The Effect of Temperature on Development and Fecundity of Scymnus Levaillanti

Abstract

Development and fecundity of Scymnus levaillanti (Mulsant) were recorded at five constant temperatures ranging from 15 to 35 +/- 1 degreesC in 5 degreesC increments, 60 +/- 5% RH and 16 h of artificial light (5000 Lux). Developmental time (egg to adult) of S. levaillanti significantly decreased with increasing temperatures, ranging from 63.9 days at 15 degreesC to 11.1 days at 35 degreesC. Development from egg to adult required 305.2 DD above a developmental threshold estimated as 11.7 degreesC. Oviposition periods lasted 86.5, 76.1, 47.2, and 31.5 days at 20, 25, 30 and 35 degreesC, respectively. No eggs were deposited at 15 degreesC. Higher temperatures resulted in shorter generation times (T-O) and in decreased net reproductive rates (R-O) of the coccinellid. S. levaillanti kept at 30 degreesC produced 0.151 females/female/day, the highest per capita rate of population growth (r(m)). The `functional response' of larvae and adults of S. levaillanti matches well that described by Holling (1959) as Type 2. Daily number of eggs deposited by females increased to a plateau with increasing prey density. Results obtained here provide information about the biology of S. levaillanti, and its feeding capacity indicates that it may act as an important control agent.