ChairpersonDr. S. Subramanian

Seminar LeaderDr. Debjani Dey

PARENTAL CARE IN INSECTs

Archana Anokhe

Roll. No - 20416

INTRODUCTION

THE EVOLUTION OF PARENTAL CARE IN INSECTS

FORMS OF PARENTAL CARE

MALE VERSES FEMALE CARE

HORMONAL REGULATION & CHEMICAL SIGNALING IN PARENTAL CARE

COST& BENEFITS OF PARENTAL CARE

CASE STUDY

OVERVIEW OF TOPIC

Parental care - any post-ovipositional behaviour that promotes survival, growth, &

development of offspring (Tallamy et al.,1984)

A prime example - altruistic trait evolved to enhance the fitness of the recipients

(offspring) at the expense to the donor (parents) (Royle et al., 2012)

Classified into 3 groups: Protect offspring Protect resources needed by the offspring Improve resources (Wood et al.,1991)

INTRODUCTION

Ecological factors - harsh environments, ephemeral food sources or predation pressure

THE EVOLUTION OF PARENTAL CARE (PC) IN INSECTS

Harsh environment

Ephemeral food

Predation pressure

Contd…..

• Egg attendance provides an alternative route to resist harsh environment

• For e.g.- staphylinid beetle, Bledius spectabilis live in intertidal saltmarsh, to prevent

flooding of their nest and anoxia of their eggs, females provide care in the form of closing &

reopening of the burrow

Harsh environmental conditions

• Burrower bug, Sehirus cinctus nymphs only eat seeds of Prunella spp. & are available for a

few weeks of spring, so mothers has to compete for this resource with in a short time span

• Specialized food of Cryptocercus spp. underlies the evolution of PC

Ephemeral or distant food sources and specialized foraging

(Tallamy et al., 2007)

Contd…..

Cont…..

• Predation play an important role in the evolution of parental care

• In the shield bug, Elasmucha spp. females shelter the eggs and nymphs by covering

them with their body and fanning their wings when attacked

• European beewolf (Philanthus triangulum), females provision brood cells with

paralysed honeybee (Tallamy et al., 2007)

Do natural enemies drive the evolution of PC ?

FORMS OF PARENTAL CARE

Diversity of social behaviour among the invertebrates - asset and challenge

Richness present in both number & forms of care provided by parents

50 families of arthropod have evolved parental care (Costa et al.,2006)

1. Trophic egg productions

2. Attending eggs and offspring

3. Protection and facilitating feeding of mobile young

a. Guarding young b. Poised to defend c. Egg dumping or brood mixing d. Formidable mother e. Blocking entry

5. Nest building and burrowing a. Hiding evidence b. Deceiving enemies

6. Brooding behavior & viviparity

Plassid beetle Cylindrocaulus patalis

Treehopper Umbonia crassicornus

a. Fungus feeding beetles Pselaphacus spsb. Assassin bug & Shield bugsc. European Earwig Forficula auriculariad. Praying mantis Oxyophthalmellus somalicuse. Myrmecine and Zacryptocerus varians

f. Solitary wasp g. Bembix sand wasps

Webspinner (Partenembia reclusa)

Cont…..Types Example

To making the correct choice of which eggs to consume, chemical cues is incorporated into the

trophic egg

Passalid beetle ,if 3rd instar larvae stridulate, they are fed by trophic egg

(Philipi et al., 2008)

Burrower bug , Sehirus cinctus produce some trophic eggs at the time when they produce viable

eggs as well as after the nymphs hatch. It provide food , when mother go for foraging

(Hironaka et al., 2005)

1. Trophic egg productions

Contd…..

• Treehopper Umbonia crassicornus, mothers tilt their elongated pronotum and fan the potential threats,

protecting their young until adulthood

• Offspring produce synchronous vibrations that inform the mother on which side threat is more

prominent (Ramaswamy et al., 2009)

• Mobile young feeding in open area vulnerable to predators & parasitoids

• Females standing nearby, not only threatening potential predators, but also stroking wandering nymphs (Lace bug) (Windsor et al., 1994)

2. Attending eggs and offspring

3. Protection of mobile young

Contd…..

a. Guarding young:- Brazilian sawfly, Themos olfersii, continues guarding their larvae even when they

fully sclerotized & starts feeding

b. Blocking entry:- In myrmecine colony major worker blocks entrance with its saucer-shaped head &

receives regurgitated liquid from a minor worker

Contd…..

Matthews & Matthews, 2010

c. Poised to defend :- Assassin bug & Shield bugs continuously watches her emerging nymphs to

defend her predator

d. Formidable mother :- The praying mantis Oxyophthalmellus spp. positioned herself at base of a

twig to intercept the predators

e. Egg dumping or brood mixing :- Spatial proximity leads to brood mixing & alloparental care

communal breeding, egg dumping (lace bug) ,take-over of nests & offspring is seen in case of

burying beetle (Smith et al., 2012)

Contd…..

1. Deceiving enemies :- A bombyliid bee fly, Parasitoid of solitary wasp larvae lay several

eggs into the fake nest entrance made by the wasp

2. Hiding the evidence:- Synchronous motions of the front tarsi , rake the sand & producing

a

characteristic pattern which hide its actual nest eg:-Bembix sand wasps•

4. Nest building & Burrowing

Contd…..

4. Brooding behavior & viviparity Contd…..

An alternative form of protection is to carry eggs or young either internally or externally

(Kolliker et al., 2013)

Contd….. 2013 The Royal Entomological Society, Ecological Entomology, 38, 123–137

Parental care – is indication of higher evolution

Types of care provided by either of the parent vary with the insect to insects

Dermapterans guard their egg until they hatch & cockroaches carry them in protective ootheca

FEMALE VS. MALE CARE

(Costa, 2006)

o Maternal care is most exclusive form of parental care

o Damsel bug is a fearsome enemy of Lace bug , if given a chance will devour every last nymph ,such case she diverts enemy by fanning her wings and climbing on its back

o Also guide the nymphs to an ideal leaf by blocking a branch which they mistakenly follow, all too often she dies in the attack (Noldus et al., 1991)

MATERNAL CARE

Tortoise beetle Acromis sparsa arrange themselves into a symmetrical ring around the hatchlings & allow them to reach near food sources in round up manner

Harlequin stink bug Tectocoris spp. defends her eggs aggressively because she lays only one batch & are her sole chance for reproductive success

Contd…..

(Ken Preston et al., 2010 )

Cont…..

P physical (nest, burrow, gallery tunnel, brood ball, etc.); B behavioural (i.e. defence display, guarding); C -chemical (defensive pheromone, aggregation pheromone, alarm pheromone , antimicrobial substance ) (Goershon et al., 2001)

Many insects raise their offspring on organic substrates where Microbes is serious threat to offspring development and survival either by decomposing their food resources or by directly infecting the offspring

Objective:- To test the maternal egg attendance in the European earwig has a function as a social defense against mold

infection

To see the effect of egg attendance on hatching success

To investigated the potential roles of egg grooming behavior and maternal transfer of chemicals on hatching

Contd…..

Experiment 1: - Effects of maternal egg attendance with and without mold exposure on hatching success (A) and mean hatchling body weight (B)

Effect of mold spore exposure on the duration of maternal egg grooming was made over the course of a 75-min observation period

Result & DiscussionContd…..

AB

Control Treated

Parameter Control Treated

Egg attendance not attended Egg attendance not attended

Hatching success (Chi square) 138.08 130.21 59.85 55.34

Hatching success (%) 80 50 75 7

Body weight (Mg) 1.68 1.78 1.57 1.98

Contd…..

Experiment 2:- Effect of maternal presence on chemical compounds on egg surface

Change of total hydrocarbon quantities over time & total hydrocarbon quantities on glass beads mingled into maternally attended clutches and unattended clutches

The major Chemical were identified as

heneicosane (C21H44), Z-9-tricosene

(C23H46), tricosane (C23H48), Z-12-

pentacosene (C25H50) & internal standard

n-octadecane (C18H38)

Contd…..

1. Maternal egg attendance reduced the detrimental effects of spore

exposure

2. Spore exposure significantly increased the duration of maternal grooming

3. Attendance lead to incorporation of chemical compounds (hydrocarbons)

on the eggs

Contd…..

PATERNAL CARE

Exclusive paternal care has evolved in 8 order of insects

Males can improve female’s mating success by providing pre-zygotic nuptial gifts & post-zygotic offspring care

Two ways in which female choice promote the expression of arthropod paternal carea) Enhanced Fecundity Hypothesisb) Handicap Principle

(Tallamy et al., 2001)

Although sexual selection and natural selection can favour paternal behaviour, a number of parameter can help to determine which has dominated in due course of evolution

Trait Sexual selection Natural selectionClutch number produced Iteroparous (>1) Semeplarous (1)Mating opportunities Many FewCare versus foraging Care interferes with female foraging Care may or may not interfere with

female foraging Female preference Preference for guarding male No preference for guarding maleClutches guarded simultaneously >1 1Paternal selfishness Males will guard unrelated eggs Males will not guard unrelated eggs

By –M. Kolliker et.al., 2000

Contd…..

After mating, receptive males perform vigorous pumping

Females respond by climbing on the male’s back

The male abruptly ‘scrubs’ the female’s hemelytra, female repositions herself and begins to lay eggs

After 5 minute, male temporary forcing the female out of & begins a new bout of vigorous pumping

This cycle continues until the female’s total egg clutch is deposited on the males back

Sex reversal role…Female

Male

Female water bugs abandon their eggs to males that proceed to care for them. What has caused such an unusual behavior?An egg-encumbered male is placed in an aquarium, highest number (97%) of the eggs will hatch

Does this high egg survival rate depend upon eggs being carried on the back of a live male water bug? If so, why?Removing egg pads from the backs of six males, Smith placed each egg pad in a separate fingerbowl in the laboratory ,none of the eggs were survived

Was something about the male exoskeleton necessary to their development?Smith killed egg-bearing males and left them with eggs intact , but these eggs also failed to hatch

So attachment to a healthy male essential for hatching. Why?He noticed, male keep egg pad at or above the water’s surface. Perhaps regular exposure to atmospheric air is required for development

Reversed sex roles in the giant water bug, Abedus sps.Case study

(Robert smith,1970)

Females always prefer males which were already guarding egg of another female

Males willing to guard more than one clutch to promote re-mating

A male always willing to guard unrelated eggs to enhance his attractiveness

Contd…..

Reasons for paternity

BIPARENTAL CARE

Female attends the offspring until they pupate

She cleans mold growth & applying antimicrobial chemicals derived from her sternal glands

Male helps to dig the nest & compact the dung pat

Food relocation to nests reduce the predation risk

Dung beetle

(Matthews & Matthews 2010)

Mechanism of parental care – By direct internal chemical signals (i.e. hormones) and indirect external chemical signals (i.e. pheromone)

(Kolliker et al., 2007)

It influence maternal reproductive physiology and future reproduction

PHYSIOLOGICAL MEASUREMENTS OF PARENTAL CARE

• Chemical signalling - important mode of communication between parent & offspring

• Apis mellifera, larvae produce a brood pheromone that influences care behaviours of

workers

• JH, regulate the trade-off between care for current offspring and the production of new

eggs/clutches

Contd…..

(Mas et al., 2008)

JH

Contd…..

JH

Hypothetical mechanism for maternal care regulation

(Scott & Panaitof 2004 )

Age, Nutritional state & JH

1.

2.

Maculina rebeli, a butterfly parasitize by wasp (Delago et al., 2009)

Host manipulation for offspring care

Ichneumon eumerus

Plesiometa argyra

Hymenoipimesis spp

3.

Bee wolf (Egyptian digger asp) Philanthhus triangulam known as paralysis inducing wasp. Its venom

contains potent neurotoxin (Philathotoxin) that evoke neuromuscular paralysis Of Bee prey

(Delago et al., 2009)

Contd…..

4.

Sphecid wasp Ampulex compressa

paracitising Periplanata americana

for egg laying

Contd…..

(Delago et al.,2009 )

Parental investment benefits a current progeny at the expense of future reproductive

success

Protection of eggs is one of the most basic forms of parental care seen in many insects

(Clutton et al., 1991)

COST & BENEFIT OF PARENTAL CARE

1. Benefit of egg guarding: increased hatching success

• There is Correlation between the hatching success, offspring survival & total number of

guarding days by female presented below

QUANTIFYING THE COSTS AND BENEFITS OF PARENTAL CARE IN FEMALE TREEHOPPERS

Contd….Case study

0.0007

21.5 @ 0.23 Nymph/egg/day

No.

of

nym

ph

0.804

0.483

( ZINK et. al., 2003)

• Costs of egg guarding: decreased future reproduction

Early abandonment of eggs allowed females to increase the overall number of future broods

Means of the future number of broods initiated (A), the mean length of those future broods

(B), and the mean future guarding duration (C) for females abandoning versus remaining for

each of three stages of egg guarding.

Contd…..

4.6

6.41.23

0.62

14.4

10.0

Parameter Control (Egg guarding female) Treatment (Non egg guarding female)

Hatching success (In terms of per female) 0.007 nymph/female 0.005 nymph/female

(In terms of egg) 0.05 nymph /egg 0.03 nymph/egg

Survival of Hatchling 0.804 nymph /egg 0.483 nymph /egg

Presence of mutual friend ant

( After hatching) More i.e. 2.1 Less i.e. 1.02

Contd…..

Cost BenefitsEgg guarding represents aninvestment in terms of time , energy & reduced future fecundity

Egg guarding by adults acts to increase the hatching success

Opportunities for laying additional clutches will be reduced

Offspring survival in guarded clutch will increase increase

The egg guarding in Publilia concava shown the positive linear relationship between guarding duration and hatching success

Females that abandoned immediately after egg laying suffered a 50% reduction in hatching success

Contd……..

Case studies

Effect of Parental Care on the Duration of Larval Development and Offspring Survival in Nicrophorus mexicanus Matthews (Coleoptera: Silphidae)

Objective of study

1. To see the effect of parental presence on larval development

2. Effect of parental manipulation of the food resources on offspring survival

3. To see the difference in number of adult emerges during different treatment

By -Sofía et. al., 2011

Result & Discussion

Differences in time development & number of adult emergence among the three experimental groups in N. mexicanus 1.—Control group; 2.—Brood-mass present and parents removed; 3.—Without parental care (brood mass not present and parents removed).

10.20 +/- 0.37

11.40 +/-0.30

13.14 +/- 0.45

P<0.05

The larval development required is 10.20 +/- 0.37 ,11.40 +/-0.30 &13.14 +/- 0.45 days respectively in Group 1,2 & 3

Survival of larva at L1 is 97%,95% &90% respectively

Contd…..

Treatment groups Offspring survival

Parameter Ni L1 L2 L3

1) Control: parental care 390 97 90 70

2) With Brood-mass. Parents removed pre-hatching

468 95 89 60

3) Without parental care : with fresh meat, brood-mass no present and parents removed pre-hatching

351 90 77 28

• Significant differences in the variation the number of offspring surviving to adult emergence between three experimental groups

• The number of adults that emerged was significantly different among the three groups (X2 =11.96, df = 5, P , 0.05)

Contd….

Comparedgroups

Difference Q

1 Vs 3 28.13 – 12.78 = 15.35 3.214

1 Vs 2 28.13-25.93 = 2.2 0.47

2 Vs 3 25.93 -12.78 = 13.15 2.75

Contd….

Larval development was significantly shorter in the control group

The presence of both parents and brood mass were required for larvae to reach adulthood

The differences is due to better nutritional quality of the food prepared by parents through

the oral and anal secretions

Contd….

Objective :-

To investigate the effect of mother presence on hatching synchrony

What effect does parental care have upon hatching of embryos?

To ascertain whether embryos hatch , in response to the vibrational signal of mother

Maternal vibration induces synchronous hatching in a sub- social burrower bugCase study 2

By-Hiromi et al., 2012

Occurrence pattern of maternal vibration. Means +SD are shown for bouts/min from the start of vibration generated by seven mothers.

Hatching was synchronous, passing through a fixed series of sequential steps

Hatching pattern of embryos exposed to the different treatments. Mean + SD are shown for the percentage of hatched eggs at 5 min intervals for the first 90 min, and for 12 h and 24 h from the start of hatching.

Result & Discussion

47.8+/-17.4 bouts of vibration /min

13.7+/-1.4 bouts /min

Schematic diagram showing artificial vibration. Coiled a rigid wire around an electrodynamics cordless motor glued a dead mother touching a mature egg mass with mid-leg

a

b

39.4+/- 22.2 80.8 +/- 17.6

88.2 +/- 14.4

92.0+/- 13.7

Duration of hatching Rate of vibrationAt 1st minute 13.7+/-14.4 bouts of vibration /minAt 8th minute 47.8+/-17.4 bouts of vibration /minAt the end 39.1+/-13.8 bouts of vibration /min, Mother Starts trophic egg production

Duration of hatching Hatching success in Control & treated group

After 12 hour 97.0 +/- 4.5% and 94.5 +/- 6.5% respectivelyAfter 24 hour 97.0 +/- 4.5% and 96.0 +/- 3.5% respectivelyDuration of hatching Hatching success during artificial vibration

At 1st 15 minute 39.4+/- 22.2After 90 minute 80.8 +/- 17.6After 12 hour 88.2 +/- 14.4After 24 hour 92.0+/- 13.7

Parents regulate the hatching.

Mothers were observed to guarding the egg mass without feeding for 6 to7 days

Highly synchronous hatching begins at 8.7 +/- 1.4 , which corresponded to the peak of the

maternal vibration

Parental care have many adaptive advantage for offspring

Synchronous hatching promote aggregation of young-one

Large scale aggregation of offspring act as cooperative defense

CONCLUSION

FUTURE PROSPECTS

Study of parental care behavior help in mass killing of insect by

locating the brood site

If it is a parasitoid of any insect pest ,we can colonies it by habitat

management to control the host species