Mean Developmental Period Research Articles

Developmental biology of Aspavia armigera (Fabricius, 1775) (Hemiptera: Pentatomidae) on rice (Oryza sativa L.) (Poaceae) and three other hosts in Nigeria

Abstract The developmental biology of Aspavia armigera on four rice varieties ITA 301, ITA 305, ITA 307 and ITA 315 was studied under ambient conditions at the Plant Biology Laboratory, Olabisi Onabanjo University, Ago-Iwoye, Nigeria. Alternative host plants were also used in the experiment. The results showed that the development of A. armigera depended on its hosts. Oviposition periods were 41.7 days, 30.8 days, 22.6 days and 18.1 days on rice varieties ITA 301, ITA 305, ITA 307 and ITA 315, respectively. Fecundity ranged from 80.3 eggs on ITA 301, 79.6 eggs on ITA 307, 76.1 eggs on ITA 305 and 65.6 eggs on ITA 315. The differences in fecundity were not statistically significant. The eggs incubated for 4 to 6 days before hatching into nymphs on all the varieties. The longevity of mated and unmated males and mated females on the rice varieties were not statistically different, while unmated females lived significantly longer on ITA 305. There were five nymphal instars, which persisted for 16.8-19.5 days depending on the variety. The developmental period was significantly (p<0.05) delayed on ITA 315, and the mean growth ratio of head capsule measurements was 1.27. Oviposition periods ranged between 5 and 20 days on cowpea and 6 and 18 days on rice. A significantly higher number of eggs (fecundity) was laid by mated females of A. armigera fed on soybean than those fed on cowpea. Mean developmental periods were 25.7, 25.5, 21.4, and 20.3 days on soybean, amaranthus, rice and cowpea, respectively. Mated females lived for a significantly shorter period on cowpea (21.9 days) than on the other hosts.

Effect of Diets and Low Temperature Storage on Adult Performance and Immature Development of Phyllonorycter ringoniella in Laboratory.

The Asiatic apple leaf miner, Phyllonorycter ringoniella (Matsumura), is an important insect pest to apples. We developed a rearing method for P. ringoniella in the laboratory. Overwintering pupae were collected from our apple orchard, and crabapple seedlings were selected as oviposition substrate and food source for the larval development. The mean developmental period was 25.9 ± 0.49 days from egg to adult and the survival rate was 0.387 under 25 ± 1 °C, 65 ± 5% RH and a photoperiod of 14:10 (L:D) h. Mean egg length and egg width were 0.336 ± 0.0043 and 0.259 ± 0.0046 mm, respectively. Mean body length and head width increased from 1.070 ± 0.0245 and 0.180 ± 0.0021 mm in first instar larvae to 5.027 ± 0.0718 and 0.321 ± 0.0021 mm in fifth instar larvae, respectively. The mean weight of the pupae was 0.946 ± 0.0132 mg. The wingspan of male adult (6.280 ± 0.0639 mm) was significantly larger than female (6.040 ± 0.0753 mm). The mean fecundity (56.9 ± 8.58 eggs per female) and longevity (8.2 ± 0.55 days) of females was highest when they were provided with 10% honey solution, followed by 10% sugar, water, and control. The females preferred to lay eggs (56.5 ± 3.84%) near the secondary leaf vein in a leaf. The larval mortality increased linearly (R2 = 0.94) with the number of larvae per leaf. The mortality of pupae increased from 5.6 ± 4.01 to 51.1 ± 9.88% as storage periods at 4 °C increased from 0 to 105 days. The rearing method and its biological characteristics presented in this study will contribute to further studies on this pest insect.

Biologi, neraca hayati, dan pemangsaan Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) pada Paracoccus marginatus Williams & Granara de Willink (Hemiptera: Pseudococcidae)

Kutu putih pepaya, Paracoccus marginatus Williams & Granara de Willink (Hemiptera: Pseudococcidae), adalah hama asing invasif yang terdeteksi untuk pertama kalinya di Indonesia pada tahun 2008. Salah satu musuh alami yang umum ditemukan adalah kumbang predator Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae). Penelitian ini bertujuan untuk menentukan parameter biologi dan neraca hayati serta pemangsaan C. montrouzieri pada P. marginatus. Pengamatan biologi dan neraca hayati serta pemangsaan dilakukan dengan menempatkan predator C. montrouzieri di dalam cawan Petri yang berisi kutu putih. P. marginatus. Hasil penelitian menunjukkan bahwa rataan masa inkubasi telur C. montrouzieri adalah 4,35 hari. Perkembangan larva instar-1, instar-2, instar-3, dan instar-4 secara berurutan berlangsung 4,23; 4,21; 5,84; dan 5,93 hari. Prapupa berlangsung 1,95 hari dan pupa 7,55 hari. Masa hidup imago jantan adalah 51,34 hari, sedangkan betina 83,39 hari. Jumlah telur yang diletakkan oleh satu imago betina rata-rata 198,49 butir. Laju reproduksi bersih (Ro) 117,11 individu/betina/generasi, laju pertambahan intrinsik (rm) 0,073 individu/betina/hari, rataan masa generasi (T) 64,776 hari, masa penggandaan (Dt) 9,426 hari, dan laju pertambahan terbatas (λ) adalah 1,076 per hari. Larva instar-4 C. montrouzieri merupakan fase yang paling rakus, dengan rataan jumlah telur, nimfa instar-1, instar-2, instar-3, dan imago betina kutu putih yang dimangsa per hari berturut-turut 188,0 butir; 53,4; 44,0; 26,8; dan 15,6 individu. Indeks preferensi Manly menunjukkan bahwa larva dan imago C. montrouzieri lebih memilih telur dan nimfa instar-1 P. marginatus dibandingkan dengan fase mangsa lainnya. Hasil penelitian mengindikasikan potensi yang tinggi dari C. montrouzieri dalam pengendalian hayati P. marginatus.

Cosmolaelaps keni a polyphagous predatory mite on various insect and mite species (Acari: Laelapidae)

The predatory mite Cosmolaelaps keni is a native laelapid mite in Egypt. Development and adult longevity durations as well as fecundity of C. keni reared on five types of prey, Bactrocera zonata, Spodoptera littoralis and Corcyra cephalonica eggs (as insects prey), Aceria dioscoridis and Caloglyphus rodriguez (as mites prey) were determined under laboratory conditions. Cosmolaelaps keni was able to feed, develop and sustain oviposition on all examined insect and mite species. The mean developmental period of C. keni on B. zonata and S. littoralis eggs was significantly shorter than those fed C. cephalonica eggs and both mite species. Deutonymphs of C. keni were consumed similar number of insect eggs, while during the oviposition period, more B. zonata eggs were consumed. A diet of C. rodriguez provided the shortest oviposition period and longevity, while C. cephalonica eggs showed the longest period in this respect. During the oviposition period, preying on B. zonata and C. cephalonica eggs gave the highest fecundity rates for the predatory mite compared to S. littoralis and C. rodriguez. The sex ratio of C. keni progeny was in female-biased. Bactrocera zonata eggs as a prey gave the highest rate of oviposition as shown by the maximum fertility, net reproductive rate and gross reproductive rate as well as the shortest generation time compared to other tested prey; therefore B. zonata eggs were appropriate factitious prey for oviposition and mass rearing of the predatory mite C. keni.

Morphometric Analysis of the Developmental Stages and Insecticidal Efficacy of Three Botanical Oils Against Adult Callosobruchus analis

Abstract The developmental stages of Callosobruchus analis were observed under laboratory conditions at 28 ± 2 °C and 72 ± 5% relative humidity. The results showed that female C. analis began to lay eggs within 24 hours and have an oviposition period of 8.50 ± 0.70 days and an average of 13.00 ± 0.50 eggs were laid by individual C. analis throughout their lifetime. The mean developmental periods from egg to larva and larva to pupa were observed to be 8.50 ± 0.79 and 4.50 ± 0.70 days, respectively. The unmated bruchids were observed to have lived longer than the mated bruchids as the unmated bruchids lifespan was on average 10.50 ± 0.81 days, as opposed to 2.50 ± 0.75 days for mated females. Adult male C. analis have an average antenna length of 2.96 ± 0.08 mm which is slightly longer than 2.42 ± 0.12 mm on average for female bruchids. The three botanical oil extracts from Capsicum frutescens, Anacardium occidentale and Xylopia aethiopica used at 10.0% concentration were not effective, as none of them resulted in a mortality rate of 50% when recorded 3 days after treatment.

Life Cycle and Predation Potential of the Neotropical Ground Beetle Selenophorus seriatoporus Putzeys (Coleoptera: Carabidae) on Different Substrates

This study determined the life cycle parameters and predation potential of Selenophorus seriatoporus Putzeys (Coleoptera: Carabidae) on different substrates to examine its suitability for biological control. The mean developmental period of S. seriatoporus ranged from 43.0 to 52.2 days at 26 ± 1°C. On soil, this carabid showed faster development, lower mortality, and greater longevity. Development was slower on vermiculite and paper; however, these substrates were suitable for developing eggs and first and second instars. Selenophorus seriatoporus completed its life cycle by preying on larvae of Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae), and adults showed higher preference for T. molitor larvae than for pupae. Third instars and adults of S. seriatoporus demonstrated high predation potential, showing their suitability as biological control agents.

Development and reproduction of three predatory mites (Acari: Laelapidae and Rhodacaridae) on eggs of Ephestia kuehniella (Lepidoptera: Pyralidae)

The laelapid mites Cosmolaelaps keni and Laelaspis astronomicus beside the rhodacarid mite Protogamasellopsis denticus are biological control agents and being native predators in Egypt. In order to raise active population of above species, the biology and demographic parameters, of the three tested species were observed under laboratory conditions with eggs of Ephestia kuhniella. All predatory species were developed and reproduced with E. kuhniella eggs. The mean developmental and oviposistion periods of L. astronomicus females were the longest from the other tested species. The mean longevity of C. keni was longer than that of P. denticus. Cosmolaelaps keni consumed more E. kuhniella eggs during the oviposition and adult longevity periods than other species did. Protogamasellopsis denticus fed on E. kuhniella food gave the most rate of oviposition as shown by the maximum fertility, net reproductive rate and gross reproductive rate. Laelaspis astronomicus preying on E. kuhniella eggs gave the longest generation time, lowest rate of fecundity and all life table parameters compared to other tested species; therefore E. kuhniella eggs was appropriate for the oviposition of P. denticus and C. keni rather than L. astronomicus. This study is the first to report that E. kuhniella eggs were an acceptable factitious food for P. denticus, L. astronomicus and C. keni.

A new substitute host and its effects on some biological properties of Ooencyrtus kuvanae.

Lymantia dispar (L.) (Lepidoptera: Lymantriidae), commonly known as the gypsy moth, is a serious forest pest, and beneficial insects are particularly important for reducing its population numbers. Ooencyrtus kuvanae (Howard) (Hymenoptera: Encyrtidae) is an arrhenotokous, solitary egg parasitoid of L. dispar. In this study, we evaluated a new substitute host, Philosamia ricini (Danovan) (Lepidoptera: Saturniidae) for O. kuvanae. We investigated some of the biological effects of O. kuvanae on P. ricini eggs. In this context, the importance of the age of the female parasitoid (1, 3 or 5 days old), host age (1-2 and 3-4 days old) and host number (40, 60 and 80 host eggs) were examined under laboratory conditions (25 ± 1 °C, 65 ± 5% relative humidity and a 16 : 8 h photoperiod [light : dark]). The highest rate of offspring production (89.90%) occurred with 40 (1-2-day-old) host eggs and 5-day-old females. The mean developmental period ranged from 16.5 ± 0.08 days to 18.7 ± 0.08 days. The mean lifespan of the parasitoid was 51.10 ± 1.1 (n = 60) days with bio-honey and 3.92 ± 0.14 (n = 60) days without food. The mean fecundity was 68.88 ± 3.22 offspring/female. Peak adult emergence occurred between 2 and 9 days. The mean oviposition and mean post-oviposition periods of the female parasitoid were 22.76 ± 1.37 days and 13.64 ± 1.40 days, respectively. O. kuvanae was reared for more than ten generations on the eggs of P. ricini. Based on our findings, P. ricini can be used to rear O. kuvanae for the biological control of L. dispar.

Effects of temperature on development, molting, and population growth of Yuukianura szeptyckii Deharveng & Weiner, 1984 (Collembola: Neanuridae)

Neanuridae is one of the most diversified families of Collembola, but its biology and ecology are poorly understood. This is, to our knowledge, the first report on the biology of the neanurid species Yuukianura szeptyckii Deharveng & Weiner. Y. szeptyckii individuals were collected near a stream in Korea, and maintained on OECD artificial soil. This species showed a better reproductive performance on an artificial soil-based substrate than on charcoal-based substrate, and thus the soil-based substrate was used for investigating its biology. The sex ratio of Y. szeptyckii was found to be biased toward females (88.0%), and its mode of reproduction was sexual. The development, survival, longevity, reproduction, molting, and life table parameters of Y. szeptyckii were evaluated at 15, 20, 25, and 30°C. Individual growth was estimated by measuring head capsule widths. Mean developmental period from egg to adult decreased with increasing temperature from 73.7 d at 15°C to 25.6 d at 30°C. In the adult stage, ovipositional periods decreased with temperature from 273 d at 15°C to 45.5 d at 30°C, but senile periods increased at temperatures above 20°C. The developmental zero temperature was estimated to be 7.88°C. Median survival time (ST50s) and mean longevity decreased with temperature from 228d at 15°C to 98.0d at 30°C and from 401 d at 15°C to 177 d at 30°C, respectively. The maximum and minimum total number of eggs produced per individual were observed at 20°C (73.8 eggs) and 30°C (6.9 eggs), respectively. The head capsule width at first oviposition was significantly smaller at 25 and 30°C (0.30–0.31mm) than that at 15 and 20°C (0.45–0.46mm), while the head capsule width at last oviposition was smaller at 30°C (0.55mm) than that at 15 to 25°C (0.63–0.64mm). The molting rate (per individual per week) increased with temperature from 0.50 at 15°C to 1.43 at 30°C, but the total number of molts during the life span varied only slightly, ranging from 29.1 at 25°C to 33.2 at 30°C. The population reared at 20°C had the highest intrinsic rate of increase (0.060) and net reproductive rate (84.5), indicating that the optimal temperature for Y. szeptyckii population growth is 20°C. This study demonstrated that temperature can profoundly affect the development, molting, and population growth of Y. szeptyckii.

Assessment of population and damage of pulse beetle, Callosobruchus chinensis L. on different pulse grains

Population development and grain damage by C. chinensis was assessed on eight different host-grains viz., greengram (Vigna radiata L.), blackgram (Vigna mungo L.), Bengalgram (Cicer arietinum L.), redgram (Cajanus cajan L.), cowpea (Vigna sinensis L.), soybean (Glycine max L.), pea (Pisum sativum L.) and pillipesara (Phaseolus trilobus L.) were estimated. Among all the host-grains, maximum oviposition was recorded in blackgram (7.75 eggs/ 5 g grain). Survival was highest in bengalgram (86.43) and mean developmental period was shortest in greengram (28.47 days) which were on par with that in pillipesara (28.77 days) whereas index of susceptibility was highest in greengram (6.09) and was followed by pillipesara (6.03). The damage in terms of percentage of grains damaged and weight loss of grains increased with increase in storage period. Among all the host-grains bengalgram recorded significantly maximum percentage of grain damage (90.65%) and weight loss of grains (58.55%).

Parasitoid, <I>Aenasius arizonensis</I> (Girault) (Hymenoptera: Encyrtidae): its Biology, Morphometrics, Host Stage Preference and use in Biological Control

Aenasius arizonensis (Girault) ( = Aenasius bambawalei Hayat) (Hymenoptera: Encyrtidae), a solitary endoparasitoid of Phenacoccus solenopsis Tinsley, is a major invasive pest in several cotton growing countries around the globe. It has been recorded as an effective natural enemy of P. solenopsis . The biological characteristics of parasitoid were studied on P. solenopsis under laboratory conditions. The mean duration of development of A. arizonensis from oviposition to mummy formation was 5.9 ± 0.31 days for both male and female, while from mummy formation to adult emergence was 5.9 ± 0.31 and 7.3 ± 0.3 for male and female, respectively. The mean developmental period of male and female was 12.2 ± 0.33 and 14.2 ± 0.37 days, respectively. Males were short lived (16.3 ± 1.41 days) as compared to females (26.2 ± 1.72 days). Female started ovipositing on the day of emergence. The mean pre-oviposion, oviposition and post-oviposition periods were <1, 23.1 ± 1.66 and 3.1 ± 0.55 days, respectively. Mean daily and total fecundity in terms of number of parasitized host per female was 4.24 ± 0.2 and 100.5 ± 11.57, respectively. Sex ratio was skewed towards female and recorded as 1:2. Maximum percentage of parasitization occurred in adult host stage i.e. 90% followed by 3 rd , 2 nd , and 1 st instar nymph with 73.33%, 33.33% and 0 per cent, respectively. Among the three nymphal stages 3rd instar nymph was the most suitable stage for mass multiplication of parasitoid. Its successful utilization in mealybug management can be optimized by multiplying at this stage of host in the laboratory and thereafter inoculative release into the field. This report provides a detailed diagnostic description of A. arizonensis with illustration to facilitate easy identification & morphological differences between male & female along with the morphometric measurements of pupa & mummy.

Parasitoid, &lt;I&gt;Aenasius arizonensis&lt;/I&gt; (Girault) (Hymenoptera: Encyrtidae): its Biology, Morphometrics, Host Stage Preference and use in Biological Control

&lt;em&gt;Aenasius arizonensis&lt;/em&gt; (Girault) ( = &lt;em&gt;Aenasius bambawalei&lt;/em&gt; Hayat) (Hymenoptera: Encyrtidae), a solitary endoparasitoid of &lt;em&gt;Phenacoccus solenopsis&lt;/em&gt; Tinsley, is a major invasive pest in several cotton growing countries around the globe. It has been recorded as an effective natural enemy of &lt;em&gt;P. solenopsis&lt;/em&gt;. The biological characteristics of parasitoid were studied on &lt;em&gt;P. solenopsis&lt;/em&gt; under laboratory conditions. The mean duration of development of &lt;em&gt;A. arizonensis&lt;/em&gt; from oviposition to mummy formation was 5.9 ± 0.31 days for both male and female, while from mummy formation to adult emergence was 5.9 ± 0.31 and 7.3 ± 0.3 for male and female, respectively. The mean developmental period of male and female was 12.2 ± 0.33 and 14.2 ± 0.37 days, respectively. Males were short lived (16.3 ± 1.41 days) as compared to females (26.2 ± 1.72 days). Female started ovipositing on the day of emergence. The mean pre-oviposion, oviposition and post-oviposition periods were &amp;lt;1, 23.1 ± 1.66 and 3.1 ± 0.55 days, respectively. Mean daily and total fecundity in terms of number of parasitized host per female was 4.24 ± 0.2 and 100.5 ± 11.57, respectively. Sex ratio was skewed towards female and recorded as 1:2. Maximum percentage of parasitization occurred in adult host stage i.e. 90% followed by 3&lt;sup&gt;rd&lt;/sup&gt;, 2&lt;sup&gt;nd&lt;/sup&gt;, and 1&lt;sup&gt;st&lt;/sup&gt; instar nymph with 73.33%, 33.33% and 0 per cent, respectively. Among the three nymphal stages 3rd instar nymph was the most suitable stage for mass multiplication of parasitoid. Its successful utilization in mealybug management can be optimized by multiplying at this stage of host in the laboratory and thereafter inoculative release into the field. This report provides a detailed diagnostic description of &lt;em&gt;A. arizonensis&lt;/em&gt; with illustration to facilitate easy identification &amp;amp; morphological differences between male &amp;amp; female along with the morphometric measurements of pupa &amp;amp; mummy.

CERTAIN STORAGE PROTEINS AND THEIR ROLE IN THE RESISTANCE OF SOME LEGUME SEED TYPES AND VARIETIES TO INFESTATION WITH THE COWPEA SEEDS BEETLE, Callosobruchus maculatus (F.)

Seventeen legume seed varieties belonging to ten types were analyzed for each of total proteins, trypsin inhibitors, vicilins and lectins to study the relationship between the presence of the storage seed proteins in legume seeds and resistance to infestation with the cowpea seeds beetle, Callosobruchus maculatus (F.) under no-choice bioassay at constant conditions of 29±1°C and 70 ± 5% RH. The tested types and varieties were cowpea (Fitriat, Forage and Kafr El-Sheikh), fababean (Aquadams, Giza 843 and Sakha 1), pea (Master B and Smooth) common bean (Bronco and Nepraska), lupin (Giza 1 and White lupin), chickpea (Giza 195), soyabean (Giza 111), lentil (Giza 9), guar (Guvar bean) and lablab (Egyptian kidney bean). To clarify the impact of the storage seed proteins in legume seed varieties and types on infestation with C. maculatus, larval period, pupal period, least and mean complete developmental periods, number of emerged adults per female, percentage of adults emergence and sex ratio (as percentage of males) were determined. Moreover, susceptibility index, infested seeds (%), mean number of holes per infested seed, seeds weight loss (%), weight of early emerged adult and number of dead individuals inside seeds per female were assessed as infestation parameters. The obtained results showed that, each of total proteins, trypsin inhibitors, vicilins and lectins of different tested legume seed varieties and types are negatively correlated with all aforesaid resistance parameters with the exception of those respecting larval and pupal durations, least and mean complete developmental periods and number of dead individuals inside seeds per female. As regards total proteins of varieties, larval period, least and mean complete developmental periods, susceptibility index and number of dead individuals inside seeds per female reached high significance degree at 0.01 level of probability, whereas pupal period obviously showed significant correlation coefficient at 0.05 level of probability. But, the other studied resistance parameters did not demonstrate significant correlations. Significancy test of correlation relationships respecting trypsin inhibitors clearly proved to be insignificant for all studied characters, except for those of larval stage period, least and mean developmental periods which cleared highly significant correlations and significant ones with susceptibility index, number of holes per infested seed and number of dead individuals inside seeds per female. All tested seed varieties of guar, lupin and common bean revealed completely linear inverse relationship between trypsin inhibitors and susceptibility to cowpea seeds beetle infestation indicating deterring effects for insect development. Also, vicilins content proved that simple correlation coefficient values regarding the abovementioned resistance parameters reached high significancy degree excepting those concerning larval stage period, percentage of infested seeds, seeds weight loss percentage and weight of emerged adult that showed significant correlation as well as insignificant ones were recorded with sex ratio as percentage of adult males and number of dead individuals inside seeds per female. All tested legume seed varieties of soyabean- Giza111 and lentil- Giza 9 revealed almostly linear inverse relationship between vicilins and susceptibility to cowpea seeds beetle infestation and showed retarding effects for insect development. As concerns lectins of the infested legume seed varieties, the correlation relationships proved to be highly significant with larval stage period, least and mean complete developmental periods, susceptibility index and number of dead individuals inside seeds per female, while in case of number of emerged adults per female, adults emergence percentage, number of holes per infested seed and seeds weight loss percentage the correlation was significant. The correlation of other resistance parameters did not attain significancy degree.

Determination of Thermal Constant and Development Threshold of Fruit and Shoot Borer, Earias vitella (F.)

Effect of constant temperatures viz, 18 ± 1, 21 ± 1, 24 ± 1, 27 ± 1, 30 ± 1 and 33 ± 1 °C on egg, larval and pupal development of Earias vitella revealed that the development rate of egg, larvae and pupae gradually increased with increase in temperature, while total development period decreased. Mean developmental period of the pest decreased from 58.7 days at 18 ± 1 °C to 22.4 days at 33 ± 1 °C. Thermal constant for egg, larva (I–V instar) and pupa were determined to be 50, 50, 62.5, 52.6, 58.8, 62.5 and 142.8 degree days (DD), respectively with corresponding development threshold being 11.4, 10.7, 8.0, 9.7, 8.3, 8.0 and 10.5 °C. Thermal constant to complete a generation was found to be 479.2 DD.

Development and Life History ofSitophilus zeamais(Coleoptera: Curculionidae) on Cereal Crops

The maize weevil,Sitophilus zeamaisMotschulsky (Coleoptera: Curculionidae), is one of the most destructive pests of stored cereals. Knowledge of the life history and biology is important to the development of an integrated pest management program. Investigation was carried out on developmental biology ofS. zeamaison four main cereal crops, maize, rice, sorghum, and millet, under laboratory conditions. Egg incubation, oviposition periods, and larval instar development were not different significantly among the food hosts. Number of eggs laid varied significantly among the cereal grains; mean fecundity was highest on maize (67.2±3.16) and lowest on millet (53.8±0.17). Number of immature (larva and pupa) and adult stages varied significantly among the cereal grains. There exist four larval instars with a varied mean head capsule width, with a mean total instar larval developmental period of 23.1, 22.2, 22.2, and 21.6 d on maize, rice, sorghum, and millet, respectively. There was linear relationship and significant correlation between the stages of larval development and head capsule width. The mean developmental period from egg to adult varied, being highest on maize (34.7 d) and lowest on sorghum (33.5 d).

Screening for Resistance Against Pulse Beetle, Callosobruchus analis (F.) in Greengram (Vigna radiata (L.) Wilczek) Accessions

The susceptibility of eighty five green gram accessions were evaluated against pulse beetle, Callosobruchus analis (F.) under laboratory conditions. Accessions which exhibited lesser susceptibility index during the preliminary free choice tests were further subjected to ‘force choice’ test for confirmation of bruchid resistance. No green gram accession was found immune to bruchid infestation and showed significant difference in terms of oviposition, developmental period, adult emergence and seed weight loss. Two accessions viz, Km-12-5 and P-S-16 revealed lesser per cent adult emergence of 12.22 and 14.29, respectively. Prolonged developmental period (25.67 and 26.00 days, respectively) and lesser susceptibility index (0.042 and 0.044 respectively) in comparison to highly susceptible Ganga 8, which exhibited a survival of 71.67 %, developmental period of 20.67 days and susceptibility index of 0.09. Correlation between GI and other growth parameters of pulse beetle on different accessions indicated that GI had negative relationship with mean developmental period (−0.924) and significant positive relationship with adult emergence (0.931), weigh loss (0.952) and eggs laid (0.734). Hence, these accessions can be effectively used as promising donors for developing bruchid resistant varieties which would ensure food security by reducing postharvest losses under storage conditions.

&lt;p&gt;&lt;strong&gt;Life histories of three predatory mites feeding upon &lt;/strong&gt;&lt;strong&gt;&lt;em&gt;Carpoglyphus lactis&lt;/em&gt;&lt;/strong&gt;&lt;strong&gt;&lt;em&gt; &lt;/em&gt;&lt;/strong&gt;&lt;strong&gt;(&lt;/strong&gt;&lt;strong&gt;Acari, &lt;/strong&gt;&lt;strong&gt;Phytoseiidae; &lt;/strong&gt;&lt;strong&gt;Carpoglyphidae)&lt;/strong&gt;&lt;/p&gt;

The phytoseiid mites, Amblyseius swirskii (Athias-Henriot) and Neoseiulus cucumeris (Oudemans) are important biological control agents introduced from outside of China. On the other hand, Amblyseius eharai Amitai &amp; Swirski that is native to China and Japan is considered to be an effective natural enemy in China citrus orchards and bamboo forests. In order to develop effective mass production of these three species, the life history parameters, net reproductive rates (R0 /female), and intrinsic rates of increase (rm /day) of the three species, A. swirskii (Athias-Henriot) and N. cucumeris (Oudemans), were observed under experimental conditions (25 ± 1°C, 90 ± 5% RH and L:D = 14:10 h) with Carpoglyphus lactis (Linnaeus) produced by dry yeast. All species could normally develop and reproduce with C. lactis. The mean developmental period of A. swirskii females was the longest and was different from the other two species. The mean oviposition period and the fecundity of the three predatory species did not differ. The mean longevities of A. swirskii and A. eharai were shorter than that of N. cucumeris. The total fecundity among the three predatory species was not significantly different. Although no differences in R0 were found among the three predators, the rm of A. swirskii was lower than that of A. eharai because of its long mean generation time (T). Additionally, the rm of N. cucumeris was the lowest among the three predators because it had the longest T. As such we established C. lactis as a suitable extra-guild prey species for A. eharai, A. swirskii and N. cucumeris in a comparison with previous reports that tested various food types, such as pollen, insects and mites. This study is the first to report that C. lactis was prey for A. eharai and N. cucumeris. Populations of C. lactis increased easily with dry yeast, and thus, this prey was very suitable for the present experiments.

Determination of thermal constant and development threshold of Bihar hairy caterpillar, Spilarctia obliqua Walker

Effect of six constant temperatures viz., 18±1, 21±1, 24±1, 27±1, 30±1 and 33±10C was studied on the egg hatchability, larval pupal development and adult survival of Spilarctia obliqua. Development rate of egg, larva and pupa gradually increased with increase in temperature, while total developmental period decreased. Mean developmental period of the pest decreased from 93.73 days at 18±10C to 31.20 at 33±10C. The lowest and the highest temperatures at which no development took place were found to be 12±10C and 39±10C, respectively. Regression equations between development rate and temperature were found to be Y= 0.0189 X -0.1998 (R2=0.88) for egg, Y=0.00122 X -0.0248 (R2=0.84) for small larva (1-3rd instar), Y=0.0058 X -0.0675 (R2=0.76) for large larva (4-6th instar), Y=0.0074 X-0.1075 (R2=0.94) for pupa and Y=0.0142 X-0.4363 (R2=0.79) for adults. Developmental threshold were determined to be 10.57, 11.27, 11.55, 15.28 and 10.92oC for egg, small larva, large larva, pupa, and adult respectively with corresponding thermal constant being 52.91, 344.82, 243.90, 142.85 and 70.42 degree days (DD). Thermal constant to complete a generation was found to be 854.90 DD. This was the first studies on this aspects, these estimated thermal thresholds and degree days could be used to predict the S. obliqua activity in the field for their effective management through pest forecasting.

English

Laboratory studies were conducted at the University of Port Harcourt to evaluate the response of dried yam chips as a host for Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae). The test was conducted using four improved yam varieties namely; Adaka, Ame, Nwokpoko and Obiaturugo. Ten grams of each substrate of the dried yam chips were placed in plastic containers of 300 ml and each container was infested with three pairs of one to three days old P. truncatus. Data on insect developmental periods in the various dried chips, as well as the susceptibility of the substrates, weight gain on the chips and the weight of frass produced were recorded. The beetles exhibited differential levels of preference for the yam chips from different varieties. They developed better on Obiaturugo and Nwokpoko than on Adaka and Ame. The mean developmental period of P. truncatus on yam dried chips were 96.33 and 65.33 days for Obiaturugo and Nwokpoko, respectively but failed to develop on Adaka and Ame. There was significant difference (P<0.05) in weight between the amount of frass produced on Obiaturugo and that produced on the other substrates. Also, there was significant difference (P<0.05) in weight gained between Nwokpoko and the other substrates. The study has shown that of the dried chips from the four varieties of yam, only Nwokpoko and Obiaturugo were found to be possible hosts of P. truncatus and thus need protection against the pest during storage. Key words: Prostephanus truncatus, infestation, yam, chips.

Determination of Thermal Constant and Development Threshold of Pink Borer, Sesamia inferens Walker

Effect of constant temperatures viz, 18 ± 1, 21 ± 1, 24 ± 1, 27 ± 1, 30 ± 1 and 33 ± 1 °C was studied on the egg, larval and pupal development of Sesamia inferens. Development rate of egg, larva and pupa gradually increased with increase in temperature, while total developmental period decreased. Mean developmental period of the pest decreased from 116.6 days at 18 ± 1 °C to 31.8 days at 33 ± 1 °C. The lowest and the highest temperatures at which no development took place were found to be 9 ± 1 and 39 ± 1 °C, respectively. Regression equations between development rate and temperature were found to be Y = 0.021X–0.290 (R2 = 0.94) for egg; Y = 0.002X–0.020 (R2 = 0.92) for small larva (1st–3rd instar); Y = 0.005X–0.056 (R2 = 0.76) for large larva (4th–5th instar) and Y = 0.006X–0.076 (R2 = 0.89) for pupa, respectively. Thermal constant for egg, small larva, large larva and pupa were determined as 47.6, 500.0, 200.0 and 166.7 degree days (DD), respectively with corresponding development threshold being 13.8, 10.0, 11.2 and 12.7 °C. Thermal constant to complete a generation was found to be 874.3 DD.