The population dynamics and host utilization of ... - Phthiraptera

290 R.W. Rus~
natural light. Every seventh day of an experiment an additional 21 of water were
added to the surface.
Two different treatments were designed for gophers placed in the artificial
system. Newly eclosed first instar nymphs were introduced on a clean gopher, and
the animal was released in a system for a set period--6, 10, 15, 20, 25, and 30 days.
Freshly caught gophers were cleaned of parasites, empty lice eggs were plucked
from the animal, and the remaining lice eggs were counted and mapped. These
animals were released in a system for 20, 30 and 40 days. At the end of an experiment,
the animal was sacrificed and cleaned.
Statistical analyses used in this study were Student's t-test, linear regression and
correlation, single class analysis of variance and curvilinear regression.
Results
Macro- and Microenvironmental Parameters
During this study, average monthly temperatures varied from a low
of 3.3~ in winter to a high of 25.4~ in summer. The Davis weather
station mean maximum temperatures were 16.2 ~ and 30.2~ and the
mean minima were 5.1 ~ and 11.8~ in winter and summer, respectively.
Average monthly precipitation was from a high of 61.5 mm in winter
months to 1 mm in summer months. Average monthly soil temperatures
at 101 mm depth ranged from a low of 7.2~ in January to a high of
32.3~ in July. The soil moisture averaged 6.6% in winter and 5.3% in
summer. The high summer soil moisture level was maintained by irrigation.
The alfalfa fields were flood-irrigated at approximately 30-day
intervals from April to September, with water covering the fields, except
irrigation levees, for nearly 24 h.
The relative humidity of the burrow measured 97.4• (N-=96).
Kennerly (1964), McSTab (1966), and Darden (1970) also recorded the
near saturated atmosphere of the gopher burrow. Darden (1970) determined
that the CO S concentration of the gopher burrow averaged 2.3 %,
and 03 averaged 18%. MeNab (1966) found an average CO S concentration
of 1.4 % in the burrow of Geomys pinetis Rafinesque, and Kennerly
(1964) measured only 0.8 % CO S in Geomys bursarius (Shaw) burrows. The
burrow temperatures showed less fluctuation than ambient temperatures
and were out of phase with them. Rust (1973b) showed the relationship
between ambient and burrow temperatures at two extreme times,
August and January.
In the artificial burrow system, the nest chamber temperature
averaged 20.5-V0.6~ C (N-=30) and the CO S concentration was 2.4-4-0.1%
(N=24). The soil moisture averaged 6.2% and ranged from 7.2% to
4.1%. The greenhouse temperature was maintained between 14.4 ~ and
25.0 ~ C. Thus, the conditions for experimentation are considered similar
to those that would be found in a natural burrow system, except during
the cooler winter months.