D3300: Behavior of Helicoverpa zea pre-pupae and emergence of adults in different soil types and moisture levels

Helicoverpa zea is one of the main pests in the southern United States, attacking
many agricultural crops. When the larvae reach the last larval stage, they quest
for a place to bury themselves and eclose into pupae in the soil for protection
against parasitoids, predators and harmful abiotic factors. This research aimed
to investigate the influence of different levels of soil moisture on the burrowing
behavior, survival and emergence of Helicoverpa zea pupae. A greenhouse
experiment was set up with sandy and clay soil in buckets, in a completely
randomized design with two treatments. Twelve laboratory-reared H. zea
caterpillars were added per bucket. In the first treatment, both soils were started
with a moisture level of 5% defined by weight. Seven days after the caterpillars
were added, soil moisture level in half the buckets was increased to 50%. In the
other treatment, soil moisture was kept at 25%. Each treatment was replicated
ten times. The number of caterpillars that burrowed after 24 and 48 hours and
number of emerged moths were recorded daily until emergence ceased. In this
experiment, increasing water content did not affect emergence of H. zea adults.
However, moisture level did influence the burrowing behavior of pre-pupal larvae;
more larvae (34.7) burrowed when soils were at an intermediate level of moisture
(25%) than a lower level of moisture (28.3; 5%), supporting the idea that moisture
is an influential factor for H. zea burrowing behavior.