field ecology studies on migratory locust

FIELD ECOLOGY STUDIES

ON MIGRATORY LOCUST

Terminal report presentation at the Office of the Vice Chancellor for Research and

Extension ,UP Los Baños ,College Laguna. February 21, 2011.

Bonifacio F. CayabyabProject Leader

National Crop Protection Center

Crop Protection Cluster

UP Los Baños, College Laguna

Dominador CanlasStudy Leader

DA Region III

San Fernando, Pampanga


Extension, UP Los Baños ,College Laguna. February 21, 2011.

IMPLEMENTING AGENCY :

COOPERATING AGENCIES :

NCPC-CPC-UPLB

College, Los Baños, Laguna

DA – Region III

San Fernando, Pampanga

LGU’s

DURATION : 1996-1998

FUNDING AGENCY : PCARRD-DOST

Los Baños, Laguna

TOTAL BUDGET : P 508,708.92



INTRODUCTION

Locust infestation started in 1992 in Central

Luzon where ash and lahar covered environment

promoted the concentration of incipient locust

populations. The site where swarms originated was

called the outbreak area. The suspected outbreak

area in Central Luzon was the mountainous vicinity

of Cawag, Subic, Zambales (Mt. Redondo). This

area was adjacent to the Zambales – Tarlac –

Pangasinan mountain range which was identified as

a permanent breeding area of locust.



Mt Redondo, Cawag Subic, Zambales the suspected outbreak

area of migratory locust in Central Luzon (white specks at

the foreground at right are adult flyers)



OBJECTIVES

• To study the biometrics and morphology of solitary

and gregarious locust individuals of both sexes.

• To observe and measure rates of development of

different life stages of locust in the field.

• To investigate the possible environmental and other

factors that influence population development and

shift from solitary to migratory phases.

• To study the ecology of breeding sites of locust.

• To observe and understand the aggregation process,

swarm formation and flight pattern of locust.



METHODS

Biometrics and Morphology of Locust

The biometrics and morphology of solitary

and gregarious locusts individuals of both sexes

were studied. These will aid in the unambiguous

recognition of locust phases in the field. Thus, the

different phases of locust were observed closely

to record the peculiarities of each and relate

morphometrics data with migration.



Life Stages Development

Observation and measurement of rates of

development of different life stages of locust in the

field were done. The following were determined:

oviposition, emergence, natural mortality, nymphal

development, adult longevity and fecundity.

The possible environmental and other factors

that influenced population development and shift from

solitary to migratory phases were investigated. These

involved both laboratory and field observations on the

effect of temperature and humidity and correlate

locust outbreaks with meteorological data before and

during outbreaks.



The ecology of breeding sites of locust was

also observed. Analysis of floral and faunal structure

associated with locust, terrain, soil type and

composition, and changes occurring in the breeding

sites due to season were noted.

Field Ecological Factors Affecting Population

Development



Biometrics and Morphology of Locust

RESULTS

The solitary and migratory forms



Body Parts

(mm)

PHASES*

Solitary Migratory

Male Female Male Female

Head 6.23 7.43 6.50 7.02

Femur 21.01 26.16 20.67 21.58

Elytron 41.85 51.60 43.29 46.51

* Data taken from 49 males and 51 females solitary locust and 132 males and 91

females migratory locust from Anonas, Floridablanca, Pampanga

Morphometrics of solitary and migratory locust*

The migratory forms have relatively shorter body

parts in preparation for flight as compared to the

solitary forms .



Development of Different Life Stages in the Field

The migratory locust have three development

stages namely; egg (ovum), nymph (hopper) and adult

(flyer).

Migratory locust eggs (ova) Migratory locust egg field (holes indicate

female abdominal probes for egg laying)



Egg (Ovum)

Banana shape, approximately 8 mm long, yellow

– orange in appearance arranged in 30-80 eggs per pod.

Eggs were laid at a depth of 3-6 cm below sandy or

sandy loam soil . Around 5 pods can be laid by a gravid

female in the duration of its life. Eggs hatched from 14-

18 days depending on the type of soil where they were

oviposited.



Migratory locust egg pod on peanut and talahib



Nymph (Hopper)

There were five nymphal instars or stages.

Ecdysis, which is the act of molting or shedding of outer

cuticular layer or “skin” can last up to seven (7) minutes.

The color transformation from creamy white to black is

about 50 minutes.

1st instar - 6 days

2nd instar - 6 days

3rd instar - 6 days

4th instar - 7 days

5th instar - 8 days

33 days

These developmental figures in days were very close to

the findings of Camus (1921). Morphologically, the first to

the third instars have tiny wings pads.



1st instar nymph of migratory locust

First to the fifth nymphal instars

Nymphs/hoppers that are separated from the main

hopper band turned to green solitary color while others

turn to brown, the intermediate form’s color.



Fledges

These are newly emerged adults or flyers

from the last nymphal stage (5th instar). They

move out of the feeding/breeding areas

within 3 days after molting. This is a

propitious time to spray insecticides to arrest

flight later.



Adult (Flyer)

The adult form becomes sexually mature

within 10 days. Courtship, paring and mating

occurred on the ground. The adult male

migratory locust cannot distinguish the live from

the dead female. Egg laying commenced one

week after mating. The adults can live from 50-

80 days.



Mating migratory locust on invaded sugarcane

fields (male-yellow; female brown)



The Pigmentation (Color) of Solitary and

Migratory Locust

The solitary locust were green for both

sexes, the intermediate forms were light brown

and the migratory forms are brown for female

and yellow for male (Table 3). Green solitary

adults took ten (10) days to change into

migratory forms color.

Phase

Sex

Female Male

Migratory Brown Yellow

Intermediate Brown Brown

Solitary Green Green

Intermediate Light brown Light brown

The pigmentation of solitary and migratory locust



The Natural Enemies of Migratory Locust

Insectivorous birds, known locally as “pirpiriw”,

purok-purok, parik-parik, parek-parek, Merops sp. prey

on locust. They have the ability to make nest holes even

in stony/rocky hills. Their usual habitat was on sandy

hills or sandy promontories near the rivers and creeks of

the breeding and invaded areas.

The layang-layang or balinsasayao, Hirundo tahitica

abboti (Oberholser) was the predominant predator in

invaded sugar cane fields.

Red ants, Solenopsis geminata rufa (Jerdon),

attacked newly molted hoppers and fledges that fall from

their perches.



Cane toads, Bufo marinus L. were the numerous

ground predators in invaded areas such as sugar

cane fields. An adult toad can accommodate three

adult flyers in its stomach.

Three generations of adult migratory locust

were observed in San Narciso, Zambales from

December 1996 – May 1997. Only the third

generation showed the presence of a Podapolypid

parasytic mites.

A Podapolypid mite on the thoraxic wings of a migratory locust



Human beings were the number one predators

since they feast on migratory locust for food source.

The Oribatid spider, Argiope catenulata Doleschall

a web spider traps adult locusts in “talahib” areas.

Other predators noted in the field were chicken,

praying manthis, tuko, field and house lizards.

The oribatid spider, (Argiope catenulata rufa

Jerdon with trapped adult migratory locust.



Other Field Observations

Migratory locust were extremely sensitive to

noise or disturbance during paring and courtship.

Disturbed migratory locusts do not mate at daytime.

Instead they commence mating from dusk (6:00 pm)

to dawn (5:00 am).

There was 1:1 ratio between the male and female

migratory locust in the invaded areas.

Smaller rice grass hoppers , Oxya hyla intricata

Stal congregate in areas where migratory locust

are present. The presence of this species in unusual

number could indicate that the locusts were in the

vicinity.



Oxya hyla intricata Stal



Field Ecological Factors Affecting Population

Development

Cause of Locust Population Outbreak

Studies made by Uichanco (1936; 1939) have

shown that outbreaks of locust occurred after periods

of drought or below average rainfall. During such

periods, vegetation becomes sparse so that locusts

tend to aggregate in patches of edible grasses. The

crowded condition promotes the transformation of

locusts from solitary to gregarious phase through

mutual stimulation. Crowding also elevates the rate of

mating and reproduction. More than one generation

was needed to complete gregarization (Kennedy, 1956).



The eruption of Mount Pinatubo in June 1991 has

a profound effect on the locusts in these zones. Volcanic

ash fell over vast areas around the volcano, covering the

vegetation completely. Deposition of volcanic debris

therefore eliminated wide areas suitable for breeding.

This condition may have forced the surviving locusts to

congregate in the remaining tracts of land where feeding

and breeding is possible. This situation could have

continued in the succeeding generations until the

observed gregarious band of hoppers in July 1992. Our

field investigation in and around Mt. Pinatubo clarified the

previous belief that the locust breeds in this volcano.

The surrounding area was full of gravel and oozes with

hot steam and smoke even five years after its eruption.

Thus, locust cannot lay eggs in this desolate and

inhospitable environment.



Volcanic debris and ash fall at Mt. Pinatubo, San Marcelino, Zambales

Nevertheless,the eruption of Mt. Pinatubo may

have promoted the complete gregarization of locusts at

Cawag, Subic, Zambales resulting to the outbreak.

Waning of the El Niño phenomenon may have also helped

in the process by providing favorable environmental

conditions such as rainfall for sustained locust

reproduction. The data on rainfall and temperature before

and after the eruption provide ample evidence about this

fact.

Terminal report presentation at the Office of the Vice Chancellor for Research

and Extension ,UP Los Baños ,College Laguna. February 21, 2011.

pH OM N P K

% ppm

Cawag, Subic,

Zambales*

6.0 .57 .03 52.63 .09

Pasbul, Porac,

Pampanga**

5.7 .68 .02 103.31 .12

Mayantoc, Tarlac*** 5.1 3.31 .17 7.02 .45

Dinalupihan, Bataan*** 5.3 4.72 .31 59.65 .87

* Outbreak area

** Breeding area in Pampanga

*** Infested Areas

Soil analysis of locust outbreak area and secondary breeding/infested areas.



Sugarcane field at

Concepcion Tarlac

Peanut field in Mangatarem,

Pangasinan

A hill at San Narciso, Zambales Newly prepared sugarcane

Field at Porac, Pampanga



Rainfall and Temperature Patterns

There was low precipitation in 1991(122.59

mm) and in 1992(105.02 mm) followed by a very wet

year in 1993(282.09) in the outbreak area. There

was also a hotter temperature in the vicinity of Mt.

Pinatubo due to semi-arid condition and lack of

vegetation. This dry and hot condition and

subsequent wet year that followed could have

triggered aggregation/gregarization of migratory

locust followed by rapid multiplication that finally

led to migration.



Soil temperature in the breeding

area during the hot months of April-May

ranged from 23°C-35°C. These values were

very close to the temperature in the

outbreak and breeding areas before and

after the eruption of Mt. Pinatubo which

ranged from 31°C-33°C from 1990-1993.



Locust Movement/Recurrence

The northeast wind drives back

migratory locust from the plains to the breeding

sites in Zambales from November – February

(amihan). This remnant populations from the

plains and those that were present in the

breeding sites mate and reproduce during the

months of March-May due to the availability of

food. The southwest wind (habagat) during the

monsoon months of June onwards drives down

the migrating population later to the lowlands of

Central Luzon and Pangasinan .



The Breeding Areas in Zambales

The continued presence of locust in Zambales

breeding areas was due to the numerous rivers, creeks

and tributaries that favor the growth and development

of locust food plants in the area . The following were

the vital river systems and creeks that sustain

migratory locust reproduction in the breeding areas.

BREADING SITE RIVERS AND CREEKS

Mt. Pimayong, San Narciso,

Zambales

Sta. Fe River, Macolcol River, Sto

Tomas River and unnamed creek at

300 meters elevation

Mt. Paete, San Narciso, Zambales Kakilingan River, Sta Fe River and

Barisbis Creek

Mt. Quimalogong, San Felipe,

Zambales

Kakilingan River, Gabor River, and

Gorongoro River

Rivers and creeks in the breeding areas that provide moisture for

egg laying and supply of host plants.



Some river systems and mountainous breeding areas in Zambales



Formation of gregarization and subsequent migration

Dispersed patches of migratory locust nymph

populations were present in wide expanses of talahib

(S. spontaneum) and other grasses during the

summer breeding period. They eventually aggregate

at the end of nymphal period. Each distinct groupings

were near each other or they may come together

during gregarization in the vicinity of the breeding

areas .At other times the process of gregarization

was disrupted by non stop rain as what we observed

at Carusucan, Asingan, Pangasinan swarm formation.



Migratory locust on talahib, Sacharum spontaneum Linn.



Flora Attacked by Migratory Locust

Plants attacked by locust are not limited to

grasses. The dominant species eaten by locust in the

outbreak area was Themeda gigantea ( Cav.) Hack .

Themeda gigantea (Cav. ) Hack, the dominant weed at

Mt. Redondo, Cawag, Sbic, Zambales



Cawag Valley

Cawag, Subic

Umaya Marshes

Umaya, San

Narciso

Umaya

Highland

Umaya, San

Narciso

Mt.

Pimmayong

Sta Fe, San

Marcelino

Imperatata

cylindrica

-do - -do - -do -

Saccharum

spontaneum

-do - -do - -do -

Themeda gigantea -do - -do - -do -

Phylosena maxima -do - Themeda

triandra

-do -

Rhynchelutrum

repens

-do - -do - -do -

Cyperus

compactus

Penisetum

polystachyon

Cyperus

compactus

-do -

Eragrostis cumingi Chrysopogan

aciculatus

Some common grasses in the breeding areas of Zambales

Ten species of grasses in the outbreak and breeding

areas are readily available to the migratory locust. Sacharum

spontaneum predominates in secondary breeding areas.



ORDER FAMILY NAME SCIENTIFIC NAME

Cyperales Cyperaceae Cyperus iria Linn.

Euphorbiales Euphorbiaceae Manihot esculenta Pohl.

Euphorbiales Euphorbiaceae Antidesma ghaesambilla Gaertn.

Euphorbiales Euphorbiaceae Bridelia stipularis (Linn) Blume

Fabales Papilionaceae Arachis hypogeal Linn.

Fabales Papilionaceae Alysicarpus vaginalis (Linn.)

Genetianales Rubiacea Wendladia luzonensis D.C.

Lamiales Vervenaceae Vitex parviflora Juss.

Lamiales Vervenaceae Vitex regundo Linn.

Malvales Malvaceae Sida rhombifolia Linn.

Malvales Tiliaceae Trichospermum lanigerum (Blco.)

Merr.

Poales Graminae Themeda arundinaceae Hack.

Poales Graminae Themeda triandra Hack.

Poales Graminae Pinnesitum palystuchium Linn.

Poales Graminae Sorghum nitidum Pers.

Poales Graminae Saccharum spontaneum Linn.

Poales Graminae Panicum sp. Linn.

Flora attacked by migratory locust



Seventeen species from seven families

and eight orders of flora were observed being

attacked by locust in invaded areas. The food

crops that were eaten by voracious locust were:

Manihot esculenta (kamoteng kahoy), Cocos

nucifera (coconut), Zea mays (corn), Sorghum

vulgare (sorghum), Oryza sativa (rice), and

Saccharum oficinarum (sugar cane).

Peanut was an additional crop that was

attacked by locust. The grasses below peanuts

are eaten first, then the latter are devoured.



SUMMARY AND CONCLUSION

The life history and morphometrics of the

migratory locust, Locusta migratoria manilensis Meyen

has not changed much during the last 63 years.

The suspected population outbreak area which

is at Cawag, Subic, Zambales show edaphic factors and

floral structures that can sustain a gregarious

population that eventually migrated in the lowlands.

The Zambales, Pampanga, Tarlac mountain range

inclusive of Mt. Pinatubo was an identified breeding

zone of migratory locust.

The continued presence of locust in Zambales

breeding areas was due to the numerous rivers and

tributaries and the availability of food plants in the

area.



New information and records that were generated

from this research were the following:

• The eruption of Mt Pinatubo that covered vast tract of

lands with ash fall constricted and limited the grassy

areas where solitary locust congregates. One such area

was Mt. Redondo at Cawag, Subic,Zambales. This

phenomenon led to gregarization and finally to an

elevated population leading to migration.

• The interplay of hot and dry weather followed by rains

in the outbreak area after Mt. Pinatubo eruption

provided a favorable environment for population

increased .



• Themeda gigantea , was the dominant food source of

locust in the outbreak area. Talahib,cogon, buho,

and bikal were the key food plants in mountainous

secondary breeding areas after the population

outbreak.

• The main source of locust population in Central

Luzon after the population outbreak were the

mountainous areas of Zambales due to the presence

of rivers and creeks that provide moisture for the

food plants of migratory locust.



• The pirpiriw, Merops sp., layang layang, Hirundo

tahatica abboti, red ants, Solenopsis geminata, a

Podapolypid mite and an oribatid spider, Argiope

catenulata were the natural enemies observed in the

field. The presence of these predators in large

numbers can serve as indicators for

monitoring/surveillance works.

• Human beings were the number one predators of

migratory locust.

• The belief that migratory locust breeds at Mt.

Pinatubo was clarified and disproven due to the hot

and dry weather in the area where locust egg laying

was impossible to happen.



• In a relatively dry field locust eggs were laid at the

base of green vegetations especially shrubs.

• The recurrence of migratory locust invasion in

lowlands was due to the wind movement in the

breeding areas. The northeast wind drives back

migratory locust to the breeding sites in Zambales

from November – February (amihan). These

remnant populations from the plains and those

that were present in the breeding sites mate and

reproduce during the months of March-May due to

the availability of food. The southwest wind

(habagat) during the monsoon months of June

onwards drives down the migrating population to

the lowlands of Central Luzon and Pangasinan .



• Gregarization and swarm formation can be

disrupted by unfavorable wet environment

where continuous rainfall prevents close

contact between individuals.

• Monitoring of migratory locust should be done

regularly during El Niño episodes particularly

in the breeding areas not only in Zambales but

also in other regions of the country that have

history of locust invasions.



ACKNOWLEDGEMENT

We wish to thank the DA RFU III Directors and

staff and LGU’s in Central Luzon and Pangasinan. We

appreciate very much the fund support from PCARRD.

The CA-UPLB Dean’s Office under Dr. Cecilio R.

Arboleda and the Pahinungod Program led by Prof.

Severino Cuevas were instrumental in our active

participation on the RD&E and management/control of

locust in Central Luzon. Ms. Alice G. Aquino, Fredelino

P. Peñalba, Reynaldo Arapan and, Egay Gutierrez were

our overall support in the laboratory, field and

administrative activities.



field ecology studies on migratory locust

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