by a degree-day model established from physiological data (development threshold: 10.5 \u00b0C; thermal constant: 480.6 DD for one generation). Laboratory experiments at four constant temperatures (17, 22, 27, and 32 \u00b0C) established the lower developmental thresholds and thermal constants for each life stage: egg (t0 = 11.86 \u00b0C; K = 40.10 DD), larva (t0 = 7.56 \u00b0C; K = 283.76 DD), pupa (t0 = 12.27 \u00b0C; K = 149.50 DD), and pre-oviposition period (t0 = 12.58 \u00b0C; K = 23.96 DD). Six successive generations (observed generations) appeared after the overwintering generation each year, with the overwintering generation consistently initiating in early May each season. The capture dates from the male sex-pheromone traps coincided with the adult emergence dates calculated by the accumulated heat model; deviations between observed (the occurrence of the real peak days) and predicted generation dates ranged from \u22122 to +2 days in the vast majority of cases, except for in the 2nd generation of the 2019 season, when the observed generation occurred 4 days before the expected generation date. Mean accumulated thermal units per generation ranged from 479.62 to 483.78 DD across the three seasons (grand mean: 481.95 DD), with overall mean seasonal deviations of 0.00, \u22120.14, and \u22120.43 days, confirming that the model predicts generation peaks to within \u00b12 days in the vast majority of cases. The integration of the two methods improves the reliability of phenological forecasting for S. littoralis, opens new opportunities for sustainable pest suppression, and improves the timing of control actions. This combined approach is recommended as a practical decision-support tool for IPM programs targeting S. littoralis in Egypt and comparable Mediterranean agroecosystems.<\/jats:p>","DOI":"10.3390\/insects17080787","type":"journal-article","created":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T13:53:31Z","timestamp":1785333211000},"page":"787","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Field and Laboratory Studies for Predicting Annual Generations of Spodoptera littoralis (Boisd.) Using Sex Pheromone Traps and Cumulative Heat Unit Measurements in Egypt"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1986-4151","authenticated-orcid":false,"given":"Ahmed M. M.","family":"Ahmed","sequence":"first","affiliation":[{"name":"Plant Protection Department, Faculty of Agriculture, Assiut University, Assiut 71526, Egypt"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ver\u00f3nica","family":"Andrade-Yucailla","sequence":"additional","affiliation":[{"name":"Centro de Investigaciones Agropecuarias, Facultad de Ciencias Agrarias, Universidad Estatal Pen\u00ednsula de Santa Elena, Santa Elena, La Libertad 204102, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eslam A. Y.","family":"Allam","sequence":"additional","affiliation":[{"name":"Agricultural Research Center, Plant Protection Research Institute, Dokki, Giza 12611, Egypt"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-4631-7592","authenticated-orcid":false,"given":"Mohammed A. A.","family":"Saad","sequence":"additional","affiliation":[{"name":"Plant Protection Department, Faculty of Agriculture, Assiut University, Assiut 71526, Egypt"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Samer H.","family":"Manaa","sequence":"additional","affiliation":[{"name":"Plant Protection Department, Faculty of Agriculture, Assiut University, Assiut 71526, Egypt"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hassan F.","family":"Dahi","sequence":"additional","affiliation":[{"name":"Agricultural Research Center, Plant Protection Research Institute, Dokki, Giza 12611, Egypt"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"M. S.","family":"Yones","sequence":"additional","affiliation":[{"name":"National Authority for Remote Sensing and Space Science, Cairo 11843, Egypt"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Freddy","family":"Alcocer-Quishpe","sequence":"additional","affiliation":[{"name":"Centro de Investigaciones Agropecuarias, Facultad de Ciencias Agrarias, Universidad Estatal Pen\u00ednsula de Santa Elena, Santa Elena, La Libertad 204102, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9608-5912","authenticated-orcid":false,"given":"Marcos","family":"Barros-Rodr\u00edguez","sequence":"additional","affiliation":[{"name":"Department of Animal Nutrition and Rumen Biotechnology, Ruminant Feedlot Ranch-PROCESA, Street Playita\u2013Estero Hondo, La Man\u00e1 050202, Cotopaxi, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"17314","DOI":"10.1038\/s41598-023-44441-8","article-title":"Modeling the potential global distribution of the Egyptian cotton leafworm, Spodoptera littoralis under climate change","volume":"13","author":"ElShahed","year":"2023","journal-title":"Sci. Rep."},{"key":"ref_2","unstructured":"EPPO (2026, May 10). Spodoptera littoralis; Distribution; EPPO Global Database. Available online: https:\/\/gd.eppo.int\/taxon\/SPODLI\/distribution."},{"key":"ref_3","first-page":"311","article-title":"Spodoptera littoralis male capture suppression in processing spinach using two kinds of synthetic sex-pheromone dispensers","volume":"65","author":"Lanzoni","year":"2012","journal-title":"Bull. Insectol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"379","DOI":"10.1017\/S0007485300031266","article-title":"The arrival of male moths of the cotton leaf-worm Spodoptera littoralis (Boisd.) (Lepidoptera, Noctuidae) at a new continuously recording pheromone trap","volume":"64","author":"Campion","year":"1974","journal-title":"Bull. Entomol. Res."},{"key":"ref_5","unstructured":"Hill, D.S. (1983). Agricultural Insect Pests of the Tropics and Their Control, Cambridge University Press."},{"key":"ref_6","first-page":"199","article-title":"Egyptian cotton leafworm Spodoptera littoralis development on artificial diet in relation to heat unit requirements","volume":"83","author":"Dahi","year":"2005","journal-title":"Egypt. J. Agric. Res."},{"key":"ref_7","first-page":"103","article-title":"Threshold Temperatures and Thermal Requirements of Cotton Leafworm, Spodoptera littoralis Hb","volume":"14","author":"Allam","year":"2021","journal-title":"Egypt. Acad. J. Biol. Sci. A Entomol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1005","DOI":"10.1016\/0022-1910(74)90142-5","article-title":"Sex pheromone of the cotton leafworm, Spodoptera littoralis","volume":"20","author":"Tamaki","year":"1974","journal-title":"J. Insect Physiol."},{"key":"ref_9","first-page":"314","article-title":"Field trapping of the cotton leafworm Spodoptera littoralis with its sex pheromone","volume":"90","author":"Salama","year":"1980","journal-title":"Z. Angew. Entomol."},{"key":"ref_10","first-page":"1091","article-title":"Monitoring the population fluctuations of the cotton leafworm, Spodoptera littoralis (Boisd.), by using sex pheromone traps","volume":"28","year":"1990","journal-title":"Ann. Agric. Sci. Moshtohor"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"47","DOI":"10.1007\/s00114-021-01757-7","article-title":"Climate change risk to pheromone application in pest management","volume":"108","author":"Ganji","year":"2021","journal-title":"Sci. Nat."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"543","DOI":"10.1093\/ee\/10.4.543","article-title":"Heat unit requirements for emergence of overwintering tobacco budworm, Heliothis virescens (F.), in Arizona","volume":"10","author":"Potter","year":"1981","journal-title":"Environ. Entomol."},{"key":"ref_13","first-page":"3037","article-title":"Using heat accumulation and sex pheromone catches to predict the American bollworm, Helicoverpa armigera (Hub.) field generations","volume":"32","author":"Dahi","year":"2007","journal-title":"J. Agric. Sci. Mansoura Univ."},{"key":"ref_14","first-page":"430","article-title":"The determination and significance of the base temperature in a linear heat unit system","volume":"74","author":"Arnold","year":"1959","journal-title":"Proc. Am. Soc. Hortic. Sci."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"419","DOI":"10.4039\/Ent107419-4","article-title":"Thermal constants for development of the pea aphid (Homoptera: Aphididae) and some of its parasites","volume":"107","author":"Campbell","year":"1975","journal-title":"Can. Entomol."},{"key":"ref_16","first-page":"1","article-title":"Heat accumulations and sex pheromone traps as tools for predicting the cotton leaf worm Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) field generations at Assiut Governorate","volume":"7","author":"Salman","year":"2022","journal-title":"J. Sohag Agrisci."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"269","DOI":"10.1093\/jee\/76.2.269","article-title":"Predicting Spring flight of Nantucket pine tip moth (Lepidoptera: Olethreutid) by heat unit accumulation","volume":"76","author":"Richmond","year":"1983","journal-title":"J. Econ. Entomol."},{"key":"ref_18","unstructured":"Snedecor, G.W., and Cochran, W.G. (1980). Statistical Methods, Iowa State University Press. [7th ed.]."},{"key":"ref_19","unstructured":"CoHort Software (2004). CoSta, CoHort Software. Version 6.303 copyright (1998\u20132004)."},{"key":"ref_20","unstructured":"Clement, S.L., Levine, E., and Rings, R.W. (1979, January 5\u201311). Population trends of the black cutworm correlated with thermal units accumulations. Proceedings of the IX International Congress of Plant Protection and 71st Annual Meeting of the American Phytopathological Society, Washington, DC, USA."},{"key":"ref_21","first-page":"1563","article-title":"Thermal requirements and prediction models for pink bollworm (PBW) Pectinophora gossypiella (Saund.)","volume":"10","author":"Moftah","year":"1988","journal-title":"Minia J. Agric. Res. Dev."},{"key":"ref_22","first-page":"37","article-title":"Pheromone trapping of cotton insects in relation to some climatic factors","volume":"11","author":"Taman","year":"1990","journal-title":"Alex. Sci. Exch."},{"key":"ref_23","unstructured":"El-Shafei, S.M. (1980). Ecological Studies on the Cotton Leafworm, Spodoptera littoralis (Boisd.). [Master\u2019s Thesis, Faculty of Agriculture, Ain Shams University]."},{"key":"ref_24","first-page":"144","article-title":"Seasonal fluctuations of the pink bollworm, Pectinophora gossypiella (Saund.) and prediction of generations in relation to heat units accumulation","volume":"75","author":"Hashem","year":"1997","journal-title":"Bull. Ent. Soc. Egypt"},{"key":"ref_25","unstructured":"Emara, S.A. (1999, January 6\u20138). Developmental biology, thermal requirements and prediction models for cotton leafworm Spodoptera littoralis (Boisd.) in cotton fields. Proceedings of the 2nd International Conference of Pest Control, Mansoura, Egypt."},{"key":"ref_26","unstructured":"Rashwan, R.S. (2009). Predicting the Changes in the Population Density of Some Cotton Insect Pests. [Ph.D. Thesis, Faculty of Agriculture, Ain Shams University]."},{"key":"ref_27","first-page":"1","article-title":"Laboratory studies on the development, longevity, and fecundity of six lepidopterous pests of cotton in Arizona","volume":"1454","author":"Fye","year":"1972","journal-title":"USDA Tech. Bull."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Shope, J., Salazar-Mendoza, P., Ben-Zvi, Y., and Rodriguez-Saona, C. (2024). Refining degree-day models for sparganothis fruitworm in cranberry by biofix and variety. Horticulturae, 10.","DOI":"10.3390\/horticulturae10121346"}],"container-title":["Insects"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2075-4450\/17\/8\/787\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T14:02:01Z","timestamp":1785333721000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2075-4450\/17\/8\/787"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,29]]},"references-count":28,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["insects17080787"],"URL":"https:\/\/doi.org\/10.3390\/insects17080787","relation":{},"ISSN":["2075-4450"],"issn-type":[{"value":"2075-4450","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,29]]}}}