Progeny Emergence Research Articles

Screening of Maize Genotypes against Maize Weevil (Sitophilus zeamais Motsch.) in Laboratory Condition

Maize (Zea mays) is the second-most important staple food crop in Nepal. However, it suffers from severe post-harvest losses. Maize weevil (Sitophilus zeamais Motschulsky) is one of the major storage pests of economic importance. Thus, an experiment was conducted in a Completely Randomized Design with three replications to screen 10 maize genotypes (Manakamana-4, Arun-4, Rampur Hybrid-4, CAH- 1715, Rampur Hybrid-6, Rampur Composite, Khumal Hybrid-2, Arun-2, Rampur Hybrid-10, and Poshilo Makai-1) against S. zeamais for tolerance and their effects on progeny emergence, grain damage, and weight loss in no-choice condition at National Entomology Research Centre, Khumaltar during November 2020 to May 2021 Among tested genotypes, least number of progeny emergence was observed in Rampur Composite (1.00) and Khumal Hybrid-2 (1.00) and highest was observed in Manakamana-4 (6.66) followed by Poshilo Makai-1 (3.00). The lowest percent grain damage was recorded in Khumal Hybrid-2 (1.03) followed by Rampur Hybrid-4 (1.28) and Rampur Composite (1.29) showing their tolerance to maize weevil. Similarly, the highest percent grain damage was recorded in the genotypes Manakamana-4 (6.57) and Poshilo Makai-1 (2.58) showing their susceptibility to maize weevil attack. The highest and lowest percent weight loss was recorded in Manakamana-4 (4.86) and Rampur Hybrid-4 (1.48) respectively. The other remaining genotypes were intermediate types. This finding is helpful to improve maize grain protection in storage and varietal improvement program.

Comparative Efficacy of Aqueous Extracts of Lime (Citrus aurantifolia) and Grape (Citrus paradisi) Peel in the Control of Callosobruchus maculatus (F.)

A laboratory study was conducted in the Department of Crop Protection, University of Ilorin, to evaluate the single and mixed insecticidal action of aqueous extracts of grape (Citrus paradisi) and lime (Citrus aurantifolia) peel in the control of cowpea beetle, Callosobruchus maculatus. The experiment was laid out in a completely randomized design. There were four treatments with three replicates per treatment. The treatments were applied at the following rates, 0.5ml, 1.0ml, and 1.5ml per 100g of cowpea seeds. The following parameters were used to assess the efficacy of the treatments; adult mortality, oviposition, number of larvae, number of pupae and F1 progeny emergence. The findings of this experiment showed that 1.0 ml of aqueous peel extract of grape + lime had significantly higher female mortality compared to control at 3rd and 5th DAT. Aqueous peel extract of lime caused a significantly lower (70.67 + 4,3) oviposition rate compared to control (141.33+ 7.4) at 2 DAT with 1.5 ml being the most effective rate of application at 4 DAT. Aqueous peel extracts of lime was most effective in significantly reducing larval emergence (1.33 + 0.3) compared to control (8.33 + 0.5). The trend was similar for pupal emergence. Aqueous peel extracts of grape was most effective in reducing male F1 progeny emergence while lime was most effective in reducing female F1 progeny of C maculatus. Aqueous peel extract of lime could be included in control measures used by local farmers in storage of their grains for two months.

Evaluation of selected botanicals for the management of maize weevil (Sitophilus zeamais) on maize (Zea mays L.) grain under laboratory condition in Gabilay District, Somaliland

One of the most reliable crops in the research region is maize. However, a variety of post-harvest insect pests like Sitophilus zeamais and Angoumois grain moths pose a hazard to the cultivation and storage of maize. Hence, a laboratory experiment was conducted in Gabilay District Somaliland in 2021 to assess selected botanicals effectiveness against maize weevil. The treatments of consisted of six botanicals namely neem seed, neem leaves, garlic, lantana, ginger, and pepper tree leaves at 50 g/kg of each were evaluated. Malathion 5% dust at 0.05 g/kg as standard check and the control/untreated check/were included for comparison. The Experiment was designed in a Completely Randomized Design and replicated three times, All the botanical powders were more effective than the control by causing high insect mortality, by lowering grain damage, weight loss, and emergence of F1 progeny. Neem seed and Garlic showed 100% adult mortality, which had a similar effect to Malathion 5% dust. Neem seeds produced the lowest F1 offspring, followed by garlic. Neem seeds and garlic had the least amount of seed damage among the botanicals (0%) and (4%), respectively. The control/untreated check/resulted in the most seed damage (45%). Similarly, the highest weight loss among the botanicals was recorded on the control check, Ginger and Pepper tree 11%, 5%, and 4% respectively. The ability of seeds to germinate was unaffected by the botanicals. A conclusion, neem seed and garlic leaves are the most effective treatment against maize weevil.

Efficacy of food-grade diatomaceous earth as grain protection against <em>Rhyzopertha dominica</em> - Lesser Grain Borer in stored chickpea under tropical conditions

The efficacy of different concentrations of diatomaceous earth against the <em>Rhyzopertha dominica</em> in chickpea was evaluated. The selected concentrations were 0.01%, 0.05%, 0.1%, 0.5%, and 1% on (W/W) basis. Each treatment was replicated three times and 20 same-aged unsexed adult <em>Rhyzopertha dominica</em> species were introduced into each jar. The percentage of mortality <em>Rhyzopertha dominica</em> species and weight reduction of chickpea commodity were recorded weekly for five weeks. After the 5th week onwards the samples were let to progeny development without any disturbance. The progeny counts were carried out at the end of the 9^thweek. The results showed that mortality percentage <em>Rhyzopertha dominica</em> species, weight reduction of chickpea commodity, and progeny emergence highly affected by different concentrations of diatomaceous earth (DE). The maximum percentage of mortality was attained early, when the concentration was 1%, at the end of the 3rd week (100%). The percentage of weight reduction is relatively less for 1% concentration compared with other treatments. After 9 weeks of exposure, the chickpea commodity treated with 1% and 0.5% concentrations of DE shows the zero number of visible pupal stage and F1 adult progeny of <em>Rhyzopertha dominica</em> species. While chickpea commodity treated with 0.1% concentration of DE shows the dead visible F1 generation of <em>Rhyzopertha dominica</em> species. This means, the larva has emerged as adults but at the end of the 9 weeks of the exposure period, F1 progenies were completely suppressed. The percentage of mortality <em>Rhyzopertha dominica</em> species, weight reduction of chickpea commodity, and the emergence of the progeny of <em>Rhyzopertha dominica</em> species depend upon the different concentrations of DE and applying 1% of DE highly effective concentration to control the <em>Rhyzopertha dominica</em> species in the chickpea commodity.

Integrating Tithonia Diversifolia, Piper Guineense and Oil Palm Bunch Residue Ash for the Management of Sweet Potato Weevil (Cylas Puncticollis Boh.) and on Yield of Sweet Potato in Fako Division of Cameroon

This research was to evaluate the effects of integrating T. diversifolia, P. guineense and OPBRA to manage Cylas puncticollis infestation and on the yield of sweet potatoes. Bioassay 1, 5g T. diversifolia + 5g P guineense /100mL and 10g P guineense /100mL showed significant low (P &lt; 0.05) in mortality, number of eggs laid, percentage repellence and progeny emergence of C. puncticollis. Bioassay 2: 20 g OPBRA /100mL, 5g OPBRA + 5g P guineense /100mL, and 10g P guineense /100mL. The lowest progeny emergence was 5g OPBRA + 5g P guineense /100mL. 5g OPBRA + 5g P guineense /100mL, and 10g P guineense /100mL showed significant difference (P &lt; 0.05) in mortality, mean number of eggs laid of C. puncticollis with the control. Bioassay 3 and 4: showed significant effect (P &lt; 0.05) of T. diversifolia, OPBRA and P. guineense pastes on weight loss due and root sizes to C. puncticollis damage of sweet potato. On the field, sweet potatoes that were treated with 2 ton/ha T. diversifolia + 2 ton/ha OPBRA + 0.33 ton/ha P. guineense and 0.67 ton/ha P. guineense showed significantly (P &lt; 0.05) less infestation than the other treatments. Plants treated with 2 tons/ha T. diversifolia +2 tons/ha OPBRA + O.33 tons/ha P. guineense had the highest yield. The combination of T. diversifolia, OPBRA and small proportion of P guineense could serve as an alternative of source of synthetic pesticides managing C. puncticolis infestation as well as source of organic matter improve soil fertility.

Bioactive constituents and fumigant toxicity of Datura metel extracts as grain protectant and progeny emergence inhibition of Callosobruchus maculatus (Coleoptera: Bruchidae)

Bioactive constituents and fumigant toxicity of Datura metel extracts as grain protectant and progeny emergence inhibition of Callosobruchus maculatus (Coleoptera: Bruchidae)

THE EFFICACY OF Azadirachta indica (NEEM PLANT) LEAF POWDER AGAINST MAIZE WEEVIL, Sitophilus zeamais MOTSCHULSKY

The experiment was set up to assess the insecticidal properties of Azadirachta indica (neem plant) leaf powder on Sitophilus zeamais Motschulsky. The experiment was laid out in a completely randomized design (CRD), using four replications each for two treatments and also four replications for the control (untreated), from December, 2012 to March, 2013 at the University of Benin, Benin City, Nigeria. These were incubated for 46 days; the F1 progeny and weevil mortality were taken daily. Temperature and relative humidity ranged from 290C to 310C and 70% to 83% respectively. Mortality was highest (3.25) in 10g concentration and lowest (0.25) in the untreated (control). Progeny emergence was highest (187.50) in the untreated (control) and lowest (20.75) in the 10g concentration. The mean progeny emergence in the untreated maize grains was significantly different (P&lt;0.05) from emergence in the treated grains. Analysis of variance showed that Azadirachta indica powders caused significant mortality to the maize weevil, Sitophilus zeamais. There was however, no significant difference between the concentrations, but there was significant difference (P&lt;0.05) between the concentrations and the control. The study suggests that leaf powder of Azadirachta indica can be used as a good alternative to pesticides against Sitophilus zeamais.

Efficacy of Piper guineense (Shum and Thonn), Dennettia tripetala (G. Baker), and Ocimum gratissimum (Linnaeus) powders admixed with selected excipients for the control of Callosobruchus maculatus (Fabricus) infesting cowpea, Vigna unguiculata (L. Walp), seed

The use of synthetic insecticides to control stored product insects causes various health and Ecological challenges to man. Therefore, there is a need for alternative formulations like plant materials with the least possible side effects for the effective control of cowpea bruchid, Callosobruchus maculatus (Fabricius), a cosmopolitan pest of pulses. This study evaluated the efficacy of insecticidal dust formulations using three botanicals (Piper guineense, Dennettia tripetala and Ocimum gratissimum), three excipients (rice bran, maize husk and cowpea pod husk), admixed at ratios 70:30, 60:40, 50:50, 40:60 and 30:70 botanical to an excipient, for the control of C. maculatus. Four particle sizes (212, 300, 500 and 1000 µm) applied at dosages of 0.1- 0.5 g / 20 g cowpea seeds were assayed and untreated cowpea seeds served as controls. Ten C. maculatus adults (sex ratio 1:1) were used to infest the treated and untreated cowpea seeds separately in Petri dishes. Data were collected on mortality, Oviposition, F1 progeny emergence and damaged cowpea seeds. The data were subjected to analysis of variance and means were separated with Least Significant Difference at a 5% significance level. All dosage ratios of the formulated dusts caused significantly (p˂ 0.05) higher mortality of bruchids, reduced the number of laid eggs, F1 progeny emergence and damaged cowpea seeds due to C. maculatus infestation. Regardless of the assayed botanical, 212 µm particle size was outstanding and the formulation ratio of 70:30 (botanical: excipient) was significantly (p˂ 0.05) better than other formulation ratios. The formulation with P. guineense with any excipient at 0.5 g/ 20 g cowpea seeds using 212 µm was superior to other formulations as cowpea protectant against C. maculatus. Therefore, it is recommended as an alternative to over-dependence on synthetic insecticides.

Evaluation of three German enhanced diatomaceous earth formulations for the management of two major storage pests in Ghana

In Ghana major stored product insect pests of maize and rice are controlled by the use of synthetic insecticides which are very expensive for farmers, might affect worker safety if not properly applied due to lack of technical know-how. Moreover, its use might eventually lead to some toxic residues in the end product for human consumption. In an attempt to look for alternatives to synthetic insecticides to control storage pest of cereals in Ghana in general, three improved diatomaceous earths (DEs), InsectoSec®, Diatomeenerde Probe-A and Fossil Shield® 90.0 were tested in the laboratory against Sitophilus zeamais Motschulsky (Coleoptera: Dryophthoridae) and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) from Ghana. Application rates on stored maize or rice were 500, 1000, 2000 and 3000 ppm. Adult mortality was recorded after 32 days and, progeny production after 6 weeks. InsectoSec® was most toxic against the adults of S. zeamais followed by Fossil Shield and Diatomeenerde Probe-A. For the progeny production InsectoSec® and Diatomeenerde suppressed S. zeamais on maize better than Fossil Shield®. In contrast, Fossil Shield® and InsectoSec® were better compared to Diatomeenerde in suppressing progeny production of T. castaneum. There was no significant difference in mortality among the highest dosages of the three DE's against S. zeamais and T. castaneum up to the 14th day, while InsectoSec® and Fossil Shield® were more effective than Diatomeenerde at the lower dosages. Mortality of the adult beetles was dose-dependent. The LT50 ranged from 9 d to 13 d for T. castaneum exposed to 1.0% InsectoSec® and 1.0% Fossil Shield®, respectively. LT50 of 5 d, 6 d, and 9 d were recorded for S. zeamais exposed to the highest dosage of 3.0% Fossil Shield®, InsectoSec® and Diatomeenerde, respectively. All formulations reduced the progeny emergence compared to the control. The potential of using diatomaceous earth for the bio-rational control of major storage pests in Ghana is discussed.

Insecticidal activity of leaf powders against rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae)

In laboratory studies leaf powders of ten plants, namely, Ageratum conyzoides L., Chromolaena odorata (Asteraceae) Lantana camara L., Vitex negundo L. (Verbenaceae), Piper nigrum L., Piper longum Linn (Piperaceae), Ricinus communis L. (Euphorbiaceae), Azadiracta indica L. (Meliaceae), Mangifera indica L. (Anacardiaceae), Annona squamosa Linn. (Annonaceae) were evaluated for their efficacy to cause mortality, reduction in progeny emergence and repellency against rice weevil, Sitophilus oryzae L (Coleoptera: Curculionidae). Adult weevils were exposed to three concentrations (1, 5 and 10%) of each plant powder. Observations for contact toxicity were recorded upto 7 days after treatment at 24 hours interval. Highest mortality was recorded from leaf powders of P. nigrum and P. longum at 7 DAT. Lowest emergence of S. oryzae adults were documented from A. conyzoides, A. indica, L. camara in all concentrations tested whereas leaf powders of A. reticulata, A. indica and P. longum effected more repellence towards S. oryzae adults at 24 HAT.

Botanical Pesticides: Use of Plants in pest management

Plants play a vital role in human life since the beginning of life on earth. Plants are not only directly used as a feed and fodder for humans and animals but are also used as drugs, food additives, pesticides, in flavor and fragrances and dye and pigments. The plants produce compounds for their growth and development and also produce secondary metabolites which provide additional properties to plants. These secondary metabolites produced by plant are responsible for these activities. Plants as a whole or in extracts/fractions form have been used as pesticides for protection of plants since thousands of years. Pyrethrum, neem, rotenone are such plants which has been used in many cultures and traditions for crop protection since ages and hold relevance in today’s world as well. The plant extracts contain secondary metabolites which provide protection to plants against pests by either causing mortality of pests or act as repellent to them. They can also impact pests by causing anti-feedancy, toxicity, alters insects behavior during oviposition and mating and inhibition of progeny emergence in pests. Essential oils isolated from the plants have also pesticidal properties. Lemongrass essential oil, Citronella essential oils, Tea tree essential oils and Oregano essential oils are the commonly used essential oils against the pests. In this review, botanical pesticides are discussed and their role in pest management and their advantageous over synthetic pesticides in terms of biodegradability, posing no or low risk to humans, environment and non-target organisms. Also, the future of botanical pesticides is discussed where they can be an alternative to synthetic pesticides if more research is done on their stability, efficacy, safety, modes of action, cost reduction is done.

Seed powder extract of physic nut (Jatropha curcas) as a biopesticide for weevils (Callosobruchus maculatus) in stored cowpea (Vigna unguiculata)

The study explored the effectiveness of physic nut (Jatropha curcas) in the control of cowpea weevils (Callosobruchus maculatus). The repellence, mortality rates and progeny emergence of weevils were observed, as well as germination viability of the treated cowpea seeds. The study adopted experimental research, using complete randomized block design. The results showed that seed powder extract of physic nut is effective in disrupting the normal activities of the weevils. However, the repellence and mortality rates of the weevils depended on the dosage administered and the duration of exposure to the treatment. The treatment was found to be most effective at 20 g, where repellence and mortality rates were 53.3% and 60.0%, respectively, while 0 progeny emergence occurred during the experimental period. The treated seeds were also found to be viable for planting as there was 100% seed germination. The study adds to the literature on innovative, sustainable and indigenous pest control measures in post-harvest storage of edible seeds in Africa.

Parasitoid age and host age interact to improve life history parameters and rearing of Trichogramma euproctidis

ABSTRACT Trichogramma euproctidis (Girault) is an egg parasitoid under consideration for mass production and augmentative biological control of major lepidopteran pests in Iran and other countries. The main objective of this research was to determine the effects of T. euproctidis female age and Ephestia kuehniella Zeller egg age on life history parameters of T. euproctidis. Experimental design involved exposing 1-, 2-, 3-, or 4-d-old E. kuehniella eggs to 1-, 2-, 3-, or 4-d-old T. euproctidis females in glass test tubes. Results indicated that host egg age and parasitoid female age interacted significantly to improve parasitism rate, progeny emergence rate, sex ratio, longevity, and fecundity of T. euproctidis. The age of T. euproctidis females affected parasitism rate; 1-d-old females, rather than the other ages, parasitised more E. kuehniella eggs. The highest mean total fecundity (81.62 eggs) was recorded from adult progeny produced by 1-d-old T. euproctidis females reared from 1-d-old E. kuehniella eggs. Trichogramma euproctidis development time increased as the age of E. kuehniella eggs increased, but the parasitoid female age and host egg age interaction was not significant. A life table analysis confirmed the results that 1-d-old T. euproctidis females and 1-d-old E. kuehniella eggs resulted in optimal effects on T. euproctidis life history. This study implies that mass rearing systems designed to expose young-aged T. euproctidis females to young-aged E. kuehniella eggs would maximise T. euproctidis progeny production.

Assessment of Insecticidal Potency of Eggshell Powder Against Maize Weevil

Efficacy of chicken eggshell powder at concentrations 0, 0.25, 0.5, 1.0 and 2.0 g /100 g maize, for control of Sitophilus zeamais, were compared with permethrin at dosage rate of 0.167g / 100 g of yellow maize. Experiments were conducted at Biotechnology laboratory (NSPRI), Ilorin under ambient condition (26±3oC 65±5% RH). Mortality of S. zeamais increased with increasing dosages of the CESP as well as with days of exposure. CESP at 2.0g gives 96.67% mortality which is not significantly different from the positive control. The mean progeny emergence (0.00%), weight loss (1.11%), and percentage grain damage (19.68%) by S. zeamais was significantly (P ≤ 0.05) decreased with increased dosage of CESP. However, CESP did not significantly affect seed germination. Total coliform count at 2.0 g (2.48 x 102) was significantly different from both positive and negative controls at p&lt;0.05 Therefore, CESP can serve as a good maize protectant which can be used as substitute for synthetic chemicals.

Evaluation of three cold storage methods of Bagrada hilaris (Hemiptera: Pentatomidae) and the effects of host deprivation for an optimized rearing of the biocontrol candidate Gryon gonikopalense (Hymenoptera: Scelionidae)

The cold storage of host eggs has been utilized in the production of egg parasitoids used in biological control programs. However, similar stockpiling methods can lead to various responses depending on the parasitoid species considered. Hence, standardization of storage methods is difficult. The egg parasitoid Gryon gonikopalense Sharma, is currently being evaluated as a biocontrol agent of Bagrada hilaris (Burmeister), an invasive pest on Brassicaceae crops in the Americas. In this study, we investigated cold storage methods and the effect of host deprivation on G. gonikopalense in order to optimize its rearing process. Laboratory tests were conducted with bagrada bug eggs stored under three temperature treatments (-20 °C, 5 °C, 13 °C) and six durations (one week to three months). In addition, we assessed the effect of host deprivation on parasitoid fecundity and progeny development. Bagrada bug eggs stored at 5 °C up to one month allowed three and nine times more parasitism than eggs stored at 13 and -20 °C respectively. Progeny emergence rate was also the best with eggs stored at 5 °C (94.1%) while eggs stored at 13 and -20 °C led to 77.7 and 89.2 % of emergence respectively. However, the different storage treatments led to similar longevities and body lengths for male and female progeny. In addition, G. gonikopalense did parasitize bagrada eggs after 60 days of host deprivation, but fecundity was reduced by 84%. The results can be used to optimize bagrada bug egg production for use in laboratory and / or field experiments and improve G. gonikopalense rearing and production.

TOXICITY OF Piper guineense SCHUM AND THONN AND Chlorpyrifos POWDERS FOR THE CONTROL OF Callosobruchus subinnotatus (Pic.) ON STORED Vigna subterranea (L.) Verdcourt IN GOMBE STATE, NIGERIA

A study was conducted with aim of determining toxicity effects of Piper guineense and chlorpyrifos powders on adult mortality of Callosobruchus subinnotatus, progeny emergence (F1), damage and weight loss, germination of Bambara nuts. Study was carried out at Botany laboratory, Gombe State University, Gombe State, Nigeria. P. guineense and chlorpyrifos were mixed at 0.0g and 0.8g concentration with 20g Bambara nuts inside 1000ml plastic containers. Experiment was conducted in randomized complete block design in three replicates. Ten pairs of adult C. subinnotatus unsexed were introduced into treatments nuts and stored for 7days. Bruchid mortality, progeny emergence, nut damage and weight loss, and germination were assessed. Data obtained were subjected to analyses of variance, significant differences of treatment mean were separated using New Duncan’s multiple range test at 5% probability level. Piper guineense and chlorpyrifos powders had comparable toxicity effects, causing 100% C. subinnotatus adult mortality between 5-7 days of treatment. P. guineense and chlorpyrifos powders proved effective as lower C. subinnotatus progeny emergence was observed compared with control. Progeny emergence under control was 93.42% and 100% higher than nuts treated with P. guineense and chlorpyrifos, respectively. P. guineense and chlorpyrifos did not cause significant reduction in seed germination. Study recommends P. guineense is a reliable organic material that could offer protection to Bambara nuts against C. subinnotatus

Effects of defect action level of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) fragments on quality of wheat flour.

Tribolium castaneum (Herbst) is one of the most important secondary storage pests of all types of flour and flour-based products. The present study focuses on the fragment producing behaviour of T. castaneum in wheat flour during storage and its effect on the quality parameters and defect action level (DAL) of fragments. The US Food and Drug Administration has set a DAL of 75 insect fragments in 50 g of flour. Box-Behnken design was used to optimize the storage conditions (storage period in days and temperature in degrees Celsius) and insect density (numbers) to keep insect fragments below the DAL. Optimization results indicated that the presence of single number of adult of T. castaneum is enough to cross the DAL of insect fragments within a storage period of 21 days at a storage temperature of 30 °C. Insect fragments cause perceptible changes in the quality of wheat flour. When sample attained DAL of T. castaneum fragments in wheat flour,the various quality parameters were analysed in that moisture content of wheat flour was 10.8 ± 0.26%, total colour change was 2.052 (ΔE value), T. castaneum progeny emergence was 19.66 ± 1, uric acid was 1.8 ± 0.16 g kg-1 and microbial count was 7.34 ± 0.5cfu g-1 . Results from the present study indicate that the presence of even a single adult of stored pest in wheat flour should not be ignored. It is mandatory to determine the threshold level and frequent sampling is required to achieve zero tolerance of stored product insects in food commodities. © 2021 Society of Chemical Industry.

Influence of Holding Conditions and Storage Duration ofHalyomorpha halys(Hemiptera: Pentatomidae) Eggs on Adventive and Quarantine Populations ofTrissolcus japonicus(Hymenoptera: Scelionidae) Behavior and Parasitism Success

Halyomorpha halys (Stål) is an invasive pest in the United States and other countries. In its native range, H. halys eggs are parasitized by a co-evolved parasitoid, Trissolcus japonicus (Ashmead). In the United States, T. japonicus, a classical biological control candidate, is being redistributed in many states where adventive populations exist. To establish if H. halys egg holding conditions affect T. japonicus foraging behavior or successful parasitism, naïve, female parasitoids from an adventive population were allowed to forage in laboratory bioassay arenas with either fresh or frozen (-20 or -80°C) egg masses, the latter held for five durations ranging from 1 h to 112 d. Parasitoid movements were recorded for 1 h. Thereafter, parasitoids were transferred with the same egg mass for 23 h. Additionally, female parasitoids from a quarantine colony were exposed to: 1) pairs of fresh egg masses and egg masses frozen at -40°C (>24 h) or 2) a single fresh egg mass or egg mass frozen at -40°C (<1 h). All exposed egg masses were held to assess progeny emergence. In the foraging bioassay, holding temperature and storage duration appeared to influence host-finding and host quality. Egg masses held at -80°C and fresh egg masses resulted in significantly greater levels of parasitism and progeny emergence compared with eggs held at -20°C. No differences were recorded between egg masses held at -40°C for ≤1 h and fresh egg masses. These results will help refine methods for preparation of egg masses for sentinel monitoring and parasitoid mass rearing protocols.

Evaluation of different blood-feeding frequencies on Glossina palpalis gambiensis performance in a mass-rearing insectary

BackgroundThe main challenge to the successful mass-rearing of the tsetse fly in insectaries, especially in Africa, is a sustainable supply of high-quality blood meals. As such, the collection of high-quality blood in large quantities can be an important constraint to production. One possible strategy to lessen the impact of this constraint is to modify the blood-feeding frequency. In the study reported here, we evaluated the effect of three blood-feeding frequencies on the colony performance of Glossina palpalis gambiensis, a riverine tsetse fly species.MethodsThe effect of three, four and six blood-feedings per week on female survival and productivity were evaluated over a 30-day period. Progeny emergence rate and flight ability were also evaluated.ResultsFemale survival was significantly higher in flies fed four times per week (87%) than in those fed three (72%) and six times per week (78%; P < 0.05). Productivity was similar between flies fed four and six times per week (457 and 454 larvae) but significantly reduced in flies fed three times per week (280 larvae produced; P < 0.05). Both emergence rate and flight ability rate were also similar between flies fed four times per week (97 and 94%, respectively) and six times per week (96 and 97%, respectively), but they were significantly reduced when flies were fed three times per week (89 and 84%, respectively; P < 0.05).ConclusionsBlood-feeding frequency could be reduced from six times per week to four times per week without affecting mass-rearing production and progeny quality. The implications of these results on tsetse mass-rearing production are discussed.Graphical

Susceptibility of ten rice brands to weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae), and their influence on the insect and infestation rate

BackgroundSusceptibility studies keep farmers, managers and household users informed and enhance breeding program’s testing against infestation and damage by storage insect pests. Therefore, laboratory tests were carried out to examine the susceptibility of ten rice brands to rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae), infestation under temperature and relative humidity of 25 ± 2 °C and 75 ± 5%, respectively. The specific objectives of the study were to identify some commercially available rice brands with resistance to S. oryzae, by determining whether brand difference influences insect body weight at emergence and whether infestation is related to brand palatability and appearance. The ten brands used for the study were royale stallion, Mama royale, parboiled rice, Mama gold, white rice, Super eagle, Indian rice, champion rice, Abakiliki rice and Mama Africa, and standard methods were used to achieve the objectives. The indices measured were F1 progeny emergence, grain weight loss and frass accumulation.ResultsThe results showed that Abakiliki rice was poor in both palatability and appearance, whereas Super eagle was the most palatable and white rice was visually excellent. The results further showed that no brand was resistant to infestation and damage by S. oryzae. Males that were bred on the different rice brands did not differ in weight at emergence, but the weight of females at emergence was influenced by brand difference, and this suggests that female insects are more sensitive to brand difference at weight gain.ConclusionPalatability and appearance were important in the susceptibility of rice brands to S. oryzae. The proliferation of diverse genotypes of rice (branded) with enhanced resistance to S. oryzae should be strongly encouraged to reduce susceptibility and increase rice security.