Fruit flies (Diptera: Tephritidae) are major pests worldwide. The sterile insect technique, where millions of flies are reared, sterilized by irradiation and then released, is one of the most successful and ecologically friendly methods of controlling populations of these pests. The mating behaviour of irradiated and non-irradiated flies has been compared in earlier studies, but there has been little attention paid to the anti-predator behaviour of mass-reared flies, especially with respect to wild flies. Tephritid flies perform a supination display to their jumping spider predators in order to deter attacks. In this study, we evaluated the possibility of using this display to determine the anti-predator capabilities of mass-reared irradiated, non-irradiated flies, and wild flies. We used an arena setup and observed bouts between jumping spiders (Phidippus audax Hentz) and male Mexican fruit flies (Anastrepha ludens Loew). We show that although all flies performed a supination display to their predator, wild flies were more likely to perform a display and were significantly more successful in avoiding attack than mass-reared flies. We suggest that this interaction can be used to develop a rapid realistic method of quality control in evaluating anti-predator abilities of mass-reared fruit flies.

The arachnids from the late Eocene Insect Limestone of the Isle of Wight are reviewed. Only spiders (Araneae) have been recorded, of which several dozen are known, mostly juveniles. Nearly all are araneomorphs; the putative mygalomorph Eoatypus woodwardii McCook, 1888 was removed from that infraorder by Selden (2001), but new specimens, yet to be described, could belong in this group. Among the adult specimens, which are thus identifiable to family level, most belong to the argyronetid water-spider Vectaraneus yulei Selden, 2001; some resemble araneids, and a small number can be referred to other families. New morphological information on the holotype of Vectaraneus is presented, and three other specimens are described in more detail here, in Segestriidae, Araneidae and Salticidae. Segestriids are nocturnal sedentary hunters living in tubular retreats in rock or bark crevices. Araneids are the archetypal weavers of orb webs. Salticids are the familiar jumping spiders; the one described here is an ant mimic. Their presence suggests a drier habitat was present somewhere in the source environment for the fossil biota, and they were probably inhabitants of the raised hammocks suggested for the Insect Bed palaeoenvironment.

The distinctions between a predator's diet, its prey-choice behaviour and its preferences are illustrated in a study of Aelurillus muganicus, a salticid spider from the Apsheron Peninsula in Azerbaijan. Laboratory experiments showed that A. muganicus has an innate predisposition to choose ants as prey. The natural diet of this species was determined by sampling individuals seen feeding in the field (n = 64). Ten arthropod orders were represented. Seven were from the class Insecta (Coleoptera, Collembola, Diptera, Heteroptera, Homoptera, Hymenoptera, Lepidoptera) and three from the class Arachnida (Acari, Araneae, Pseudoscorpiones). Collectively, four orders accounted for >70% of the prey records: Hymenoptera (20%), Lepidoptera (19%), Acari (19%) and Homoptera (14%). No other order accounted for >10% of the prey records. Of the 45 insects among the prey, 13 (29%) were Hymenoptera, with ants (family Formicidae) alone accounting for 24% of the prey records. Although ants were the preferred prey of A. muganicus, as revealed by laboratory testing, and also the most common single category of prey from the field prey records, records of A. muganicus feeding on prey other than ants were actually more common than records of it feeding on ants, suggesting that, besides prey choice, other factors have a strong influence on the diet of this species.

Portia fimbriata from Queensland, Australia, is an araneophagic jumping spider (Salticidae) that includes in its predatory strategy a tactic (cryptic stalking) enabling it to prey effectively on common sympatric salticids from other genera. Using standardized tests in which only optical cues were available (prey enclosed in small glass vial within large cage), the reactions of P. fimbriata to 114 salticid species were investigated. Except for Myrmarachne spp. (ant mimics), all salticids tested triggered cryptic stalking by P. fimbriata. This included not only sympatric, but also allopatric, salticids. The salticid on which P. fimbriata most commonly preys in nature is Jacksonoides queenslandicus, but cryptic stalking was triggered by salticid species with considerably different appearances, including beetle mimics, species with unusual body shapes and species with a wide variety of camouflaging markings. Portia fimbriata was also tested with lycosid, clubionid, theridiid and desid spiders and with flies and ants, but none of these arthropods triggered cryptic stalking. Optical cues used by P. fimbriata for discrimination between salticid and non-salticid prey are discussed.

Nectivory was studied in 90 species from the spider family Salticidae. Observations of 31 of these species feeding on nectar from flowers in nature was the impetus for laboratory tests in which all 90 species fed from flowers. That sugar, not just water, is relevant to salticids was implied by choice tests where salticids spent more time drinking from a simulated nectar source (30% sucrose solution) than from distilled water. Our findings suggest that nectar feeding may be widespread, if not routine, in salticid spiders.

Distances at which jumping spiders (Salticidae) use optical cues to distinguish between prey insects and conspecific rivals were investigated using adult males of 37 species. During tests, salticids walked up a ramp toward a mirror or toward an insect enclosed in a transparent petri dish. All species directed threat displays toward their own mirror images and the displays were comparable to each species' typical behaviour during male–male interactions. The salticids never displayed in tests with insects at the top of the ramp. The virtual distances at which the spiders displayed are interpreted as an indication of the distances at which each species can distinguish rivals from prey. Representative species were from the subfamilies Lyssomaninae, Spartaeinae and Salticinae. Discrimination distances relate well to the foveal layer I receptor mosaics of the anterior median eyes for the three subfamilies. Compared with the salticines, the lyssomanines and, except for Portia, the spartaeines tended to have shorter discrimination distances. Portia spp. had discrimination distances comparable to the longest recorded for the salticines. The longest discrimination distances found were for the salticine Mogrus neglectus (max. 320 mm or 42 body lengths) and for the spartaeine Portia fimbriata (280 mm or 47 body lengths).