نامه انجمن حشرهشناسی ایران (Nov 2019)
Estimation of the lower temperature threshold and thermal requirement of Cryptolaemus montrouzieri Mulsant (Coleoptera; Coccinelidae) using Degree-Day and Ikemoto-Takai linear models
Abstract
The mealybug destroyer, Cryptoleamus montrouzieri Mulsant is the most important natural enemy of the mealybugs. Increasing knowledge regarding ecological compatibilities of the natural enemies lead to increase their efficacy for controlling the pests. In this study, the effect of temperature as the most effective environmental factor on development of the mealybug destroyerwas studied. Developmental time of incubation period, all larval instars, pupal period, and overall immature stages of the mealybug destroyer were recorded in temperatures ranging 15-35°C, 50-60% RH, and a photoperiod of (L:D) 16:8h. According to the ANOVA, temperature affected significantly developmental time of the mealybug destroyer at 1% probability level and increasing temperature lead to decreasing developmental time. Degree-Day and Ikemoto-Takai linear models were used to describe temperature-dependent development of the mealybug destroyer. While, both of the linear models had shown an acceptable fit to data, because of better statistical criteria, estimation of the Ikemoto-Takai linear model was considered for thermal indices. Estimated values for thermal requirement of incubation period, 1st, 2nd, 3rd, and 4th larval instars, total larval period, pupal period and overall immature stages of the C. montrouzieri were 45.38, 43.67, 53.04, 113.27, 256.89, 143.29 and 483.59 degree-days, respectively. Moreover, the values of the lower temperature threshold for the mentioned developmental stages were 9.79, 10.74, 10.28, 9.67, 10.06, 10.07, 9.18 and 9.64°C, respectively, using Ikemoto and Takaei linear model.According to the results, clarifying some aspects of thermal characteristics of the mealybug destroyer, would increase our knowledge to improve biological control program of the mealybugs.
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