Resistance to pyrethroids and organophosphates increased fitness and predation potential of Chrysoperla carnae (Neuroptera: Chrysopidae).

Insect natural enemies can develop resistance to insecticides in the field like their host insects. Recently, a high level of resistance to several groups of insecticides from Pakistan has been shown in Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae). Here, we were interested to determine the impact of insecticides resistance on fitness of various populations of C. carnea collected over three consecutive years (2005-2007) from different areas of Pakistan. The populations were examined for intrinsic rate of population increase, growth index, fertility, eggs viability, survival to adult hood and doubling time. The results of the study showed significantly higher intrinsic rate of population increase in insecticides resistant population compared with laboratory susceptible population Lab-PK. Similarly, the resistant population laid more numbers of eggs, which were significantly more viable than susceptible population. The survival to adulthood and doubling time were greater in field populations than the susceptible. The most intriguing finding was that the predation potential of all resistant populations was significantly great compared with Lab-PK. The data point to the fact that resistance to insecticides had positive impact on C. carnea, which could be used in integrated pest management system. The potential for introducing these natural enemies into cropping systems where they have not developed resistance could be a useful tactic for management of various insect pests.