Feeding Performance and Effectiveness of Ladybird Beetles (Coleoptera: Coccinellidae) for Cowpea Aphid

(Aphis craccivora Koch) Control.

ByD.K Murahwi

Supervisors: Mr. Matsiga Prof. Mvumi

BACKGROUND

Many farmers in Zimbabwe are relying on pesticides for control of crop pests, (Mudimu et al. 1995).

Pesticides tend to have a non-selective effect on insects, (Ali et al. 2011).

There is a global shift towards organic and sustainable agriculture.

BACKGROUND CONT’

Ladybird beetles are the perfect candidate as biological control agents, since they are voracious predators (in both larval and adult stage), (Brewer & Oswald II 1995).

Can supplement their diet with pollen, nectar, or honeydew, (Cranshaw, 2014).

Although slow this method is effective in both curative and preventative measures of dealing with phytophagous insects.

RESEARCH PROBLEM and JUSTIFICATION

Research ProblemAphids are a major crop pest and tend to develop resistance to pesticides.

There are side effects associated with chemical pesticides

Thus chemical control being pushed out especially in the wake of organic farming

Justification Berlandier et al, (1998) research on aphid effect on lupin plants.

The beneficial aspects of insects outweigh the detrimental effects, (Goodwin 2014).

OBJECTIVES

Broad DetermineTo determine feeding performance and effectiveness of ladybird beetles for the control of cowpea aphids.

Specific1. To evaluate the feeding of native ladybird beetles on

cowpea aphids.2. To evaluate the feeding of native ladybird beetles

possible alternative diets.3. To identify the native ladybird species most suited to

effectively control cowpea aphids.

HYPOTHESES

1. H1: Native ladybird beetles are effective consumers of cowpea aphids.

2. H1: Ladybird beetles can survive on possible alternative food sources.

3. H1: Different native ladybird beetle species have different consumption rates of cowpea aphid.

MATERIALS AND METHODSGENERALUZ Crop Science Dept. cowpea plot in Natural Region 2a (18o12’S, and 31o 05’E) for the aphid and ladybird beetle source.

UZ Crop Science Dept. Entomology Laboratory averaging 26oC and 42% RH for food source experiments 1, 2, 3 and 4.

Study design had 3 treatments (Cheilonomes geisha, Hippodamia variegata and Cheilonomes lunata) and blocking by day for all 4 experiments.

Feeding samples were taken for each treatment and the weight changes averaged for the specific day to the particular treatment.

MATERIALS AND METHODS

30mg of food source was presented to the test subjects and after a 2 hour period the weight change of the food source was measured and recorded.

This was repeated for each day the experiment was run.

MATERIALS AND METHODS

OBJECTIVE 1Experiment 4 using cowpea aphid as the food source was done (02/03/15).

OBJECTIVE 2Experiment 1, 2 and 3 using Bee Pollen (07/01/15), Dried Ground Chicken Liver(13/03/15) and Shredded Tuna (18/03/15) respectively as the alternative diets.

OBJECTIVE 3Experiment 4 on cowpea aphid as the food source (02/03/15).

DATA COLLECTION AND ANALYSIS

Weight changes were measured at 2 hour intervals for the feeding samples which were ranging from 3 to 20 and averaged for each particular species.

This was done each day the experiment was run.Statistical package Minitab16 was used for analysis of the generated data.

Friedman’s test was carried out for test of significance and box plots used for graphical display of significance.

RESULTS

Figure 4.1: C. geisha, H. variegata and C. lunata

EXPERIMENT 1

Table 4.2: Friedman’s Test on Bee Pollen Data

Species Weight Changes (mg)

C. geisha 29.1

H. variegata 29.3

C. lunata 29

Grand median 29.1

P value 0.202

EXPERIMENT 2

Table 4.4: Friedman’s Test on Dried Ground Chicken Liver

Species Weight Changes (mg)

H. variegata 29.25

C. lunata 28.35

Grand median 28.8

P value 0.564

EXPERIMENT 3

Table 4.6: Friedman’s Test on Shredded Tuna

Treatments Weight Changes (mg)

Control 5.8667

H. variegata 6

C. lunata 5.2333

Grand median 5.7

P value 0.529

EXPERIMENT 4

C.lunataH.variegataC.geisha

30

28

26

24

22

20

18

16

Species

Weig

ht C

hang

e (mg

)

Boxplot of Weight Change

Figure 4.3: Box Plot of Aphid Consumption.

EXPERIMENT 4

Figure 4.4: Line graph of Ladybird Beetle Field Population

DISCUSSION

In this study, the ladybird beetles could not be reared on the possible alternative food sources Bee Pollen, Dried Ground Chicken Liver and Shredded Tuna.

Smith (1960) successfully reared ladybird beetles on corn pollen.

Kariluoto et al. (1976) and Kariluoto (1980) in Da Silva et al. (2010; pg 15) reveal diets based on pig liver have been developed.

DISCUSSION

The ladybird beetles were effective feeders of aphids. C. lunata was the heavier aphid feeder among the three species followed by H. variegata and C. geisha was the least.

Ladybird beetles are voracious feeders of aphids influenced prey and predator attributes, (Ferran & Dixon 1993).

In North Dakota in the period June and July of 1949 successful control of aphid infestation in wheat (Munroi & Somsen 1949).

CONCLUSION

The native ladybird beetle were found to be effective cowpea aphid feeders.

Although an alternative diet for rearing was not found in the current study, C. lunata was observed to be most suitable for control of Aphis craccivora Koch.

RECOMMENDATION

Maize pollen and cowpea pollen should be considered for research as alternative diet.

Research on possible artificial diets for the mass laboratory production of C. lunata would be important for cost effective production of the biological control agent for successful control of Aphis craccivora Koch

ACKNOWLEDGEMENTS

Peace Mujuru for the source of aphidsMrs Mutisi and Mr Vengai from Entomology Department of DR&SS for species identification

Dr David Icishahayo for statistical aidDr Mabasa for technical and technological assistanceDepartment of Crop Science Staff for their time and dedication

My Colleagues for moral and academic support

Thank you