The effect of temperature on host patch exploitation by an egg parasitoid

Area of Science:

• * Entomology
• * Behavioral Ecology
• * Climate Change Biology

Background:

• * Temperature is a critical factor influencing insect behavior and reproductive success.
• * Understanding temperature effects on parasitoid foraging is vital for biological control strategies.
• * The egg parasitoid Anaphes listronoti (Hymenoptera: Mymaridae) is an important natural enemy of the carrot weevil, Listronotus oregonensis.

Purpose of the Study:

• * To investigate the influence of different temperatures on the foraging behavior of Anaphes listronoti.
• * To determine how temperature affects host patch exploitation, host acceptance, and offspring characteristics.
• * To assess the implications of temperature variations for parasitoid performance in the context of climate change.

Main Methods:

• * Laboratory experiments were conducted to observe Anaphes listronoti behavior at five distinct temperature points (15.9°C, 20°C, 25°C, 30°C, and 32.8°C).
• * Behavioral assays focused on host patch exploitation, including parasitism rates, host acceptance mechanisms, and time spent on the patch.
• * Offspring sex ratio and clutch size were analyzed across different temperature treatments.

Main Results:

• * Temperature significantly affected the tendency of Anaphes listronoti females to exploit host patches, with higher parasitism rates observed at intermediate temperatures (20-30°C).
• * Extreme temperatures (15.9°C and 32.8°C) resulted in reduced parasitism, with altered host acceptance mechanisms at high temperatures (32.8°C), possibly due to impaired sensory detection.
• * Increasing temperatures led to decreased time spent on the host patch, but patch-leaving rules remained unaffected.

Conclusions:

• * Anaphes listronoti exhibits suboptimal foraging performance at both low and high temperatures, with supra-optimal temperatures being particularly detrimental.
• * Altered host handling and sensory perception at high temperatures can compromise parasitoid effectiveness.
• * Projected climate change scenarios may negatively impact the efficacy of Anaphes listronoti as a biological control agent for the carrot weevil.