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RENCANA KEGIATAN PEMBELA JARAN (Bagian Hama)

Topik

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Identifikasi Hama Berdasarkan Karakteristik Morfologi

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Identifikasi serangga berdasarkan tipe alat mulut dan gejala kerusakan yang diakibatkannya

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Bioekologi Hama

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Interaksi hama dan tanaman inang

4. BIO-EKOLOGI HAMA

TEAM TEACHING HAMA

DEPARTEMEN HAMA DAN PENYAKIT TUMBUHAN FAKULTAS PERTANIAN UNIVERSITAS PADJADJARAN

-How Insects Become Pests -Pests Status -Factors Regulates Population Growth - External Factors - Internal Factors

Bacaan: 1. PW Price et al 2011. Insect ecology 373-397 2. Insect Ecology-I: 3. https://opentextbc.ca/conceptsofbiologyopenstax/chapte r/population-growth-and-regulation/ 4. http://www.entomologa.ru/outline/253.htm 5. https://bio.libretexts.org/Bookshelves/Introductory_and_ General_Biology/Book%3A_General_Biology_(Boundle ss)/45%3A_Population_and_Community_Ecology/45.2 %3A_Environmental_Limits_to_Population_Growth/45. 2A%3A_Exponential_Population_Growth

How Insects Become Pests 1. Introduction outside of native range 2. Becomes disease vector – Plant or animal (inclu. human) disease vector 3. Host shift in native insect – (e.g., CPB, apple maggot, Helicoverpa) 4. Vast areas of crop monocultures – Lots of food for insect; fewer natural enemies 5. Agricultural practices – e.g., continuous cropping; pesticides eliminate natural enemies

Pests Status:

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Figures 16.1. Schematic graphs of the fluctuations of theoretical insect populations in relation to their general equilibrium population (GEP), economic threshold (ET), and economic injury level (EIL). From comparison of the general equilibrium density with the ET and EIL, insect populations can be classified as: (a) non-economic pests if population densities never exceed the ET or EIL; (b) occasional pests if population densities exceed the ET and EIL only under special circumstances; (c) perennial pest s if the general equilibrium population is close to the ET so that the ET and EIL are exceeded frequently; or (d) severe or key pest s if population densities always are higher than the ET and EIL. In practice, as indicated here, control measures are instigated bef ore the EIL is reached. (After Stern et al. 1959).

Status hama berhubungan dengan besarnya/ukuran populasi yang perubahannya Ditentukan oleh Faktor: Faktor Primer Faktor sekunder Untuk mempelajari penyebab menggunakan Life Table

perubahan

populasi

salah

satunya

A "life table" is a kind of bookkeeping system that ecologists often use to keep track of stage-specific mortality in the populations they study. It is an especially useful approach in entomology where developmental stages are discrete and mortality rates may vary widely from one life stage to

another. From a pest management standpoint, it is very useful to know when (and why) a pest population suffers high mortality

Exponential model: Nt = No + rNo

Logistic model: Nt = No + rNo((K-No)/K)

Figure 1: When resources are unlimited, populations exhibit (a) exponential growth, shown in a J-shaped curve. When resources are limited, populations exhibit (b) logistic growth. In logistic growth, population expansion decreases as resources become scarce, and it levels off when the carrying capacity of the environment is reached. The logistic growth curve is S-shaped. https://opentextbc.ca/conceptsofbiologyopenstax/chapter/population-growth-and-regulation/

External Factors:

• The environment of an insect population consists of:

• Biological factors such as other members of the same insect species; food sources; natural enemies (including predators, parasitoids, and diseases); and competitors (other organisms that use the same space or food sources).

• Physical factors such as temperature, wind, humidity, light, and pesticides;

Limiting Factors – A limiting factor is a factor that controls the growth of a population. – There are several kinds of limiting factors. – Some—such as competition, predation, parasitism, and disease— depend on population density. – Others—including natural disasters and unusual weather— do not depend on population density.

Density-Dependent Limiting Factors – What limiting factors depend on population density? – Density-dependent limiting factors include competition, predation, – herbivory, parasitism, disease, and stress from overcrowding.

Density-Dependent Limiting Factors – Density-dependent limiting factors operate strongly only when population density—the number of organisms per unit area—reaches a certain level. These factors do not affect small, scattered populations as much. – Density-dependent limiting factors include competition, predation, herbivory, parasitism, disease, and stress from overcrowding.

Competition –

When populations become crowded, individuals compete for food, water, space, sunlight, and other essentials.

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Some individuals obtain enough to survive and reproduce.

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Others may obtain just enough to live but not enough to enable them to raise offspring.

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Still others may starve to death or die from lack of shelter. – Competition can lower birthrates, increase death rates, or both.

Competition – Competition is a density-dependent limiting factor. The more individuals living in an area, the sooner they use up the available resources. – Often, space and food are related to one another. Many grazing animals compete for territories in which to breed and raise offspring. Individuals that do not succeed in establishing a territory find no mates and cannot breed. – For example, male wolves may fight each other for territory or access to mates.

Competition – Competition can also occur between members of different species that attempt to use similar or overlapping resources. – This type of competition is a major force behind evolutionary change.

Predation & Parasitism – The effects of predators on prey and the effects of parasitoid on insect host are two very important density-dependent population controls.

Parasitism and Disease – Parasites and disease-causing organisms feed at the expense of their hosts, weakening them and often causing disease or death. – Parasitism and disease are densitydependent effects, because the denser the host population, the more easily parasites can spread from one host to another.

Stress From Overcrowding – Some species fight amongst themselves if overcrowded. – Too much fighting can cause high levels of stress, which can weaken the body’s ability to resist disease. – In some species, stress from overcrowding can cause females to neglect, kill, or even eat their own offspring. – Stress from overcrowding can lower birthrates, raise death rates, or both, and can also increase rates of emigration.

Food (Faktor makanan): • Tersedianya makanan dengan kualitas baik → naiknya populasi dengan cepat • Makanan kurang → populasi hama menurun • (Populasi tikus menurun sampai 70% pada awal penggarapan sawah)

Density-Independent Limiting Factors (Faktor bebas kepadatan) – What limiting factors do not typically depend on population density?

Density-Independent Limiting Factors – What limiting factors do not typically depend on population density? – Unusual weather such as hurricanes, droughts, or floods, and natural disasters such as wildfires, can act as densityindependent limiting factors.

Density-Independent Limiting Factors – Density-independent limiting factors affect all populations in similar ways, regardless of population size and density. – Unusual weather such as hurricanes, droughts, or floods, and natural disasters such as wildfires, can act as density-independent limiting factors. – Wind, Temperature, Relative humidity, light intensity

The relationship between temperature & development time of insects.

Density-Independent Limiting Factors – A severe drought, for example, can kill off great numbers of plant and insect. – In response to such factors, a population may “crash.” After the crash, the population may build up again quickly, or it may stay low for some time.

Internal Factors :

Internal Factors: • Sex ratio (can be known from life table study) • Fecundity • Type of reproduction • Mating Frequency • Life cycle

Sex ratio

Keperidian Contoh: • Penggerek batang Tryporyza innotata dapat bertelur rata-rata 150 -420 butir • Kumbang S. oryzae betina maksimal 575 butir • Lembing Scotinophara sp. 300-680 butir • Nengata Heliothis assulta 500-2000 butir

Tipe Reproduksi: The reproductive organs of insects are similar in structure and function to those of vertebrates: a male's testes produce sperm and a female's ovaries produce eggs (ova). Both types of gametes are haploid and unicellular, but eggs are usually much larger in volume than sperm. Most insect species reproduce sexually -- one egg from a female and one sperm from a male fuse (syngamy) to produce a diploid zygote.

Male Reproductive System

But there are also many species that reproduce by parthenogenesis, asexual reproduction in which there is growth and development of an unfertilized egg. Some species alternate between sexual and asexual reproduction (not all generations produce males), others are exclusively parthenogenetic (no males ever occur) (Occur in Hymenoptera and Aphids) Haplodiploidy fertilized egg = 2N = female unfertilized egg = N = male Arrhenotoky: Telur dibuahi: Betina; Tdk dibuahi: Jantan Deuterotoky: Telur tdk dibuahi ada jantan dan betina Telyotoky: telur tidak dibuahi menjadi betina semua

Amazing! Aphid cloning - Battle of the Animal Sexes - BBC Wildlife.flv

Tipe dan Lama perkembangan srg Insect life span • Generation time: time required to complete one life cycle • Immature period: time laps from oviposition to adult emergence • Pre-reproductive period: immature + preoviposition period • Reproductive period: period when insects are reproductively active (egg laying) -important in pest control • Post-reproductive period: last days after oviposition of mating

egg

Without Metamorphosis nymphs

adult

Without meta

The first type is "without" metamorphosis which the wingless primitive orders such as silverfish (Thysanura) and springtails (Collembola) possess. The young resemble adults except for size.

Incomplete Metamorphosis egg

naiads

adult

Incomplete meta

The second type is "incomplete" metamorphosis which is found among the aquatic insect orders such as mayflies (Ephemeroptera) and dragonflies (Odonata).

Gradual Metamorphosis The third type is "gradual" metamorphosis seen in such orders as the grasshoppers (Orthoptera), termites (Isoptera), thrips (Thysanoptera), and true bugs (Hemiptera). This life cycle starts as an egg, but each growth, or nymphal stage looks similar, except it lacks wings and the reproductive capacity that the adult possesses.

egg

nymphs

adult

Complete Metamorphosis The fourth type is "complete" metamorphosis found in butterflies (Lepidoptera), beetles (Coleoptera), flies (Diptera), and bees, wasps, and ants (Hymenoptera). This life cycle has the four stages of egg, larva, pupa, and adult. Each stage is quite distinct.

egg

larvae

pupa

Complete Life Cycle of the Monarch Butterfly.flv

adult

Contoh (Life cycle): • • • •

Nilaparvata lugens 21-28 hari Crocidolomia binotalis 22-30 hari Sitophillus oryzae 30-45 hari Oryctes rhinoceros ± 100 hari

Contoh Adult Life span: • Pada umumnya serangga memiliki umur imago pendek. Sebagai contoh: ngengat T. innotata 414 hari • N. Lugens rata-rata 10 hari. Helopelthis theiovera 5-10 hari. • Makin lama umur imago betina (misalnya kumbang betina S. oryzae 3-5 bulan), makin besar kesempatan untuk bertelur

• Insect life cycle • Development from egg to adult and again to egg represents one life cycle or generation • Voltinisme = number of generations completed by a species per year 1. 2. 3. 4.

univoltine (one generation per yr) bivoltine (2 generations per yr) multivoltine (many generations per yr) perennial (one generation in more than one year, e.g or large insects)

Perennial insects • Require more than one year for a generation • generally large insects • some require 2 to 5 years, or even 10 yrs

Many reasons for the prolongation 1. nutrition (e.g. cerambycid beetle, bupretid) 2. Intrinsic factors (some spp. of cicada spend 13 to 17 years as nymphs and this is fixed genetically, whereas white grubs and mayflies have life cycle of 2-3 yrs) 3. temperature (a sp may be univoltine in a warm climate but perennial in a cooler climate) E.g. Walking stick inhabiting the US

Ringkasan Faktor-faktor yang mempengaruhi perkembangan hama/serangga hama:

Faktor dalam

Faktor Yang mempengaruhi Perkembangan organisme serangga/hama

Faktor luar

▪ kemampuan berkembang biak ▪ perbandingan kelamin ▪ sifat mempertahankan diri ▪ daur hidup ▪ umur imago

Faktor fisis

▪ suhu ▪ kisaran suhu ▪ kelembaban/hujan ▪ cahaya/warna/bau ▪ angin

Faktor makanan

▪ kuantitas ▪ kualitas

Faktor hayati

▪ predator ▪ parasit ▪ patogen ▪ kompetisi - intraspesifik - interspesifik