Obtaining accurate measurements of the size and volume of insects fed to nestlings from video recordings

Video recordings are commonly used to study the types, amount, and size of food items provided to nestling birds. However, the accuracy and repeatability of estimates of the size of food items from video recordings has not been examined. We assessed three aspects of the reliability of measuring prey size from video recordings of Great Tits (Parus major) provisioning nestlings. To test the accuracy of measurements of prey size (length and width) used to determine prey volume, we molded artificial plasticine caterpillars and compared their size and volume as determined using measurements of length and width on screenshots of video recordings (using the vertical diameter of nest‐box entrance holes as a size reference) to their actual size and volume. We also examined within‐ and among‐observer repeatability of measurements of the size and volume of actual prey items delivered to nestlings by adult Great Tits. We found that observers were able to accurately measure prey size and determine volume, with high agreement between the actual size and volume of plasticine caterpillars and the size and volume as determined from measurements made on screenshots from video recordings (r_ICC = 0.99). In addition, within‐ and among‐observer repeatability were also high (r_ICC = 0.98 and 0.93, respectively). Overall, our results suggest that the size of prey items delivered to nestlings by adults in video recordings can be accurately measured and those measurements, in turn, can be used to accurately determine the volume of those insect prey.     

SIMULATING THE SPATIO-TEMPORAL DYNAMICS OF THE PINE CATERPILLAR (DENDROLIMUS PUNCTATUS WALKER) DAMAGE USING THE GENERALIZED CA MODEL

Abstract  A nonlinear model for simulating the spatio-temporal dynamics of the damage level of the pine caterpillar, Dendrolimus punctatus Walker, is proposed in this study. It includes the self-dependence (interaction) component, the reaction component, and the cross effect component. The average distance of interaction and reaction and how the dependence changes along distance are detected by using variogram and correlogram. The simulation result shows that the model may forecast the high damage level properly, but a bit underforecast for the low damage area. The predicted trend of damage is the same as the actually occurred.     

Fluorescent Brighteners Improve Anticarsia gemmatalis (Lepidoptera: Noctuidae) Nucleopolyhedrovirus (AgMNPV) Activity on AgMNPV-Susceptible and Resistant Strains of the Insect

Fluorescent (optical) brighteners are known for their characteristics of protecting baculoviruses against deactivation by ultraviolet (UV) light and enhancing the activity of these agents as microbial insecticides on hosts and semipermissive hosts. These substances were evaluated in combination with the velvetbean caterpillar, Anticarsia gemmatalis Hübner, multiple-embedded nucleopolyhedrovirus (AgMNPV). The first trial involved 4 fluorescent brighteners (Blankophor BBH, Blankophor HRS, Blankophor RKH, and Tinopal LPW) obtained from the United States. The second trial was conducted with 11 fluorescent brighteners (Tinopal UNPA-GX, Tinopal DMS, Tinopal CBS, Leukophor DUB, Leukophor BSBB, Hostalux KS-N, Hostalux ETBN, BRY 10 D2 100, BRY 10 D2 150, Uvitex BHT, and Uvitex NFW) available in Brazil in combination with the AgMNPV to determine the degree of enhancement of viral activity. These brighteners were also evaluated with regard to AgMNPV protection against deactivation by UV light. Combinations of the virus with selected fluorescent brighteners were tested against both AgMNPV-susceptible and resistant strains of A. gemmatalis. In the first trial, brighteners obtained from the United States promoted increases in AgMNPV activity from 5.2-fold (Blankophor HRS) to 76.6-fold (Blankophor RKH) and reduced the mean time to death by 2.8 to 3.5 days. In the second trial, the most effective brightener (Tinopal UNPA-GX) reduced the LC₅₀ in A. gemmatalis larvae from 7083 occlusion bodies (OBs)/ml (virus alone) to 77.8 OBs/ml (≈90-fold). When 4 selected brighteners were tested in combination with the AgMNPV in resistant insects, the LC₅₀ was reduced by ca. 10,000-fold (Leukophor DUB) to ca. 62,000-fold (Tinopal UNPA-GX), in comparison to the LC₅₀ of 3.7 × 10⁷ OBs/ml observed for the virus alone. Therefore, mortality of highly resistant A. gemmatalis larvae to the AgMNPV increased dramatically when the virus was combined with some fluorescent brighteners. UV protection measured by original activity remaining (OAR) varied from <30% OAR (Uvitex NFW) to >90% OAR (Tinopal UNPA-GX and BRY 10 D2 100). All efficacious brighteners were stilbene disulfonic acid derivatives and, when used alone, none showed negative effects against A. gemmatalis larvae.     

Susceptibility of the pine processionary caterpillar Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeidae) toward δ-endotoxins of Bacillus thuringiensis under laboratory conditions

A series of natural crystal proteins from B. thuringiensis subsp. Alesti 12–25, caucasicus, galleriae 11–67, galleriae 6–96, kenyae, and shondungensis and spore‐crystal preparations from finitimus 11–66 and from a recombinant strain of B. thuringiensis subsp. kurstaki expressing Cry 1 Ga1 only, were assessed as a toxic agent for the pine processionary caterpillar, Thaumetopoea pityocampa. Some preparations had a thoroughly investigated composition and contained Cry1Aa, Cry1Ab2, Cry1Ab7, Cry1D, Cry1F, Cry 1 Ga1, Cry9Aa, Cry26 crystal proteins, whereas crystals of B. thuringiensis subsp. caucasicus, kenyae, and shondungensis harboured predominantly unidentified toxins distant from commonly used prototypes. Bioassays were based on the simultaneous assignment of each treatment to groups of 20 full sibling first‐instar larvae, obtained from broods of a population from North‐western Italy. The toxin was applied to pine needles by the leaf dipping method and the effect was registered in both feeding inhibition and mortality. B. thuringiensis subsp. caucasicus, kenyae, galleriae 6–96, alesti, and galleriae 11–67 gave the best results in terms of both feeding inhibition and larval mortality. Broods tested in B. thuringiensis bioassays showed a substantial variation in susceptibility to the toxins, suggesting the potential development of resistance in the population.     

Temperature and population density: interactional effects of environmental factors on phenotypic plasticity,immune defenses,and disease resistance in an insect pest

Temperature and crowding are key environmental factors mediating the transmission and epizooty of infectious disease in ectotherm animals. The host physiology may be altered in a temperature‐dependent manner and thus affects the pathogen development and course of diseases within an individual and host population, or the transmission rates (or infectivity) of pathogens shift linearly with the host population density. To our understanding, the knowledge of interactive and synergistic effects of temperature and population density on the host–pathogen system is limited. Here, we tested the interactional effects of these environmental factors on phenotypic plasticity, immune defenses, and disease resistance in the velvetbean caterpillar Anticarsia gemmatalis. Upon egg hatching, caterpillars were reared in thermostat‐controlled chambers in a 2 × 4 factorial design: density (1 or 8 caterpillars/pot) and temperature (20, 24, 28, or 32°C). Of the immune defenses assessed, encapsulation response was directly affected by none of the environmental factors; capsule melanization increased with temperature in both lone‐ and group‐reared caterpillars, although the lone‐reared ones presented the most evident response, and hemocyte numbers decreased with temperature regardless of the population density. Temperature, but not population density, affected considerably the time from inoculation to death of velvetbean caterpillar. Thus, velvetbean caterpillars succumbed to Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV) more quickly at higher temperatures than at lower temperatures. As hypothesized, temperature likely affected caterpillars' movement rates, and thus the contact between conspecifics, which in turn affected the phenotypic expression of group‐reared caterpillars. Our results suggest that environmental factors, mainly temperature, strongly affect both the course of disease in velvetbean caterpillar population and its defenses against pathogens. As a soybean pest, velvetbean caterpillar may increase its damage on soybean fields under a scenario of global warming as caterpillars may reach the developmental resistance faster, and thus decrease their susceptibility to biological control by AgMNPV.     

The effects of group size and host species on development and survivorship of a gregarious caterpillar Halisidota caryae (Lepidoptera: Arctiidae)

Abstract. 1. The effect on growth and survivorship of the number of Halisidota caryae (Harris) caterpillars in groups feeding on three taxonomically distinct hosts was examined experimentally in the field.
2. Caterpillars grew more rapidly and survived better in larger sized groups than in smaller sized groups.
3. Caterpilliars grew more rapidly and survived better on Carya ovata (Koch) than on Hamamelis virginiana (L) or Quercus velutina (Lam.).
4. There were equal numbers of invertebrate predators on groups of different sizes and thus larger groups had significantly fewer predators per caterpillar than did smaller groups.
5. Invertebrate predators accounted for at least a 10% daily decrease in survivorship.
6. Local movement reduced predation because moving groups had fewer predators than did stationary groups.     

The effect of deprivation on the microstructure of feeding by the Tobacco hornworm caterpillar

An automated device was used to examine, in detail, feeding on disks of wheat germ medium by fifth-instar Manduca sextacaterpillars. Comparisons were made between some animals which had ad libitum access to food at all times and others which were deprived of food for 1–5 h before being tested. Feeding patterns of both groups indicated regulation of feeding both between and within meals. Deprived animals ate more during their first meal than did nondeprived animals chiefly by increasing (a) the number of chewing bouts (and thus the meal duration) and (b) the bite frequency. Calculations indicated that the deficit caused by deprivation was made up during the first meal. However, deprived animals continued to eat more than nondeprived ones in subsequent feeding also. Passage of food through the gut was examined by dissecting out the contents of each region of the gut at various times after a colored test meal. Food passed through the foregut directly into the anterior part of the midgut. It stayed in the middle third of the midgut longer than in the anterior and posterior thirds, and the first pellet resulting from the test meal appeared 4 h after the meal. The following mechanisms of feeding regulation are proposed: (a) volumetric feedback mediated by stretch receptors of the foregut and anterior third of the midgut which terminates meals; (b) the development and subsequent reduction of satietyspecific behaviors mediated either by stretch receptors or by some other means which, e.g., allow the next meal to begin; and (c) metabolites whose levels drop during deprivation, triggering a series of events which lead to the excess feeding observed.     

Isolation and characterization of microsatellite markers from the panic moth,Saucrobotys futilalis L. (Lepidoptera: Pyralidae: Pyraustinae)

The panic moth is a widely distributed North American pyralid moth with gregarious, nest‐building larvae. Primers for 12 polymorphic microsatellite loci were developed to assay relatedness in nest groups and population structure in the eastern half of the moth's range. Primers were tested on 42 individuals (one from each of 42 nests) collected in the states of New York, Virginia and Georgia. All loci were polymorphic and exhibited varying degrees of allelic variation (4–24 alleles). These primers will enable further research into the social structure of these gregarious caterpillars.     

松毛虫雌性信息素的研究与应用

目前,在我国对松林危害最严重的害虫主要有马尾松毛虫Dendrolimnspunctatus(Walker)、落叶松毛虫D.superaus(Butler)、油松毛虫D.tabulaeformisTsaietLiu、赤松毛虫D.spectabilis(Butler)、思茅松毛虫D.kikuchiiMatsumura、云南松毛虫D.houiLajonqui埁re等。综述6种松毛虫的雌性信息素的成分鉴定、合成、EAG反应,人工合成雌性信息素的田间活性测定,性诱剂在林间的设置技术及种群监测等应用。