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Entom 767

The max carrying capacity or the plateau from the functional response graph can be reached by several different factors. For example a limited food source which inhibits the ability of the insect to find a valuable source of energy will affect population density.  Also limited space within the insects natural climate can be factor towards survival and reproduction.

The insect density number is the variable that determines the level of the plateau on the graph.  Many different things can take place and disrupt the number of prey attacked by a predator.  Weather and field distribution play a big key in the attack rates.  Number of predators within a population can also correlate with the number of prey attacked.  Higher populations mean more encounters and lower populations might mean fewer interactions. 

During the trial the lady beetle I observed had 7 events (attacks).  I classified an event on the basis of attacking an aphid (start time) and recording the results up to the next attack (end time).  The times from event 1-event 7 are as follows:

1) 41 sec
2) 11 sec
3) 2 min
4) 25 sec
5) 39 sec
6) 4 min 36 sec
7) 1 min 46 sec

Between events 3-4 and 4-5 after the prey was consumed the predator (lady beetle) would groom its mouth parts and continue on.  The grooming seemed odd.  My best guess is that the lady beetle was cleaning its mouth parts for the next victim.  My lady beetle was very aggressive compared to my surrounding classmates.  Within the time of approximately 10 minutes my lady beetle had consumed 7 different aphids which show that possible bio-control with insects (natural enemies) could be beneficial and cost effective.  The standard error for the 7 events was 1.885.

Compared to the table in the handout the handling times are longer and more extensive than in the trials that I conducted.

My responsibility was to trace the search pattern of the lady beetle in search of prey.  The patterns for both predators were random and they spent the majority of their time along the straight edges of the case.  The second lady beetle found the aphid infested leaf about half way through the trial ( @ 3 minutes). 

I was not surprised that the second lady beetle found the leaf but rather surprised that the first lady beetle had a hard time coming up with the find.  Being confined to a small area with only two leafs visible in the center should have been simpler compared to field conditions.  It is possible that the lady beetle was not use to the unfamiliar habitat and was thrown off track.  Either way with high population numbers in a field situation I gained a better understanding with this experiment that bio-control with insects can be potentially useful in a management system.

In the analysis of behavioral sequences we observed 2 events.  Within both trials we calculated the time spent walking, grooming, resting, and feeding. 
Results determined from standard error:

walking (24.74)
resting (7.07)
feeding (31.81)
grooming (no time)