Abstract Interactions between biocontrol agents of crop pests can lead to neutral, detrimental, or improved outcomes for pest control. We investigated the existence and the nature of the additive interactions between a parasitoid, Diadegma semiclausum (Hellén) (Hymenoptera: Ichneumonidae), and two hemipteran predators, Oechalia schellenbergii Guérin‐Méneville (Pentatomidae) and Nabis kinbergii Reuter (Nabidae), of the diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), under laboratory conditions. In the presence of the parasitoid, both O. schellenbergii and N. kinbergii increased predation by 56 and 66%, respectively. The escape response of the prey to avoid being parasitized (moving backwards and sometimes spinning down from the leaf on a silk thread, becoming less cryptic to the predators), may be at the basis of the enhanced predation by these predatory bugs; however, further studies are necessary to test this hypothesis. As the predators did not preferentially consume either parasitised or unparasitised larvae, coincidental intraguild predation should not affect this positive outcome in relation to DBM suppression. The findings highlight the potential utility of combining these natural enemies and may have important implications for the management of DBM in brassica crops in Australia and other multi‐species systems.
Epiphyas postvittana (Walker, 1863), or light brown apple moth (LBAM), is a highly polyphagous native Australian species and a major insect pest in Australian vineyards. Dolichogenidea tasmanica (Cameron, 1912) is the most abundant parasitoid of the larval stages of LBAM. The prime objective of our study was to determine the parasitism success of D. tasmanica on different larval stages of E. postvittana. Additionally, we aimed to find out if larval head capsule width could be used to determine the instar number by examining the variability in head capsule size of each instar of LBAM and the effect of rearing temperature on larval head capsule size. To determine which of the first three larval stages of LBAM parasitised is most effectively by D. tasmanica, choice and no-choice tests were conducted in a wind tunnel. Head capsule widths varied with rearing temperature, especially in the final fifth or sixth instar. We showed that the ranges of head capsule widths overlaps between successive instars three through six, which makes it impossible to distinguish these instars of LBAM using head capsule size alone. We showed that first, second and third instars of LBAM are parasitised by D. tasmanica. No-choice and choice tests revealed that there are significant differences in parasitism among the three susceptible instars, with the highest percentage of parasitism found in second instars in no-choice and choice tests (65.1% and 65.8%, respectively) compared with first instars (61.1% and 45.1%) and third instars (27.3% and 37.5%). Wasps developed faster in third instars, but the wasp female's size was not significantly different among the instars attacked. These data confirm that D. tasmanica is capable of parasitising early larval instars, which is important for minimising damage through biological control.
The responses of the parasitic wasp Orgilus lepidus to potato plants infested by its host Phthorimae, operculella were investigated. Wasps flew to both undamaged and mechanically damaged potatoes when they were presented alone in a flight tunnel, indicating that the odour of potato alone is attractive to them. When given a choice, females flew preferentially to either mechanically damaged plants or to plants infested by P. operculella rather than to intact plants. Thus, when O. lepidus is searching for hosts, it first flies toward the odour of plants, especially those that are damaged. There was no difference in the behaviour of wasps on either undamaged or mechanically damaged potato leaves, but they spent considerably more time probing with their ovipositor on leaves infested by their host. Wasps responded similarly to leaves infested with hosts and leaves from which hosts were removed, indicating that plant damage caused by their host or host products are the primary cues used to discriminate different kinds of damage.
Summary Parasitoids are predicted to spend longer in patches with more hosts, but previous work on Cotesia rubecula (Marshall) has not upheld this prediction. Tests of theoretical predictions may be affected by the definition of patch leaving behaviour, which is often ambiguous. In this study whole plants were considered as patches and assumed that wasps move within patches by means of walking or flying. Within‐patch and between‐patch flights were distinguished based on flight distance. The quality of this classification was tested statistically by examination of log‐survivor curves of flight times. Wasps remained longer in patches with higher host densities, which is consistent with predictions of the marginal value theorem ( Charnov 1976 ). Under the assumption that each flight indicates a patch departure, there is no relationship between host density and leaving tendency. Oviposition influences the patch leaving behaviour of wasps in a count down fashion ( Driessen et al . 1995 ), as predicted by an optimal foraging model ( Tenhumberg, Keller & Possingham 2001 ). Wasps spend significantly longer in the first patch encountered following release, resulting in an increased rate of superparasitism.
Background: HIV-infected children have abnormal cerebral metabolites, measured by proton MR spectroscopy (1H-MRS), but how these abnormalities relate to brain function is unclear. Methods: Metabolite concentrations in five brain regions of 20 HIV-infected and 13 control children were measured, and these findings were correlated with age, log10 plasma viral load, CD4 count, and neuropsychological scores. Results: Compared with control subjects, HIV patients had decreased choline concentration [Cho] in left frontal white matter (LFW) (−12%; p = 0.04); those with high viral load (>5,000 HIV RNA copies/mL) had decreased right basal ganglia (RBG) [Cho] (−15%; p = 0.005), and [Cr] (−13%; p = 0.02). Patients with high viral load also had higher [Cho] in the midfrontal gray matter (MFG) (+25%; p = 0.002) and lower myo-inositol [Ins] in the RBG (−18%; p = 0.04) than patients with low HIV viral load. N-Acetyl aspartate concentration ([NAA]) correlated with age in right frontal white matter (RFW) (r = 0.59, p = 0.04), LFW (r = 0.66, p = 0.02), and right hippocampus (RHIP) (r = 0.69, p = 0.02) only in control subjects. In contrast, [Ins] correlated with age in both RFW and LFW (r = 0.71, p = 0.0006; r = 0.65, p = 0.006) only in the HIV patients. Log10 plasma viral load correlated positively with [Ins] in RFW (r = 0.54, p = 0.02) and [Cho] in MFG (r = 0.49, p = 0.04). Compared with control subjects, HIV patients had poorer spatial memory (p = 0.045) and delayed spatial memory correlated with [Cho] in RHIP (r = 0.68, p = 0.02). Conclusions: These data suggest that normal brain development may be affected in children infected with HIV at birth, particularly evidenced by the lack of age-related increases in the neuronal marker [NAA]. Early, aggressive treatment of infants with HIV before development of encephalopathy is warranted.
The Working Party has met twice since the last report: in Seoul, South Korea 2014, and in London, UK 2015, both in association with the International Society of Blood Transfusion (ISBT) Congress. As in previous meetings, matters pertaining to blood group antigen nomenclature were discussed. Eleven new blood group antigens were added to seven blood group systems. This brings the current total of blood group antigens recognized by the ISBT to 346, of which 308 are clustered within 36 blood groups systems. The remaining 38 antigens are currently unassigned to a known blood group system.
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