ACE Nutrition & Dietary Needs 3 — Questions and Answers
Question 1: What nutritional deficiency most commonly limits insect performance when feeding on plant phloem?
- Carbohydrate deficiency
- Essential amino acid deficiency (Correct answer)
- Lipid deficiency
- Mineral deficiency
Correct answer: Essential amino acid deficiency
Phloem sap is rich in sugars but poor in essential amino acids, making nitrogen the key limiting nutrient for phloem-feeding insects.
Question 2: An insect's ability to regulate the ratio of protein to carbohydrate intake is best described by which concept?
- Nutritional geometry (geometric framework) (Correct answer)
- Liebig's law of the minimum
- Bergmann's rule
- Holling's disk equation
Correct answer: Nutritional geometry (geometric framework)
The geometric framework of nutrition (nutritional geometry) models how insects actively regulate macronutrient intake to reach a specific protein-to-carbohydrate target.
Question 3: Which vitamin is particularly critical for insect vision and is often limiting in herbivorous insects feeding on mature leaves?
- Vitamin B12
- Vitamin C
- Beta-carotene (Vitamin A precursor) (Correct answer)
- Vitamin K
Correct answer: Beta-carotene (Vitamin A precursor)
Beta-carotene, a precursor to retinal used in photoreceptor pigments, is especially important for insect visual function and can be limited in senescing plant tissue.
Question 4: Coprophagy in certain insects such as termites primarily serves to:
- Eliminate excess nitrogen
- Re-acquire gut symbionts and nutrients (Correct answer)
- Deter predators with fecal chemicals
- Regulate gut pH
Correct answer: Re-acquire gut symbionts and nutrients
Termites practice coprophagy to re-inoculate their gut with essential protozoa and bacteria and to recover incompletely digested nutrients.
Question 5: Which of the following best describes the dietary classification of a polyphagous pest?
- Feeds on a single host plant species
- Feeds on a narrow range of related plant families
- Feeds on a wide variety of unrelated plant species (Correct answer)
- Feeds only on animal tissue
Correct answer: Feeds on a wide variety of unrelated plant species
Polyphagous insects consume a broad range of taxonomically unrelated hosts, making them particularly challenging pests from a management perspective.
Question 6: In holometabolous insects, the nutritional needs of larvae and adults are often very different because:
- Adults lack a functional digestive system
- Larvae accumulate reserves for metamorphosis while adults focus on reproduction (Correct answer)
- Adults consume more protein than larvae
- Larvae rely entirely on maternal nutrition
Correct answer: Larvae accumulate reserves for metamorphosis while adults focus on reproduction
Larvae of holometabolous insects function primarily as feeding and growth stages, storing nutrients used during pupal metamorphosis, while adults focus on dispersal and reproduction.
Question 7: What is the primary function of the fat body in insect nutrition?
- Produce digestive enzymes for the midgut
- Store and metabolize nutrients including lipids, glycogen, and proteins (Correct answer)
- Synthesize chitin for the cuticle
- Regulate water balance through the Malpighian tubules
Correct answer: Store and metabolize nutrients including lipids, glycogen, and proteins
The insect fat body is a multifunctional metabolic organ that stores lipids, glycogen, and proteins and mobilizes them during starvation, metamorphosis, and reproduction.
ACE Nutrition & Dietary Needs 3
What nutritional deficiency most commonly limits insect performance when feeding on plant phloem?