The Effects of Malathion on the Activity of the Bowl and Doily Spiders, Frontinella pryamitella

Kathy Patterson Aug-Dec. 1998

and

Malinda Brussell

Disscussion:

Pesticides may not only effect the targeted species (pests) but they may inadvertently effect the well-being of other non-targeted species. Research on sublethal effects of pesticides has concentrated mostly on economically important arthropods and vertebrate species, rather than spiders who act as "natural pesticides" for spiders behave as insect predators and control agents. Malathion, a common pesticide is hypothesized to effect the nervous systems of various species of spiders.

The spider investigated is Frontinella pyramitella. This species was chosen for research because of its availability and its unique web structure makes it easy to identify in the field. Plus, their smallness makes them easier to work with.

Purpose of Research:

• To see the effects of the pesticide, Malathion, has on the spider, Frontinella pryamitella (a non-targeted species).
• To develop useful methods for dosing spiders under laboratory conditions.
• To test developed assays that record changes in the spider’s behavior, such as, the amount of movement.
• Record changes in the movement of Frontinella and determine if the dosed spiders will recover from sublethal effects.

Materials:

• Forty Frontinella pyramitella species and water.

• Petri dishes, tape, computer, video camera, backlight, web cylinders, propriatory software, and stata quest.
• Malathion

Procedures and Observations:

In the field, the spiders were captured and collected in petri dishes and sealed with portions of their webs still attached. Frontinella pyramitella, commonly know as the Bowl and Doily spider is a very common species of spiders that can be found in shrubbery, spruces, evergreens, holly trees or anywhere that has a lot of gaps. Once spiders were located according to their unique web structure, some were photographed and observed.

In the lab, the control, undosed, spiders were placed in individual web cylinders sitting in the bottom of a water filled petri dish and topped for closure. Time was allotted for adapting and web building. Next, two cylinders labeled appropriately were placed on the backlight and each spider was observed by vid-cam for a 24 hour period to record their movements. This portion of the procedure was repeated for only nine spiders, because we lost quite a few due death (heat, and lack of water) and through escape. After data was collected for all control spiders, the recorded videos were observed and movement was recorded using the propriatory program xy-input develops specifically for the research. This program allowed for the calculations for distance and amount of movement for the undosed spiders.

Once all the movement data was completed for the control group, the undosed spiders were then dosed with 10m l of malathion.

Results:

The mean distance traveled by the control animals was 341.8687 +/- 364.138 pixels while dosed animals traveled 588.9104 +/- 495.326 pixels. A one way ANOVA (p<0.0002) and a Kruskal Wallis test (p<0.0072) were both sign indicating that dosed animals moved farther than undosed.

Conclusions:

Our results indicate that Malathion does appear to have an effect on Frontinella pyramitella. There was a significant increase in movement of the dosed animals as opposed to the undosed animals. Would have a negative effect on pry capture in the wild. Too much movement by the animal would distract prey from flying or crawling into the web.

This research is not complete. Additional research on the dosed animal is yet to be done. This includes more movement research as well as the effects that Malathion has on web structue.