Cotton mealybug, Phenacoccus solenopsis Tinsley is an important polyphagous insect pest and causes severe losses to different crops worldwide. In the current study, we investigated the effect of different host plants, such as Caesalpinia pulcherrima, Plumeria rubra, Anthurium andraeanum, Jasminum sambac, and Hibiscus rosasinensis, on the biological parameters of P. solenopsis. The survival rate from crawler to adult, female nymphal duration, development time from crawler to female adult, and female adult weight were significantly different on the different hosts. Male nymphal duration, development time from crawler to male adult, pupal weight, emergence rate of male adults, and mean relative growth rate for male were similar on all the tested host plants. Pupal duration and generation time of male and female on H. rosasinensis were significantly shorter than on the other hosts. Adult male and female P. solenopsis longevity was significantly shorter on H. rosasinensis compared to other hosts. The fecundity was lower on C. pulcherrima and A. andraeanum and hatchability was lower on C. pulcherrima than on the other hosts. The net reproductive rate, the intrinsic rate of natural increase, and biotic potential and mean relative growth rate for female of P. solenopsis were significantly different on the tested hosts. Our results point to the role of host plants in increasing the populations of P. solenopsis and could help to design cultural management strategies.

The aphid sex pheromone component (4aS,7S,7aR)-nepetalactone is considered to be a potential tool for enhancing biological control of aphids. Studies have confirmed its potential to attract parasitoids, increase parasitism rates in the field and also alter the spatial distribution of parasitoids. An important aspect that has been overlooked is the impact that the introduction of nepetalactone may have on aphid populations already present in field or glasshouse environments. The most prevalent pest aphid populations in glasshouse and field environments are the asexual morphs, which are capable of exponential growth if populations are not controlled. The short-term implications of the sex pheromone on asexual aphids were observed through their behavioural response. Using Y-tube olfactometry, it is shown that virginoparae of the peach-potato aphid, Myzus persicae, are repelled by high concentrations of nepetalactone. Long-term effects of the pheromone which may span the aphid's life, or even generations, were assessed via mean relative growth rate (MRGR) and the intrinsic rate of natural increase (rm). Electroantennography also demonstrated that asexual female aphids are able to detect aphid sex pheromone components. To our knowledge, this is the first time it has been reported that M. persicae virginoparae are able to detect aphid sex pheromone components or that their behavioural response and/or performance has been studied. The implications of these results and their significance in understanding semiochemical communication are discussed.