Spiders occur in relatively large numbers in most agro-ecosystems, and are thought by many pest management (IPM) experts to represent the typical “generalist” predator.
In tropical fruit crops I am often impressed by the abundance and diversity of the very small “Jumping spiders” (Family Salticidae). These are usually ( 1 to 2 cm ) in size, and typically can only be viewed for a few seconds before they either rapidly scurry away or more likely catapult themselves to a new location.
Their jumping behaviour is of interest to arthropod physiologists, as incredibly these critters have few muscles and mange their incredible athletic feats by suddenly adjusting their blood pressure forcing the legs to kick out in a sort of hydraulic-like mechanism. It’s a pretty effective trick, and allows them to cover distances 30 cm or more in a single jump.
Now, what I hope is that jumping spiders will help to catch stray female fruit flies (Family Tephritidae, Genus Bactrocera; picture at bottom ) that wander into the orchard. I have never actually seen one get caught by a spider, but I have seen the jumping spiders catch other small flies so imagine it’s possible that they help. The problem of course with all generalist predators is that they will tend to kill other beneficial; organisms ( eg: parasitic hymenoptera) as well as the bad ones.
A: He doesn't have a web he had a website!
In tropical fruit crops I am often impressed by the abundance and diversity of the very small “Jumping spiders” (Family Salticidae). These are usually ( 1 to 2 cm ) in size, and typically can only be viewed for a few seconds before they either rapidly scurry away or more likely catapult themselves to a new location.
Their jumping behaviour is of interest to arthropod physiologists, as incredibly these critters have few muscles and mange their incredible athletic feats by suddenly adjusting their blood pressure forcing the legs to kick out in a sort of hydraulic-like mechanism. It’s a pretty effective trick, and allows them to cover distances 30 cm or more in a single jump.Jumping spiders are said to also have incredible telescopic vision, facilitated by a network of four eyes that run across the front of their head. I am sure no prey (or foe) manages to escape their notice. Trying to catch them is real difficult, as they see you coming a long way off.
A cool feature of most Malaysian jumping spiders is their attractive coloration. The most common 
species in orchards (above) has an amazing metallic green colour , reminding me somewhat of a automobile, and making them seem much more “friendly” than the average spider
species in orchards (above) has an amazing metallic green colour , reminding me somewhat of a automobile, and making them seem much more “friendly” than the average spiderNow, what I hope is that jumping spiders will help to catch stray female fruit flies (Family Tephritidae, Genus Bactrocera; picture at bottom ) that wander into the orchard. I have never actually seen one get caught by a spider, but I have seen the jumping spiders catch other small flies so imagine it’s possible that they help. The problem of course with all generalist predators is that they will tend to kill other beneficial; organisms ( eg: parasitic hymenoptera) as well as the bad ones.
Anyone know how to increase populations of jumping spiders ? The good news is that they don’t seem to be harmed by most pesticides or farm chemicals, although I ‘ve never done a specific bioassay, I notice that jumping spiders are still present even after a farm has been sprayed.
And finally, here’s todays cheesy Naturalist joke:
Q: How do you recognize a modern spider?
A: He doesn't have a web he had a website!
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