We investigated volatile infochemicals possibly involved in location of the generalist predatory mite Neoseiulus californicus to plants infested with spider mites in a Y-tube olfactometer. The predators significantly preferred volatiles from lima bean leaves infested with Tetranychus urticae to uninfested lima bean leaves. Likewise, they were attracted to volatiles from artificially damaged lima bean leaves and those from T. urticae plus their visible products. Significantly more predators chose infested lima bean leaves from which T. urticae plus their visible products had been removed than artificially damaged leaves, T. urticae, and their visible products. These results suggest that N. californicus is capable of exploiting a variety of volatile infochemicals originating from their prey, from the prey-foodplants themselves, and from the complex of the prey and the host plants (e.g., herbivore-induced volatiles). We also investigated predator response to some of the synthetic samples identified as volatile components emitted from T. urticae-infested lima bean leaves and/or artificially damaged lima bean leaves. The predators were attracted to each of the five synthetic volatile components: linalool, methyl salicylate, (Z)-3-hexen-1-ol, (E)-2-hexenal, and (Z)-3-hexenyl acetate. The role of each volatile compound in prey-searching behavior is discussed.

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The silverleaf whitefly, Bemisia argentifolii Bellows et Perring (Bellows et al., 1994), also known as B-biotype of B. tabaci (Gennadius) (Byrne and Miller, 1990), has become one of the most serious agricultural pests in the world. This whitefly is polyphagous and infests a broad range of crops, including eggplant, cucumber, squash, tomato and sweet potato . Damage by B. argentifolii consists of direct feeding damage, deposition of large quantities of honeydew, plant physiological disorders, such as squash silverleaf disorder in pumpkin and irregular ripening of tomato fruit, and transmission of several plant viruses (Matsui, 1995).In Japan, B. argentifolii was first found to infest poinsettia (Ohto, 1990) and since has infested many plants, including cucumber, eggplant, sweet pepper and tomato. The biology of B. argentifolii has been studied extensively (Bethke et al., 1991;Enkegaard, 1993;Simmons, 1994;Wagner, 1995;Tsai and Wang, 1996;Wang and Tsai, 1996;Yee and Toscano, 1996;Nava-Camberos et al., 2001), although, with the exception of a study by Tsueda and Tsuchida (1998), the biology of the Japanese B. argentifolii population has not been investigated.To develop a successful integrated pest management (IPM) program for its host crops, it is critical to understand the life-history parameters of B. ar- Appl. Entomol. Zool. 42 (1): 63-70 (2007)

The influence of food supply on the survival and oviposition ability of Cotesia plutellae, the larval parasitoid of the diamondback moth, Plutella xylostella, was examined in the laboratory. The longevity of the parasitoid decreased drastically under a lack of sugar availability. The oviposition ability, evaluated by functional response to host density, was highly suppressed by a lack of food supply. Thus, sugar availability is a very important condition for the effective utilization of C. plutellae as a biological control agent of P. xylostella in greenhouses.

Several braconid and aphelinid parasitoids, midges, lacewings, and ladybird beetles are used to control aphids in greenhouses. Here, I review three topics as ecological bases for the biological control of aphids in a protected culture: the preliminary evaluation of biological control agents, natural enemy release strategies, and the effects of intraguild predation (IGP) on biological control. A comparison of several parasitoid species was conducted to select agents for the biological control of aphids; the intrinsic rate of natural increase was a useful criterion in the preliminary evaluation. To compare predators as biological control agents, the aphid‐killing rate must be considered as a critical criterion, rather than reproductive criteria. The banker plant system (open rearing system) is used as a release method for Aphidius colemani and other natural enemies of aphids. Continuous release of parasitoid adults, which is the important characteristic of this method, has a stabilizing effect on population fluctuation in the aphid–parasitoid system. Two species of natural enemies can be used to control aphids in greenhouses. When one parasitoid and one predator are used simultaneously in a greenhouse, IGP of the parasitoid by the predator can occur, but the effect of IGP is less important in greenhouses than in the field.

Orius sauteri (Poppius) (Heteroptera: Anthocoridae) is a polyphagous predator used as a biological control agent of palm thrips, Thrips palmi (Karny) (Thysanoptera: Thripidae). We studied O. sauteri' s searching efficiency, time allocation on a leaf, leaving tendency, and attacking of prey. Approximately 78% of the encountered prey was eaten. Searching for prey was concentrated for 86% of the time on the lower leaf side, where palm thrips are usually found. Patch residence times on empty leaves were different from those on leaves with T. palmi larvae. Walking activity was not affected by the thrips density, and walking took place during 64% of the total search time. The leaving tendency of O. sauteri was affected by the time from patch entry and the presence or absence of palm thrips, but not by the thrips density. If prey were present, the leaving tendency decreased (multiplication factor 0.327), resulting in longer giving-up times than when no prey was present. The fact that the leaving tendency increases when patch exploitation lasts longer suggests that not much time is wasted on patches where encounters with prey are scarce.

SummaryA simple mathematical model of host‐parasitoid interaction with host‐feeding was presented with special reference to the system of the greenhouse whitefly and the parasitoid Encarsia formosa. In the model, when a parasitoid encounters a host, it has a choice between feeding the host and ovipositing one egg in the host. It was shown that an intermediate value of the feeding ratio of all attacks gives the minimum equilibrium host density and the minimum amplitudes of fluctuation in the densities of the two species. Computer simulations of a modified model with time lags also gave the similar results. The model suggested for natural enemy introduction program that parasitoid species with host‐feeding habits are promising agents for effective controls for pest insects and that the timing of introduction is very important. By an evolutionary analysis, it was shown that the feeding ratio evolves to minimize the host density under natural selection among parasitoids.

Mass rearing techniques are essential elements in developing a reliable and economic biological control method for Orius sauteri, a promising indigenous Orius species for biological control of Thrips palmi in greenhouses. Orius sauteri was reared on Ephestia kuehniella eggs and life history parameters and the minimum number of E. kuehniella eggs for rearing O. sauteri individuals were measured at 25°C and L16:D8. Developmental time during the nymphal stages was about 14 days for both sexes. Total fecundity and female longevity were 103.9 and 27.9 days, respectively. The intrinsic rate of natural increase per day was 0.115. An individual requires at least 30 eggs for nymphal development and survival and 20 eggs for adult oviposition and survival per four days.