The composition of the egg-parasitoid guild of the golden egg bug, Phyllomorpha laciniata (Heteroptera: Coreidae), in Spain

The golden egg bug (Phyllomorpha laciniata (Villers)) is a phytophagous insect with an unusual reproductive system. Females use the bodies of conspecifics, both males and females, as oviposition substrates. In addition, a varying fraction of the eggs is laid on the food plant. Egg carrying on conspecifics increases offspring survival. Predators and, especially, hymenopteran parasitoids are themain cause of egg mortality. So far, only the wasp Gryon bolivari (Giard) (Hymenoptera: Scelionidae) has been reported as an egg parasitoid of P. laciniata in several Mediterranean populations. In this study, three new egg-parasitoid species are recorded from P. laciniata: the primary solitary parasitoids Gryon monspeliense (Picard) and Telenomus sp. (Hymenoptera: Scelionidae), and the facultative hyperparasitoid Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae). All of these parasitoids have been reared from host eggs being carried by conspecific bugs. We discuss the taxonomy and biology of the individual parasitoid species, as well as ecological and evolutionary aspects of the interactions in this host-parasitoid system.

Parasitoid guild and parasitism rate of the obliquebanded leafroller in IPM orchards and adjacent woodlands

The obliquebanded leafroller (OBLR), Choristoneura rosaceana (Harris) [Lepidoptera: Tortricidae], a primary pest in Quebec apple orchards, can be naturally parasitized. Knowing that habitats around crop’s peripheries are reservoirs for natural enemies of pests, the objective of the present investigation was to assess parasitism and parasitoid guild composition associated with the OBLR. The two-year study included orchards under integrated pest management, their edges, and adjacent woodlands. Parasitism was assessed using sentinel OBLR larvae and considered spring, early summer and late summer. Parasitism rates between regions with different vegetation composition were not significantly different. The first year, late summer larvae showed higher parasitism in orchards (27%), compared to edges (7%) and woodlands (11%). The following year, larvae exposed in early summer had higher parasitism rate in edges (28%) compared to orchards and woodlands (17% in both zones). Nineteen parasitoid species parasitized sentinel larvae. The tachinid Actia interrupta (Curran), the most abundant species, represented 28 and 62% of species the first and the second year respectively. Our research demonstrates that natural biological regulation of the OBLR is the result of a highly diversified parasitoid guild and this should be taken into account in any Integrated Pest Management program.

Impact of introduced parasitoid Cotesia vestalis (Hymenoptera: Braconidae) on Plutella xylostella (Lepidoptera: Plutellidae) and its parasitoid guild on kale in semi-arid areas in Kenya

Cotesia vestaliswas introduced into Kenya from South Africa in March 2003 for biological control ofPlutella xylostellawith initial release in 2004. To confirm establishment, the rate of spread beyond the release sites and parasitism rates byC. vestaliswere assessed between October 2011 and April 2012 in eastern and southeastern Kenya (Kitui, Mwingi/Yatta and Loitokitok areas). Monthly observations on kale infestation by diamondback moth, damage scores, parasitism and parasitoid guild were undertaken on 20 randomly selected plants in farmer-managed kale farms. Sampled larval and pupal stages were placed in containers and taken to the laboratory for parasitoid emergence. The infestation levels ranged from 0.4 to 2.5 DBM per plant, while damage scores ranged from 1.2 to 1.6, which correlated with the infestation levels.Cotesia vestaliswas not only the most abundant parasitoid, but it had also spread to new areas from the release sites. In December, the three sites recorded an average of 50% fromC. vestalis. Excluding the exotic parasitoidsC.vestalisandD. semiclausum, indigenous parasitoids accounted for less than 5% total parasitism. The parasitoid guild of the diamondback moth varied between months and study sites with January recording the highest species diversity and evenness of 1.15 and 0.63, 1.28 and 0.80, 1.08 and 0.47 in Loitokitok, Kitui and Mwingi/Matuu, respectively. Therefore,C.vestalishad an impact on the management of the DBM with parasitism rate of 35% to 88% and had spread beyond the release sites.

Phenological diversity in the interactions between winter moth (Operophtera brumata) larvae and parasitoid wasps in sub-arctic mountain birch forest

Population cycles of the winter moth (Operophtera brumata) in sub-arctic coastal birch forests show high spatiotemporal variation in amplitude. Peak larval densities range from levels causing little foliage damage to outbreaks causing spatially extensive defoliation. Moreover, outbreaks typically occur at or near the altitudinal treeline. It has been hypothesized that spatiotemporal variation in O. brumata cycle amplitude results from climate-induced variation in the degree of phenological matching between trophic levels, possibly between moth larvae and parasitoids. The likelihood of mismatching phenologies between larvae and parasitoids is expected to depend on how specialized parasitoids are, both as individual species and as a guild, to attacking specific larval developmental stages (i.e. instars). To investigate the larval instar-specificity of parasitoids, we studied the timing of parasitoid attacks relative to larval phenology. We employed an observational study design, with sequential sampling over the larval period, along an altitudinal gradient harbouring a pronounced treeline outbreak of O. brumata. Within the larval parasitoid guild, containing seven species groups, the timing of attack by different groups followed a successional sequence throughout the moth's larval period and each group attacked 1–2 instars. Such phenological diversity within parasitoid guilds may lower the likelihood of climate-induced trophic mismatches between victim populations and many/all of their enemies. Parasitism rates declined with increasing altitude for most parasitoid groups and for the parasitoid guild as a whole. However, the observed spatiotemporal parasitism patterns provided no clear evidence for or against altitudinal mismatch between larval and parasitoid phenology.