Termite Embryos
Undergraduate Category: Physical and Life Sciences Degree Seeking: Biology Abstract ID# 1916
Termite Embryos: Defenses from Within
Chorion
Alexa Diiorio, Jeremy McDavid, Rebeca Rosengaus, Erin Cole Approach
Opportunity Abstract
Methods
The dampwood termite, Zootermopsis angusticollis, lives in environments heavily colonized by diverse microbial communities. Termites have adapted immune responses to combat entomopathogens such as bacteria and fungus. To test whether termite embryos that are oviposited into this same microbial-rich environment have any anti-fungal properties of their own, we incubated conidia of the entomopathogenic fungus Metarhizium anisopliae with termite embryos of different developmental stages and recorded conidia germination rates. The antifungal activity was stage-dependent, with more mature embryos (Stage 3) exhibiting significantly higher antifungal activity than intermediate (Stage 2) embryos and recently oviposited (Stage 1) embryos. This data therefore, debunks the idea that embryological stages of insects are at the mercy of pathogens and shows that termite embryos may have innate responses to prevent mycosis.
• •
Z. angusticollis embryos were collected from mature colonies and staged under a microscope at 400x magnification using the classification process pictured on the right Embryos were then designated to one of three experimental groups: •
•
•
Zootermopsis angusticollis (Commonly referred to as the ”Pacific dampwood termite”) • Indigenous to the Pacific coast of North America • Colonize in wood containing high-moisture, including rotting tree stumps and other microbial-rich environments • Eusocial colonies with cooperative brood care • Division of labor between reproductives and non-reproductives Metarhizium anisopliae A queen termite • Fungus that thrives in soil An insect that has • Common pathogen to insects, including termites become infected by • Mitotic spores (conidia) germinate on and penetrate insect exoskeletons Metarhizium anisopliae • Commonly used as a biological insecticide Possible sources of antifungal activity in termite embryos Chorion • Extraembryonic: • Parental care (salivary secretions) • Actinomycetes present in soil (highly antifungal bacteria) • Intraembryonic: Embryo • Genes for resistance to certain fungi • Immune system development with embryonic development
• • • • •
Results
Intraembryonic fungistatic effect: Surface sterilized and then sonicated embryos in solution • Tests effects of intraembryonic factors
•
Overall fungistatic effect: Non-surface sterilized and sonicated embryos in solution • Tests effects of intraembryonic + extraembryonic factors
n=33
The three classified stages of embryonic development of a termite
The solution used contained Tween 80 (a detergent), PBS (Phosphate buffered saline), and PI (protease inhibitor) Embryos in each experimental group were incubated with conidia of M. anisopliae for 24 hours The embryos and conidia in solution were then plated on PDA slides and incubated for 18 hours in a moist environment at room temperature Germination rates of the conidia were observed at 400x magnification and recorded Two controls groups were used in each experimental trial • Conidia + Tween 80: Demonstrates that conidia is viable and gives germination rates under normal circumstances • Conidia + Tween 80 + PBS/PI: Demonstrates the minimal effect that the addition of PBS/PI has on germination rates
Impact
Extraembryonic Effect n=15
Extraembryonic fungistatic effect: Non-sonicated embryos in solution • Tests effects of extraembryonic factors
•
Introduction •
Embryo
n=24
Intraembryonic Effect n=6
Overall Effect
n=12 n=3
n=34 n=39 n=31
n=12
• No significant differences in antifungal activity • Suggests that extraembryonic influences may not be responsible for significant anti-fungal properties
• Although intraembryonic influences seem to show a slight decrease in median, these differences are not statistically significant
• Differences in antifungal activity are statistically significant
• Although not significant, intraembryonic influences may play a greater role later in embryonic development
• When combined, intraembryonic and extraembryonic fungistatic influences may play a greater role later in embryonic development
• Statistical insignificance might be attributed to very low sample size
Acknowledgements:
Conclusions • Termite embryos possess fungistatic properties that appear to be most significant when environmental (extraembryonic) influences, such as parental care by way of salivary secretions or actinomycetes that are present in soil, are coupled with genetic (intraembryonic) influences, such as genes that carry resistance to certain fungi • Defense mechanisms increase in strength as termites progress through embryonic development, making them increasingly less vulnerable to fungal infection • Increases the likelihood that these embryos will grow to be healthy, adult termites that will positively contribute to the overall strength of the colony •
Conidia of Metarhizium anisopliae on a termite cuticle
Our study delves into a rather untapped area of insect immunology research; that of insects that have yet to be hatched • There is very little research on the anti-microbial properties of embryos • This may help determine exactly how/when immune responses are acquired by termites
I would like to thank all members of Professor Rosengaus’ lab for all of their assistance and guidance, and for making the lab such a fun and friendly environment!
A cluster of termite embryos within a colony
Termite Embryos: Defenses from Within
Chorion
Alexa Diiorio, Jeremy McDavid, Rebeca Rosengaus, Erin Cole Approach
Opportunity Abstract
Methods
The dampwood termite, Zootermopsis angusticollis, lives in environments heavily colonized by diverse microbial communities. Termites have adapted immune responses to combat entomopathogens such as bacteria and fungus. To test whether termite embryos that are oviposited into this same microbial-rich environment have any anti-fungal properties of their own, we incubated conidia of the entomopathogenic fungus Metarhizium anisopliae with termite embryos of different developmental stages and recorded conidia germination rates. The antifungal activity was stage-dependent, with more mature embryos (Stage 3) exhibiting significantly higher antifungal activity than intermediate (Stage 2) embryos and recently oviposited (Stage 1) embryos. This data therefore, debunks the idea that embryological stages of insects are at the mercy of pathogens and shows that termite embryos may have innate responses to prevent mycosis.
• •
Z. angusticollis embryos were collected from mature colonies and staged under a microscope at 400x magnification using the classification process pictured on the right Embryos were then designated to one of three experimental groups: •
•
•
Zootermopsis angusticollis (Commonly referred to as the ”Pacific dampwood termite”) • Indigenous to the Pacific coast of North America • Colonize in wood containing high-moisture, including rotting tree stumps and other microbial-rich environments • Eusocial colonies with cooperative brood care • Division of labor between reproductives and non-reproductives Metarhizium anisopliae A queen termite • Fungus that thrives in soil An insect that has • Common pathogen to insects, including termites become infected by • Mitotic spores (conidia) germinate on and penetrate insect exoskeletons Metarhizium anisopliae • Commonly used as a biological insecticide Possible sources of antifungal activity in termite embryos Chorion • Extraembryonic: • Parental care (salivary secretions) • Actinomycetes present in soil (highly antifungal bacteria) • Intraembryonic: Embryo • Genes for resistance to certain fungi • Immune system development with embryonic development
• • • • •
Results
Intraembryonic fungistatic effect: Surface sterilized and then sonicated embryos in solution • Tests effects of intraembryonic factors
•
Overall fungistatic effect: Non-surface sterilized and sonicated embryos in solution • Tests effects of intraembryonic + extraembryonic factors
n=33
The three classified stages of embryonic development of a termite
The solution used contained Tween 80 (a detergent), PBS (Phosphate buffered saline), and PI (protease inhibitor) Embryos in each experimental group were incubated with conidia of M. anisopliae for 24 hours The embryos and conidia in solution were then plated on PDA slides and incubated for 18 hours in a moist environment at room temperature Germination rates of the conidia were observed at 400x magnification and recorded Two controls groups were used in each experimental trial • Conidia + Tween 80: Demonstrates that conidia is viable and gives germination rates under normal circumstances • Conidia + Tween 80 + PBS/PI: Demonstrates the minimal effect that the addition of PBS/PI has on germination rates
Impact
Extraembryonic Effect n=15
Extraembryonic fungistatic effect: Non-sonicated embryos in solution • Tests effects of extraembryonic factors
•
Introduction •
Embryo
n=24
Intraembryonic Effect n=6
Overall Effect
n=12 n=3
n=34 n=39 n=31
n=12
• No significant differences in antifungal activity • Suggests that extraembryonic influences may not be responsible for significant anti-fungal properties
• Although intraembryonic influences seem to show a slight decrease in median, these differences are not statistically significant
• Differences in antifungal activity are statistically significant
• Although not significant, intraembryonic influences may play a greater role later in embryonic development
• When combined, intraembryonic and extraembryonic fungistatic influences may play a greater role later in embryonic development
• Statistical insignificance might be attributed to very low sample size
Acknowledgements:
Conclusions • Termite embryos possess fungistatic properties that appear to be most significant when environmental (extraembryonic) influences, such as parental care by way of salivary secretions or actinomycetes that are present in soil, are coupled with genetic (intraembryonic) influences, such as genes that carry resistance to certain fungi • Defense mechanisms increase in strength as termites progress through embryonic development, making them increasingly less vulnerable to fungal infection • Increases the likelihood that these embryos will grow to be healthy, adult termites that will positively contribute to the overall strength of the colony •
Conidia of Metarhizium anisopliae on a termite cuticle
Our study delves into a rather untapped area of insect immunology research; that of insects that have yet to be hatched • There is very little research on the anti-microbial properties of embryos • This may help determine exactly how/when immune responses are acquired by termites
I would like to thank all members of Professor Rosengaus’ lab for all of their assistance and guidance, and for making the lab such a fun and friendly environment!
A cluster of termite embryos within a colony
