Host stage preference and parasitism behaviour of Aenasius bambawaleian an encyrtid parasitoid of Phenacoccus solenopsis

In Pakistan, the cotton mealybug, Phenacoccus solenopsis Tinsley (Sternorrhyncha (Homoptera): Pseudococcidae), is a serious pest of many cultivated plants. A parasitoid, Aenasius bambawalei Hayat (Hymenoptera: Encyrtidae), is associated with P. solenopsis. In order to mass rear A. bambawalei for a biological control program, it is important to investigate the parasitoid’s host stage preference and its parasitism behavior for P. solenopsis in order to optimize production. The present tudy showed that under both choice and no choice conditions, the parasitoid preferred 3rd instar and pre-reproductive host stage mealybugs for parasitism. Parasitoid larva developing inside the host exhibited a greater longevity, shorter developmental period and longer body size in these preferred host stages. Our study also confirmed that A. bambawalei showed no attraction to male mealybugs and no host feeding on any host stage was recorded. The ability of the parasitoid to effectively discriminate between suitable and non-suitable stages means that it is feasible to rear it on a mixed population

Brain antigens in functionally distinct antigen-presenting cell populations in cervical lymph nodes in MS and EAE

Drainage of central nervous system (CNS) antigens to the brain-draining cervical lymph nodes (CLN) is likely crucial in the initiation and control of autoimmune responses during multiple sclerosis (MS). We demonstrate neuronal antigens within CLN of MS patients. In monkeys and mice with experimental autoimmune encephalomyelitis (EAE) and in mouse models with non-inflammatory CNS damage, the type and extent of CNS damage was associated with the frequencies of CNS antigens within the cervical lymph nodes. In addition, CNS antigens drained to the spinal-cord-draining lumbar lymph nodes. In human MS CLN, neuronal antigens were present in pro-inflammatory antigen-presenting cells (APC), whereas the majority of myelin-containing cells were anti-inflammatory. This may reflect a different origin of the cells or different drainage mechanisms. Indeed, neuronal antigen-containing cells in human CLN did not express the lymph node homing receptor CCR7, whereas myelin antigen-containing cells in situ and in vitro did. Nevertheless, CLN from EAE-affected CCR7-deficient mice contained equal amounts of myelin and neuronal antigens as wild-type mice. We conclude that the type and frequencies of CNS antigens within the CLN are determined by the type and extent of CNS damage. Furthermore, the presence of myelin and neuronal antigens in functionally distinct APC populations within MS CLN suggests that differential immune responses can be evoked

Mechanism of metal-independent decomposition of organic hydroperoxides and formation of alkoxyl radicals by halogenated quinones

The metal-independent decomposition of organic hydroperoxides and the formation of organic alkoxyl radicals in the absence or presence of halogenated quinones were studied with electron spin resonance (ESR) and the spin-trapping agent 5,5-dimethyl-1-pyrroline N-oxide (DMPO). We found that 2,5-dichloro-1,4-benzoquinone (DCBQ) markedly enhanced the decomposition of tert-butylhydroperoxide (t-BuOOH), leading to the formation of the DMPO adducts with t-butoxyl radicals (t-BuO(•)) and methyl radicals ((•)CH(3)). The formation of DMPO/t-BuO(•) and DMPO/(•)CH(3) was dose-dependent with respect to both DCBQ and t-BuOOH and was not affected by iron- or copper-specific metal chelators. Comparison of the data obtained with DCBQ and t-BuOOH with those obtained in a parallel study with ferrous iron and t-BuOOH strongly suggested that t-BuO(•) was produced by DCBQ and t-BuOOH through a metal-independent mechanism. Other halogenated quinones were also found to enhance the decomposition of t-BuOOH and other organic hydroperoxides such as cumene hydroperoxide, leading to the formation of the respective organic alkoxyl radicals in a metal-independent manner. Based on these data, we propose a mechanism for DCBQ-mediated t-BuOOH decomposition and formation of t-BuO(•): a nucleophilic attack of t-BuOOH on DCBQ, forming a chloro-t-butylperoxyl-1,4-benzoquinone intermediate, which decomposes homolytically to produce t-BuO(•). This represents a mechanism of organic alkoxyl radical formation not requiring the involvement of redox-active transition metal ions