Hao Wu

Supervisors: Dr. Appel , Dr. Hu

Committee member: Dr. Peng Zeng

July 8, 2013

Overview

Introduction: Cockroach, the Dubia Cockroaches

Part I: Instar determination

Part II: Parental care

Part III: Temperature-dependent development

Question?

1 Locomotion: Ground, Water and Air

2 Diets: Omnivores (or unknown)3 Reproduction: Great diversity Oviparity A, Oviparity B Ovoviviparity A, Ovoviviparity B Viviparity4 Sociality: Solitary, Subsocial, Eusocial (termites)5 Relation to Humans: Pests, Pet

Diet, Pet, Medicine

Cockroaches (Blattodea)

The Classical Cockroach Phylogeny of McKittrick (1964)

The Dubia Cockroaches, Blaptica dubia(Blaberidae)

Locomotion: Ground

Diets: Omnivores

Reproduction:

Ovoviviparity A

Sociality:

Subsocial (Parental Care)

Relation to Humans:

Pet, Pet Diet

Source: http://en.wikipedia.org/wiki/File:Blaptica-

Dubia-cockroaches-x3-male-female-juvenile-v2.jpg

Oothec a of the Dubia Cockroaches, Photo

courtesy of Charles Stephen

The Dubia Cockroaches as food for pets

Excellent, protein-rich diet for insect eating pets

Various lizards, turtles, and snakes

Spiders

Overview

Introduction: Cockroach, the Dubia Cockroaches

Part I: Instar determination

Part II: Parental care

Part III: Temperature-dependent development

Question?

Part I Instar determination using Gaussian mixture model Basic research and application Growth, evolution

Life table analysis

Brooks-Dyar rule (Brooks 1886, Dyar 1890, Hutchinson 1984)

Objective:

Find a general way to determine instars of B. duia

MethodsStatistical analysis

Assumption: The measurement of sclerotized characters in each instar is Gaussian

distribution

Methods

Data collection

1925 cockroaches were measured

Measure the three variables: head width, pronotum length and width of the Dubia cockroach rearing in the lab (30℃, 12:12 (L:D) and supplied with water and dry dog Chow)

Statistical analysis

Overview

MethodsStatistical analysis

Gaussian Mixture model (GMM) (Johnson & Wichern 2007)

Mixture of two Gaussian

Gaussian Mixture model (GMM)

Three variables: head Width, Pronotum Length and Pronotum Width.

The multivariate case

More than two groups

GMM

Inference is based on maximum likelihood

(Johnson & Wichern 2007)

LikelihoodWe do not know the group the data belong to. i.e. We

do not know which instar the insect is, when we take the measurements

Hierarchical clustering, EM algorithms and Bayesian Information Criterion (BIC)

Software : R package mclust (Fraley & Adrian 2012)

Results

Table 1. The 95% simultaneous -intervals of the three characters (mm) in each instar

Instar 1 Instar 2 Instar 3 Instar 4 Instar 5 Instar 6 Instar 7

N 137 152 148 234 356 324 178

Length [2.37,2.45] [2.91,3.03] [3.77,3.87] [4.84,4.98] [6.11,6.23] [7.46,7.63] [9.30,9.47]

Width [4.14,4.22] [5.13,5.30] [6.40,6.54] [7.89,8.13] [9.86,10.04] [12.15,12.41] [15.04,15.30]

Head [1.78,1.80] [2.06,2.11] [2.47,2.51] [2.94,3.00] [3.53,3.58] [4.21,4.28] [5.00,5.07]

Result assessment

Table 2. The mean of the three characters(mm) in each instar and growth ratio

Characters Instar 1 Instar 2 Instar 3 Instar 4 Instar 5 Instar 6 Instar 7 Ratio

Length 2.41 2.97 3.82 4.91 6.17 7.54 9.39 1.26 Width 4.18 5.21 6.47 8.01 9.95 12.28 15.17 1.24

Head 1.79 2.08 2.49 2.97 3.55 4.24 5.04 1.19

Brooks-Dyar rule

In another study, the development of B. dubia was monitored at the same

conditions as stated above [30 ± 2°C,12:12 (L:D) h]. We directly observed seven

instars in B. dubia over a period of 6 months.(although there is few exception). In

addition, Hintze-Podufal and Nierling (1986) also indicated that there are seven

instars in B. dubia reared at 28 ± 2°C.

Part I Summary

This approach can be used to determinate instars of the Dubia cockroaches.

1. The growth rates follow Brooks-Dyar rule.

2. There are 7 instars in the Dubia cockroaches Blaptica dubia.

3. The growth rates of pronotum length, pronotum width and head width are 1.26, 1.24, 1.19 respectively.

This approach should be applicable to other insects, since the Dubia cockroaches comply with the same growth model with other insects

Overview

Introduction: Cockroach, the Dubia Cockroaches

Part I: Instar determination

Part II: Parental care

Part III: Temperature-dependent development

Question?

Part II Parental care effect

Objective: Determine if parental care affects development of the Dubia Cockroaches

Hypothesis: The presence of parents affects development of the Dubia Cockroaches

Method:

Compare the difference of

the head width, the pronotum

width and length, and the weight

difference in the last instar.

Compare the difference of the development time

Data Analysis:

ANOVA

Diagram of Experiment Design

Effect of parental care on development time

Table 3 Effect of parental care on development time (days)

Group number Neonate only With Adult female With adult male P value

1 142.9±9.662 139.7±11.715 141.4±9.985 0.810

2 165.3±6.873 147.0±13.476 158.1±17.201 0.083

3 202.5±8.536 210.4±34.122 222.5±28.224 0.330

4 167.6±12.293 161.5±19.206 160.3±11.056 0.590

5 130.4±9.812 130.8±9.203 132.9±7.120 0.830

6 175.7±25.050 171.8±15.106 158.8±25.246 0.280

Table 4 Effect of parental care on head width (mm)

Group number Neonate only With Adult female With adult male P value

1 5.079±0.1451 5.062±0.1737 5.033±0.2315 0.89

2 5.409±0.1384 5.367±0.1370 5.444±0.0967 0.49

3 5.233±0.1175 5.215±0.1428 5.244±0.0760 0.87

Group number Neonate only With Adult female With adult male P value

1 9.693±0.2693 9.732±0.3798 9.631±0.4897 0.89

2 10.10±0.3466 10.25±0.2518 10.07±0.2362 0.40

3 9.933±0.3678 9.787±0.3298 9.876±0.2452 0.62

Table 5 Effect of parental care on pronotal length (mm)

Effect of parental care on measurable characters

Table 6 Effect of parental care on pronotal width (mm)

Group number Neonate only With Adult female With adult male P value

1 15.22±0.2531 15.17±0.6773 15.37±0.6217 0.77

2 16.25±0.3955 16.05±0.3808 15.87±0.7114 0.33

3 15.49±0.5815 15.70±0.3813 15.63±0.4670 0.66

Group number Neonate only With Adult female With adult male P value

1 2.070±0.2062 2.122±0.2615 2.046±0.2952 0.86

2 2.644±0.1862 2.743±0.1750 2.487±0.2739 0.076

3 2.057±0.2271 2.165±0.2291 2.163±0.2734 0.57

Table 7 Effect of parental care on body weight (g)

Part II summary No parental care effect is detected.

Application:

No need to put an adult when start new colony.

Overview

Introduction: Cockroach, the Dubia Cockroaches

Part I: Instar determination

Part II: Parental care

Part III: Temperature-dependent development

Question?

Part IITemperature-dependent development

Objective: Find the ideal

temperature range for the

development of the Dubia

cockroaches

Hypothesis: 30°C~35°C will be

the best temperature range

Method: degree days

Data Analysis:

Linear regression

Diagram of Experiment Design

Degree-Days Calculation

Development time (Days , Hours)

Development rate( 1/D)

Temperatue(T)

1/D = kT + b

1/D = k(T –T0)

( T0 is the development threshold)

Degree days = D(T-T0) = 1/k

Table. 8 Development time of each instar in different temperature. (mean (SD) n)

instar 20°C 25°C 30°C 35°C

1 38.8 (3.96) 28 25.4(2.84) 36 20.08(3.23) 38 17.46(5.19) 59

2 79.9(5.931) 28 51.18(3.79) 34 36.06(4.63) 36 NA

3 116.15(8.60) 26 78.32(4.83) 31 53.26(7.28) 34 NA

4 161.74(13.91) 27 106.76(7.10) 33 70.28(8.41) 36 NA

5 220.48(24.54) 27 133.45(7.71) 33 87.56(8.91) 36 NA

6 NA 167.80(10.48) 105.70(17.00) NA

7 NA 233.20(17.55) 149.20(15.69) NA

Figure 2 The linear regression of development time of 1st instar

in 20°C, 25°C, 30°C, 35°C with 95% confidence interval.

Figure 3 The linear regression of development time of 2nd instar in

20°C, 25°C, 30°C with 95% confidence interval.

Table 3. Linear regression models of temperature-dependent development in the seven instars of B. dubia

Instar Model R squred F P ( > |t|)Lower Development

Threshold (°C)Degree days

1st instar Y = 0.0021X – 0.0148 0.984 120 < 0.01 7.02 457.5

2nd instar Y = 0.0149X – 0.0172 0.997 301 0.0366 11.56 668

3rd instar Y = 0.001023X – 0.01203 0.989 90.8 0.0666 11.83 1031

4th instar Y = 0.000805X – 0.010190 0.986 69 0.0763 12.66 1317

5th instar Y = 0.000689X – 0.009398 0.993 151 0.0157 13.65 1515

6th instar Y = 0.0007X – 0.0117 NA NA NA 16.48 1429

7th instar Y = 0.000483X – 0.007783 NA NA NA 16.12 2071

Summay

Acknowledgement Dr. Arthur Appel

Dr. Xing Ping Hu

Dr. Peng Zeng

Marla Eva

Charles Stephen

Zachary Devries

Znar Barwary

Yao Xu

Question? Thank you