An astigmatid defence volatile against a phytoseiid mite

Numerous semiochemicals have been isolated from several species of astigmatid mites with various identified or unidentified functions. Alarm pheromonal activity is widespread with neryl formate and neral, being the most common compounds eliciting alarm response in conspecifics. The cosmopolitan astigmatid mite Suidasia medanensis (= S. pontifica) Oudemans (Acari: Suidasidae) has been reported to use neral as an alarm pheromone, but neral can also act as an allomone towards predators of oribatid mites. Suidasia medanensis can be utilised as a factitious prey for mass‐rearing of the phytoseiid predatory mite Amblyseius (= Typhlodromips) swirskii (Athias‐Henriot) (Acari: Phytoseiidae), which is used for biological control of insect and mite pests in protected crops. This study investigated the potential defence properties of the S. medanensis volatiles against A. swirskii, comparing the repellency to pollen‐reared (naïve) vs. S. medanensis‐reared (experienced) predators using a synthetic blend of the isomers neral and geranial (1:1) as a model compound. In a repellency bioassay, the synthetic blend elicited a significant repellence to A. swirskii with no difference between naïve and experienced predators. During capture success studies, S. medanensis under repeated attack could release sufficient quantities of the defence volatile to deter 1–5 attacks from A. swirskii, whereas hexane‐treated S. medanensis artificially depleted of volatiles were significantly more vulnerable to an attack. This is the first report of an astigmatid defence volatile with repellent activity to a phytoseiid mite and the starting point to understanding semiochemical interactions in any current or novel factitious predator‐prey mass‐rearing system.     

Life-cycle of Suidasia medanensis (=pontifica) (Acari: Suidasiidae) under laboratory conditions in a tropical environment

The life cycle of Suidasia medanensis (= pontifica) was studied under laboratory conditions at 26°C and 86% relative humidity. Freshly laid eggs were observed until they developed into adults and the periods between stages were recorded. Production of eggs by mated females was monitored until they died. The eggs required an average of 12.6 ± 0.6 days to develop into adults. Mean longevity of mated females and males was similar (48.6 ± 13 and 49.1 ± 20 days, respectively). The conditions used in this study may be considered optimal for in vitro culture of S. medanensis.     

The functional and numerical response of Typhlodromips swirskii (Acari: Phytoseiidae) to the factitious prey Suidasia medanensis (Acari: Suidasidae) in the context of a breeding sachet

The whitefly and thrips predator Typhlodromips swirskii (Athias-Henriot) (Acari: Phytoseiidae) can be reared on the factitious astigmatid mite Suidasia medanensis (Oudemans) (Acari: Suidasiidae). The predator–prey relationship allows the system to be incorporated into a breeding sachet which releases predators into a crop over several weeks ensuring predator presence on arrival of the target pests and increased predator numerical response on the crop through immigration from the breeding sachet. This study investigated whether the prey preference and functional and numerical response of T. swirskii to different development stages of S. medanensis can provide understanding of the predator–prey interactions sustaining such a breeding sachet. T. swirskii elicited a strong preference to egg stages of S. medanensis, exhibited a Type II functional response and increased oviposition rate with increasing prey density. The relevance of these attributes to a balanced breeding sachet is discussed.     

纳氏皱皮螨生活史的研究

纳氏皱皮螨Suidasia nesbitti Hughes是我国重要储藏物螨类之一.在我国大陆和台湾省,腐食酪螨Tyrophagus putrescentiae (Schrank)是最重要的储藏物螨类,其次是皱皮螨属Suidasia的二个种,即大陆的纳氏皱皮螨和台湾省的棉兰皱皮螨S. medanensis Oudemans.本文研究了纳氏皱皮螨的生活史,并对生活史各发育阶段的形态进行描述.本文还对纳氏皱皮螨和棉兰皱皮螨的形态,分布和为害情况列表进行比较.