Use of Plant Resin by a Bee Assassin Bug Apiomerus flaviventris

(Hemiptera: Reduviidae)

Apiomerus flaviventris Herrich-Schäffer

Consuming the hemolymph or enzymatically pre-digested internal tissues of prey insects

Bee assassin bug

Active predator

Injecting venom

Southern California, Arizona, and Mexico

Study area: Anza Borrego Desert State Park (April to June 2006)

Distribution of A. flaviventris

http://www.desertmuseum.org

Association with Plant Resins

Adult female

Larvae

Resinous plants

Setae on Ventral Surface

Female

Male

Metatibial comb

Metatibial Comb

Collecting Brittlebush Resin

(A~C: resin collection, D: brittlebush resin)

Resin-covered Egg Mass

What do they do with the resin?

A. flaviventris oviposition

What do they do with the resin?

With plant resin Without access to resin

Use of Resin

Formation of tightly-packed egg mass

What do they do with the resin?

Resin on Egg Mass

Protect eggs against parasitoids

Prevent the eggs from desiccating

Deter egg predators such as ants

(Swadener and Yonke 1973, Szerlip 1980, Eisner 1988)

© Szerlip

Resin Deterrence Test

Forelius pruinosus Linepithema humile

Does brittlebush resin deter omnivorous ants?

(Choe and Rust 2007)

Resin-free eggs: more readily picked up and carried away by ants

Resin-coated preys: less preferred by omnivorous ant species

Does brittlebush resin deter omnivorous ants?

Resin Deterrence Test

(Choe and Rust 2007)

Feeding Deterrence… Why?

Stickiness?

Phytochemical property of the resin: chromene and benzofuran derivatives (Kunze et al. 1995)

Deterrent as well as toxic towards various herbivorous insects

Does brittlebush resin deter omnivorous ants?

First instar larvae collected resin from the outer surface of the egg mass, coated their foretibia with the resin

First Instar Larvae

Protect larvae against predators or help prey capture (Eisner et al. 2005)

In addition to the plant resin…

Ventral abdominal surface of a adult female without access to resin sources

(Barth 1963, Szerlip 1980)

Bugs produce their own secretion?

In addition to the plant resin…

Bugs produce their own secretion?

Numerous female specific pores on ventral-abdominal surface of female

Magnified glandular pores

In addition to the plant resin…

Bugs produce their own secretion?

Internally, small ducts are associated with the pores

In addition to the plant resin…

Bugs produce their own secretion?

Small ducts associated with the pores: part of glandular unit (Barth 1963)

In addition to the plant resin…

Bugs produce their own secretion?

© Barth© Barth

What are there in the secretion?

Resin-covered eggs

Resin-free eggs

Brittlebush Resin

TLC using 100% hexane solvent system

Non-polar compounds

Polar compounds

Hydrocarbons

Identification of the secretion

C23 11

Me-

C23

C 24 11M

e-C

24

C25

mo

no

ene

C2

5M

e-C

25s

C26

C2

7

C28

C2

9

Retention time (min)

GC-MS Analysis of Hydrocarbons

Resin-covered eggs

Resin-free eggs

Identification of the secretion

Higher amount of hydrocarbons in the resin covered egg mass

Major alkanes (C25, 27, 29) per egg 8 : 1

Major methyl-branched alkanes (Me-C23, Me-C25s) per egg

13 ~ 15 : 1

What are there in the secretion?

Identification of the secretion

Acknowledgments

Anza Borrego Desert State Park

Anza Borrego Foundation and Institute

California State Parks Colorado Desert District

Jocelyn Millar

Steve McElfresh

Douglas Yanega

Hyunchung Yoo

Not only resin, but also …

Summary & Discussion

Under UV CharredA: Resin-covered egg mass extract

B: Brittlebush resin

A B A B 3:1= hexane: ethyl acetate

• A: Extract of 44 eggs coated with brittlebush resin by a female bug

• B: Extract of 44 resin-free eggs

• 2 μl of each extracts spotted (i.e., each spot contains approximately 0.088 egg equivalent hydrocarbons)

Summary & Discussion

A B

Hydrocarbons