28. Laboratory bioassays were conducted with commercial dipha-
 cinone baits, following accelerated shelf-life tests. The results
 revealed that the toxicity of the baits was not affected, however,
 palatability may have deteriorated.

 29. CAT (DRC-2698; N-(3-chloro-4-methylphenyl) acetamide) is being
 developed as a bird toxicant and biological data required to meet
 regulatory agency registration requirements are being accumulated.
 One of these requirements is the acute oral toxicity to rats. We
 found the LD50 to be 760 (673-859) mg/kg.

 30. Preliminary laboratory trials were conducted to examine the
potential for using "rodent glues" as an alternative nontoxic control
method in agricultural crops. Three commercial products were tested
with encouraging results. The glues trapped and held the rats even
though they were wet, as would likely be the case in the fields, espe-
cially in rice paddies. Further evaluations are planned, both in the
laboratory and under field conditions.

 31. Work continued on studies designed to evaluate rodent feeding
patterns and their relationship to the effectiveness of control pro-
grams with toxic baits. We are especially interested in the phenomena
of bait shyness. These investigations have shown that rats feed on
bait for only limited portions (i.e., 30-90 min) of each 24-h period
and that feeding on toxic baits is characterized by intermittent 1- to
3-min samplings of small quantities of the bait. Feeding on nontoxic
baits, however, consists of several 5- to 10-min "meals" of larger
quantities of bait, indicating that rats are sensitive to adulterated
foods. Despite these results, major problems were encountered in data
acquisition, reduction, and analysis, primarily because of inherent
design problems in the equipment. Newly acquired equipment should
eliminate these difficulties and allow in-depth study of bait shyness
phenomena.

 32. Conditioned taste aversion is currently being proposed as a
nonlethal method for control of agricultural damage by a variety of
vertebrate species. Preliminary work was initiated to examine the
feasibility of drug-induced taste aversion for reducing crop damage
by the ricefield rat and the factors that are likely to influence
field application of this technology.

 33. Development of the nonlethal electric barrier continued.
Previous laboratory and field data have demonstrated the efficacy of
the concept but a major impediment to large-scale field application
is the high cost of materials. Several modified designs using low-
cost, locally available materials were tested in the laboratory. The
results indicate that less expensive and more readily available
materials can be used with no loss in efficacy. Fourteen electrode