The effect of irradiation and mass rearing on the anti-predator behaviour of the Mexican fruit fly, Anastrepha ludens (Diptera: Tephritidae)

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.

Premières mentions des araignées (Araneae) Phidippus audax Hentz, 1845 (Salticidae) et Tetragnatha viridis Walckenaer, 1841 (Tetragnathidae) au Québec

Nous rapportons, pour la première fois au Québec, la présence de l’araignée sauteuse Phidippus audax Hentz, 1845 (Salticidae Blackwall, 1841) et de la tétragnathe verte Tetragnatha viridis Walckenaer, 1841 (Tetragnathidae Menge, 1866). Nous décrivons les conditions de leur découverte et commentons leur répartition. Nos observations concernant l’araignée P. audax suggèrent que cette espèce soit à la fois une espèce indigène (trouvée en milieu naturel en Mauricie et à Longueuil), mais aussi une espèce introduite comme en témoigne sa découverte dans des camions importés du Minnesota. La tétragnathe verte fut trouvée à 2 endroits éloignés (Contrecoeur et Terrebonne), dans des habitats très différents au cours des mois de juin et de septembre 2010.

Secondary eyes mediate the response to looming objects in jumping spiders ( Phidippus audax , Salticidae)

Some species have sensory systems divided into subsystems with morphologically different sense organs that acquire different types of information within the same modality. Jumping spiders (family Salticidae) have eight eyes. Four eyes are directed anteriorly to view objects in front of the spider: a pair of principal eyes track targets with their movable retinae, while the immobile anterior lateral (AL) eyes have a larger field of view and lower resolution. To test whether the principal eyes, the AL eyes, or both together mediate the response to looming stimuli, we presented spiders with a video of a solid black circle that rapidly expanded (loomed) or contracted (receded). Control spiders and spiders with their principal eyes masked were significantly more likely to back away from the looming stimulus than were spiders with their AL eyes masked. Almost no individuals backed away from the receding stimulus. Our results show that the AL eyes alone mediate the loom response to objects anterior to the spider.

Passive hemagglutination inhibition test for diagnosis of brown recluse spider bite envenomation

Our goal was to recreate a passive hemagglutination inhibition (PHAI) test to diagnose brown recluse spider (BRS; Loxosceles reclusa) bite envenomation for treatment trials. Guinea pigs received intradermal injections of concentrated spider venom from the following species: Loxosceles reclusa, Argiope aurantia, Argiope trifasciata, Phidippus audax, and Lycosa frondicola. Skin lesion exudate was collected and tested with the BRS venom PHAI assay. From 51 separate collections of exudate, test sensitivity was 90% as long as 3 days after venom injection. Specificity was 100% with venom from the other spider species listed above in vivo (7 test samples) and in vitro (5 test samples), as well as with random bacterial exudate with and without added serial dilutions of BRS venom (10 test samples). The test was reproducible over repetitive assays to within one 10-fold dilution. A positive PHAI test result could function as an entry criterion for BRS bite victims in human treatment trials.

FIELD OBSERVATIONS OF PREDATION BY PHIDIPPUS AUDAX (ARANEAE: SALTICIDAE) ON ARTHROPODS ASSOCIATED WITH COTTON

Evidence of 58 predation events by Phidippus audax (Hentz) was obtained during 17–31 October 1986 from a 0.1 ha old field site that included cotton in the Delta of Mississippi. Three crop pest species accounted for 60% of the prey records: tarnished plant bug (TPB) (22%), spotted cucumber beetle (SCB) (22%), and three-cornered alfalfa hopper (TAH) (16%). Censuses (35) of cotton at this site indicated that the most abundant potential prey, SCB, had one of the lowest capture rates by P. audax, 1.9%. Other spiders as a group were captured at a rate of 11.4%, TAH at a rate of 10.2%, and TPB at a rate of 4.3%. Considering the total potential arthropod prey population, P. audax consumed approximately 3.3% during a 2-week period. Predation by P. audax usually occurred between 1030 and 1500 hours, with 7.6% of the P. audax population expected to be consuming prey at any one time. It is estimated that in late-season habitats P. audax may remove ca. 10% of the TPB population every 1–2 weeks.

EFFECTS OF ABAMECTIN ON PHIDIPPUS AUDAX (HENTZ) (ARANEAE: SALTICIDAE) WHEN INGESTED FROM PREY1

Phidippus audax (Hentz) were allowed to feed on bollworm, Heliothis zea (Boddie), larvae which had ingested diet containing three concentrations of abamectin. Significantly reduced weight gain was noted for spiders feeding on the treated larvae and toxicity effects were visible in most of the spiders within 48 h. Over 80% of the spiders that fed on larvae from diet containing 10 ppm abamectin were either torpid or dead, and 100% of spiders that fed on larvae from diet containing 40 ppm abamectin were torpid or dead.