Host-feeding and oviposition by parasitoids on hosts of different fitness value: Influences of egg load and encounter rate |
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Authors: | Robert McGregor |
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Institution: | (1) Behavioral Ecology Research Group, Simon Fraser University, V5A 1S6 Burnaby, B.C., Canada;(2) Cropconsult Ltd., 3041 West 33rd Avenue, V6N 2G6 Vancouver, B.C., Canada |
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Abstract: | A dynamic optimization model is presented for the decision to host feed or oviposit on hosts by female parasitoids. Optimal
host utilization decisions are compared between two host types with different fitness payoffs for oviposition. The model predicts
that hosts of higher fitness value should always be used for oviposition unless the egg load approaches zero. This general
prediction is not influenced by levels of host availability or metabolic reserves, the age of the parasitoid, or the magnitude
of the fitness difference. An egg-load threshold is predicted above which lower value hosts should be used for oviposition
and below which they are used for host feeding. The position of this egg-load threshold is higher when the difference in fitness
between host types is larger. The threshold is also higher when overall host availability is high or metabolic reserves for
the production of new eggs are low. The threshold for oviposition on low-value hosts decreases to zero near the end of the
parasitoid’s life. Under conditions where high-value hosts are rarely encountered compared to low-value hosts, the model predicts
that lower value hosts should be accepted for oviposition at a lower egg-load threshold. |
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Keywords: | dynamic optimization models parasitoids host feeding egg load oviposition behavior |
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