Parasitoid, <I>Aenasius arizonensis</I> (Girault) (Hymenoptera: Encyrtidae): its Biology, Morphometrics, Host Stage Preference and use in Biological Control

Abstract

Aenasius arizonensis (Girault) ( = Aenasius bambawalei Hayat) (Hymenoptera: Encyrtidae), a solitary endoparasitoid of Phenacoccus solenopsis Tinsley, is a major invasive pest in several cotton growing countries around the globe. It has been recorded as an effective natural enemy of P. solenopsis . The biological characteristics of parasitoid were studied on P. solenopsis under laboratory conditions. The mean duration of development of A. arizonensis from oviposition to mummy formation was 5.9 ± 0.31 days for both male and female, while from mummy formation to adult emergence was 5.9 ± 0.31 and 7.3 ± 0.3 for male and female, respectively. The mean developmental period of male and female was 12.2 ± 0.33 and 14.2 ± 0.37 days, respectively. Males were short lived (16.3 ± 1.41 days) as compared to females (26.2 ± 1.72 days). Female started ovipositing on the day of emergence. The mean pre-oviposion, oviposition and post-oviposition periods were <1, 23.1 ± 1.66 and 3.1 ± 0.55 days, respectively. Mean daily and total fecundity in terms of number of parasitized host per female was 4.24 ± 0.2 and 100.5 ± 11.57, respectively. Sex ratio was skewed towards female and recorded as 1:2. Maximum percentage of parasitization occurred in adult host stage i.e. 90% followed by 3 rd , 2 nd , and 1 st instar nymph with 73.33%, 33.33% and 0 per cent, respectively. Among the three nymphal stages 3rd instar nymph was the most suitable stage for mass multiplication of parasitoid. Its successful utilization in mealybug management can be optimized by multiplying at this stage of host in the laboratory and thereafter inoculative release into the field. This report provides a detailed diagnostic description of A. arizonensis with illustration to facilitate easy identification & morphological differences between male & female along with the morphometric measurements of pupa & mummy.