16 Reproductive Damage
This protocol aims to assess damage by insect herbivores to reproductive parts of plants (i.e., flowers, fruits, and/or seeds). This is a supplement to the Primary Protocol, which aims to randomly select and sample 30 plants, plus their nearest conspecific neighbor, within a population.
Objectives: The goal is to measure the proportional damage to reproductive organs on each plant within the surveyed population. That is, for each individual plant we will record the number of damaged and undamaged reproductive organs. Ideally, these measurements should be taken as supplemental data for the same individual plants (focal and neighbor plants) for which leaf damage was taken for the primary protocol, although reproductive damage measurements are welcome from other plant populations from which no leaf damage measurements have been taken.
16.1 Protocol
Step 1: Select a species to survey: We are hoping to get broad taxonomic and geographic coverage of damage to reproductive organs. Therefore, any species could be surveyed. However, to ensure that the data are comparable across sites/species/families/etc, the plants should have the following characteristics:
At least half of the individuals at your site should possess reproductive material. If most of the plants are in a vegetative stage, you probably won’t be able to survey enough reproductive individuals to get a decent sample size. Ideally, >30 of the sampled plants will have reproductive damage data.
Each individual plant should produce enough flowers/fruits/seeds so that you can survey between 15-30 reproductive units per plant. These ‘units’ could be flowers, fruits, or seeds, whichever will give you enough things to count. For example, if your plants have just a few fruits, try opening fruits and counting a random sample of seeds, which could get you higher numbers. If some plants have fewer units (~5-10 flowers/fruits/pods/seeds), that is okay, as long as most have at least 15. If your species typically has only one or a few flowers, we have provided a modified protocol below
Most of the plants should be in a similar phenological stage. If there is a mixture of flowering and fruiting plants within the population, it might be difficult to get a large enough sample size for one organ type. Additionally, different phenological stages will likely be attacked by different insects.
If your plant does not meet these requirements, please skip measuring damage to reproductive organs. That’s okay. Or get in touch if you have questions
Step 2: Establish transect and select plants. Use the Primary Protocol to establish a transect, pick/calculate a quadrat radius, and randomly select focal/nearest neighbor plants.
Step 3. Identify the reproductive tissue you will be surveying (e.g., flowers, fruits, pods, seeds) and record data for each plant (see Figure 16.1):
- Phenology of the plant (i.e., budding, flowering, fruiting, etc.).
- Total number of units examined.
- Herbivore damage per unit: Either percent or count of injuries
- Pathogen damage per unit
- Unknown damage per unit (i.e., any damage not attributable to either herbivores or pathogens).
Ideally at least 30 reproductive units will be examined per plant. For plants that have much more than 30 units, examine a haphazard subsample of 30 units per plant. These should be sampled from different parts of the plant to obtain a good representative sample of damage levels to the plant. Damage measurements will be highly variable among species, depending on the types of flowers or fruits produced as well as the type of damage that is most common in the population. Below we give some general guidelines.
There likely will need to be modifications for some species, but we trust collaborators to do the best they can in their systems while maintaining the overall spirit of the protocol. For example, if your species has only one or a few flowers/fruit, you can estimate the damage as a percentage. Keep in mind that the goal is to capture the variability in damage rates among plants within a population, so you will want to choose a measure of flower/fruit/seed damage that best captures this variability.
16.1.1 Data Recording Tips
Record the following data in the provided printable and digital datasheets.
Start by surveying the type of damage that is most common on the reproductive structures of plants in the population. Look for damage by insects that may chew on developing flowers (e.g. katydids, beetles), insects that bore into flower heads or seeds (e.g. larval weevils, leps, or flies), or true bugs that may probe/pierce into the seeds or fruits (looks like little black dots on the fruits). In many cases you will need to tear open the seed head/fruit to look for boring insects inside the seeds/fruit. Look for signs of chewing damage inside the fruit, such as destroyed seeds and insect frass.
The best measurements of damage will depend on the type and extent of damage present. If the plant species experiences damage to multiple organs (e.g., petals, stamens, etc.), focus on the damage to the primary reproductive parts if it is not feasible to measure multiple organs.
In the reproUnit column of the reproData sheet in the template Excel datasheet, please record what organs you are recording damage on (e.g., stamens, petals for flowers). If present and identifiable, record the number and identity of the florivore, frugivore, seed predator
If your species has only one or a few flowers per plant and it’s possible to record the percent damage to a flower or fruit, you can record these percent damages in the percR# columns. 15 such columns are provided but please add more if you are able to record the per-unit damage of more than 15 reproductive structures
In the damageUnit column, record ‘count’ or ‘percent’ depending on whether you are recording the number of damage reproductive units or the percent damage to a single unit
Note that numReproHerb can be less than the sum of the counts of types of damage because a single reproductive unit can have multiple types of damage.
16.1.2 Examples of different types of damage to reproductive material
