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Biological control approaches such as seeding and augmentation releases of populations of natural enemies mostly rely on the indoor production of predator or parasitoid species, often with the use of alternative prey/host species. In this study, we investigated several development parameters of four egg parasitoid species: Ooencyrtus fecundus, O. near fecundus, O. pityocampae and O. telenomicida, and compared their performance on their natural host, the variegated caper bug (CB) Stenozygum coloratum, and on an alternative, factitious host, the silk moth (SM) Bombyx mori. Survival was higher and development duration shorter in CB eggs, making the CB a better host for these congeners. However, adult longevity was generally longer for individuals that developed in SM eggs. Moreover, O. fecundus and O. pityocampae females that had developed in SM eggs displayed higher fecundity than all other female/host combinations. Survival also varied according to the age of the SM eggs: parasitoid survival rates were significantly higher in 9- to 12-month-old (post-diapausing) eggs than in young (about 1 month old) ones. These results were probably influenced by differences among the egg sizes of the studied hosts. The number of non-laying females and self-superparasitism rates were exceptionally high in O. near fecundus. These findings suggest that SM eggs, and especially those which are being utilized after a long storage, could serve for mass rearing of the studied Ooencyrtus spp.

The variegated caper bug Stenozygum coloratum Klug is common in the Middle East, where it is a minor agricultural pest. Recently, it was found that S. coloratum is an alternative host for the egg parasitoid Ooencyrtus pityocampae Mercet, an important natural enemy of the pine processionary moth Thaumetopoea wilkinsoni Tams, a major pest of pines. This discovery, coupled with the general lack of knowledge of S. coloratum, prompted the present study, which focused on seasonal activity of S. coloratum in Israeli pine forests, bidirectional interactions between the bug and its host the caper plant Capparis spp., and parasitism of its eggs. Stenozygum coloratum activity lasted mainly from May to October, and was followed by an adult winter diapause. Individuals formed large aggregations, causing early withering of plants and a shortening their annual growth periods. Reproductive activity peaked in August and ended in September. Egg parasitism rates increased throughout this period. Several Ooencyrtus spp., including known natural enemies of various pests, parasitized the eggs of S. coloratum and other associated pentatomids found on the caper plants. Thus, capers probably serve as a refuge for these potentially important egg parasitoids. The potential of caper plants and their fauna for biological control programmes is discussed.

The way in which species coexist is an important ecological question. Often, several parasitoid species may share a common host species. Five species of Ooencyrtus Ashmead (Hymenoptera: Encyrtidae) co-inhabit the egg clusters of Stenozygum coloratum Klug (Hemiptera: Pentatomidae), in the East Mediterranean region. Their relative abundance and spatial and seasonal occurrence were investigated. Parasitism and parasitoid male ratios gradually increased to about 50 and 26.8 %, respectively, from May to October. O. telenomicida Vassiliev was dominant in Mediterranean climatic regions and absent from arid areas, O. fecundus Ferriere and Voegele dominated semi-arid areas, and O. near nigerrimus was the commonest in hot-arid areas. O. near fecundus occurred everywhere but was most abundant in the more extreme weather conditions. O. pityocampae Mercet was uncommon in most areas and absent from arid ones. O. telenomicida abundance was positively, and that of O. fecundus negatively, correlated with annual rainfall. O. near fecundus and O. near nigerrimus abundance was positively correlated with temperature extremes. The results display a clear picture for climatic based spatial niche partitioning, although there is evidence that interspecific competition also plays a significant role in the frequency of occurrence of the studied Ooencyrtus spp.

The variegated caper bug (CB) Stenozygum coloratum (Klug, 1845) is common in the Eastern Mediterranean region and a minor agricultural pest. CB eggs were recently shown to serve as alternative hosts for Ooencyrtus pityocampae Mercet, 1921, an important natural enemy of the pine processionary moth (PPM) Thaumetopoea wilkinsoni Tams, 1924 (Lepidoptera: Notodontidae). In this study various aspects of the life history of CB were studied, including its distribution, host range, development, reproduction and ability to develop on various cultivated species of plants. CB occurs in almost all areas and habitats in Israel, except in the coldest regions, attacking several caper species (Capparis spp.). When reared on Capparis zoharyi at 25°C, one generation lasted 6 weeks and females laid a single 12-egg cluster every 3 days. Decreases in temperature, but not changes in day length, terminated reproductive activity. CB nymphs survived for up to three months, or even completed their development, on some agricultural plants. However, reproductive activity was initiated only if adults were fed capers. These findings emphasize the importance of capers in the CB life cycle and account for why other plants are rarely attacked. These plants may serve as a temporary refuge for CB when capers are scarce or unsuitable, mainly late in the season. Morphology of developmental stages, egg deposition, cannibalistic behaviour, sex ratio and effects of temperature on egg production were also studied. The possibility of using CB for enhancing the biological control of PPM is discussed.