Overwintering of Aenasius arizonensis (Girault) (=Aenasius bambawalei Hayat) (Hymenoptera:Encyrtidae) under Screen House/Semi-Natural Conditions

Abstract

Overwintering studies were carried out by placing newly emerged adults of the parasitoid, Aenasius arizonensis (Girault) (=Aenasius bambawalei Hayat) (Hymenoptera: Encyrtidae) and one day old mummies of Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) (i.e. parasitoid in pupal stage) during winter season under screen house conditions in 2012- 13. Maximum mean pupal period of male and female parasitoids was 86.47 and 92.67 days, respectively, when mummies were exposed on 5^th December followed by 73.69 and 82.83 days, respectively. When exposed on 20^th December the emergence of parasitoid adults from the overwintering mummies seemed to be well synchronized with ambient weather conditions. This implies that there is no diapause in A. arizonensis. There was no adult emergence until 10^th standard week due to prevailing low temperature conditions during December and January with average maximum and minimum temperatures of 20.9, 6.4°C and 17.1, 4.1°C, respectively. Emergence of parasitoid adults from overwintering mummies of different exposure dates viz., December 05 and December 20, 2012; January 04, January 19, February 03 and February 18, 2013 started from 11^th standard week (first week of February), reached maximum in 14^th standard week (first week of March) and continued until 16^th standard week (third week of March). Maximum temperature ranged between 20.3 and 29.6°C and minimum between 6.6 and 12.5°C during the period of adult emergence. Adult parasitoids successfully overwintered when provided with honey. Males survived for 52-84 days (69.33 days) and females survived for 69-103 days (83.40 days) during winter season in absence of host, when exposed on 5^th December, 2012. Our results demonstrate that the parasitoid is able to successfully overwinter as pupa and adult via combination of slow development and increased adult longevity. This information seems to be useful in enhancing population of this parasitoid in spring when A. arizonensis can suppress solenopsis mealybug on cotton crop.