UNDERSTANDING HOW PARASITOIDS BALANCE FOOD AND HOST NEEDS - IMPORTANCE TO BIOLOGICAL-CONTROL

Adult parasitoids must not only find hosts for reproductive purposes b ut also locate food to meet their short-term nutritional needs. A know ledge of how parasitoid females deal with the often competing needs fo r these two vital resources is essential for understanding their forag ing strategies. Studies show that availability and accessibility of fo od sources, such as nectar or honeydew in a target area, strongly affe ct parasitoid retention and host-finding efficacy. For parasitoids to maintain high reproductive success it is important that disruption of their host foraging process is minimal so that most of their time and energy can be allocated to finding hosts. The use of olfactory and vis ual cues from plants, usually enhanced by learning, helps minimize thi s disruption and plays important and sometimes interacting roles in th eir searching for food and hosts. Thus, the provision of food sources such as floral and extrafloral nectar by plants along with associated foraging signals plays a crucial role in the tritrophic interplay amon g plants, herbivores, and parasitoids. A broader understanding of trit rophic level interactions that encompasses parasitoid food considerati ons can enhance our ability to design effective biological control str ategies. Herein, we discuss how the internal state of parasitoids alon g with characteristics of their foraging environment, can influence th eir ability to find food and consequently affect their parasitizing ef ficiency. Suggestions are made for maximizing food-finding efficacy to improve biological control with parasitoids. (C) 1998 Academic Press.