DEVELOPMENTAL THRESHOLDS AND THERMAL REQUIREMENTS NEEDED FOR SOME AGRO-ECOSYSTEM STRAINS OF CERTAIN PESTS INHABITING COTTON FIELDS: | ||||
| Journal of Plant Protection and Pathology | ||||
| Article 1, Volume 30, Issue 12, December 2005, Page 8095-8106 PDF (123.11 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jppp.2005.239450 | ||||
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| Author | ||||
| Y. E.Y. Abdallah | ||||
| Plant Protection Department, Fac. Agric., Ain Shams Univ., Cairo, Egypt | ||||
| Abstract | ||||
| A laboratory experiment was conducted to estimate the developmental threshold for immature stages of the spiny bollworm. Earias insulana (8oisd.) and the accumulated thermal units needed for completion of one generation. Eggs from different Agro-ecosystems viz. Qalyubyia. Sharkia and Minia Governorates were subjected to the present experiment in addition to a laboratory strain. Obtained results .reveat that egg developmental period was greatly affected by rearing temperature. At 20'C. eggs from Qalyubyia strain developed faster as compared to other field strains. At 30'C. eggs of the laboratory am: field strains developed at a range of 2.8-3.0 days. The lower thresholds of egg we:» 7.55. 7.59 and 10.5rC for Sharkia. Qalyubyia and Minia, respectively, while thermal units needed for eggs to hatch were 64.69.60.61 and 54.05 DDs. Larvae of the laboratory strain were faster in development than others of different Agro-ecosystems. At 25°C. larval duration lasted for 14 5±1.15 days for the laboratory strain while it ranged between 16-18 days for the field strains. The developmental threshold did not significantly differ between the tested governorates since it ranged between 11.02°C and 12.39'C. Thermal constants, however were higher for Minia strain (277.7800s) followed by Sharkia (243.90 ODs). Qalyubyia (238 09 cos: and laboratory strain (227 27 DDs). Pupae of the laboratory strain developed faster than those reared from different Agro-ecosystems. At 25 and 30'C, pupae from Sharkia and Qalyubyia eco- types developed faster than those of Minia Governorate. The zero of development values were very close, it ranged between 10.26 and 11.06'C. Thermal requirements were 181.82 DDs for Minia and laboratory strains, 168.08 DDs for Qalyubyia and 222.22 for Sharkia strain. Since females resulted from eggs collected from different Agro-ecosystems and fed as larvae on an artificial diet failed to lay eggs after mating, so the pre- oviposition period was estimated for females resulted from laboratory strain only. This period ranged between 4.33±0.SO and 2,30±0.48 days at 20DC and 30'C, respectively. The zero of development for this pence was 9.1 T'C and the thermal requirements estrr<ated were 49.02 DDs.The whole generation duration for the laboratory strain was 61.18, 33.80 and27.97 days at 20. 25 and 30DC respectively. The zero of development for the wholegeneration was estimated as 11.04°C, while the amount of thermal units needed forcompleting one generation were 512.82 ODs. | ||||
| Keywords | ||||
| Earias insulana; spiny bollworm; biofeatures; developmental threshold; zero of development; heat units; agroecosystem | ||||
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