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Dalmatian and yellow toadflax, Linaria dalmatica and L. vulgaris, are exotic weeds in North America, and their classical biological control has been improved by the establishment of seed-feeding (Rhinusa antirrhini) and stem-mining (Mecinus janthinus and Mecinus janthiniformis) weevils. Here, we evaluated the complex of hymenopteran parasitoids attacking these weevils in Colorado. Ten species were identified of the genera Neocatolaccus, Eurytoma, Pteromalus, Brasema, Telenomus and Bracon. Neocatolaccus tylodermae was the most abundant parasitoid of M. janthinus, M. janthiniformis and R. antirrhini. This is the first report of N. tylodermae attacking the weevil genera Mecinus and Rhinusa feeding on the genus Linaria. [ABSTRACT FROM AUTHOR]

This study determined the effects of cold storage of mummies on the biological characteristics of Aphidius colemani Viereck (Hymenoptera Braconidae), a solitary, koinobiont endoparasitoid of more than 40 species of aphids. The effects of three constant temperatures (5, 7 and 9 °C) at five time periods (5, 10, 15, 20 and 30 days) were evaluated on eight quality control parameters of the parasitoid (adult emergence, sex ratio, time elapse before emergence, adult longevity, length of the hind tibia, flight capacity, percent parasitism and sex ratio of F1 wasps). The results showed that all parameters except the sex ratio of F1 were negatively affected by cold storage duration in comparison to control treatment (25 °C). Based on the adult emergence and sex ratio, A. colemani could be stored for 15 days at 5 and 7 °C and for 10 days at 9 °C but it is important to consider other quality control parameters (time elapse before emergence, adult longevity, adult size, flight capacity and percent parasitism). However, when the mummies of A. colemani were stored for longer than 10 days, their quality criteria were more negatively affected at all three temperatures. The results are discussed in order to facilitate the planning of A. colemani mass rearing and aphid biocontrol programs. [ABSTRACT FROM AUTHOR]

The importance of Cotesia vestalis (Haliday) has been well documented as one of the most significant biocontrol agents for the diamondback moth, Plutella xylostella (L.). The aim of the present study was to optimize the procedure of mass rearing of C. vestalis. The effects of space and plant-herbivore-parasitoid biomass on the quality of produced wasps were investigated. In particular, the effects of food and space resources of P. xylostella and C. vestalis on mass-reared C. vestalis were investigated. The results indicated that there was no significant difference between treatments for percentage parasitism, survival rate and larval developmental period of the produced wasps. However, developmental period of pupa, the ratio of female offsprings and sex ratio of the mass-reared wasps were significantly affected by the given treatments. Based on these findings, it can be concluded that the extent of available resources plays a crucial role in mass rearing of C. vestalis. [ABSTRACT FROM AUTHOR]

Laboratory studies were performed to explore the effects of host-plant quality on the vulnerability ofPlutella xylostellatoBacillus thuringiensis.P. xylostellawere kept on different host plants, includingBrassica pekinensis(Chinese cabbage) cv. Hero,Brassica oleraceavar.botrytis(cauliflower) cv. Royal, andB. oleraceavar.capitata(common cabbage) cv. Globe Master (white cabbage) and cv. Red Dynasty (red cabbage) for at least two generations. These host plants are considered as the high (Chinese cabbage), intermediate (cauliflower and white cabbage) and low-quality (red cabbage) hosts forP. xylostella. The vulnerability of the pest larvae was then tested using two formulation ofB. thuringiensisvar.kurstaki, including Biolarv®and Biolep®. The results demonstrated that the susceptibility ofP. xylostellatoB. thuringiensiswas influenced by host-plant quality. Indeed,B. thuringiensisacted better on the pest fed on the low-quality host plant compared with that on the high-quality host plant. The interaction between the pathogen and plant quality/resistance resulted in more mortality of the pest larvae, implying a synergistic effect. From a pest management viewpoint, these findings may be promising for the integration of the pathogen and the low-quality/partially resistant host plants againstP. xylostellain field studies. [ABSTRACT FROM AUTHOR]

The recent major outbreaks of diamondback moth,Plutella xylostella(Lepidoptera: Plutellidae), in cruciferous plants in Iran has led to attempts for sustainable pest management strategies, mainly based on the natural enemies. The present study aimed to investigate naturally occurring parasitism ofP. xylostellain cabbage and cauliflower fields of central Iran. For this purpose, field studies were performed to identify parasitoids ofP. xylostella, and to evaluate percentage parasitism ofP. xylostellausing the recruitment method in main cabbage-growing areas of Isfahan province in 2009. In present study, seven species of parasitoid wasps (five larval and two pupal parasitoids) and two species of hyperparasitoid wasps were determined. The parasitoids included the braconidsCotesia vestalis(Kurdjumov),Bracon hebetorSay andApantelessp., the ichneumonidDiadegma semiclausum(Hellen), and the eulophidOomyzus sokolowskii(Kurdjumov) as larval parasitoids, and the ichneumonidsDiadromus collaris(Gravenhorst) andDiadromus subtilicornis(Gravenhorst) as pupal parasitoids. In addition, the pteromalidsMokrzeckia obscuraGraham andPteromalussp. were identified as the hyperparasitoids, which in turn parasitiseC. vestalis. The most predominant species wereC. vestalisandD. semiclausumwith the proportional abundance of 0.43 and 0.42, respectively. Percentage parasitism varied significantly between host plants, but not between areas; the parasitised proportion ofP. xylostellalarvae fed on common cabbage was significantly greater than that on cauliflower (0.42 vs. 0.34). The mean percentage parasitism varied between 14.5 and 68.4 for different fields, and accounted for 37.4% ofP. xylostellapopulation on an average. The greatest parasitism was achieved byC. vestalis,D. semiclausumandO. sokolowskii, with a parasitism of 21.0, 12.9 and 3.5% of field populations ofP. xylostella, respectively. These findings illustrated the important role of parasitoids for sustainable management of diamondback moth. [ABSTRACT FROM AUTHOR]

Anthocoris nemoralis(Fabricius) (Hemiptera: Anthocoridae) is an important predatory insect in pear orchards and is considered as a biological control agent against the pear psylla,Cacopsylla pyricola(Förster) (Hemiptera: Psyllidae). In order to investigate the effects of plant resistance on predation ofC. pyricolabyA. nemoralis, consumption rate of both the sexes ofA. nemoralison pear psylla nymphs was studied on three pear varieties including, “Shahmivea”, as a susceptible host plant, and “Siberi” and “Coscia”, as partially resistant host plants. Different densities ofC. pyricolanymphs were offered to singleA. nemoralisand predation proceeded for 24 h. The experiments were carried out under constant environmental conditions (27 ± 1 °C, 70 ± 5% RH and L:D 16:8 h). The results showed that the effect of variety on the consumption rate ofA. nemoralisfemale was significant and most consumption happened on Shahmivea. However, different results were found when the male predator was examined. The findings have been discussed in relation with combining the predator and pear varieties for pear psylla management in a multitrophic context. [ABSTRACT FROM AUTHOR]

1. Little is known about underlying mechanisms by which plants indirectly affect parasitism success in hymenopteran endoparasitoids. The hypothesis that host-plant effects can challenge the innate immune system of an insect host was experimentally tested in this study using a model tritrophic, crucifer – lepidopteran [ Plutella xylostella (L.)] – parasitoid [ Cotesia plutellae (Kurdjumov)], system. 2. The effects of host-plant suitability on herbivore performance and parasitism were examined. The bottom-up effect of plant suitability on host-parasitoid immune responses was then evaluated using measures of cellular and humoral effectors. 3. Host-plant quality showed a significant effect on the encapsulation response of P. xylostella to first instar but not to second instar parasitoid larvae. Encapsulation was never sufficient to prevent parasitoid emergence. 4. Poor host-plant suitability suppressed phenoloxidase activity in the absence of the parasitoid. The suppressive effect of C. plutellae on phenoloxidase activity was much greater and no plant effects were detectable after insects had been parasitized. 5. Despite strong plant effects on parasitism, those on immune effectors of the host were transitory or overwhelmed by the effect of the parasitoid. 6. These results demonstrated that plant-mediated variation in parasitism success by C. plutellae were not as a result of plant nutritional status or other attributes affecting the immune function of P. xylostella, nor to host-plant effects on superparasitism. 7. In these experiments, P. xylostella was a fully permissive host to C. plutellae and host-plant-mediated effects on the innate immune response appeared to play no part in parasitoid survival within hosts. [ABSTRACT FROM AUTHOR]